Parameter calibration method and metal detection method for security door

Abstract

The application relates to a parameter calibration method and a metal detection method for a security door. According to the application, by testing sample metal objects of multiple selected object categories with different object attributes, a single-category correlation between a control parameter of a detection component of the security door and a single-category metal induction intensity of each selected object category can be determined, and by comprehensively considering the correlation of the multiple selected object categories and the respective corresponding sensitivity target values, the control parameter can be calibrated to an optimal frequency phase combination that promotes the overall detection sensitivity of the multiple selected object categories to approach the respective corresponding sensitivity target values, and thus for an application scenario with multiple object categories with different object attributes as detection targets, the risk of missed detection of the object categories can be reduced, thereby reducing the overall missed detection rate of the security door.

Description

Technical Field

[0001] This application relates to security inspection equipment, and in particular to a parameter calibration method for a security gate, a metal detection method for a security gate, a parameter calibration device for a security gate, a metal detection device for a security gate, and a security gate. Background Technology

[0002] The security gate has a detection channel for target objects to pass through, and a detection assembly for metal detection. The detection assembly may include a transmitting circuit and a receiving circuit, as well as a transmitting coil and a receiving coil deployed across the detection channel. The transmitting circuit generates a transmitting signal which can be transmitted into the detection channel by the transmitting coil to form a physical magnetic field within the detection channel. This physical magnetic field can induce eddy current signals in the receiving coil assembly, and the receiving circuit can obtain a received signal through signal processing of the eddy current signals generated by the receiving coil.

[0003] When no metal object enters the detection channel, the physical magnetic field may consist only of the primary magnetic field generated by the transmitted signal. If the target object passing through the detection channel carries a metal object, the physical magnetic field within the detection channel will further include a secondary magnetic field generated by the metal object being excited by the primary magnetic field. That is, the presence of the secondary magnetic field will cause a change in the induced intensity of the physical magnetic field by the receiving coil. Since the signal strength of the eddy current signal is used to characterize the induced intensity of the physical magnetic field by the receiving coil, the change in induced intensity caused by the secondary magnetic field can be presented as a change in the signal strength of the received signal based on the eddy current signal.

[0004] The amplitude of the signal strength change in the received signal, which reflects the change in induction intensity caused by the secondary magnetic field, can be considered as the metal induction intensity of the security gate (i.e., the detection component) for metal objects. Furthermore, the metal induction intensity affects the detection sensitivity of the security gate (i.e., the detection component) for metal objects. Detection sensitivity can be considered as the probability of successfully identifying a metal object appearing in the detection channel through the received signal. The metal induction intensity of the security gate (i.e., the detection component) for metal objects is related to the properties of the metal object and the control parameters of the detection component (i.e., the transmission frequency of the transmitted signal and the receiving control phase of the receiving coil). Therefore, if the control parameters are set reasonably, when a target object in the detection channel is carrying a target metal object, the metal induction intensity can be identified from the received signal, thus accurately detecting the metal object; that is, high detection sensitivity. Otherwise, even if a target object in the detection channel is carrying a metal object, the metal induction intensity cannot be identified from the received signal, resulting in missed detection of the metal object; that is, low detection sensitivity.

[0005] In practical applications of security gates, multiple categories of items with different properties (e.g., different metal materials and / or shapes) are often involved. If the control parameters of the detection component are set with the goal of achieving the optimal detection sensitivity for one category, the detection sensitivity for other categories may be too low, resulting in some categories being missed. Furthermore, current technology lacks a solution for setting the control parameters of the detection component to balance the detection sensitivity of multiple categories of items with different properties. Therefore, in applications involving multiple categories of items with different properties, there is a risk of some categories being missed, leading to a high overall miss rate for the security gate.

[0006] It is evident that reducing the overall false negative rate of security gates in application scenarios where multiple categories of items with different attributes are targeted for inspection has become a technical problem that needs to be solved in the existing technology. Summary of the Invention

[0007] In the embodiments of this application, a parameter calibration method for a security gate, a metal detection method for a security gate, a parameter calibration device for a security gate, a metal detection device for a security gate, and a security gate are provided, which help reduce the overall missed detection of security gates in application scenarios where multiple categories of items with different attributes are the detection targets.

[0008] One embodiment of this application provides a parameter calibration method for a security gate. The security gate includes a detection channel and a detection component. The detection component includes a transmitting coil component and a receiving coil component arranged at intervals between the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil component, and a receiving circuit for obtaining a receiving signal from the receiving coil component. The control parameters of the detection component include a frequency-phase combination for controlling the transmitting signal frequency of the transmitting circuit and for controlling the receiving control phase of the receiving circuit. The parameter calibration method includes:

[0009] Based on the received signal obtained by the receiving coil assembly during the testing phase, the single-sample test results for multiple sample metal items are determined, wherein the multiple sample metal items belong to multiple selected item categories with different item attributes, and the single-sample test result of each sample metal item is used to characterize the single-sample metal induction intensity of the sample metal item in multiple tests in which the control parameters are configured to different frequency and phase combinations.

[0010] Based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of the control parameters, the single-category association relationship between the single-category metal induction intensity of each selected item category and the frequency phase combination of the control parameters is determined. The single-category metal induction intensity is used to characterize the metal induction intensity of any metal item belonging to the corresponding selected item category when the control parameters are configured to any frequency phase combination.

[0011] Based on the single-category association and the sensitivity target value of the detection sensitivity for each selected item category, the calibration frequency phase combination of the control parameters is determined.

[0012] In some examples, optionally, determining the calibration frequency-phase combination of the control parameters based on the single-category association and the sensitivity target value of the detection sensitivity for each selected item category includes: determining a multi-category association between the weighted sensing intensity of the single-category metal sensing intensity of multiple selected item categories and the frequency-phase combination of the control parameters based on the single-category association and the sensitivity target value of the detection sensitivity for each selected item category, wherein the weight of the single-category metal sensing intensity of each selected item category in the weighted sensing intensity is associated with the corresponding sensitivity target value; and determining the calibration frequency-phase combination of the control parameters based on the multi-category association.

[0013] In some examples, optionally, the single-category association includes a single-category intensity function, wherein the function value of the single-category intensity function is used to characterize the metal induction intensity of any metal object of the corresponding selected item category when the control parameters are configured to an arbitrary frequency-phase combination; the multi-category association includes a multi-category intensity function, wherein the function value of the multi-category intensity function is used to characterize the weighted induction intensity, the function value of the multi-category intensity function is obtained by weighting the function values ​​of the single-category intensity functions corresponding to multiple selected item categories respectively, and the weight of the function value of the single-category intensity function corresponding to each selected item category in the function value of the multi-category intensity function is associated with the corresponding sensitivity target value.

[0014] In some examples, optionally, determining the calibration frequency phase combination of the control parameters based on the multi-category association includes: determining the frequency phase combination that causes the weighted induction intensity to be maximized as the calibration frequency phase combination of the control parameters based on the multi-category association.

[0015] In some examples, optionally, the selected item categories include a category of items subject to inspection and a category of items exempt from inspection, wherein the weight of the single-category metal induction intensity corresponding to each of the item categories subject to inspection is a positive value in the weighted induction intensity, and the weight of the single-category metal induction intensity corresponding to each of the item categories exempt from inspection is a negative value in the weighted induction intensity.

[0016] In some examples, optionally, the parameter calibration method further includes: obtaining an alarm rate set for each of the inspectable item categories and a pass rate set for each of the exempted item categories, wherein the alarm rate is used to characterize the sensitivity target value corresponding to the inspectable item category, and the pass rate is used to characterize the sensitivity target value of the exempted item category; based on the alarm rate and the pass rate, determining the weight of the single-category metal sensing intensity of each of the inspectable item categories and each of the exempted item categories in the weighted sensing intensity, wherein: the alarm rate has the same monotonicity as the sensitivity target value, and the single-category metal sensing intensity corresponding to each of the inspectable item categories has a positive weight in the weighted sensing intensity with the alarm rate; the pass rate has a monotonicity opposite to the sensitivity target value, and the single-category metal sensing intensity corresponding to each of the exempted item categories has a negative weight in the weighted sensing intensity with the pass rate.

[0017] In some examples, optionally, the detection channel includes multiple zones, the detection assembly includes sensing units respectively deployed in alignment with the multiple zones, the transmitting coil assembly includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil assembly includes receiving coils respectively deployed in the multiple sensing units; multiple tests for each sample metal object include multiple sets of tests where each sample metal object is individually located in the multiple zones, and each set of tests where each sample metal object is individually located in any one of the zones includes configuring the control parameters to different frequency and phase combinations. Multiple tests; the single-sample test result for each of the sample metal items includes multiple sets of single-zone test results obtained from multiple tests in multiple defense zone spaces, and each set of single-zone test results for each sample metal item corresponding to each defense zone space includes: single-sample defense zone metal induction intensity obtained from multiple tests on the sample metal item located alone in that defense zone space based on different frequency phase combinations of the control parameters; the determination of single-category metal for each selected item category based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of the control parameters. The single-category correlation between the sensing intensity and the frequency-phase combination of the control parameters includes: determining the single-category zone correlation between the single-sample zone metal sensing intensity of each selected item category in each zone space and the frequency-phase combination of the control parameters, based on the single-sample zone metal sensing intensity of each sample metal item corresponding to multiple zone spaces. The single-category zone sensing intensity is used to characterize the metal sensing intensity of any metal item belonging to the corresponding selected item category and located within the corresponding zone space when the control parameters are configured to any frequency-phase combination. Based on the single-category correlation, and... The occurrence probability of each selected item category in multiple defense zones is determined, and the single-category correlation between the single-category metal sensing intensity of each selected item category and the frequency-phase combination of the control parameters is determined. The single-category metal sensing intensity of each selected item category is characterized by the weighted result of the single-category defense zone sensing intensity of the selected item category in multiple defense zones. Furthermore, the weight of the single-category defense zone sensing intensity of each selected item category in any one defense zone in the weighted result is associated with the occurrence probability of the selected item category in that defense zone.

[0018] In some examples, optionally, the single-zone association includes a zone strength function, wherein the function value of the zone strength function is used to characterize the intensity of the single-class zone sensing of the corresponding selected item category in the corresponding zone space when the control parameters are configured to an arbitrary frequency phase combination; the single-class association includes a single-class strength function, wherein the function value of the single-class strength function is used to characterize the metal sensing intensity of any metal item of the corresponding selected item category when the control parameters are configured to an arbitrary frequency phase combination, the function value of the single-class strength function is obtained by weighting the function values ​​of the zone strength functions corresponding to the same selected item category and corresponding to multiple zone spaces, and the weight of the function value of the zone strength function corresponding to each selected item category in multiple zone spaces is associated with the occurrence probability of the selected item category in the multiple zone spaces.

[0019] Another embodiment of this application provides a metal detection method for a security gate, the security gate including a detection channel and a detection component, the detection component including a transmitting coil component and a receiving coil component arranged at intervals between the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil component, and a receiving circuit for obtaining a receiving signal from the receiving coil component, the control parameters of the detection component being configured as the calibration frequency and phase combination determined by the parameter calibration method described in the foregoing embodiments, and the metal detection method including:

[0020] Based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel, the object metal induction intensity of the target object is detected.

[0021] Based on the metal induction intensity of the object, it is determined whether the target object carries a target metal item belonging to the target item category, wherein the target item category is any one of the selected item categories to be inspected.

[0022] In some examples, optionally, the security gate is deployed at the entrance of the target scene, and the passage of the target object through the detection channel includes passing through the detection channel in the entry direction into the target scene and passing through the detection channel in the exit direction away from the target scene; the object metal detection intensity includes: the entry metal detection intensity of the target object detected based on the received signal generated by the receiving coil assembly during the entry passage, and the exit metal detection intensity of the target object detected based on the received signal generated by the receiving coil assembly during the exit passage; determining whether the target object carries a target metal item belonging to the target item category based on the object metal detection intensity includes: determining whether the target object carries the target metal item belonging to the target item category during the exit passage based on the consistency between the entry metal detection intensity and the exit metal detection intensity.

[0023] In some examples, optionally, the detection channel includes multiple defense zones, the detection assembly includes sensing units respectively deployed in alignment with the multiple defense zones, the transmitting coil assembly includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil assembly includes receiving coils respectively deployed in the multiple sensing units; the step of detecting the object metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel includes: detecting the entry defense zone metal induction intensity of the target object in the multiple defense zones based on the received signals generated by the multiple sensing units respectively using their respective receiving coils when passing through the entry zone, and determining the entry metal induction intensity based on the sum of the entry defense zone metal induction in the multiple defense zones; detecting the exit defense zone metal induction intensity of the target object in the multiple defense zones based on the received signals generated by the multiple sensing units respectively using their respective receiving coils when passing through the exit zone, and determining the exit metal induction intensity based on the sum of the exit defense zone metal induction in the multiple defense zones.

[0024] In some examples, the metal detection method may optionally further include: acquiring the identity information of the target object, wherein both the entry sensing intensity and the exit sensing intensity are associated with the successfully acquired identity information.

[0025] In some examples, optionally, determining whether the target object carries the target metal item belonging to the target item category when leaving the site based on the consistency between the entry metal sensing intensity and the exit metal sensing intensity includes: if the exit metal sensing intensity is greater than the entry metal sensing intensity, then determining that the target object carries the target metal item belonging to the target item category when leaving the site.

[0026] In some examples, optionally, the receiving coil assembly includes multiple sets of receiving coils arranged at multiple height positions in the height direction, and each set of receiving coils at each height position includes a first-side receiving coil and a second-side receiving coil arranged opposite to each other on a first side and a second side in the width direction of the detection channel; the object metal sensing intensity includes: a first unilateral sensing intensity of the target object near the first side at each height position, detected based on the receiving signal generated by the first-side receiving coil, and a second unilateral sensing intensity of the target object near the second side at each height position, detected based on the receiving signal generated by the second-side receiving coil; determining whether the target object carries a target metal item belonging to the target item category based on the object metal sensing intensity includes: determining the projection shape of the target object carrying a metal item in a projection plane jointly defined by the width direction and the height direction based on the first unilateral sensing intensity and the second unilateral sensing intensity of the target object at multiple height positions; and determining whether the carried metal item is the target metal item based on the projection shape of the carried metal item.

[0027] In some examples, optionally, determining the projection shape of the metal-carrying article of the target object on the projection plane jointly defined by the width and height directions based on the first unilateral sensing intensity and the second unilateral sensing intensity of the target object at multiple height positions includes: determining the local width boundary position of a local portion of the metal-carrying article at each height position based on the intensity relationship between the first unilateral sensing intensity and the second unilateral sensing intensity at each height position; and determining the projection shape of the metal-carrying article based on the local width boundary position of the local portion of the metal-carrying article at multiple height positions.

[0028] In some examples, optionally, determining the local width boundary position of a local portion of the metal-carrying object at each height position based on the intensity relationship between the first unilateral sensing intensity and the second unilateral sensing intensity at each height position includes: determining the local centroid position of the local portion of the metal-carrying object at that height position based on the intensity relationship at each height position and the width dimension of the detection channel in the width direction; and determining the local width boundary position of the local portion of the metal-carrying object at each height position based on the local centroid position at each height position and the first unilateral sensing intensity and the second unilateral sensing intensity.

[0029] In some examples, optionally, the detection channel includes multiple zone spaces, the detection assembly includes sensing units respectively deployed in alignment with the multiple zone spaces, the transmitting coil assembly includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil assembly includes receiving coils respectively deployed in the multiple sensing units; the first-side receiving coil and the second-side receiving coil in a set of receiving coils at each height position are respectively located in a pair of sensing units deployed in alignment with the zone space at that height position; the first unilateral sensing intensity is characterized by a first unilateral normalized intensity, wherein the first unilateral normalized intensity is: based on The first unilateral induction intensity, determined by the received signal generated by the first side receiving coil in a set of receiving coils at each height position, is the percentage of the overall metallic induction intensity of the sensing unit to which the first side receiving coil in the set of receiving coils belongs; the second unilateral induction intensity is characterized by a second unilateral normalized intensity, wherein the second unilateral normalized intensity is: the percentage of the first unilateral induction intensity, determined by the received signal generated by the second side receiving coil in a set of receiving coils at each height position, in the overall metallic induction intensity of the sensing unit to which the second side receiving coil in the set of receiving coils belongs.

[0030] In some examples, optionally, determining the projected shape of the metal-carrying object based on the local width boundary positions of local portions of the metal-carrying object at multiple height positions includes: obtaining the projected outline of the metal-carrying object on the projection plane by connecting the local width boundary positions of local portions of the metal-carrying object within multiple height intervals; and determining the projected shape of the metal-carrying object based on shape recognition of the projected outline.

[0031] Optionally, in some examples, obtaining the projected profile of the metal-carrying object on the projection plane by connecting the local width boundary positions of local portions of the metal-carrying object within multiple height intervals includes: obtaining a fitted profile of the metal-carrying object by fitting discrete coordinates of the local width boundary positions of the local portions of the metal-carrying object within multiple height intervals, wherein the fitted profile includes straight line boundary segments connecting every two adjacent local width boundary positions; and correcting the position of the local width boundary positions based on the local centroid position and the tilt angle of the straight line boundary segments relative to the width direction, so that the fitted profile is optimized into the projected profile by the position correction of the local width boundary positions.

[0032] In some examples, optionally, correcting the position of the local width boundary position based on the local centroid position and the tilt angle of the straight line boundary segment relative to the width direction includes: using the local centroid position as a reference and the reciprocal of the inverse cosine function value of the tilt angle as a correction coefficient to correct the position of the local width boundary position.

[0033] In some examples, optionally, determining whether the carried metal is the target metal item based on the projected shape of the carried metal item includes: detecting the projected shape against a reference projected shape pre-set for a plurality of selected item categories, and determining the carried metal item as the target metal item in response to a detection result that the projected shape successfully matches the reference projected shape of any one of the selected item categories.

[0034] In some examples, optionally, the security gate is deployed at the entrance of the target scene, and the passage of the target object through the detection channel includes entering the target scene via the detection channel along an entry direction and exiting the target scene via the detection channel along an exit direction. The first unilateral sensing intensity at each height position includes: a first unilateral entry sensing intensity of the target object near the first side at each height position, detected based on the received signal generated by the first-side receiving coil during entry passage, and a first unilateral exit sensing intensity of the target object near the first side at each height position, detected based on the received signal generated by the first-side receiving coil during exit passage. The second unilateral sensing intensity at each height position includes: a second unilateral entry sensing intensity of the target object near the second side at each height position, detected based on the received signal generated by the second-side receiving coil during entry passage, and a second unilateral exit sensing intensity of the target object near the second side at each height position, detected based on the received signal generated by the second-side receiving coil during exit passage. The image represents the second unilateral departure sensing intensity near the second side at each height position; the projection shape includes: the entrance projection shape of the target object on the projection plane determined based on the first unilateral entrance sensing intensity and the second unilateral entrance sensing intensity of the target object at multiple height positions, and the departure projection shape of the target object on the projection plane determined based on the first unilateral departure sensing intensity and the second unilateral departure sensing intensity of the target object at multiple height positions; the determination of whether the carried metal item is the target metal item based on the projection shape of the carried metal item includes: detecting the consistency between the entrance projection shape and the departure projection shape; in response to the detection result that the departure projection shape differs from the entrance projection shape, detecting the matching degree between the departure projection shape and the reference projection shape pre-set for multiple selected item categories; in response to the detection result that the departure projection shape successfully matches the reference projection shape of any one of the selected item categories, determining that the carried metal item is the target metal item.

[0035] Another embodiment of this application provides a parameter calibration device for a security gate. The security gate includes a detection channel and a detection component. The detection component includes a transmitting coil component and a receiving coil component arranged at intervals between the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil component, and a receiving circuit for obtaining a receiving signal from the receiving coil component. The control parameters of the detection component include a frequency-phase combination for controlling the transmitting signal frequency of the transmitting circuit and for controlling the receiving control phase of the receiving circuit. The parameter calibration device includes:

[0036] The sample detection module is used to determine the single-sample test result of multiple sample metal items based on the received signal obtained by the receiving coil component during the test phase. The multiple sample metal items belong to multiple selected item categories with different item attributes. The single-sample test result of each sample metal item is used to characterize the single-sample metal induction intensity of the sample metal item in multiple tests in which the control parameters are configured to different frequency and phase combinations.

[0037] The single-category analysis module is used to determine the single-category association between the single-category metal induction intensity of each selected item category and the frequency phase combination of the control parameters based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of the control parameters. The single-category metal induction intensity is used to characterize the metal induction intensity of any metal item belonging to the corresponding selected item category when the control parameters are configured to any frequency phase combination.

[0038] The comprehensive analysis module determines the calibration frequency phase combination of the control parameters based on the single-category association and the sensitivity target value of the detection sensitivity for each selected item category.

[0039] In some examples, optionally, the comprehensive analysis module is specifically configured to: determine a multi-category association between the weighted sensing intensity of the single-category metal sensing intensity of multiple selected item categories and the frequency-phase combination of the control parameters, based on the single-category association and the sensitivity target value of the detection sensitivity of each selected item category, wherein the weight of the single-category metal sensing intensity of each selected item category in the weighted sensing intensity is associated with the corresponding sensitivity target value; and determine the calibration frequency-phase combination of the control parameters based on the multi-category association.

[0040] In some examples, optionally, the single-category association includes a single-category intensity function, wherein the function value of the single-category intensity function is used to characterize the metal induction intensity of any metal object of the corresponding selected item category when the control parameters are configured to an arbitrary frequency-phase combination; the multi-category association includes a multi-category intensity function, wherein the function value of the multi-category intensity function is used to characterize the weighted induction intensity, the function value of the multi-category intensity function is obtained by weighting the function values ​​of the single-category intensity functions corresponding to multiple selected item categories respectively, and the weight of the function value of the single-category intensity function corresponding to each selected item category in the function value of the multi-category intensity function is associated with the corresponding sensitivity target value.

[0041] In some examples, the comprehensive analysis module is optionally configured to: determine the frequency phase combination that maximizes the weighted induction intensity as the calibration frequency phase combination of the control parameters based on the multi-category association relationship.

[0042] In some examples, optionally, the selected item categories include a category of items subject to inspection and a category of items exempt from inspection, wherein the weight of the single-category metal induction intensity corresponding to each of the item categories subject to inspection is a positive value in the weighted induction intensity, and the weight of the single-category metal induction intensity corresponding to each of the item categories exempt from inspection is a negative value in the weighted induction intensity.

[0043] In some examples, optionally, the parameter calibration device further includes a weight configuration module, configured to: obtain an alarm rate set for each of the inspectable item categories and a pass rate set for each of the exempted item categories, wherein the alarm rate is used to characterize the sensitivity target value corresponding to the inspectable item category, and the pass rate is used to characterize the sensitivity target value of the exempted item category; based on the alarm rate and the pass rate, determine the weight of the single-category metal sensing intensity of each of the inspectable item categories and each of the exempted item categories in the weighted sensing intensity, wherein: the alarm rate has the same monotonicity as the sensitivity target value, and the single-category metal sensing intensity corresponding to each of the inspectable item categories has a positive weight in the weighted sensing intensity with the alarm rate; the pass rate has a monotonicity opposite to the sensitivity target value, and the single-category metal sensing intensity corresponding to each of the exempted item categories has a negative weight in the weighted sensing intensity with the pass rate.

[0044] In some examples, optionally, the detection channel includes multiple defense zones, the detection component includes sensing units respectively deployed in alignment with the multiple defense zones, the transmitting coil component includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil component includes receiving coils respectively deployed in the multiple sensing units; multiple tests of each sample metal object include multiple sets of tests where each sample metal object is individually located in the multiple defense zones, and each set of tests where each sample metal object is individually located in any one defense zone includes multiple tests with the control parameters configured to different frequency and phase combinations; the single-sample test result of each sample metal object includes multiple sets of single-zone test results obtained from multiple sets of tests in the multiple defense zones, and a set of single-zone test results for each sample metal object corresponding to each defense zone includes: single-sample defense zone metal sensing intensity obtained from multiple tests of the sample metal object individually located in that defense zone based on different frequency and phase combinations of the control parameters; the single-class analysis module is specifically configured to: based on each sample metal object The single-sample zone metal induction intensity of each item category in multiple zone spaces is used to determine the single-zone correlation between the single-category zone induction intensity of each selected item category in each zone space and the frequency-phase combination of the control parameters. The single-category zone induction intensity characterizes the metal induction intensity of any metal item belonging to the corresponding selected item category and located within the corresponding zone space when the control parameters are configured to any frequency-phase combination. Based on the single-zone correlation and the occurrence probability of each selected item category in multiple zone spaces, the single-category correlation between the single-category metal induction intensity of each selected item category and the frequency-phase combination of the control parameters is determined. The single-category metal induction intensity of each selected item category is characterized by a weighted result of the single-category zone induction indices of the selected item category in multiple zone spaces. Furthermore, the weight of the single-category zone induction intensity of each selected item category in any zone space is associated with the occurrence probability of the selected item category in that zone space.

[0045] In some examples, optionally, the single-zone association includes a zone strength function, wherein the function value of the zone strength function is used to characterize the intensity of the single-class zone sensing of the corresponding selected item category in the corresponding zone space when the control parameters are configured to an arbitrary frequency phase combination; the single-class association includes a single-class strength function, wherein the function value of the single-class strength function is used to characterize the metal sensing intensity of any metal item of the corresponding selected item category when the control parameters are configured to an arbitrary frequency phase combination, the function value of the single-class strength function is obtained by weighting the function values ​​of the zone strength functions corresponding to the same selected item category and corresponding to multiple zone spaces, and the weight of the function value of the zone strength function corresponding to each selected item category in multiple zone spaces is associated with the occurrence probability of the selected item category in the multiple zone spaces.

[0046] Another embodiment of this application provides a metal detection device for a security gate, the security gate including a detection channel and a detection assembly, the detection assembly including a transmitting coil assembly and a receiving coil assembly arranged at intervals across the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for obtaining a receiving signal from the receiving coil assembly, the control parameters of the detection assembly being configured as the calibration frequency phase combination determined by the parameter calibration device described in the foregoing embodiments, and the metal detection device including:

[0047] The object detection module is used to detect the object metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel;

[0048] The detection and decision module is used to determine whether the target object carries a target metal item belonging to the target item category based on the metal induction intensity of the object, wherein the target item category is any one of the selected item categories to be inspected.

[0049] In some examples, optionally, the security gate is deployed at the entrance of the target scene, and the passage of the target object through the detection channel includes passing through the detection channel in the entry direction into the target scene and passing through the detection channel in the exit direction away from the target scene; the object metal induction intensity includes: the entry metal induction intensity of the target object detected based on the received signal generated by the receiving coil assembly when passing through the entrance, and the exit metal induction intensity of the target object detected based on the received signal generated by the receiving coil assembly when passing through the exit; the detection decision module is specifically configured to: determine whether the target object is carrying the target metal item belonging to the target item category when passing through the exit, based on the consistency of the entry metal induction intensity and the exit metal induction intensity.

[0050] In some examples, optionally, the detection channel includes multiple defense zones, the detection component includes sensing units respectively deployed in alignment with the multiple defense zones, the transmitting coil component includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil component includes receiving coils respectively deployed in the multiple sensing units; the object detection module is specifically configured to: detect the entry defense zone metal induction intensity of the target object in the multiple defense zones based on the received signals generated by the multiple sensing units using their respective receiving coils during the entry passage, and determine the entry defense zone metal induction intensity based on the sum of the entry defense zone metal induction in the multiple defense zones; detect the exit defense zone metal induction intensity of the target object in the multiple defense zones based on the received signals generated by the multiple sensing units using their respective receiving coils during the exit passage, and determine the exit defense zone metal induction intensity based on the sum of the exit defense zone metal induction in the multiple defense zones.

[0051] In some examples, the metal detection device may optionally further include an identity detection module for acquiring the identity information of the target object, wherein the entry sensing intensity and the exit sensing intensity are both associated with the successfully acquired identity information.

[0052] In some examples, the detection and decision module is optionally configured to: if the departure metal sensing intensity is greater than the entry metal sensing intensity, then determine that the target object is carrying the target metal item belonging to the target item category when leaving the area.

[0053] In some examples, optionally, the receiving coil assembly includes multiple sets of receiving coils arranged at multiple height positions in the height direction, and each set of receiving coils at each height position includes a first-side receiving coil and a second-side receiving coil arranged opposite each other on a first side and a second side in the width direction of the detection channel; the object metal sensing intensity includes: a first unilateral sensing intensity of the target object near the first side at each height position, detected based on the receiving signal generated by the first-side receiving coil, and a second unilateral sensing intensity of the target object near the second side at each height position, detected based on the receiving signal generated by the second-side receiving coil; the detection decision module is specifically configured to: determine the projection shape of the metal-carrying item of the target object on the projection plane jointly defined by the width direction and the height direction based on the first unilateral sensing intensity and the second unilateral sensing intensity of the target object at multiple height positions; and determine whether the carried metal is the target metal item based on the projection shape of the carried metal item.

[0054] In some examples, the detection decision module is optionally configured to: determine the local width boundary position of a local portion of the metal-carrying object at each height position based on the intensity relationship between the first unilateral sensing intensity and the second unilateral sensing intensity at each height position; and determine the projected shape of the metal-carrying object based on the local width boundary positions of the local portions of the metal-carrying object at multiple height positions.

[0055] In some examples, the detection decision module is optionally configured to: determine the local centroid position of a local portion of the metal-carrying object at each height position based on the intensity relationship at each height position and the width dimension of the detection channel in the width direction; and determine the local width boundary position of a local portion of the metal-carrying object at each height position based on the local centroid position at each height position, and the first unilateral sensing intensity and the second unilateral sensing intensity.

[0056] In some examples, optionally, the detection channel includes multiple zone spaces, the detection assembly includes sensing units respectively deployed in alignment with the multiple zone spaces, the transmitting coil assembly includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil assembly includes receiving coils respectively deployed in the multiple sensing units; the first-side receiving coil and the second-side receiving coil in a set of receiving coils at each height position are respectively located in a pair of sensing units deployed in alignment with the zone space at that height position; the first unilateral sensing intensity is characterized by a first unilateral normalized intensity, wherein the first unilateral normalized intensity is: based on The first unilateral induction intensity, determined by the received signal generated by the first side receiving coil in a set of receiving coils at each height position, is the percentage of the overall metallic induction intensity of the sensing unit to which the first side receiving coil in the set of receiving coils belongs; the second unilateral induction intensity is characterized by a second unilateral normalized intensity, wherein the second unilateral normalized intensity is: the percentage of the first unilateral induction intensity, determined by the received signal generated by the second side receiving coil in a set of receiving coils at each height position, in the overall metallic induction intensity of the sensing unit to which the second side receiving coil in the set of receiving coils belongs.

[0057] In some examples, the detection decision module is optionally configured to: obtain the projection outline of the metal-carrying object on the projection plane by connecting the local width boundary positions of local portions of the metal-carrying object in multiple height ranges; and determine the projection shape of the metal-carrying object based on the shape recognition of the projection outline.

[0058] In some examples, optionally, the detection decision module is specifically configured to: obtain a fitted profile of the metal-carrying object by fitting discrete coordinates of the local width boundary positions of local portions of the metal-carrying object within multiple height intervals, wherein the fitted profile includes straight line boundary segments connecting every two adjacent local width boundary positions; and correct the position of the local width boundary positions based on the local centroid position and the tilt angle of the straight line boundary segments relative to the width direction, so that the fitted profile is optimized into the projected profile by the position correction of the local width boundary positions.

[0059] In some examples, the detection decision module is optionally configured to: correct the position of the local width boundary position based on the local centroid position and using the reciprocal of the inverse cosine function value of the tilt angle as a correction coefficient.

[0060] In some examples, the detection decision module is optionally configured to: detect the projected shape against a reference projected shape pre-set for a plurality of selected item categories, and, in response to a detection result that the projected shape successfully matches the reference projected shape of any one of the selected item categories, determine that the carrying metal item is the target metal item.

[0061] In some examples, optionally, the security gate is deployed at the entrance of the target scene, and the passage of the target object through the detection channel includes entering the target scene via the detection channel along the entry direction and exiting the target scene via the exit direction; the first unilateral sensing intensity at each height position includes: a first unilateral entry sensing intensity of the target object near the first side at each height position, detected based on the received signal generated by the first-side receiving coil during entry passage, and a first unilateral exit sensing intensity of the target object near the first side at each height position, detected based on the received signal generated by the first-side receiving coil during exit passage; the second unilateral sensing intensity at each height position includes: a second unilateral entry sensing intensity of the target object near the second side at each height position, detected based on the received signal generated by the second-side receiving coil during entry passage, and a second unilateral entry sensing intensity of the target object near the second side at each height position, detected based on the received signal generated by the second-side receiving coil during exit passage. The received signal detects the second unilateral departure sensing intensity of the target object at each height position near the second side; the projection shape includes: the entrance projection shape of the target object on the projection plane determined based on the first unilateral entrance sensing intensity and the second unilateral entrance sensing intensity of the target object at multiple height positions, and the departure projection shape of the target object on the projection plane determined based on the first unilateral departure sensing intensity and the second unilateral departure sensing intensity of the target object at multiple height positions; the detection decision module is specifically configured to: detect the consistency between the entrance projection shape and the departure projection shape; in response to the detection result that the departure projection shape differs from the entrance projection shape, detect the matching degree between the departure projection shape and the reference projection shape pre-set for multiple selected item categories; in response to the detection result that the departure projection shape successfully matches the reference projection shape of any one of the selected item categories, determine that the carrying metal item is the target metal item.

[0062] Another embodiment of this application provides a security gate, including:

[0063] The door panel assembly includes a first door panel and a second door panel respectively arranged on opposite sides of the detection channel in the width direction;

[0064] The coil assembly includes a transmitting coil assembly and a receiving coil assembly that are deployed opposite to each other on the first door panel and the second door panel across the detection channel;

[0065] A processor component for performing the parameter calibration method or metal detection method as described in the embodiments.

[0066] Another embodiment of this application provides a non-transitory computer-readable storage medium that stores instructions that, when executed by a processor, cause the processor to perform a parameter calibration method or a metal detection method as described in the foregoing embodiments.

[0067] Based on the embodiments of this application, by testing sample metal items of multiple selected item categories with different item properties, the single-category correlation between the control parameters of the security gate's detection components and the single-category metal sensing intensity of each selected item category can be determined. Furthermore, by comprehensively considering the correlation between multiple selected item categories and their respective corresponding sensitivity target values, it is helpful to calibrate the control parameters to have an optimal frequency and phase combination that causes the overall detection sensitivity of multiple selected item categories to approach their respective corresponding sensitivity target values. Thus, for application scenarios where multiple item categories with different item properties are the detection targets, the risk of missed detection of the item categories can be reduced, thereby reducing the overall missed detection rate of the security gate. Attached Figure Description

[0068] The following figures are for illustrative purposes only and do not limit the scope of this application:

[0069] Figure 1 This is a schematic diagram of the test process for parameter calibration of a security gate in an embodiment of this application;

[0070] Figure 2 This is a schematic diagram illustrating the parameter calibration principle for security gates in an embodiment of this application;

[0071] Figure 3 This is an optimized schematic diagram of the parameter calibration principle used for security gates in the embodiments of this application;

[0072] Figure 4 This is a schematic diagram of the positive and negative samples used for parameter calibration of security gates in the embodiments of this application;

[0073] Figure 5 This is a schematic diagram illustrating the principle of dividing the detection channel of the security gate into defense zones in an embodiment of this application;

[0074] Figure 6 For the basis of Figure 5 The diagram shown illustrates the principle of obtaining single-sample test results through multi-zone spatial determination.

[0075] Figure 7 This is a schematic diagram of a first detection example of metal detection for a security gate in this application embodiment;

[0076] Figure 8 For example Figure 7 A schematic diagram of the multi-zone spatial accumulation principle in the first detection example shown;

[0077] Figure 9 This is a schematic diagram of a second detection example for metal detection in a security gate, as described in this application.

[0078] Figure 10 For example Figure 9 A schematic diagram of the projection shape detection principle in the second detection example shown;

[0079] Figure 11 For example Figure 9 A schematic diagram of the edge localization principle used for projected shape detection in the second detection example shown;

[0080] Figure 12 This is a schematic diagram of a third detection example for metal detection in a security gate, as described in this application.

[0081] Figure 13 This is an exemplary flowchart illustrating the parameter calibration method for security gates in this application embodiment;

[0082] Figure 14 For example Figure 13 The diagram shows the optimization process of the parameter calibration method.

[0083] Figure 15 This is an exemplary flowchart of a metal detection method for a security gate in an embodiment of this application;

[0084] Figure 16 For example Figure 15 The flowchart of the first example of the metal detection method is shown.

[0085] Figure 17 For example Figure 15 The flowchart of the second example of the metal detection method is shown.

[0086] Figure 18 For example Figure 15 The flowchart of the third example of the metal detection method is shown;

[0087] Figure 19 This is an exemplary structural diagram of a parameter calibration device for a security gate in an embodiment of this application;

[0088] Figure 20This is an exemplary structural diagram of a metal detection device for a security gate in an embodiment of this application. Detailed Implementation

[0089] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments.

[0090] Figure 1 This is a schematic diagram of the test process for parameter calibration of a security gate in an embodiment of this application. Please refer to... Figure 1 In embodiments of this application, the security gate may include a detection channel 100 and a detection component 30.

[0091] The security gate may include a door panel assembly 10, which may include a first door panel 11 and a second door panel 12 arranged at intervals. In this case, the detection channel 100 may be located between the first door panel 11 and the second door panel, that is, the door panel assembly 10 may include the first door panel 11 and the second door panel 12 respectively arranged on opposite sides in the width direction x of the detection channel 100. Furthermore, the door panel assembly 10 may also preferably include a top plate 13 covering the detection channel 100, that is, the top plate 13 may be connected between the top ends of the first door panel 11 and the second door panel 12 in the height direction y of the detection channel.

[0092] The detection component 30 may include a transmitting coil component 310 and a receiving coil component 320 arranged at intervals in the width direction x, separated by the detection channel 100. That is, each of the first door plate 11 and the second door plate 12 may be equipped with a transmitting coil component 310 and a receiving coil component 320. The transmitting signal generated by the transmitting coil component 310 deployed in the first door plate 11 can induce the receiving coil component 320 deployed in the second door plate 12 to generate an eddy current signal. Similarly, the transmitting signal generated by the transmitting coil component 310 deployed in the second door plate 12 can induce the receiving coil component 320 deployed in the first door plate 11 to generate an eddy current signal.

[0093] The detection component 30 may further include a transmitting circuit 31 for providing a transmitting signal to the transmitting coil component 310, a receiving circuit 32 for obtaining a receiving signal from the receiving coil component 320, and a processor component 35 that is signal-connected to the transmitting circuit 31 and the receiving circuit 32. The control parameters of the detection component 30 include a frequency-phase combination Comb{f,ψ} for controlling the transmitting signal frequency f of the transmitting circuit 31 and the receiving control phase ψ of the receiving circuit 32.

[0094] Based on the frequency-phase combination Comb{f,ψ} in the control parameters:

[0095] The transmitting circuit 31 provides the transmitting coil assembly 310 with a transmitting signal frequency f defined by the frequency-phase combination Comb{f,ψ} in the control parameters. Furthermore, the eddy current signal generated by the receiving coil assembly 320 and the receiving signal obtained by the receiving circuit 32 have the same signal frequency f as the transmitting signal defined by the frequency-phase combination Comb{f,ψ}.

[0096] The phase difference between the received signal and the transmitted signal obtained by the receiving circuit 32 can be controlled within the receiving control phase ψ defined by the frequency phase combination Comb{f,ψ}.

[0097] For example, the transmitting circuit 31 may include at least a full-bridge drive circuit and a full-bridge inverter circuit connected in series between the processor component 35 and the transmitting coil component 310. The processor component 35 may generate a PWM (Pulse Width Modulation) signal to the full-bridge drive circuit of the transmitting circuit 31. The PWM signal generated by the processor component 35 may cause the full-bridge drive circuit to generate an excitation pulse signal to the gate of the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) of the full-bridge inverter circuit. The full-bridge inverter circuit may generate an AC voltage signal by utilizing the gate voltage change of the MOSFET. This AC voltage signal is provided to the transmitting coil component 310 for transmission as a transmitting signal. The signal frequency of this AC voltage signal is the transmitting signal frequency f, and the transmitting signal frequency f may be controlled by the PWM signal generated by the processor component 35.

[0098] For example, the receiving circuit 32 may include at least a bandpass filter circuit and an analog-to-digital converter circuit connected in series between the receiving coil assembly 320 and the processor assembly 35. The received signal acquired by the receiving circuit 32 and provided to the processor assembly 35 may be a digital signal obtained by analog-to-digital conversion of the eddy current signal filtered by the bandpass filter circuit. Furthermore, the filtering of the eddy current signal generated by the receiving coil assembly 320 by the bandpass filter circuit can constrain the phase difference between the received signal and the transmitted signal (i.e., the receive control phase ψ).

[0099] In the embodiments of this application, regardless of how the frequency-phase combination Comb{f,ψ} in the control parameters is configured, the processor component 35 can detect the magnitude of the change in signal intensity in the received signal that reflects the change in induction intensity caused by the secondary magnetic field (i.e., the metal induction intensity of the metal object appearing in the detection channel 100).

[0100] For example, the processor component 35 can be specifically configured to demodulate the received signal using the signal strength of the transmitted signal, with the primary magnetic field as the carrier. This demodulation can include any demodulation method such as IQ (quadrature) demodulation that can identify the secondary magnetic field from a physical magnetic field including the primary and secondary magnetic fields. The embodiments of this application do not impose any limitations on this. Furthermore, the demodulation result can be used to characterize the magnitude of the signal strength change that reflects the change in induction intensity induced by the secondary magnetic field (i.e., the metal induction intensity of a metal object appearing in the detection channel 100).

[0101] That is, in the embodiments of this application, the processor component 35 can be used to control the transmitting circuit 31 and to perform data processing on the received signal acquired by the receiving signal 32. For example, the processor component 35 may include any kind of logic device such as an FPGA (Field Programmable Gate Array), and / or a processing device such as a CPU (Central Processing Unit) or an MCU (Microcontroller Unit) that has at least signal generation and data processing capabilities. Moreover, the processor component 35, as well as the transmitting circuit 31 and the receiving circuit 32, can all be mounted on the top plate 13 of the door panel assembly 10.

[0102] Based on the above-described structure and working principle of the security gate, in the embodiments of this application, multiple selected item categories ctg_1~ctg_m with different item attributes can be determined according to the detection requirements of the application field of the security gate. Furthermore, multiple sample metal items Sp_ctg_1~Sp_ctg_m belonging to the multiple selected item categories ctg_1~ctg_m are provided for metal induction intensity testing. That is, the multiple sample metal items Sp_ctg_1~Sp_ctg_m belong to the multiple selected item categories ctg_1~ctg_m with different item attributes.

[0103] Where m is a positive integer greater than or equal to 2, the different item attributes of multiple selected item categories ctg_1~ctg_m can at least include that the metal materials of multiple selected item categories ctg_1~ctg_m are different from each other, and preferably, the different item attributes of multiple selected item categories ctg_1~ctg_m can further allow that the item shapes of any two selected item categories are different.

[0104] In the embodiments of this application, the metal induction intensity of multiple sample metal items Sp_ctg_1 to Sp_ctg_m can be tested during the testing phase. Furthermore, during the testing phase of testing the metal induction intensity of multiple sample metal items Sp_ctg_1 to Sp_ctg_m, each sample metal item Sp_ctg_i can be tested multiple times.

[0105] In a single test of each sample metal item Sp_ctg_i, the sample metal item Sp_ctg_i is located alone in the detection channel. For example, the sample metal item Sp_ctg_i can be carried by the tester alone and follow the tester through the detection channel once.

[0106] In multiple tests of each sample metal item Sp_ctg_i, multiple (i.e. n) pre-selected frequency-phase combinations Comb{f,ψ}_1~Comb{f,ψ}_n can be used respectively. That is, the frequency-phase combination Comb{f,ψ}_j configured for the control parameters in any one test of each sample metal item Sp_ctg_i is different from the configuration of the control parameters in the other tests of that sample metal item Sp_ctg_i.

[0107] For example, the processor component 35 can be configured to have a frequency and phase sweep function. In multiple tests on each sample metal item Sp_ctg_i, by enabling the frequency and phase sweep function, the transmit signal frequency f in the frequency phase combination Comb{f,ψ} traverses different frequency values ​​within a preset frequency range (e.g., 5kHz-20kHz) in a preset frequency step order, and the control receive phase ψ in the frequency phase combination Comb{f,ψ} traverses different phase values ​​within a preset phase range (e.g., 0°-360°) in a preset phase step, thereby obtaining multiple frequency and phase combinations Comb{f,ψ}_1~Comb{f,ψ}_n obtained by combining the traversed frequency values ​​and phase values.

[0108] Based on the detection of the received signal by the processor component 35, the single-sample test results of each sample metal item Sp_ctg_i (i.e., the sample metal item Sp_ctg_i belonging to each selected item category ctg_i) corresponding to multiple frequency phase combinations Comb{f,ψ}_1~Comb{f,ψ}_n can be obtained. Here, i is a positive integer greater than or equal to 1 and less than or equal to m, n represents the number of different frequency phase combinations used in the multiple tests of each sample metal item Sp_ctg_i, n is a positive integer greater than or equal to 2, n can be the same as m or different from m, and j is a positive integer greater than or equal to 1 and less than or equal to n.

[0109] Furthermore, the single-sample test result of each metal item Sp_ctg_i can be used to characterize the single-sample metal induction intensity {MI_i_1,…MI_i_j,…MI_i_n} in multiple tests where the control parameters are configured with different frequency and phase combinations Comb{f,ψ}_1~Comb{f,ψ}_n. For example, the method for determining the single-sample test result (i.e., the single-sample metal induction intensity {MI_i_1,…MI_i_j,…MI_i_n}) based on the received signal can refer to the signal demodulation method described above, which will not be repeated here.

[0110] In the embodiments of this application, the single-sample test results of multiple sample metal articles Sp_ctg_1~Sp_ctg_m, that is, the single-sample metal induction intensity {MI_1_1,…MI_1_j,…MI_1_n}……{MI_m_1,…MI_m_j,…MI_m_n}, can be used to calibrate the Comb{f,ψ} in the control parameters of the detection component 30.

[0111] Figure 2 This is a schematic diagram illustrating the parameter calibration principle of a security gate in an embodiment of this application. Please refer to... Figure 2 In embodiments of this application, the processor component 30 may also be used for:

[0112] Based on the received signals acquired by the receiving coil assembly 320 during the testing phase of testing the metal induction intensity of multiple sample metal items Sp_ctg_1 to Sp_ctg_m, the single-sample test results of the multiple sample metal items Sp_ctg_1 to Sp_ctg_m described above are determined, that is, the single-sample metal induction intensity {MI_1_1,…MI_1_j,…MI_1_n}……{MI_m_1,…MI_m_j,…MI_m_n}, as shown above. Figure 2 S510 in;

[0113] Based on the single-sample metal induction intensities {MI_i_1,…MI_i_j,…MI_i_n} of the control parameters corresponding to different frequency-phase combinations of control parameters for each sample metal item Sp_ctg_i, the single-category metal induction intensity MI_i of each selected item category ctg_i is determined to be related to the frequency-phase combination of control parameters Comb{f,ψ}. The single-category metal induction intensity MI_i characterizes the metal induction intensity of any metal item belonging to the corresponding selected item category ctg_i when the control parameters are configured to any frequency-phase combination Comb{f,ψ}_j. For example, in embodiments of this application, the single-category association may include a single-category intensity function g(f,ψ) The single-category intensity function g(f,Ψ) takes the transmitted signal frequency f and the received control phase Ψ as independent variables. Furthermore, the function value of g(f,Ψ)_i for each selected item category ctg_i can be used to characterize the metal induction intensity of any metal item of the corresponding selected item category ctg_i when the control parameters are configured to an arbitrary frequency-phase combination Comb{f,ψ}_j, such as... Figure 2 The S530 in the middle;

[0114] Based on the single-category associations of multiple selected item categories ctg_1~ctg_m (e.g., single-category intensity functions g(f, ψ)_1~g(f, ψ)_m) and the sensitivity target value Sen_i of the detection sensitivity of each selected item category ctg_i, the calibration frequency-phase combination Comb_ref ​​of the control parameters is determined. This calibration frequency-phase combination Comb_ref ​​can include the calibration transmit signal frequency f_ref and the calibration receive control phase Ψ_ref, i.e., Comb_ref={f_ref, ψ_ref}, as shown below. Figure 2 The S550 in the series.

[0115] Based on the embodiments of this application, by testing sample metal items Sp_ctg_1~Sp_ctg_m of multiple selected item categories ctg_1~ctg_m with different item attributes, the single-category correlation between the control parameters of the detection component 30 of the security gate and the single-category metal sensing intensity of each selected item category ctg_i can be determined. Furthermore, by comprehensively considering the correlation between multiple selected item categories ctg_1~ctg_m and their respective corresponding sensitivity target values ​​Sen_1~Sen_m, it is helpful to calibrate the control parameters to have an optimal frequency-phase combination Comb_ref={f_ref, ψ_ref} that causes the overall detection sensitivity of multiple selected item categories ctg_1~ctg_m to approach their respective corresponding sensitivity target values ​​Sen_1~Sen_m. Therefore, for application scenarios where multiple inspectable item categories with different item attributes (e.g., all or part of multiple selected item categories ctg_1~ctg_m) are the detection targets, the risk of missed detection of inspectable item categories can be reduced, thereby reducing the overall missed detection rate of the security gate.

[0116] Figure 3 This is an optimized schematic diagram illustrating the parameter calibration principle for security gates in this application embodiment. Please refer to... Figure 3 To facilitate the clear quantification of the correlation between multiple selected item categories ctg_1~ctg_m and their corresponding sensitivity target values ​​Sen_1~Sen_m, and to more accurately obtain the calibration frequency phase combination Comb_ref ​​that minimizes the overall false detection rate of the security gate, in the embodiments of this application, S550 for the processor component 35 to determine the calibration frequency phase combination Comb_ref ​​may specifically include:

[0117] Based on the single-class association relationships of multiple selected item categories ctg_1~ctg_m (e.g., the single-class strength functions g(f, ψ)_1~g(f, ψ) of multiple selected item categories ctg_1~ctg_m). The system determines the calibration frequency-phase combination of control parameters, Comb_ref, and establishes a multi-class correlation relationship between the single-class metal induction intensity MI_i of each selected item category ctg_i and the weighted induction intensity MI_w of MI_i and the frequency-phase combination of control parameters, respectively, and ∑Sen_i×g(f,Ψ). For example, if the single-class correlation relationship can include a single-class intensity function g(f,Ψ), then the multi-class correlation relationship can include a multi-class intensity function ∑Sen_i×g(f,Ψ). The function value of the multi-category intensity function (ψ)_i is used to characterize the weighted sensing intensity MI_w. This multi-category intensity function is obtained by weighting the function values ​​of the single-category intensity functions g(f, ψ)_1 to g(f, ψ)_m corresponding to multiple selected item categories ctg_1 to ctg_m. Furthermore, the weight of the single-category intensity function g(f, ψ)_i corresponding to each selected item category ctg_i in the function value of the multi-category intensity function MI_w = ∑Sen_i × g(f, ψ)_i is associated with the sensitivity target value Sen_i corresponding to that selected item category ctg_i. Figure 3 S551 in;

[0118] Based on multi-class correlations (e.g., multi-class intensity functions ∑Sen_i×g(f, ψ)_i), the calibration frequency-phase combination of control parameters, Comb_ref={f_ref, ψ_ref}, is determined. For example, based on multi-class correlations, the frequency-phase combination that maximizes the weighted induction intensity MI_w can be determined as the calibration frequency-phase combination of control parameters, Comb_ref={f_ref, ψ_ref}, that is, {f_ref, ψ_ref} satisfies: Max{MI_w}=∑Sen_i×g(f_ref, ψ_ref)_i, such as... Figure 3 S553 in the middle.

[0119] In the embodiments of this application, the multiple selected item categories ctg_1~ctg_m can all be the item categories that should be inspected in the application scenario of applying a security gate, or the multiple selected item categories ctg_1~ctg_m can also be a combination of the item categories that should be inspected and the item categories that are exempt from inspection in the application scenario of applying a security gate.

[0120] If multiple selected item categories ctg_1~ctg_m simultaneously include both inspectable and exempted item categories, then the single-category metal induction intensity of the inspectable item category can be regarded as a positive sample used to determine the calibration frequency phase combination Comb_ref, and the single-category metal induction intensity of the exempted item category can be regarded as a negative sample used to determine the calibration frequency phase combination Comb_ref.

[0121] Figure 4 This is a schematic diagram of the positive and negative samples used for parameter calibration of the security gate in the embodiments of this application. Please refer to... Figure 4 Taking multiple selected item categories ctg_1~ctg_m that simultaneously include inspectable item categories ctg_Pos_1~ctg_Pos_p and exempted item categories ctg_Neg_1~ctg_Neg_q as an example, where p+q=m, the weight of the single-category metal induction intensity MI_Pos corresponding to each inspectable item category ctg_Pos (e.g., represented by the function value of the corresponding single-category intensity function g(f, ψ)_Pos) in the weighted induction intensity MI_w is positive, and the weight of the single-category metal induction intensity MI_Neg corresponding to each exempted item category ctg_Neg (e.g., represented by the function value of the corresponding single-category intensity function g(f, ψ)_Neg) in the weighted induction intensity MI_w is negative.

[0122] That is, if multiple selected item categories ctg_1~ctg_m simultaneously include both inspectable item categories ctg_Pos_1~ctg_Pos_p and exempted item categories ctg_Neg_1~ctg_Neg_q, then the multi-category strength function used to represent the multi-category association can be expressed as MI_w=∑Sen_Pos×g(f, ψ)_Pos-∑Sen_Neg×g(f, ψ)_Neg, where Sen_Pos can refer to a sensitivity target value from Sen_1~Sen_m corresponding to any inspectable item category, Sen_Neg can refer to a sensitivity target value from Sen_1~Sen_m corresponding to any exempted item category, and g(f, ψ)_Pos can refer to a single-category strength function from g(f, ψ)_1~g(f, ψ)_m corresponding to any inspectable item category, and g(f, ψ)_Pos can refer to a single-category strength function from g(f, ψ)_1~g(f, ψ)_m corresponding to any inspectable item category. ψ)_Neg can refer to a single-category intensity function in g(f, ψ)_1~g(f, ψ)_m that corresponds to any category of exempted items.

[0123] Furthermore, the sensitivity target value Sen_Pos corresponding to each category of items subject to inspection (ctg_Pos_1~ctg_Pos_p) and the sensitivity target value Sen_Neg corresponding to each category of items exempt from inspection (ctg_Neg) can be determined through user-configurable parameters.

[0124] For example, processor component 35 can also be used for:

[0125] Obtain the alarm rate R_alr set for each inspectable item category ctg_Pos and the pass rate R_ign set for each exempt item category ctg_Neg. That is, the above configurable parameters can include the alarm rate R_alr and the pass rate R_ign. The alarm rate R_alr is used to characterize the sensitivity target value Sen_Pos corresponding to the inspectable item category ctg_Pos, and the pass rate R_ign is used to characterize the sensitivity target value Sen_Neg of the exempt item category ctg_Neg.

[0126] Based on the obtained alarm rate R_alr and pass rate R_ign, the weights of the single-category metal sensing intensity MI_Pos of each inspectable item category ctg_Pos and the single-category metal sensing intensity MI_Neg of each exempt item category ctg_Neg in the weighted sensing intensity MI_w are determined respectively.

[0127] If the weight of the single-category metal induction intensity MI_Pos corresponding to each inspectable item category ctg_Pos in the weighted induction intensity MI_w is positive, and the weight of the single-category metal induction intensity MI_Neg corresponding to each exempt item category ctg_Neg in the weighted induction intensity MI_w is negative, then:

[0128] The alarm rate R_alr has the same monotonicity as the sensitivity target value Sen_Pos of the item category ctg_Pos to be inspected, and the single-category metal induction intensity MI_Pos corresponding to each item category ctg_Pos can be weighted positively in the weighted induction intensity MI_w with the corresponding configured alarm rate R_alr.

[0129] The pass rate R_ign has a monotonicity opposite to the sensitivity target value Sen_Neg of the exempt item category ctg_Neg, and the single-category metal induction intensity MI_Neg corresponding to each exempt item category ctg_Neg is weighted negatively in the weighted induction intensity MI_w with the pass rate R_ign.

[0130] Suppose there are 5 selected item categories ctg_1 to ctg_5, of which 3 item categories ctg_1 to ctg_3 belong to the item category ctg_Pos that should be inspected, and the other 2 item categories ctg_1 to ctg_3 belong to the item category ctg_Neg that is exempt from inspection. Then, the configurable parameters obtained by the processor component 35 can be shown in Table 1, which represents the inspection configuration parameters of the item category ctg_Pos that should be inspected, and in Table 2, which represents the inspection exemption configuration parameters of the item category ctg_Neg that is exempt from inspection.

[0131]

[0132] Table 1: Configuration Parameters to be Inspected

[0133]

[0134] Table 2: Inspection-Exempt Configuration Parameters

[0135] In this case, the weighted induction intensity MI_w can be expressed as:

[0136]

[0137] Among them, Sen_1~Sen_3, which have positive weights, can be taken from the three alarm rates R_alr corresponding to ctg_1~ctg_3 in Table 1, namely 100%, 90% and 95%, respectively. And Sen_4~Sen_5, which have negative weights, can be taken from the two pass rates R_ign corresponding to ctg_4~ctg_5 in Table 2, namely 100% and 90%, respectively.

[0138] In addition, the inspection-required configuration parameters shown in Table 1 may also include inspection-required importance, and the exemption-from-inspection configuration parameters shown in Table 2 may also include exemption-from-inspection importance. The inspection-required importance and exemption-from-inspection importance can be used only as supplementary remarks; alternatively, they can also be used as input parameters. In this case, the alarm rate in the inspection-required configuration parameters shown in Table 1 can be automatically generated based on the input inspection-required importance and the pre-set parameter correspondence between inspection-required importance and alarm rate. Similarly, the pass rate in the exemption-from-inspection configuration parameters shown in Table 2 can be automatically generated based on the input exemption-from-inspection importance and the pre-set parameter correspondence between exemption-from-inspection importance and pass rate.

[0139] Based on the embodiments of this application, by further introducing sample metal items of the exempt item category ctg_Neg as countersamples, the attention to the single-category metal induction intensity MI_Pos of the corresponding item category ctg_Pos can be further increased when determining the calibration frequency phase combination Comb_ref. Thus, it is more conducive to controlling the calibration frequency phase combination Comb_ref ​​of the parameters to make the detection sensitivity of the item category ctg_Pos generally approach its corresponding sensitivity target value Sen_Pos. Therefore, for application scenarios that use multiple item categories ctg_Pos with different item attributes as detection targets, the risk of the item category ctg_Pos being missed can be further reduced, thereby further reducing the overall missed detection rate of the security gate.

[0140] In embodiments of this application, the security gate can also be configured to support zone detection, that is, the detection channel 100 may include multiple zone spaces.

[0141] Figure 5 This is a schematic diagram illustrating the principle of dividing the detection channel of a security gate into security zones, as described in this embodiment of the application. Figure 5 In the illustration, the detection channel 100 includes 12 zones. The 12 zones include 6 first side zones A_pa_1 to A_pa_6 on the first side of the detection channel 100 near the first door panel 11 in the width direction x, and 6 second side zones A_pb_1 to A_pb_6 on the second side of the detection channel near the second door panel 12 in the width direction x.

[0142] In the case where detection channel 100 includes multiple defense zones:

[0143] The detection component 30 may include sensing units deployed in alignment with multiple defense zones, respectively. Figure 5In this process, the detection component 30 may include first-side sensing units 300_pa_1~300_pa_6 respectively deployed in alignment with the six first-side defense zones A_pa_1~A_pa_6, and second-side sensing units 300_pb_1~300_pb_6 respectively deployed in alignment with the six second-side defense zones A_pb_1~A_pb_6. Correspondingly, the transmitting coil component 310 may include transmitting coils respectively deployed in the multiple sensing units, and the receiving coil component 320 may include receiving coils respectively deployed in the multiple sensing units. That is, each receiving coil in the first-side sensing units 300_pa_1~300_pa_6 and the second-side sensing units 300_pb_1~300_pb_6 may include at least one transmitting coil and multiple receiving coils.

[0144] Multiple tests for each sample metal item Sp_ctg_i can include multiple sets of tests where each sample metal item Sp_ctg_i is individually located in multiple defense zones. For example, multiple tests for each sample metal item Sp_ctg_i can include multiple sets of tests where it traverses multiple defense zones. Furthermore, each set of tests where each sample metal item Sp_ctg_i is individually located in any one of the first side defense zones A_pa_1~A_pa_6 and the second side defense zones A_pb_1~A_pb_6 can include multiple tests where the control parameters are configured to different frequency and phase combinations Comb{f,ψ}_1~Comb{f,ψ}_n. For example, each sample metal item Sp_ctg_i can achieve multiple tests within the defense zone by traversing the same defense zone multiple times.

[0145] Figure 6 For the basis of Figure 5 The diagram illustrates the principle of obtaining single-sample test results through multi-zone spatial determination. Please refer to [link / reference]. Figure 6The single-sample test result for each sample metal item Sp_ctg_i can include multiple sets of single-zone test results obtained from multiple tests of the sample metal item Sp_ctg_i in multiple defense zones. Furthermore, each set of single-zone test results for each sample metal item Sp_ctg_i corresponding to each defense zone can include: the single-sample defense zone metal induction intensity obtained from multiple tests of the sample metal item Sp_ctg_i located solely in that defense zone based on different frequency phase combinations of control parameters, Comb{f,ψ}_1~Comb{f,ψ}_n. That is, the single-sample metal induction intensity {MI_i_1,…MI_1_j,…MI_1_n}……{MI_m_1,…MI_m_j,…MI_m_n} of each sample metal item Sp_ctg_i can be characterized by the single-sample defense zone metal induction intensity of the sample metal item Sp_ctg_i in multiple defense zones.

[0146] For example, in Figure 6In this context, the single-sample defense zone metal induction intensity characterization of the sample metal item Sp_ctg_i in multiple defense zone spaces (e.g., first side defense zone spaces A_pa_1~A_pa_6 and second side defense zone spaces A_pb_1~A_pb_6) can include: the single-sample defense zone metal induction intensity of the sample metal item Sp_ctg_i in the first side defense zone space A_pa_1 {MI_i_pa1_1,…MI_i_pa1_j,…MI_i_pa1_n}, the single-sample defense zone metal induction intensity of the sample metal item Sp_ctg_i in the first side defense zone space A_pa_2 {MI_i_pa2_1,…MI_i_pa2_j,…MI_i_pa2_n}, and the single-sample defense zone metal induction intensity of the sample metal item Sp_ctg_i in the first side defense zone space A_pa_3 {MI_i_pa3_1,…MI_i_pa3_j ... The single-sample zone metal induction intensities {MI_i_pa4_1,…MI_i_pa4_j,…MI_i_pa4_n} in the first side defense zone space A_pa_4, the single-sample zone metal induction intensities {MI_i_pa5_1,…MI_i_pa5_j,…MI_i_pa5_n} in the first side defense zone space A_pa_5, the single-sample zone metal induction intensities {MI_i_pa6_1,…MI_i_pa6_j,…MI_i_pa6_n} in the first side defense zone space A_pa_6, and the single-sample zone metal induction intensities {MI_i_pb1_1,…MI_i_pb1_j,…MI_i_pb1_n} in the second side defense zone space A_pb_1 The single-sample metal induction intensities in the second side defense zone space A_pb_2 are {MI_i_pb2_1,…MI_i_pb2_j,…MI_i_pb2_n}. The single-sample metal induction intensities in the second side defense zone space A_pb_3 are {MI_i_pb3_1,…MI_i_pb3_j,…MI_i_pb3_n}. The single-sample metal induction intensities in the second side defense zone space A_pb_4 are {MI_i_pb4_1,…MI_i_pb4_j,…MI_i_pb4_n}. The single-sample metal induction intensities in the second side defense zone space A_pb_5 are {MI_i_pb5_1,…MI_i_pb5_j,…MI_i_pb5_n}.}, the single-sample zone metal induction intensity of the second side zone space A_pb_6 {MI_i_pb6_1,…MI_i_pb6_j,…MI_i_pb6_n}.

[0147] Therefore, as such Figure 2 and Figure 3 In the alternative to the S510 shown, the processor component 53 can be specifically configured as follows:

[0148] Based on the single-sample zone metal induction intensity of each sample metal item Sp_ctg_i corresponding to multiple zone spaces, the single-category zone induction intensity MI_i_u of each selected item category ctg_i in each zone space A_u (i.e., the u-th zone space in the first side zone space A_pa_1~A_pa_6 and the second side zone space A_pb_1~A_pb_6 ordered in any way) and the frequency-phase combination Comb{f,ψ} of the control parameters are determined. The single-category zone induction intensity MI_i_u is used to characterize the metal induction intensity Comb{f,ψ}_j of any metal item belonging to the corresponding selected item category ctg_i and located in the corresponding zone space A_u when the control parameters are configured to any frequency-phase combination.

[0149] For example, a single zone association may include a zone intensity function g(f, ψ)_i_u, where the function value of the zone intensity function g(f,Ψ)_i_u is used to characterize the single-class zone sensing intensity MI_i_u of the corresponding selected item category ctg_i in the corresponding zone space (e.g., the u-th zone space in the first side zone space A_pa_1~A_pa_6 and the second side zone space A_pb_1~A_pb_6 ordered in any way), when the control parameter is configured to an arbitrary frequency phase combination Comb{f,ψ}_j.

[0150] For example, processor component 53 can:

[0151] Based on the single-sample defense zone metal induction intensity {MI_i_pa1_1,…MI_i_pa1_j,…MI_i_pa1_n} of each sample metal item Sp_ctg_i in the first side defense zone space A_pa_1, the single-category defense zone induction intensity MI_i_pa1 of the selected item category ctg_i in the first side defense zone space A_pa_1 and the frequency phase combination Comb{f,ψ} of the control parameters are determined, that is, the partition intensity function g(f, ψ)_i_pa1;

[0152] Based on the single-sample defense zone metal induction intensity {MI_i_pa2_1,…MI_i_pa2_j,…MI_i_pa2_n} of each sample metal item Sp_ctg_i in the first side defense zone space A_pa_2, the single-category defense zone induction intensity MI_i_pa2 of the selected item category ctg_i in the first side defense zone space A_pa_2 and the frequency phase combination Comb{f,ψ} of the control parameters are determined, that is, the partition intensity function g(f, ψ)_i_pa2;

[0153] Based on the single-sample defense zone metal induction intensity {MI_i_pa3_1,…MI_i_pa3_j,…MI_i_pa3_n} of each sample metal item Sp_ctg_i in the first side defense zone space A_pa_3, the single-category defense zone induction intensity MI_i_pa3 of the selected item category ctg_i in the first side defense zone space A_pa_3 is determined, and the single-zone correlation between the frequency phase combination Comb{f,ψ} of the control parameters is determined, that is, the partition intensity function g(f, ψ)_i_pa3;

[0154] Based on the single-sample defense zone metal induction intensity {MI_i_pa4_1,…MI_i_pa4_j,…MI_i_pa4_n} of each sample metal item Sp_ctg_i in the first side defense zone space A_pa_4, the single-zone correlation between the single-category defense zone induction intensity MI_i_pa4 of the selected item category ctg_i in the first side defense zone space A_pa_4 and the frequency phase combination Comb{f,ψ} of the control parameters is determined, that is, the partition intensity function g(f, ψ)_i_pa4;

[0155] Based on the single-sample defense zone metal induction intensity {MI_i_pa5_1,…MI_i_pa5_j,…MI_i_pa5_n} of each sample metal item Sp_ctg_i in the first side defense zone space A_pa_5, the single-zone correlation between the single-category defense zone induction intensity MI_i_pa5 of the selected item category ctg_i in the first side defense zone space A_pa_5 and the frequency phase combination Comb{f,ψ} of the control parameters is determined, that is, the partition intensity function g(f, ψ)_i_pa5;

[0156] Based on the single-sample defense zone metal induction intensity {MI_i_pa6_1,…MI_i_pa6_j,…MI_i_pa6_n} of each sample metal item Sp_ctg_i in the first side defense zone space A_pa_6, the single-class defense zone induction intensity MI_i_pa6 of the selected item category ctg_i in the first side defense zone space A_pa_6 is determined, and the frequency phase combination Comb{f,ψ} of the control parameters is determined, that is, the partition intensity function g(f, ψ)_i_pa6;

[0157] Based on the single-sample defense zone metal induction intensity {MI_i_pb1_1,…MI_i_pb1_j,…MI_i_pb1_n} of each sample metal item Sp_ctg_i in the second side defense zone space A_pb_1, {MI_i_pb2_1,…MI_i_pb2_j,…MI_i_pb2_n} of the second side defense zone space A_pb_2, {MI_i_pb3_1,…MI_i_pb3_j,…MI_i_pb3_n} of the second side defense zone space A_pb_3, and {MI_i_pb4_1,…MI_i_pb4_n} of the second side defense zone space A_pb_4,...MI_i_pb4_j,… ... The single-sample zone metal induction intensities {MI_i_pb5_1,…MI_i_pb5_j,…MI_i_pb5_n} and the single-sample zone metal induction intensities {MI_i_pb6_1,…MI_i_pb6_j,…MI_i_pb6_n} of the second side zone space A_pb_5 are determined respectively. The single-zone correlation between the selected item category ctg_i and the single-category zone induction intensities MI_i_pb1~MI_i_pb6 of the second side zone space A_pb_1~A_pb_6 and the frequency phase combination Comb{f,ψ} of the control parameters is determined, that is, the partition intensity function g(f, ψ)_i_pb1~g(f, ψ)_i_pb6 is determined in the same way.

[0158] That is, the partition intensity function g(f, ψ)_i_u used for simplified expression can refer to any one of g(f, ψ)_i_pa1~g(f, ψ)_i_pa6 and g(f, ψ)_i_pb1~g(f, ψ)_i_pb6, and the single-class partition sensing intensity MI_i_u used for simplified expression can refer to any one of the single-class defense zone sensing intensities MI_i_pa1~MI_i_pa6 and MI_i_pb1~MI_i_pb6 mentioned above.

[0159] Therefore, the processor component 35 can determine the single-class metal induction intensity MI_i of the item category ctg_i and the frequency phase combination Comb{f,ψ} of the control parameters based on the single-zone association relationship of each item category ctg_i corresponding to multiple zone spaces (e.g., the partition intensity function g(f, ψ)_i_pb1~g(f, ψ)_i_pb6), and the occurrence probabilities w_i_pa1~w_i_pa6 and w_i_pb1~w_i_pb6 of each selected item category ctg_i in multiple zone spaces (e.g., the first side zone space A_pa_1~A_pa_6 and the second side zone space A_pb_1~A_pb_6).

[0160] In this context, the single-category metal sensing intensity MI_i of each selected item category ctg_i is represented by the weighted result of the single-category zone sensing intensities (e.g., MI_i_pa1~MI_i_pa6 and MI_i_pb1~MI_i_pb6) of multiple zone spaces (e.g., the first side zone spaces A_pa_1~A_pa_6 and the second side zone spaces A_pb_1~A_pb_6) corresponding to the selected item category ctg_i in the single-category zone sensing intensity MI_i_u of any zone space A_u corresponding to each selected item category ctg_i in the weighted result, and is associated with the occurrence probability w_i_u of the selected item category ctg_i in the corresponding zone space A_u (i.e., one of w_i_pa1~w_i_pa6 and w_i_pb1~w_i_pb6).

[0161] That is, for each selected item category ctg_i, the single-category intensity function g(f, ψ)_i, which represents the single-category correlation between its single-category metal induction intensity MI_i and the frequency-phase combination of control parameters Comb{f,ψ}, can be expressed as: g(f,Ψ)_i=∑w_i_u×g(f, ψ)_i_u.

[0162] As can be seen above, the function value of the single-category intensity function g(f, ψ)_i can be obtained by weighting the function values ​​of the partition intensity functions (e.g., g(f, ψ)_i_pa1~g(f, ψ)_i_pa6 and g(f, ψ)_i_pb1~g(f, ψ)_i_pb6) corresponding to the same selected item category ctg_i and corresponding to multiple defense zones (e.g., the first side defense zone A_pa_1~A_pa_6 and the second side defense zone A_pb_1~A_pb_6). Furthermore, the weight of the function values ​​of these partition intensity functions corresponding to the multiple defense zones for each selected item category ctg_i in the function value of the single-category intensity function g(f, ψ)_i is associated with the occurrence probability of the selected item category ctg_i in the multiple defense zones (e.g., w_i_pa1~w_i_pa6 and w_i_pb1~w_i_pb6).

[0163] Therefore, the multi-class intensity function described above can be transformed into MI_w=∑[Sen_i×∑w_i_u×g(f,ψ)_i_u].

[0164] If multiple selected item categories ctg_1~ctg_m simultaneously include both the inspectable item categories ctg_Pos_1~ctg_Pos_p and the exempted item categories ctg_Neg_1~ctg_Neg_q, then the above multi-category intensity function can also be transformed into:

[0165] MI_w=∑[Sen_Pos×∑w_Pos_u×g(f,ψ)_Pos_u]-∑[Sen_Neg×∑w_Neg_u×g(f,ψ)_Neg_u]

[0166] The meanings of Sen_Pos and Sen_Neg are explained above and will not be repeated here; w_Pos_u and g(f, ψ)_Pos_u can respectively refer to the probability of occurrence w_i_u of any category of items subject to inspection and the partition strength function g(f, ψ)_i_u, and w_Neg_u and g(f, ψ)_Neg_u can respectively refer to the probability of occurrence w_i_u of any category of items exempt from inspection and the partition strength function g(f, ψ)_i_u.

[0167] Based on the embodiments of this application, the single-category metal sensing intensity MI_i of each item category ctg_i can be optimized from the average sensing intensity within the detection channel 100 to a weighted sensing intensity that highlights the differences in the carrying position of the item at the granularity of the protected area space. This further enhances the influence of the carrying position of the corresponding item category ctg_Pos on the single-category metal sensing intensity when determining the calibration frequency phase combination Comb_ref. Consequently, the calibration frequency phase combination Comb_ref, which controls the parameters, can more effectively make the overall detection sensitivity of the item categories ctg_Pos with different habitual carrying positions approach their respective corresponding sensitivity target values ​​Sen_Pos. Therefore, for application scenarios where multiple item categories ctg_Pos with different item attributes are used as detection targets, the risk of missing detection of item categories ctg_Pos at habitual carrying positions can be further reduced, thereby further reducing the overall missed detection rate of the security gate.

[0168] When the control parameters of the detection component 30 are configured as the calibration frequency phase combination Comb_ref ​​in the aforementioned embodiment, the security gate can perform metal detection with multiple inspectable item categories ctg_Pos of different item attributes as detection targets. Correspondingly, the processor component 35 can also be used for:

[0169] Based on the received signal generated by the receiving coil assembly 320 when the target object passes through the detection channel 100, the object metal induction intensity MI_Obj of the target object is detected.

[0170] Based on the detected object metal induction intensity MI_Obj, it is determined whether the target object carries a target metal item belonging to the target item category. The target item category can be any one of the selected item categories ctg_1~ctg_m described above, namely ctg_Pos.

[0171] Since the control parameters of the detection component 30 are configured to cause the detection sensitivity of multiple selected item categories ctg_1~ctg_m to generally approach the calibration frequency phase combination Comb_ref ​​of their respective corresponding sensitivity target values ​​Sen_1~Sen_m, the detection sensitivity of the metal item successfully detected by the security gate can reach the expected level, regardless of which item category ctg_Pos the metal item carried by the target object belongs to.

[0172] Additionally, the security gate may include an alarm component, which may include an audio component for generating an audio alarm and / or an optical component for generating a visual alarm. In this case, the processor component 35 may also trigger the alarm component to generate an alarm in response to a determination that the target object carries a target metal object belonging to the target item category.

[0173] Figure 7 This is a schematic diagram of a first detection example of metal detection for a security gate, as described in this application. Please refer to... Figure 7 The first detection example of this application can identify target metal items belonging to the target item category carried by the target object by the difference in metal induction intensity in the target scene where the target object enters and exits the security gate.

[0174] Specifically, in such Figure 7 In the first detection example shown, the security gate can be deployed at the entrance of the target scene. The passage of the target object through the detection channel 100 can include passing through the entrance of the detection channel 100 along the entrance direction into the target scene and passing through the exit of the detection channel 100 along the exit direction away from the target scene.

[0175] Furthermore, the object metal induction intensity MI_Obj detected by the processor component 35 may include: the target object's entry metal induction intensity MI_Obj_enter detected based on the received signal generated by the receiving coil component 320 when the target object enters and passes through, and the target object's exit metal induction intensity MI_Obj_exit detected based on the received signal generated by the receiving coil component 320 when the target object leaves and passes through.

[0176] In this case, the processor component 35 can determine whether the target object carries a target metal item belonging to the target item category based on the detected object metal sensing intensity by: determining whether the target object carries a target metal item belonging to the target item category when leaving the site based on the consistency of the entry metal sensing intensity MI_Obj_enter and the exit metal sensing intensity MI_Obj_exit.

[0177] For example, in a scenario where the target environment is a factory area producing metal products, the target object can be a worker or a visitor, and the target item category can include all metal products prohibited from being taken out of the factory area. Therefore, if the departure metal detection intensity MI_Obj_exit generated by the departure detection channel 100 is greater than the entry metal detection intensity MI_Obj_enter generated by the entry detection channel 100, it indicates that there is a possibility that the target object is carrying metal products from the factory area. Thus, it can be determined that the target object is carrying a target metal item belonging to the target item category when leaving, and the alarm component is triggered to generate an alarm. Therefore, security gates deployed in such target environments can also be called "loss prevention gates."

[0178] Preferably, the security gate may further include an identity detection component, which may include an RFID reader and / or a biometric detection device such as fingerprint recognition or facial recognition. This identity detection component can detect the identity information of the target object about to enter the detection channel 100. In this case, the processor component 35 can also be used to acquire the identity information of the target object successfully detected by the identity detection component, and associate both the entry sensing intensity MI_Obj_enter and the exit sensing intensity MI_Obj_exit with the successfully acquired identity information. Furthermore, if the identity detection component fails to detect the identity information of the target object about to enter the detection channel 100, the processor component 35 can also trigger an alarm component to generate an alarm prompt, reminding the on-site administrator to manually verify the identity of the target object.

[0179] For example, the processor component 35 can obtain the identity information of the target object that is about to pass through the detection channel 100 before the target object enters and leaves the detection channel. That is, the processor component 35 can associate and store the determined entry sensing intensity MI_Obj_enter with the identity information successfully obtained before the current entry passage. In addition, the processor component 35 can also query the entry sensing intensity MI_Obj_enter associated with the identity information successfully obtained before the current exit passage in response to each determination of the exit sensing intensity MI_Obj_exit.

[0180] Figure 8 For example Figure 7 The diagram illustrates the multi-zone spatial accumulation principle in the first detection example shown. Please refer to [link / reference]. Figure 8 If detection channel 100 includes multiple defense zones (e.g., ... Figure 5 The diagram shows the first side defense zone spaces A_pa_1 to A_pa_6 and the second side defense zone spaces A_pb_1 to A_pb_6. The detection component includes sensing units (e.g., [missing information]) deployed in alignment with the multiple defense zones. Figure 5 The first-side sensing units 300_pa_1~300_pa_6 and the second-side sensing units 300_pb_1~300_pb_6 shown are provided. Then, the processor component 35 can detect the object metal sensing intensity MI_Obj (i.e., the entry sensing intensity MI_Obj_enter and the exit sensing intensity MI_Obj_exit) of the target object in the following manner:

[0181] Based on the received signals generated by the receiving coils of multiple sensing units during entry and passage, the entry zone metal induction intensity of the target object in multiple defense zones is detected (for example, the entry zone metal induction intensity MI_Obj_pa1_enter~MI_Obj_pa6_enter and MI_Obj_pb1_enter~MI_Obj_pb6_enter of the target object in the first side sensing unit 300_pa_1~300_pa_6 and the second side sensing unit 300_pb_1~300_pb_6, respectively). Furthermore, based on the sum of the entry zone metal induction induction intensities of the target object in multiple defense zones, the entry zone metal induction intensity MI_Obj_enter is determined.

[0182] Based on the received signals generated by the respective receiving coils of multiple sensing units during departure passage, the departure zone metal induction intensity of the target object in multiple defense zones is detected respectively (for example, the departure zone metal induction intensity MI_Obj_pa1_exit~MI_Obj_pa6_exit and MI_Obj_pb1_exit~MI_Obj_pb6_exit of the target object in the first side sensing unit 300_pa_1~300_pa_6 and the second side sensing unit 300_pb_1~300_pb_6 respectively). Furthermore, the departure zone metal induction intensity MI_Obj_exit is determined based on the sum of the departure zone metal induction intensities in the multiple defense zones.

[0183] Figure 9 This is a schematic diagram of a second detection example of metal detection for security gates in this application embodiment. Figure 10 For example Figure 9 The diagram illustrates the projection shape detection principle in the second detection example. Please refer to [link / reference]. Figure 9 and Figure 10 The second detection example of this application can determine the shape of the metal object by the distribution of the metal induction intensity, and identify the target metal object belonging to the target object category carried by the target object by the shape of the metal object.

[0184] like Figure 9 and Figure 10As shown, the receiving coil assembly 320 may include multiple sets of receiving coils 320_pair_1 to 320_pair_H arranged at multiple height positions Py_1 to Py_H in the height direction. Each set of receiving coils 320_pair_h at each height position Py_h may include a first-side receiving coil 320_pa_h and a second-side receiving coil 320_pb_h arranged relative to a first side and a second side in the width direction x of the detection channel 100. Here, Py_1 represents the bottom reference position of the detection channel 100, Py_H represents the top reference position of the detection channel 100, and multiple intermediate positions may be distributed between Py_1 and Py_H according to a preset unit height. h is a positive integer greater than or equal to 1 and less than or equal to H, and h represents the number of unit heights.

[0185] For example, the multiple coil units described above include first-side sensing units 300_pa_1~300_pa_6 and second-side sensing units 300_pb_1~300_pb_6. Therefore, there are 6 sensing units in the height direction, whether on the first side or the second side. Furthermore, each coil unit can include k rows of receiving coils, for example, k can be 8. Therefore, there are 6×8 rows of receiving coils in the height direction, whether on the first side or the second side, i.e., H can be 48. In this case, the 48 rows of receiving coils included in the first-side sensing units 300_pa_1~300_pa_6 can serve as multiple sets of receiving coils 320_pa_1~320_pa_H, and the 48 rows of receiving coils included in the second-side sensing units 300_pb_1~300_pb_6 can serve as multiple sets of receiving coils 320_pb_1~320_pb_H. In addition, preferably, each row of the coil unit can include a pair of receiving coils. The two eddy current signals generated by each pair of receiving coils can be combined into one by a differential circuit so that the noise in the eddy current signal of the pair of receiving coils can be weakened by differential combining. That is, the first side receiving coil 320_pa_h and the second side receiving coil 320_pb_h in a pair of receiving coils 320_pair_h at each height position Py_h are both a pair of receiving coils with differentially combined signals.

[0186] It is understood that the unit height used to characterize the granularity of height position can be determined by the coil size of the receiving coil in the height direction y and the row distance between two adjacent rows of receiving coils. Since the granularity of height position can be arbitrarily set according to actual detection needs, the embodiments of this application do not intend to make unnecessary limitations on the above description of the number of rows of receiving coils and the row distance not described in the examples.

[0187] When the receiving coil assembly 320 includes multiple sets of receiving coils 320_pair_1 to 320_pair_H arranged at multiple height positions Py_1 to Py_H, the object metal induction intensity MI_Obj may include: a first single-sided induction intensity MI_Obj_pa_h of the target object detected based on the received signal generated by the first side receiving coils 320_pa_1 to 320_pa_H at each height position Py_h near the first side where the first door panel 11 is located, and a second single-sided induction intensity MI_Obj_pb_h of the target object detected based on the received signal generated by the second side receiving coils 320_pb_1 to 320_pb_H at each height position Py_h near the second side where the second door panel 12 is located.

[0188] If the first-sided sensing intensity MI_Obj_pa_1~MI_Obj_pa_H and the second-sided sensing intensity MI_Obj_pb_1~MI_Obj_pb_H of the target object at multiple height positions Py_1~Py_H are not all 0, then it indicates that the target object is carrying a metal object. In order to determine whether the metal object carried by the target object is the target metal object, the processor component 35 can be specifically configured as follows:

[0189] Based on the first unilateral sensing intensity MI_Obj_pa_1~MI_Obj_pa_H and the second unilateral sensing intensity MI_Obj_pb_1~MI_Obj_pb_H of the target object at multiple height positions Py_1~Py_H, the projection shape of the projection plane xy jointly defined by the width direction x and the height direction y of the metal object is determined.

[0190] Based on the projection shape of the target metal object on the projection plane xy, determine whether the carrying metal object belongs to the target object category.

[0191] In embodiments of this application, the projection shape can be determined by locating the boundary position of the metal object in the width direction x. In this case, the processor component 35 can specifically determine the projection shape of the target metal object on the projection plane xy in the following manner:

[0192] Based on the intensity relationship between the first unilateral sensing intensity MI_Obj_pa_h and the second unilateral sensing intensity MI_Obj_pb_h at each height position, the local width boundary positions Px_pa_h and Px_pb_h of the local portion of the target metal object at each height position P_x are determined.

[0193] Based on the local width boundary positions {Px_pa_1, Px_pb_1}~{Px_pa_H, Px_pb_H} of the local parts of the target metal object at multiple height positions Py_1~Py_H, the projection shape of the target metal object on the projection plane xy is determined.

[0194] To ensure that the local width boundary position Px_pa_h on the first side and the positioning reference of Px_pb_h on the second side are the same, and to guarantee the positioning accuracy of the boundary position, in the embodiments of this application, for the local width boundary positions Px_pa_h and Px_pb_h of the local portion of each height position Py_h, the processor component 35 can be specifically configured as follows:

[0195] Based on the intensity relationship between the first unilateral sensing intensity MI_Obj_pa_h and the second unilateral sensing intensity MI_Obj_pb_h at each height position Py_h, and the width dimension W0 of the detection space 100 in the width direction x, the local centroid position Px_c_h of the local part of the target metal object at the height position P_x is determined.

[0196] Based on the local centroid position Px_c_h of each height position Py_h, and the first unilateral induction intensity MI_Obj_pa_h and the second unilateral induction intensity MI_Obj_pb_h, the local width boundary positions Px_pa_h and Px_pb_h of the local portion of the height position Py_h are determined.

[0197] According to the Biot-Savart Law, the magnitude of the magnetic induction intensity dB produced by a current element Idl at a spatial location P is directly proportional to the magnitude of the current element Idl, directly proportional to the sine of the angle between the position vector of the current element Idl and the spatial location P, and inversely proportional to the square of the distance between the current element Idl and the spatial location P.

[0198] Therefore, we can assume that the location of the current element Idl is the deployment location of the sensing unit, and that the spatial location P is the spatial location carrying the metal object. Then, the method for determining the local centroid location Px_c_h can be specifically expressed as follows:

[0199] ,or,

[0200]

[0201] That is, the local centroid position Px_c_h of each height position Py_h can be determined as: the product of the width dimension W0 of the detection channel 100 and the square root of the ratio of the first unilateral sensing intensity MI_Obj_pa_h or the second unilateral sensing intensity MI_Obj_pb_h at that height position Py_h to the sum of the first unilateral sensing intensity MI_Obj_pa_h and the second unilateral sensing intensity MI_Obj_pb_h at that height position Py_h.

[0202] Furthermore, the method for determining the local width boundary positions Px_pa_h and Px_pb_h can be specifically expressed as follows:

[0203]

[0204] Wherein, b is a configurable scaling factor, which is used to represent the scale of the projected shape in the width direction x. Furthermore, the scaling factor can be adjusted and calibrated by comparing the projected shape obtained from multiple tests of the sample metal object with the measured projected shape of the sample metal object.

[0205] That is, the local width boundary position Px_pa_h or Px_pb_h of each height position Py_h can be determined as: the position superposition result of the position offset superimposed on the local centroid position Px_c_h of the height position Py_h as the reference position in the width direction x, and the position offset can be the product of a pre-configured scaling factor and the sum of the first unilateral sensing intensity MI_Obj_pa_h or the second unilateral sensing intensity MI_Obj_pb_h of the height position Py_h.

[0206] In practical use, the metal objects carried by the target may be located in different defense zones. Since multiple sensing units corresponding to multiple defense zones can generate transmission signals using their own independent transmitting coils, and there may be differences in coil performance between multiple sensing units, in order to reduce or even eliminate the influence of the coils on the above positioning, the first one-sided sensing intensity MI_Obj_pa_h and the second one-sided sensing intensity MI_Obj_pb_h at each height position Py_h can be normalized. Furthermore, the result of the normalization process can be used to replace the first one-sided sensing intensity MI_Obj_pa_h and the second one-sided sensing intensity MI_Obj_pb_h representing each height position Py_h during positioning.

[0207] Figure 11 For example Figure 9 The diagram illustrates the edge localization principle used for projected shape detection in the second detection example shown. Please refer to [link / reference]. Figure 11In the embodiments of this application, for the detection channel 100 including multiple defense zones as described above (e.g., first side defense zones A_pa_1~A_pa_6 and second side defense zones A_pb_1~A_pb_6), and the detection component 300 including sensing units (e.g., first side sensing units 300_pa_1~300_pa_6 and second side sensing units 300_pb_1~300_pb_6) respectively deployed in alignment with the multiple defense zones:

[0208] The first one-sided induction intensity MI_Obj_pa_h at each height position Py_h can be characterized by the corresponding first one-sided normalized intensity MI_Obj_pa_h_nrm, where the first one-sided normalized intensity MI_Obj_pa_h_nrm is: the proportion of the first one-sided induction intensity MI_Obj_pa_h determined by the received signal generated by the first-sided receiving coil Px_pa_h in a group of receiving coils at each height position Py_h in the overall metal induction intensity MI_Obj_pa_unitsum of the induction unit to which the first-sided receiving coil Px_pa_h belongs in the group of receiving coils, that is, MI_Obj_pa_h_nrm is MI_Obj_pa_h / MI_Obj_pa_unitsum;

[0209] The second one-sided induction intensity MI_Obj_pb_h at each height position Py_h can be characterized by the corresponding second one-sided normalized intensity MI_Obj_pb_h_nrm, where the second one-sided normalized intensity MI_Obj_pb_h_nrm is: the proportion of the second one-sided induction intensity MI_Obj_pb_h determined by the received signal generated by the second-side receiving coil Px_pb_h in a set of receiving coils at each height position Py_h in the overall metallic induction intensity MI_Obj_pb_unitsum of the induction unit to which the second-side receiving coil Px_pb_h belongs in the set of receiving coils, that is, MI_Obj_pb_h_nrm is MI_Obj_pb_h / MI_Obj_pb_unitsum.

[0210] The overall metallic induction intensity MI_Obj_pa_unitsum or MI_Obj_pb_unitsum of each coil unit can be the sum of the metallic induction intensities obtained by determining the received signals generated by all receiving coils based on that coil unit.

[0211] If the result of normalization is used to replace the first unilateral induction intensity MI_Obj_pa_h and the second unilateral induction intensity MI_Obj_pb_h representing each height position Py_h, then the method for determining the local centroid position Px_c_h can be specifically expressed as follows:

[0212] ,or,

[0213]

[0214] That is, the local centroid position Px_c_h of each height position Py_h can be determined as: the product of the width dimension W0 of the detection channel 100 and the square root of the ratio of the first one-sided normalized intensity MI_Obj_pa_h_nrm or the second one-sided normalized intensity MI_Obj_pb_h_nrm of the height position Py_h to the sum of the first one-sided normalized intensity MI_Obj_pa_h_nrm and the second one-sided normalized intensity MI_Obj_pb_h_nrm of the height position Py_h.

[0215] Furthermore, the method for determining the local width boundary positions Px_pa_h and Px_pb_h can be specifically expressed as follows:

[0216]

[0217] That is, the local width boundary position Px_pa_h or Px_pb_h of each height position Py_h can be determined as: the position superposition result of the position offset superimposed on the local centroid position Px_c_h of the height position Py_h as the reference position in the width direction x, and the position offset can be the product of a pre-configured scaling factor and the sum of the first one-sided normalized intensity MI_Obj_pa_h_nrm and the second one-sided normalized intensity MI_Obj_pb_h_nrm of the height position Py_h.

[0218] In the second detection example of this application embodiment, the processor component 35 may also:

[0219] By connecting the local width boundary positions {Px_pa_1, Px_pb_1} to {Px_pa_H, Px_pb_H} of the local portions of the metal object at multiple height positions Py_1 to Py_H, the projection profile of the metal object on the projection plane xy described above is obtained. That is, all local width boundary positions on the first side are connected sequentially along the height direction y to obtain the first side boundary profile, and all local width boundary positions on the second side are connected sequentially along the height direction y to obtain the second side boundary profile. Furthermore, the top endpoints (i.e., Px_pa_H and Px_pb_H) and bottom endpoints (i.e., Px_pa_1 and Px_pb_1) of the first and second boundary profiles are interconnected to obtain the projection profile. The outline of this projection profile can be the region profile bounded by the local width boundary positions {Px_pa_1, Px_pb_1} to {Px_pa_H, Px_pb_H}.

[0220] The process of obtaining the projected contour by connecting the local width boundary positions {Px_pa_1, Px_pb_1} to {Px_pa_H, Px_pb_H} can specifically include:

[0221] By fitting the discrete coordinates of the local width boundary positions {Px_pa_1, Px_pb_1} to {Px_pa_H, Px_pb_H} of the local parts of multiple height positions Py_1 to Py_H carrying the metal object, the fitted contour of the metal object is obtained. The fitted contour may include straight line boundary segments connecting every two adjacent local width boundary positions.

[0222] Based on the local centroid position Px_c_h of each height position Py_h, and the tilt angle θ_pa_h or θ_pb_h of the straight line boundary segment with the local width boundary position Px_pa_h or Px_pb_h of that height position Py_h as the endpoint relative to the width direction x, the position of the local width boundary position Px_pa_h or Px_pb_h of that height position Py_h is corrected so that the fitted contour is optimized into a projected contour after the position correction of the local width boundary positions Px_pa_h and Px_pb_h.

[0223] Referring to the Biosavart law mentioned above, the processor component 35 can correct the position of the local width boundary position based on the local centroid position Px_c_h of each height position Py_h and the tilt angle of the straight line boundary segment relative to the width direction.

[0224] For example, processor component 35 can be specifically configured as follows:

[0225] Using the local centroid position Px_c_h of each height position Py_h as a reference, and taking the inverse of the inclination angle θ_pa_h or θ_pb_h of the straight boundary segment whose endpoint includes the local width boundary position Px_pa_h or Px_pb_h of the height position Py_h as the correction coefficient, the local width boundary position Px_pa_h or Px_pb_h of the height position Py_h is corrected.

[0226] In other words, the corrected positions Px_pa_h' and Px_pb_h' of the local width boundary positions Px_pa_h and Px_pb_h after position correction can be represented as follows:

[0227]

[0228] In the second detection example of this application embodiment, the processor component 35 can also determine the projection shape of the metal-carrying object on the projection plane xy based on the shape recognition of the projection contour of the metal-carrying object (e.g., based on the position extremum of the projection contour in a selected direction, and / or any shape recognition method such as the piecewise integral result of the projection contour).

[0229] For example, the processor component 35 can detect the matching degree between the projected shape of the metal-carrying object and the reference projected shape pre-set for multiple selected item categories ctg_1~ctg_n respectively, and, in response to the detection result that the projected shape of the metal-carrying object successfully matches the reference projected shape of any selected item category ctg_i, determine that the metal-carrying object is a target metal-carrying object belonging to the selected item category ctg_i.

[0230] Figure 12 This is a schematic diagram of a third detection example for metal detection in a security gate, as described in this application. Please refer to... Figure 12 The third detection example of this application can identify the target metal object carried by the target object that belongs to the target item category by the projection shape of the metal object carried by the target object in the target scene where the target object enters and exits the security gate.

[0231] Similar to the first detection instance, the security gate in the third detection instance can also be deployed at the entrance of the target scene, and the passage of the target object through the detection channel 100 can include entry passage and exit passage.

[0232] Similar to the second detection example, the receiving coil assembly 320 in the third detection example may include multiple sets of receiving coils 320_pair_1 to 320_pair_H arranged at multiple height positions Py_1 to Py_H in the height direction. Each set of receiving coils 320_pair_h at height position Py_h may include a first-side receiving coil 320_pa_h and a second-side receiving coil 320_pb_h arranged relative to a first side and a second side in the width direction x of the detection channel 100. Furthermore, the target metal induction intensity M... I_Obj may include: the first single-sided induction intensity MI_Obj_pa_h of the target object at each height position Py_h near the first side where the first door panel 11 is located, obtained based on the received signal generated by the first side receiving coils 320_pa_1~320_pa_H; and the second single-sided induction intensity MI_Obj_pb_h of the target object at each height position Py_h near the second side where the second door panel 12 is located, obtained based on the received signal generated by the second side receiving coils 320_pb_1~320pb_H.

[0233] Moreover, in the third detection instance:

[0234] The first unilateral sensing intensity MI_Obj_pa_h at each height position Py_h includes: the first unilateral entry sensing intensity of the target object at the height position Py_h near the first side, detected based on the received signal generated by the first-side receiving coil 320_pa_h at the height position Py_h during entry passage; and the first unilateral exit sensing intensity of the target object at each height position Py_h near the first side, detected based on the received signal generated by the first-side receiving coil 320_pa_h at the height position Py_h during exit passage.

[0235] The second unilateral sensing intensity MI_Obj_pb_h at each height position Py_h includes: the second unilateral entry sensing intensity of the target object at the height position Py_h near the second side, detected based on the received signal generated by the second-side receiving coil 320_pb_h at the height position Py_h during entry passage; and the second unilateral exit sensing intensity of the target object at the height position Py_h near the second side, detected based on the received signal generated by the second-side receiving coil 320_pb_h at the height position Py_h during exit passage.

[0236] In the third detection example, the first unilateral sensing intensity MI_Obj_pa_1~MI_Obj_pa_H and the second unilateral sensing intensity MI_Obj_pb_1~MI_Obj_pb_H used to determine the projected shape of the carried metal object during entry are the first unilateral entry sensing intensity and the second unilateral entry sensing intensity, respectively. The projected shape determined at this time can be called the entry projected shape. During exit, the first unilateral sensing intensity MI_Obj_pa_1~MI_Obj_pa_H and the second unilateral sensing intensity MI_Obj_pb_1~MI_Obj_pb_H used to determine the projected shape of the carried metal object are the first unilateral exit sensing intensity and the second unilateral entry sensing intensity, respectively. The projected shape determined at this time can be called the exit projected shape.

[0237] That is, in the third detection example, the projection shape determined by the first unilateral sensing intensity MI_Obj_pa_1~MI_Obj_pa_H and the second unilateral sensing intensity MI_Obj_pb_1~MI_Obj_pb_H of the target object at multiple height positions Py_1~Py_H can include:

[0238] The entrance projection shape of the target object on the projection plane xy is determined based on the first and second single-sided entrance sensing intensities of the target object at multiple height positions Py_1~Py_H, and the departure projection shape of the target object on the projection plane xy is determined based on the first and second single-sided departure sensing intensities of the target object at multiple height positions Py_1~Py_H.

[0239] Therefore, the method by which the processor component 35 determines whether the carried metal is the target metal object based on the projected shape of the carried metal object can be specifically as follows:

[0240] Detect the consistency between the entrance projection shape and the exit projection shape of the same target object;

[0241] In response to the detection result that the departure projection shape of any target object differs from the entry projection shape, that is, the detection result indicates that there is a risk that the target object carries a certain metal item into the target scene and replaces the target metal item that is prohibited from being carried out of the target scene. The matching degree of the departure projection shape of the target object with the reference projection shape that is pre-set for multiple selected item categories ctg_i is then detected.

[0242] In response to the detection result that the projected shape of the carrying metal object successfully matches the reference projected shape of any selected item category ctg_i, the carrying metal object is determined to be a target metal object belonging to the selected item category ctg_i, and the alarm component can be further triggered to generate an alarm prompt.

[0243] In addition, the identity information in the first detection instance can also be used in the third detection instance. That is, the processor component 35 can obtain the identity information of the target object in the same way as in the first detection instance. Furthermore, in the third detection instance, the processor component 35 can match the entrance projection shape and the exit projection shape with the identity information of the target object.

[0244] It is understood that the metal detection scheme for security gates in this application embodiment may not depend on the calibration results described above. That is, the control parameters of the security gate used to implement the above metal detection scheme may also be determined by calibration methods other than those in this application embodiment.

[0245] Figure 13 This is an exemplary flowchart illustrating the parameter calibration method for a security gate in an embodiment of this application. Please refer to... Figure 13 The embodiments of this application also provide a parameter calibration method for a security gate. The security gate using this parameter calibration method includes a detection channel and a detection component. The detection component includes a transmitting coil component and a receiving coil component arranged at intervals across the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil component, and a receiving circuit for acquiring a receiving signal from the receiving coil component. The control parameters of the detection component include a frequency-phase combination for controlling the transmitting signal frequency of the transmitting circuit and for controlling the receiving control phase of the receiving circuit. Furthermore, the parameter calibration method includes:

[0246] S1310: Based on the received signal acquired by the receiving coil assembly during the testing phase, determine the single-sample test result for multiple sample metal items, wherein the multiple sample metal items belong to multiple selected item categories with different item attributes, and the single-sample test result of each sample metal item is used to characterize the single-sample metal induction intensity of the sample metal item in multiple tests in which the control parameters are configured to different frequency phase combinations.

[0247] S1330: Based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of control parameters, determine the single-category correlation between the single-category metal induction intensity of each selected item category and the frequency phase combination of control parameters. The single-category metal induction intensity is used to characterize the metal induction intensity of any metal item belonging to the corresponding selected item category when the control parameters are configured to any frequency phase combination.

[0248] For example, a single-class association can include the single-class strength function described above, which will not be repeated here.

[0249] S1350: Based on the single-category association and the sensitivity target value of the detection sensitivity for each selected item category, determine the calibration frequency phase combination of the control parameters.

[0250] Based on the above process, by testing sample metal items of multiple selected item categories with different item attributes, the single-category correlation between the control parameters of the security gate's detection components and the single-category metal sensing intensity of each selected item category can be determined. Furthermore, by comprehensively considering the correlation between multiple selected item categories and their respective corresponding sensitivity target values, it is helpful to calibrate the control parameters to have an optimal frequency and phase combination that makes the overall detection sensitivity of multiple selected item categories approach their respective corresponding sensitivity target values. Thus, for application scenarios where multiple item categories with different item attributes are the detection targets, the risk of missed detection of the item categories can be reduced, thereby reducing the overall missed detection rate of the security gate.

[0251] In embodiments of this application, S1350 may specifically include:

[0252] Based on the single-category association relationship of multiple selected item categories and the sensitivity target value of the detection sensitivity of multiple selected item categories, the multi-category association relationship between the weighted sensing intensity of the single-category metal sensing intensity of multiple selected item categories and the frequency-phase combination of control parameters is determined, wherein the weight of the single-category metal sensing intensity of each selected item category in the weighted sensing intensity is associated with the corresponding sensitivity target value.

[0253] Based on multi-category correlation, the calibration frequency and phase combination of control parameters are determined.

[0254] For example, if a single-class association includes the single-class strength function described above, then a multi-class association may include the multi-class strength function described above.

[0255] For example, the process of S1350 determining the calibration frequency phase combination of control parameters based on multi-category correlation can specifically include: determining the frequency phase combination that maximizes the weighted induction intensity as the calibration frequency phase combination of control parameters based on multi-category correlation.

[0256] As mentioned above, multiple selected item categories may include both inspectable item categories and exempted item categories. In this case, for the process of determining the multi-category association in S1350, the weight of the single-category metal induction intensity corresponding to each inspectable item category in the weighted induction intensity is positive, and the weight of the single-category metal induction intensity corresponding to each exempted item category in the weighted induction intensity is negative.

[0257] If the selected item categories may include both items subject to inspection and items exempt from inspection, then the parameter calibration method in this application embodiment may further include:

[0258] Obtain the alarm rate set for each category of items subject to inspection, and the pass rate set for each category of items exempt from inspection;

[0259] Based on the alarm rate and pass rate, the weight of the single-category metal induction intensity in the weighted induction intensity is determined for each category of items subject to inspection and each category of items exempt from inspection.

[0260] The physical meanings of alarm rate and pass rate, as well as the methods by which alarm rate and pass rate are used as positive and negative weights respectively, have been described above and will not be repeated here.

[0261] In this context, the parameter calibration method of this application further introduces sample metal items of the exempt item category as countersamples. This can further increase the attention paid to the single-category metal induction intensity of the item category to be inspected when determining the calibration frequency phase combination. As a result, it is more conducive to controlling the calibration frequency phase combination of parameters to make the detection sensitivity of the item category to be inspected generally approach its corresponding sensitivity target value. Therefore, for application scenarios with multiple item categories to be inspected with different item attributes as detection targets, the risk of the item category to be inspected being missed can be further reduced, thereby further reducing the overall missed detection rate of the security gate.

[0262] Figure 14 For example Figure 13 The diagram shows the optimization process of the parameter calibration method.

[0263] If the detection channel includes multiple protected zones, the detection component includes sensing units respectively deployed in alignment with the multiple protected zones, the transmitting coil component includes transmitting coils respectively deployed in the multiple sensing units, the receiving coil component includes receiving coils respectively deployed in the multiple sensing units, and the multiple tests for each sample metal object include multiple sets of tests where each sample metal object is individually located in the multiple protected zones, and each set of tests where each sample metal object is individually located in any one of the protected zones includes multiple tests with control parameters configured to different frequency and phase combinations, then:

[0264] like Figure 13 The single-sample test results for each metal sample obtained in S1310 can include multiple sets of single-zone test results obtained from multiple tests in multiple zone spaces. Each set of single-zone test results for each metal sample corresponding to each zone space includes: the single-sample zone metal induction intensity obtained from multiple tests on the metal sample located individually in that zone space based on different frequency and phase combinations of control parameters. Please refer to [link to relevant documentation]. Figure 14 ,like Figure 13 S1330 in the process shown may include:

[0265] S1331: Based on the single-sample zone metal sensing intensity of each sample metal item corresponding to multiple zone spaces, determine the single-zone correlation between the single-category zone sensing intensity of each selected item category in each zone space and the frequency-phase combination of control parameters. The single-category zone sensing intensity is used to characterize the metal sensing intensity of any metal item belonging to the corresponding selected item category and located in the corresponding zone space when the control parameters are configured to any frequency-phase combination.

[0266] S1333: Based on the single-zone association relationship and the occurrence probability of each selected item category in multiple zone spaces, determine the single-category association relationship between the single-category metal sensing intensity of each selected item category and the frequency-phase combination of control parameters. The single-category metal sensing intensity of each selected item category is characterized by the weighted result of the single-category zone sensing intensity of the selected item category in multiple zone spaces. Furthermore, the weight of the single-category zone sensing intensity of each selected item category in any zone space in the weighted result is associated with the occurrence probability of the selected item category in that zone space.

[0267] If a single-category association relationship includes a single-category strength function, then a single-zone association relationship may include the partition strength function described above.

[0268] Figure 15 This is an exemplary flowchart illustrating a metal detection method for a security gate in an embodiment of this application. Please refer to... Figure 15 In an embodiment of this application, a metal detection method for a security gate is also provided. The security gate using this metal detection method includes a detection channel and a detection component. The detection component includes a transmitting coil component and a receiving coil component arranged at intervals across the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil component, and a receiving circuit for obtaining a receiving signal from the receiving coil component. The control parameters of the detection component are configured as a calibration frequency and phase combination determined by the parameter calibration method of the foregoing embodiments. Furthermore, the metal detection method includes:

[0269] S1510: Detects the metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel;

[0270] S1530: Based on the metal induction intensity of the object, determine whether the target object carries a target metal item belonging to the target item category, wherein the target item category is any one of the selected item categories to be inspected.

[0271] Preferably, after S1530, the metal detection method in this application embodiment may further include: generating an alarm prompt in response to the determination result that the target object carries a target metal article belonging to the target article category.

[0272] Based on the above process, since the control parameters are configured to cause the detection sensitivity of multiple selected item categories to approach the calibration frequency phase combination of their respective corresponding sensitivity target values, the detection sensitivity of the metal item carried by the target object can reach the expected level regardless of which item category it belongs to.

[0273] Figure 16 For example Figure 15 The diagram shows a first example of a metal detection method. The metal detection method in the embodiments of this application is as follows... Figure 16 The first example process shown can identify target metal items belonging to the target item category carried by the target object by using the difference in metal detection intensity in the target scene where the target object enters and exits the security gate.

[0274] Specifically, applications such as Figure 16 The security gate in the first example process shown can be deployed at the entrance of the target scene. The passage of the target object through the detection channel can include passing through the detection channel in the entrance direction of entering the target scene and passing through the detection channel in the exit direction of leaving the target scene.

[0275] Please see Figure 16 The first instance procedure of the metal detection method may include S1510a, which is performed when a target object enters the field: detecting the induction intensity of the incoming metal of the target object based on the received signal generated by the receiving coil assembly when the target object enters the field.

[0276] Please see Figure 16 The first instance procedure of the metal detection method may include S1510b, which is performed when the target object enters the field: detecting the departure metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object leaves the field.

[0277] That is, the metal induction intensity of the object detected by S1510 may include: the metal induction intensity of the target object upon entry based on the received signal generated by the receiving coil assembly when the target object enters and passes through, and the metal induction intensity of the target object upon exit based on the received signal generated by the receiving coil assembly when the target object leaves and passes through.

[0278] Please see Figure 16In the first instance process, S1530 can specifically include: based on the consistency between the entry and exit metal detection intensities, determining whether the target object is carrying a target metal item belonging to the target item category when leaving the area. For example, if the exit metal detection intensity generated by the target object leaving the detection channel is greater than the entry metal detection intensity generated by the target object entering the detection channel, then it can be determined that the target object is carrying a target metal item belonging to the target item category when leaving the area, and an alarm can be generated.

[0279] Furthermore, in the first example of the metal detection method, both S1510a and S1510b can further include: acquiring the identity information of the target object, and the entry sensing intensity determined by S1510a and the exit sensing intensity determined by S1510b are both associated with the successfully acquired identity information. Additionally, if the detection of the identity information of the target object about to enter the detection channel fails in S1510a or S1510b, an alarm can be generated to remind the site administrator to manually verify the identity of the target object.

[0280] If the detection channel includes multiple defense zones, and the detection component includes sensing units deployed respectively in alignment with the multiple defense zones, then:

[0281] S1510a may specifically include: based on the received signals generated by the receiving coils of the multiple sensing units when passing through the field, detecting the entry zone metal induction intensity of the target object in multiple defense zones, and determining the entry zone metal induction intensity based on the sum of the entry zone metal induction induction in the multiple defense zones.

[0282] S1510b may specifically include: detecting the departure zone metal induction intensity of the target object in multiple defense zones based on the received signals generated by the respective receiving coils of multiple sensing units when leaving the field, and determining the departure metal induction intensity based on the sum of the departure zone metal induction in the multiple defense zones.

[0283] Figure 17 For example Figure 15 The diagram shows a second example of a metal detection method. The metal detection method in this embodiment is as follows: Figure 17 The second example process shown can determine the shape of a metal object by the distribution of metal induction intensity, and identify the target metal object belonging to the target object category by the shape of the metal object.

[0284] The receiving coil assembly of the security gate using the second example process may include multiple sets of receiving coils arranged at multiple height positions in the height direction, and each set of receiving coils at each height position may include a first-side receiving coil and a second-side receiving coil arranged opposite each other in the width direction of the detection channel.

[0285] In the second instance process, the metal induction intensity of the object detected by S1510 may include: a first unilateral induction intensity of the target object near the first side at each height position, detected based on the received signal generated by the first side receiving coil, and a second unilateral induction intensity of the target object near the second side at each height position, detected based on the received signal generated by the second side receiving coil.

[0286] Furthermore, in the second instance process, S1530 may include:

[0287] S1531: Based on the first unilateral sensing intensity and the second unilateral sensing intensity of the target object at multiple height positions, determine the projection shape of the projection plane jointly defined by the width and height directions of the metal object being carried.

[0288] S1533: Based on the projection shape of the target metal object on the projection plane, determine whether the carrying metal object is a target metal object belonging to the target object category.

[0289] Specifically, S1531 can determine the projected shape by locating the boundary position of the metal object in the width direction. In this case, it can specifically include:

[0290] Based on the intensity relationship between the first and second unilateral sensing intensities at each height position, the local width boundary position of a local portion of the target metal object at each height position is determined.

[0291] The projected shape of the target metal object on the projection plane is determined based on the local width boundary positions of local portions of the target metal object at multiple height locations.

[0292] To ensure that the local width boundary position of the first side is the same as the positioning reference of the second side, and to ensure the positioning accuracy of the boundary position, the process of determining the local width boundary position of the local portion at each height position, S1531, can specifically include:

[0293] Based on the intensity relationship between the first and second unilateral sensing intensities at each height position, and the width dimension of the detection space in the width direction, the local centroid position of a local portion of the target metal object at that height position is determined. For example, the local centroid position can be determined by referring to the algorithm that conforms to the Biot-Savart law described above, which will not be repeated here.

[0294] Based on the local centroid position of each height location, and the first unilateral sensing intensity and the second unilateral sensing intensity, the local width boundary position of the local portion of that height location is determined.

[0295] As mentioned above, the first unilateral induction intensity and the second unilateral induction intensity used by S1531 at each height position when determining the local centroid position and the local width boundary position can be characterized by the corresponding first unilateral normalized intensity and the second unilateral normalized intensity, respectively. The specific methods for obtaining the first unilateral normalized intensity and the second unilateral normalized intensity through normalization, and for determining the local centroid position and the local width boundary position using the first unilateral normalized intensity and the second unilateral normalized intensity, can be found in the previous description and will not be repeated here.

[0296] As described above, S1531 can obtain the projection profile of the metal object on the projection plane described above by connecting the local width boundary positions of the local parts of the metal object at multiple height positions. That is, S1531 can sequentially connect all the local width boundary positions on the first side along the height direction to obtain the first side boundary profile, and sequentially connect all the local width boundary positions on the second side along the height direction to obtain the second side boundary profile. Furthermore, the top and bottom endpoints of the first and second boundary profiles are interconnected to obtain the projection profile.

[0297] For example, S1531 can specifically include:

[0298] By fitting discrete coordinates of the local width boundary positions of local portions at multiple height positions of a metal object, a fitted profile of the metal object is obtained, wherein the fitted profile may include straight line boundary segments connecting every two adjacent local width boundary positions.

[0299] Based on the local centroid position of each height position, and the tilt angle of the straight line boundary segment with the local width boundary position of that height position as the endpoint relative to the width direction, the position of the local width boundary position of that height position is corrected so that the fitted contour is optimized into a projected contour by the position correction of the local width boundary position. The correction of the local width boundary position can be carried out in accordance with the Biot-Savart law method described above, which will not be repeated here.

[0300] In addition, in the second example process of the metal detection method, S1533 may specifically include: detecting the matching degree between the projected shape of the metal-carrying article and the reference projected shape pre-set for multiple selected article categories, and, in response to the detection result that the projected shape of the metal-carrying article successfully matches the reference projected shape of any selected article category, determining that the metal-carrying article is a target metal article belonging to the selected article category.

[0301] Figure 18 For example Figure 15 The diagram shows a third example of a metal detection method. The metal detection method in this embodiment is as follows: Figure 18 The third example process shown can identify the target metal item carried by the target object and belonging to the target item category by the projected shape of the metal object carried by the target object in the target scene where the target object enters and exits the security gate.

[0302] The security gate using the third instance process can be deployed at the entrance of the target scene, and the passage of the target object through the detection channel can include both entry and exit passage.

[0303] The receiving coil assembly of the security gate using the third example process may include multiple sets of receiving coils arranged at multiple height positions in the height direction. Each set of receiving coils at each height position may include a first-side receiving coil and a second-side receiving coil arranged relative to a first side and a second side in the width direction of the detection channel. Furthermore, the object metal sensing intensity determined in S1510 may include: a first unilateral sensing intensity of the target object near the first side at each height position, detected based on the receiving signal generated by the first-side receiving coil, and a second unilateral sensing intensity of the target object near the second side where the second door panel 12 is located at each height position, detected based on the receiving signal generated by the second-side receiving coil.

[0304] like Figure 18 As shown, in the third instance process, S1510 may include:

[0305] S1510c: Based on the received signals generated by the first-side receiving coil and the second-side receiving coil at each height position during the entry passage, detect the first single-sided entry induction intensity of the target object near the first side and the second single-sided entry induction intensity near the second side at that height position.

[0306] S1510d: Based on the received signals generated by the first-side receiving coil and the second-side receiving coil at each height position during departure travel, detect the first single-sided departure sensing intensity of the target object near the first side and the second single-sided departure sensing intensity near the second side at that height position.

[0307] That is, in the third detection instance:

[0308] The first unilateral sensing intensity at each height position includes: the first unilateral entry sensing intensity of the target object at that height position near the first side, detected by the received signal generated by the first-side receiving coil at that height position during entry passage, and the first unilateral exit sensing intensity of the target object at each height position near the first side, detected by the received signal generated by the first-side receiving coil at that height position during exit passage.

[0309] The second unilateral sensing intensity at each height position includes: the second unilateral entry sensing intensity of the target object at that height position near the second side, detected by the received signal generated by the second-side receiving coil at that height position during entry passage, and the second unilateral exit sensing intensity of the target object at that height position near the second side, detected by the received signal generated by the second-side receiving coil at that height position during exit passage.

[0310] See also Figure 18 In the third instance process, S1531 may include:

[0311] S1531a: Based on the first unilateral entry sensing intensity and the second unilateral entry sensing intensity of the target object at multiple height positions, determine the entry projection shape of the projection plane jointly defined by the width and height directions of the metal object being carried.

[0312] S1531b: Based on the first unilateral departure sensing intensity and the second unilateral departure sensing intensity of the target object at multiple height positions, determine the departure projection shape of the projection plane jointly defined by the width and height directions of the metal object.

[0313] That is, in the third detection example, the first one-sided sensing intensity and the second one-sided sensing intensity used to determine the projected shape of the carried metal object when entering the field are the first one-sided entry sensing intensity and the second one-sided entry sensing intensity, respectively. The projected shape determined at this time can be called the entry projected shape. When leaving the field, the first one-sided sensing intensity and the second one-sided sensing intensity used to determine the projected shape of the carried metal object are the first one-sided departure sensing intensity and the second one-sided entry sensing intensity, respectively. The projected shape determined at this time can be called the departure projected shape.

[0314] Please continue reading Figure 18 In the third instance process, S1533 can specifically include:

[0315] S1533a: Detect the consistency between the entrance projection shape and the exit projection shape of the same target object;

[0316] S1533b: In response to the detection result that the departure projection shape of any target object differs from the arrival projection shape, detect the degree of matching between the departure projection shape of the target object and the reference projection shapes that are pre-set for multiple selected item categories.

[0317] S1533c: In response to a detection result indicating that the projected shape of the carried metal object successfully matches the reference projected shape of any selected item category, the carried metal object is determined to be a target metal object belonging to that selected item category. Optionally, S1533c may further generate an alarm prompt.

[0318] Furthermore, in the third example flow of the metal detection method, both S1510c and S1510d can further include: acquiring the identity information of the target object, and the entrance projection shape determined in S1531a and the exit projection shape determined in S1531b are both associated with the successfully acquired identity information. Additionally, if the detection of the identity information of the target object about to enter the detection channel fails in S1510c or S1510d, an alarm can be generated to remind the site administrator to manually verify the identity of the target object.

[0319] It is understood that the metal detection method for security gates in this application embodiment may not rely on the calibration results of the parameter calibration method described above. That is, the control parameters of the security gate using the metal detection method may also be determined by other calibration methods besides the calibration method in this application embodiment.

[0320] Figure 19 This is an exemplary structural diagram of a parameter calibration device for a security gate, as described in an embodiment of this application. Please refer to... Figure 19 The embodiments of this application also provide a parameter calibration device for a security gate. The security gate using this parameter calibration device includes a detection channel and a detection assembly. The detection assembly includes a transmitting coil assembly and a receiving coil assembly arranged at intervals across the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for acquiring a receiving signal from the receiving coil assembly. The control parameters of the detection assembly include a frequency-phase combination for controlling the transmitting signal frequency of the transmitting circuit and for controlling the receiving control phase of the receiving circuit. Furthermore, the parameter calibration device includes:

[0321] The sample detection module 1910 is used to determine the single-sample test result of multiple sample metal items based on the received signal obtained by the receiving coil assembly during the test phase. The multiple sample metal items belong to multiple selected item categories with different item attributes. Furthermore, the single-sample test result of each sample metal item is used to characterize the single-sample metal induction intensity of the sample metal item in multiple tests in which the control parameters are configured to different frequency and phase combinations.

[0322] The single-class analysis module 1930 is used to determine the single-class correlation between the single-class metal induction intensity of each selected item category and the frequency phase combination of the control parameters based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of the control parameters. The single-class metal induction intensity is used to characterize the metal induction intensity of any metal item belonging to the corresponding selected item category when the control parameters are configured to any frequency phase combination.

[0323] The comprehensive analysis module 1950 is used to determine the calibration frequency phase combination of control parameters based on the single-category association and the sensitivity target value of the detection sensitivity for each selected item category.

[0324] Based on the above device, by testing sample metal items of multiple selected item categories with different item properties, the single-category correlation between the control parameters of the security gate's detection components and the single-category metal induction intensity of each selected item category can be determined. Furthermore, by comprehensively considering the correlation between multiple selected item categories and their respective corresponding sensitivity target values, it is helpful to calibrate the control parameters to have an optimal frequency and phase combination that makes the overall detection sensitivity of multiple selected item categories approach their respective sensitivity target values. Thus, for application scenarios where multiple item categories with different item properties are the detection targets, the risk of missed detection of the item categories can be reduced, thereby reducing the overall missed detection rate of the security gate.

[0325] In addition, for the specific principles of the sample detection module 1910, the single-class analysis module 1930 and the comprehensive analysis module 1950, please refer to the detailed explanation of S1310, S1330 and S1350 in the previous text, which will not be repeated here.

[0326] Figure 20 This is an exemplary structural diagram of a metal detection device for a security gate, as described in an embodiment of this application. Please refer to... Figure 20 In an embodiment of this application, a metal detection device for a security gate is also provided. The security gate using this metal detection device includes a detection channel and a detection assembly. The detection assembly includes a transmitting coil assembly and a receiving coil assembly arranged at intervals across the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for obtaining a receiving signal from the receiving coil assembly. The control parameters of the detection assembly are configured as a calibration frequency and phase combination determined by the parameter calibration method of the foregoing embodiments. Furthermore, the metal detection device includes:

[0327] The object detection module 2010 is used to detect the object metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel.

[0328] The detection decision module 2030 is used to determine whether a target object carries a target metal item belonging to the target item category based on the object's metal induction intensity. The target item category is any one of the selected item categories that should be inspected.

[0329] Based on the above device, since the control parameters are configured to cause the detection sensitivity of multiple selected item categories to approach the calibration frequency phase combination of their respective corresponding sensitivity target values, the detection sensitivity of the metal item carried by the target object can reach the expected level regardless of which item category it belongs to.

[0330] In addition, for the specific principles of the object detection module 2010 and the detection decision module 2030, please refer to the detailed explanation of S1510 and S1530 above, which will not be repeated here.

[0331] Similar to metal detection methods, the metal detection device for security gates in this application embodiment may also be independent of the calibration results of the parameter calibration method described above.

[0332] This application also provides a non-transitory computer-readable storage medium that stores instructions that, when executed by a processor, cause the processor to perform the parameter calibration method or metal detection method as described in the foregoing embodiments.

[0333] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A parameter calibration method for security gates, characterized in that, The security gate includes a detection channel and a detection assembly. The detection assembly includes a transmitting coil assembly and a receiving coil assembly arranged at intervals between the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for obtaining a receiving signal from the receiving coil assembly. The control parameters of the detection assembly include a frequency-phase combination for controlling the transmitting signal frequency of the transmitting circuit and for controlling the receiving control phase of the receiving circuit. Furthermore, the parameter calibration method includes: Based on the received signal obtained by the receiving coil assembly during the testing phase, the single-sample test results for multiple sample metal items are determined, wherein the multiple sample metal items belong to multiple selected item categories with different item attributes, and the single-sample test result of each sample metal item is used to characterize the single-sample metal induction intensity of the sample metal item in multiple tests in which the control parameters are configured to different frequency and phase combinations. Based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of the control parameters, the single-category association relationship between the single-category metal induction intensity of each selected item category and the frequency phase combination of the control parameters is determined. The single-category metal induction intensity is used to characterize the metal induction intensity of any metal item belonging to the corresponding selected item category when the control parameters are configured to any frequency phase combination. Based on the single-category association relationship and the sensitivity target value of the detection sensitivity of each selected item category, a multi-category association relationship is determined between the weighted sensing intensity of the single-category metal sensing intensity of multiple selected item categories and the frequency-phase combination of the control parameters, wherein the weight of the single-category metal sensing intensity of each selected item category in the weighted sensing intensity is associated with the corresponding sensitivity target value. Based on the aforementioned multi-category correlation, the calibration frequency phase combination of the control parameters is determined.

2. The parameter calibration method according to claim 1, characterized in that, The single-category association includes a single-category strength function, wherein the function value of the single-category strength function is used to characterize the metal induction intensity of any metal item of the corresponding selected item category when the control parameters are configured to an arbitrary frequency-phase combination; The multi-category association includes a multi-category intensity function, wherein the function value of the multi-category intensity function is used to characterize the weighted sensing intensity. The function value of the multi-category intensity function is obtained by weighting the function values ​​of the single-category intensity functions corresponding to multiple selected item categories. Furthermore, the weight of the function value of the single-category intensity function corresponding to each selected item category in the function value of the multi-category intensity function is associated with the corresponding sensitivity target value.

3. The parameter calibration method according to claim 1, characterized in that, The step of determining the calibration frequency phase combination of the control parameters based on the multi-category correlation includes: Based on the aforementioned multi-category correlation, the frequency-phase combination that maximizes the weighted induction intensity is determined as the calibration frequency-phase combination of the control parameters.

4. The parameter calibration method according to claim 1, characterized in that, The selected item categories include items subject to inspection and items exempt from inspection. The single-category metal induction intensity corresponding to each item subject to inspection has a positive weight in the weighted induction intensity, and the single-category metal induction intensity corresponding to each item exempt from inspection has a negative weight in the weighted induction intensity.

5. The parameter calibration method according to claim 4, characterized in that, The parameter calibration method further includes: The alarm rate set for each of the categories of items subject to inspection and the pass rate set for each of the categories of items exempt from inspection are obtained, wherein the alarm rate is used to characterize the sensitivity target value corresponding to the category of items subject to inspection, and the pass rate is used to characterize the sensitivity target value of the category of items exempt from inspection. Based on the alarm rate and the pass rate, the weight of the single-category metal induction intensity in the weighted induction intensity is determined for each of the categories of items subject to inspection and each of the categories of items exempt from inspection, respectively, where: The alarm rate has the same monotonicity as the sensitivity target value, and the single-category metal sensing intensity corresponding to each of the inspectable item categories is weighted in the weighted sensing intensity with the alarm rate as a positive value. The pass rate has a monotonicity opposite to the sensitivity target value, and the single-category metal sensing intensity corresponding to each of the exempted item categories is weighted negatively by the pass rate in the weighted sensing intensity.

6. The parameter calibration method according to claim 1, characterized in that, The detection channel includes multiple defense zones, the detection component includes sensing units respectively deployed in alignment with the multiple defense zones, the transmitting coil component includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil component includes receiving coils respectively deployed in the multiple sensing units. The multiple tests for each of the sample metal articles include multiple sets of tests in which each of the sample metal articles is individually located in multiple defense zones, and each set of tests in which each of the sample metal articles is individually located in any one defense zone includes multiple tests in which the control parameters are configured to different frequency phase combinations. The single-sample test result for each of the sample metal items includes multiple sets of single-zone test results obtained from multiple tests in multiple zone spaces. Furthermore, each set of single-zone test results for each sample metal item corresponding to each zone space includes: the single-sample zone metal induction intensity obtained from multiple tests on the sample metal item located alone in that zone space based on different frequency and phase combinations of the control parameters. The determination of the single-category correlation between the single-sample metal induction intensity of each selected item category and the frequency-phase combination of the control parameters, based on the single-sample metal induction intensity corresponding to different frequency-phase combinations of the control parameters for each sample metal item, includes: Based on the single-sample zone metal sensing intensity of each sample metal item corresponding to multiple zone spaces, the single-zone correlation between the single-category zone sensing intensity of each selected item category in each zone space and the frequency-phase combination of the control parameters is determined. The single-category zone sensing intensity is used to characterize the metal sensing intensity of any metal item belonging to the corresponding selected item category and located in the corresponding zone space when the control parameters are configured to any frequency-phase combination. Based on the single-zone association relationship and the occurrence probability of each selected item category in multiple zone spaces, the single-category association relationship between the single-category metal sensing intensity of each selected item category and the frequency-phase combination of the control parameters is determined. The single-category metal sensing intensity of each selected item category is characterized by the weighted result of the single-category zone sensing intensity of the selected item category in multiple zone spaces. Furthermore, the weight of the single-category zone sensing intensity of each selected item category in any one zone space is associated with the occurrence probability of the selected item category in that zone space.

7. The parameter calibration method according to claim 6, characterized in that, The single-zone association includes a zone strength function, wherein the function value of the zone strength function is used to characterize the intensity of the single-zone sensing intensity of the corresponding selected item category in the corresponding zone space when the control parameters are configured to an arbitrary frequency phase combination. The single-category association includes a single-category intensity function, wherein the function value of the single-category intensity function is used to characterize the metal induction intensity of any metal object of the corresponding selected item category when the control parameters are configured to an arbitrary frequency-phase combination. The function value of the single-category intensity function is obtained by weighting the function values ​​of the partition intensity functions corresponding to the same selected item category and corresponding to multiple defense zones. Furthermore, the weight of the function value of the partition intensity function corresponding to each selected item category to multiple defense zones in the function value of the single-category intensity function is associated with the occurrence probability of the selected item category in the multiple defense zones.

8. A metal detection method for security gates, characterized in that, The security gate includes a detection channel and a detection assembly. The detection assembly includes a transmitting coil assembly and a receiving coil assembly arranged at intervals between the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for obtaining a receiving signal from the receiving coil assembly. The control parameters of the detection assembly are configured as the calibration frequency-phase combination determined by the parameter calibration method as described in any one of claims 1 to 7. Furthermore, the metal detection method includes: Based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel, the object metal induction intensity of the target object is detected. Based on the metal induction intensity of the object, it is determined whether the target object carries a target metal item belonging to the target item category, wherein the target item category is any one of the selected item categories to be inspected.

9. The metal detection method according to claim 8, characterized in that, The security gate is deployed at the entrance of the target scene. The passage of the target object through the detection channel includes passing through the entrance of the detection channel along the entry direction into the target scene and passing through the exit of the detection channel along the exit direction away from the target scene. The metal induction intensity of the target object includes: the entry metal induction intensity of the target object detected based on the received signal generated by the receiving coil assembly during the entry passage, and the exit metal induction intensity of the target object detected based on the received signal generated by the receiving coil assembly during the exit passage. The step of determining whether the target object carries a target metal item belonging to the target item category based on the metal sensing intensity of the object includes: determining whether the target object carries the target metal item belonging to the target item category when leaving the venue based on the consistency between the metal sensing intensity upon entry and the metal sensing intensity upon exit.

10. The metal detection method according to claim 9, characterized in that, The detection channel includes multiple defense zones, the detection component includes sensing units respectively deployed in alignment with the multiple defense zones, the transmitting coil component includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil component includes transmitting coils respectively deployed in the multiple sensing units. The method of detecting the object metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel includes: Based on the received signals generated by the respective receiving coils of the multiple sensing units during the entry passage, the metal sensing intensity of the target object in the multiple defense zones is detected, and the entry metal sensing intensity is determined based on the sum of the metal sensing intensities in the multiple defense zones. Based on the received signals generated by the respective receiving coils of the multiple sensing units during the departure passage, the departure metal induction intensity of the target object in multiple defense zones is detected, and the departure metal induction intensity is determined based on the sum of the departure metal induction intensities in the multiple defense zones.

11. The metal detection method according to claim 9, characterized in that, The metal detection method further includes: acquiring the identity information of the target object, wherein the entry sensing intensity and the exit sensing intensity are both associated with the successfully acquired identity information.

12. The metal detection method according to claim 9, characterized in that, The step of determining whether the target object carries the target metal item belonging to the target item category when leaving the site based on the consistency between the entry metal sensing intensity and the exit metal sensing intensity includes: if the exit metal sensing intensity is greater than the entry metal sensing intensity, then it is determined that the target object carries the target metal item belonging to the target item category when leaving the site.

13. The metal detection method according to claim 8, characterized in that, The receiving coil assembly includes multiple sets of receiving coils arranged at multiple height positions in the height direction, and each set of receiving coils at each height position includes a first-side receiving coil and a second-side receiving coil arranged opposite to each other in the width direction of the detection channel. The metal induction intensity of the target object includes: a first unilateral induction intensity of the target object near the first side at each height position, detected based on the received signal generated by the first side receiving coil; and a second unilateral induction intensity of the target object near the second side at each height position, detected based on the received signal generated by the second side receiving coil. The step of determining whether the target object carries a target metal item belonging to the target item category based on the object's metal induction intensity includes: Based on the first unilateral sensing intensity and the second unilateral sensing intensity of the target object at multiple height positions, the projection shape of the metal object carried by the target object on the projection plane jointly defined by the width direction and the height direction is determined. Based on the projected shape of the carried metal object, it is determined whether the carried metal is the target metal object.

14. The metal detection method according to claim 13, characterized in that, The step of determining the projection shape of the metal object carried by the target object on the projection plane jointly defined by the width and height directions based on the first unilateral sensing intensity and the second unilateral sensing intensity of the target object at multiple height positions includes: Based on the intensity relationship between the first unilateral sensing intensity and the second unilateral sensing intensity at each height position, the local width boundary position of the local portion of the metal-carrying object at each height position is determined; The projected shape of the metal-carrying object is determined based on the local width boundary positions of local portions of the metal-carrying object at multiple height locations.

15. The metal detection method according to claim 14, characterized in that, The determination of the local width boundary position of a local portion of the metal-carrying object at each height position based on the intensity relationship between the first unilateral sensing intensity and the second unilateral sensing intensity at each height position includes: Based on the strength relationship at each height position and the width dimension of the detection channel in the width direction, the local centroid position of a local portion of the metal-carrying object at that height position is determined; Based on the local centroid position at each height location, and the first unilateral sensing intensity and the second unilateral sensing intensity, the local width boundary position of the local portion of the metal-carrying object at each height location is determined.

16. The metal detection method according to claim 15, characterized in that, The detection channel includes multiple defense zones, the detection component includes sensing units respectively deployed in alignment with the multiple defense zones, the transmitting coil component includes transmitting coils respectively deployed in the multiple sensing units, and the receiving coil component includes transmitting coils respectively deployed in the multiple sensing units. The first-side receiving coil and the second-side receiving coil in a set of receiving coils at each altitude position are respectively located in a pair of sensing units deployed in alignment with the defense zone space where that altitude position is located; The first unilateral sensing intensity is characterized by the first unilateral normalized intensity, wherein the first unilateral normalized intensity is: the proportion of the first unilateral sensing intensity determined based on the received signal generated by the first unilateral receiving coil in a set of receiving coils at each height position in the overall metallic sensing intensity of the sensing unit to which the first unilateral receiving coil belongs in the set of receiving coils. The second unilateral induction intensity is characterized by a second unilateral normalized intensity, wherein the second unilateral normalized intensity is: the proportion of the first unilateral induction intensity determined based on the received signal generated by the second unilateral receiving coil in a set of receiving coils at each height position to the overall metallic induction intensity of the induction unit to which the second unilateral receiving coil in the set of receiving coils belongs.

17. The metal detection method according to claim 15, characterized in that, Determining the projected shape of the metal-carrying object based on the local width boundary positions of local portions at multiple height locations includes: By connecting the local width boundary positions of the local portions of the metal-carrying object within multiple height ranges, the projected outline of the metal-carrying object on the projection plane is obtained. Based on the shape recognition of the projected contour, the projected shape of the metal-carrying object is determined.

18. The metal detection method according to claim 17, characterized in that, The step of obtaining the projected outline of the metal-carrying object on the projection plane by connecting the local width boundary positions of local portions of the metal-carrying object within multiple height ranges includes: By fitting discrete coordinates of the local width boundary positions of the local portion of the metal-carrying object within multiple height ranges, a fitted profile of the metal-carrying object is obtained, wherein the fitted profile includes straight line boundary segments connecting every two adjacent local width boundary positions. Based on the local centroid position and the tilt angle of the straight line boundary segment relative to the width direction, the position of the local width boundary position is corrected so that the fitted contour is optimized into the projected contour by the position correction of the local width boundary position.

19. The metal detection method according to claim 13, characterized in that, The step of determining whether the carried metal item is the target metal item based on the projected shape of the carried metal item includes: detecting the projected shape and a reference projected shape pre-set for a plurality of selected item categories, and determining the carried metal item as the target metal item in response to a detection result that the projected shape successfully matches the reference projected shape of any one of the selected item categories.

20. The metal detection method according to claim 13, characterized in that, The security gate is deployed at the entrance of the target scene. The passage of the target object through the detection channel includes passing through the entrance of the detection channel along the entry direction into the target scene and passing through the exit of the detection channel along the exit direction away from the target scene. The first unilateral sensing intensity at each height position includes: the first unilateral entry sensing intensity of the target object near the first side at each height position, detected based on the received signal generated by the first side receiving coil during the entry passage; and the first unilateral exit sensing intensity of the target object near the first side at each height position, detected based on the received signal generated by the first side receiving coil during the exit passage. The second unilateral sensing intensity at each height position includes: the second unilateral entry sensing intensity of the target object near the second side at each height position, detected based on the received signal generated by the second side receiving coil during the entry passage; and the second unilateral exit sensing intensity of the target object near the second side at each height position, detected based on the received signal generated by the second side receiving coil during the exit passage. The projection shape includes: the entrance projection shape of the target object on the projection plane, determined based on the first unilateral entrance sensing intensity and the second unilateral entrance sensing intensity of the target object at multiple height positions; and the departure projection shape of the target object on the projection plane, determined based on the first unilateral departure sensing intensity and the second unilateral departure sensing intensity of the target object at multiple height positions. The step of determining whether the carried metal is the target metal object based on the projected shape of the carried metal object includes: Detect the consistency between the entrance projection shape and the exit projection shape; In response to the detection result that the departure projection shape differs from the arrival projection shape, the matching degree between the departure projection shape and the reference projection shapes pre-set for multiple selected item categories is detected; In response to a detection result that the departure projection shape successfully matches the reference projection shape of any of the selected item categories, the carrying metal item is determined to be the target metal item.

21. A parameter calibration device for a security gate, characterized in that, The security gate includes a detection channel and a detection assembly. The detection assembly includes a transmitting coil assembly and a receiving coil assembly arranged at intervals between the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for obtaining a receiving signal from the receiving coil assembly. The control parameters of the detection assembly include a frequency-phase combination for controlling the transmitting signal frequency of the transmitting circuit and for controlling the receiving control phase of the receiving circuit. Furthermore, the parameter calibration device includes: The sample detection module is used to determine the single-sample test result of multiple sample metal items based on the received signal obtained by the receiving coil component during the test phase. The multiple sample metal items belong to multiple selected item categories with different item attributes. The single-sample test result of each sample metal item is used to characterize the single-sample metal induction intensity of the sample metal item in multiple tests in which the control parameters are configured to different frequency and phase combinations. The single-category analysis module is used to determine the single-category association between the single-category metal induction intensity of each selected item category and the frequency phase combination of the control parameters based on the single-sample metal induction intensity of each sample metal item corresponding to different frequency phase combinations of the control parameters. The single-category metal induction intensity is used to characterize the metal induction intensity of any metal item belonging to the corresponding selected item category when the control parameters are configured to any frequency phase combination. The comprehensive analysis module is used for: Based on the single-category association relationship and the sensitivity target value of the detection sensitivity of each selected item category, a multi-category association relationship is determined between the weighted sensing intensity of the single-category metal sensing intensity of multiple selected item categories and the frequency-phase combination of the control parameters, wherein the weight of the single-category metal sensing intensity of each selected item category in the weighted sensing intensity is associated with the corresponding sensitivity target value. Based on the aforementioned multi-category correlation, the calibration frequency phase combination of the control parameters is determined.

22. A metal detection device for a security gate, characterized in that, The security gate includes a detection channel and a detection assembly. The detection assembly includes a transmitting coil assembly and a receiving coil assembly arranged at intervals across the detection channel, a transmitting circuit for providing a transmitting signal to the transmitting coil assembly, and a receiving circuit for obtaining a receiving signal from the receiving coil assembly. The control parameters of the detection assembly are configured to the calibration frequency and phase combination determined by the parameter calibration device as described in claim 21. The metal detection device includes: The object detection module is used to detect the object metal induction intensity of the target object based on the received signal generated by the receiving coil assembly when the target object passes through the detection channel; The detection and decision module is used to determine whether the target object carries a target metal item belonging to the target item category based on the metal induction intensity of the object, wherein the target item category is any one of the selected item categories to be inspected.

23. A security gate, characterized in that, include The door panel assembly includes a first door panel and a second door panel respectively arranged on opposite sides of the detection channel in the width direction; The coil assembly includes a transmitting coil assembly and a receiving coil assembly deployed opposite to each other on the first door panel and the second door panel across the detection channel; A processor component for performing the parameter calibration method as described in any one of claims 1 to 7, or the metal detection method as described in any one of claims 8 to 20.

24. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores instructions, which, when executed by a processor, cause the processor to perform the parameter calibration method as described in any one of claims 1 to 7, or the metal detection method as described in any one of claims 8 to 20.

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