A method of calibrating a metal detection apparatus and a metal detection apparatus

Abstract

The application provides a correction method of a metal detection device and the metal detection device. The correction method comprises the following steps: obtaining an induction value in a correction collection time period in a current correction period; judging whether the metal detection device detects metal in the correction collection time period according to the induction value; and if not, updating a detection reference value in an adjacent next correction period according to the induction value. The correction method provided by the application can reduce errors caused by instability of the circuit of the metal detection device, improve the detection rate of the metal detection device and reduce the false alarm rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal detection, and particularly relates to a correction method of a metal detection device and the metal detection device. BACKGROUND

[0002] A metal detector is an electronic instrument for detecting metal and has been widely applied to many fields such as security inspection, mineral exploration and industrial production. A commonly used metal detector detects metal by using the principle of electromagnetic induction. When powered, the transmitting coil in the metal detector generates a periodically changing alternating magnetic field. If there is a metal object in the detection range, the alternating magnetic field can induce eddy current in the metal object, and further generate a secondary magnetic field that has interference on the original alternating magnetic field. The metal detector senses the changing magnetic field and analyzes it to realize metal detection.

[0003] However, the metal detector is easily affected by the stability of its own circuit during detection. For example, the zero drift phenomenon of the amplification circuit due to temperature, humidity and other factors can easily cause false positives or false negatives, resulting in low detection accuracy. SUMMARY

[0004] The application provides a correction method of a metal detection device and the metal detection device, which can reduce errors caused by the instability of the metal detection device itself, improve the detection rate of the metal detection device and reduce the false positive rate.

[0005] In a first aspect, the application provides a correction method of a metal detection device, which includes: acquiring an induction value in a correction collection time period in a current correction period; determining whether the metal detection device detects metal in the correction collection time period according to the induction value; and updating a detection reference value in an adjacent next correction period according to the induction value if the metal detection device does not detect metal.

[0006] Preferably, the end time of the correction collection time period in the current correction period is the same as the end time of the current correction period.

[0007] The correction method provided by the embodiments of the present application acquires the induction value in the correction acquisition time period in the current correction period, and updates the detection reference value in the adjacent next correction period according to the induction value when it is determined that the metal detection device does not detect metal in the correction acquisition time period according to the induction value. If the metal detection device does not detect metal in the correction acquisition time period, the change of the induction value is not disturbed by the metal. At this time, the change of the induction value reflects the change of the components in the circuit of the metal detection device. The present application updates the detection reference value in the next correction period according to the induction value reflecting the change of the circuit, which can reduce or even eliminate the error caused by the instability of the circuit, so that the accuracy of the updated detection reference value is higher, and then the metal detection device can have a higher detection rate and a lower false alarm rate when detecting the target metal according to the updated detection reference value. When the metal detection device executes the correction method, the foregoing steps will be repeated periodically, so that the metal detection device can be self-corrected by periodically judging whether the detection reference value can be updated and updating the detection reference value when the condition is met during the entire running time period from starting to closing, without manual intervention, which is more intelligent.

[0008] In addition, the correction method provided by the present application does not need to use new hardware, that is, the hardware circuit of the metal detection device does not need to be improved, the complexity of the circuit design is low, the cost is also low, and new errors will not be introduced.

[0009] In combination with the first aspect, in a possible implementation manner, the determining whether the metal detection device detects metal in the correction acquisition time period according to the induction value comprises:

[0010] When the absolute value of the difference between the first average value and the detection reference value in the current correction period is less than a first threshold value, it is determined that the metal detection device does not detect metal in the correction acquisition time period, wherein the first average value is the arithmetic average value of the induction value.

[0011] The updating the detection reference value in the adjacent next correction period according to the induction value comprises:

[0012] The detection reference value in the adjacent next correction period is updated as the first average value.

[0013] In the embodiment, by comparing the absolute value of the difference between the first average value (i.e. the arithmetic average value of the induction values, at this time, there are multiple induction values) and the detection reference value in the current correction period and the first threshold value, it can be determined whether the metal detection device detects metal in the correction collection time period. When the absolute value of the difference between the first average value and the detection reference value in the current correction period is less than the first threshold value, in other words, when the absolute value of the difference between the first average value and the current detection reference value is small, the change of the induction value is caused by the error due to the instability of the self-circuit, rather than being affected by the presence of metal. Therefore, only when it is determined that the metal detection device does not detect metal in the correction collection time period, the detection reference value is updated, which is more reasonable, the accuracy of the updated detection reference value is higher, and the subsequent detection process of the target metal is not affected, and the detection rate of the metal detector is improved and the false alarm rate is reduced.

[0014] In combination with the first aspect, in a possible implementation, if it is determined that metal is detected in each of the correction collection time periods in the continuous M correction periods, where M is a positive integer greater than or equal to 2;

[0015] The detection reference value in the M+1 correction period is updated according to the first average value corresponding to each of the correction collection time periods in the M correction periods.

[0016] Through the above setting, the correction method provided by the present application can reduce or even eliminate the continuous interference of the external environment on the detection process (for example, there is a metal for a long period of time, or there is a metal in the detection range of the metal detection device for a long period of time and the metal leaves the detection range at a certain moment), and the detection reference value is updated according to the change of the metal in the environment, so that the detection rate can be improved and the false alarm rate can be reduced.

[0017] In combination with the first aspect, in a possible implementation, the updating of the detection reference value in the M+1 correction period according to the first average value corresponding to each of the correction collection time periods in the M correction periods comprises:

[0018] The detection reference value in the M+1 correction period is updated according to N qualified values in the M first average values, where the absolute value of the difference between each of the qualified values and the second average value is less than the second threshold value, the second average value is the arithmetic average value of the M first average values, and N is a positive integer less than or equal to M.

[0019] In combination with the first aspect, in a possible implementation, the updating of the detection reference value in the M+1 correction period according to the N qualified values in the M first average values comprises:

[0020] If N is greater than or equal to a third threshold value, the detection reference value in the M+1th correction period is updated as an arithmetic mean of the N qualified values.

[0021] With reference to the first aspect, in a possible implementation manner, the correction method further includes:

[0022] After the metal detection device is started, a plurality of measurement values in a preset time period are acquired, and an arithmetic mean of the plurality of measurement values is taken as a detection reference value in a first correction period.

[0023] The second aspect provides a metal detection device, including:

[0024] An acquisition unit is configured to acquire an induction value in a correction acquisition time period in a current correction period;

[0025] A judgment unit is configured to judge whether the metal detection device detects metal in the correction acquisition time period according to the induction value;

[0026] An update unit is configured to update a detection reference value in an adjacent next correction period according to the induction value if the metal detection device does not detect metal in the correction acquisition time period.

[0027] The third aspect provides a metal detection device, including a memory configured to store a computer program, and a processor configured to execute the computer program to implement the correction method of the first aspect and any possible implementation manner of the first aspect.

[0028] The metal detection device provided by the present application has the advantages of the correction method provided by the first aspect, which will not be repeated here.

[0029] The fourth aspect provides a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the correction method of the first aspect and any possible implementation manner of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic flowchart of the correction method of the metal detection device provided by the embodiments of the present application;

[0031] Figure 2 is a time axis schematic diagram of the metal detection device after being started according to an embodiment of the present application;

[0032] Figure 3 is a schematic flowchart of an embodiment of the correction method provided by the embodiments of the present application;

[0033] Figure 4 is a schematic flow chart of another embodiment of the correction method provided by embodiments of the present application;

[0034] Figure 5 is a schematic block diagram of a metal detection device provided by embodiments of the present application;

[0035] Figure 6 is a structural schematic diagram of a metal detection device provided by embodiments of the present application. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0037] In the following description, specific details are set forth in order to provide a thorough understanding of embodiments of the application. However, persons of ordinary skill in the art will readily recognize that embodiments of the application can be practiced without

[0038] The term "comprising" is intended to indicate, and does not exclude, that other features, integers, steps, operations, elements, components or groups thereof can be added to the described features, integers, steps, operations, elements, components or groups thereof. The term "comprising", "including", "containing", "have" and "including" and their conjugates, shall not exclude the presence of other features, integers, steps, operations, elements, components or groups thereof, and that the described features, integers, steps, operations, elements, components or groups thereof can be supplemented with other features, integers, steps, operations, elements, components or groups thereof. Furthermore, it is clear to a person skilled in the art that features, integers, steps, operations, elements, components or groups thereof can be repeated in one or more embodiments.

[0039] In the description of the present application, "a plurality of" means two or more.

[0040] In the description of the present application, it should be understood that the terms "first", "second" are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implying the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features.

[0041] The metal detection device is an electronic instrument for detecting metal, and the metal detection device applied to the security check field, such as a security check door, a handheld detection device, etc., is mainly applied in public places with large human flow, such as airports, stations, large-scale meetings, etc., and can detect whether the person to be detected carries prohibited metal articles, such as guns, controlled knives, etc., to protect the personal safety of the crowd in the public place. The commonly used metal detection device usually uses the electromagnetic induction effect of the oscillation coil to detect metal objects. However, due to the poor stability of the circuit of the metal detection device itself, for example, the semiconductor devices (such as transistors) in the circuit are easily affected by the temperature, humidity and other factors of the environment to produce zero drift phenomenon, which easily leads to false positives and false negatives of the metal detection device.

[0042] In order to solve the above technical problems, the embodiment of the present application provides a correction method of a metal detection device and a metal detection device. The correction method periodically acquires an induction value in a correction collection time period, and when it is determined that the metal detection device does not detect metal in the correction collection time period, the detection reference value is updated according to the induction value. The detection reference value is the reference value for the metal detection device to judge whether there is target metal. In this way, the error caused by the instability of the circuit of the metal detection device itself can be reduced, and the detection rate of the metal detection device can be improved and the false positive rate can be reduced.

[0043] Figure 1 is a schematic flow chart of the correction method of the metal detection device provided by the embodiment of the present application. Hereinafter, the correction method 100 provided by the embodiment of the present application is described in combination with Figure 1 The correction method 100 provided by the embodiment of the present application can be applied to any type of metal detection device, such as a security check door, a handheld security check instrument, etc. The correction method 100 includes:

[0044] In step S101, an induction value in a correction collection time period in a current correction period is acquired.

[0045] Specifically, the correction collection time period is a period of time in the correction period, and the duration of the correction collection time period is less than the duration of the correction period. There is only one correction collection time period in each correction period.

[0046] Figure 2 is a time axis schematic diagram of the metal detection device provided by the embodiment of the present application after starting, such as Figure 2As shown, preferably, the ending time of the correction acquisition time period is the same as the ending time of the correction period. Exemplarily, the length of the correction period can be 1 minute, 3 minutes, 5 minutes, or 10 minutes, etc., and the length of the correction acquisition time period can be 2 seconds, 5 seconds, 7 seconds, or 10 seconds, etc. For example, the length of the correction period is 5 minutes, and the length of the correction acquisition time period is 5 seconds. Taking the first correction period as an example, assuming that the starting time of the first correction period is 0, then the ending time of the first correction period is 5 minutes, and the starting time of the correction acquisition time period in the first correction period is 4 minutes and 55 seconds, and the ending time is also 5 minutes.

[0047] Alternatively, the ending time of the correction acquisition time period can also be different from the ending time of the correction period. For example, the starting time of the correction acquisition time period in the first correction period can be 4 minutes, and the ending time is 4 minutes and 5 seconds. In this case, the relative position of the correction acquisition time period in each correction period is fixed. That is, the starting time of the correction acquisition time period in the second correction period is 9 minutes, and the ending time is 9 minutes and 5 seconds. That is, regardless of the relationship between the ending time of the correction acquisition time period and the ending time of the correction period, the time interval between adjacent correction acquisition time periods (the interval between the starting times of the two, the length of which is equal to the length of the correction period) is fixed. That is, when the metal detection device starts to run step S101 of the correction method 100, the operation of acquiring the induction value in the correction acquisition time period will be performed every certain time interval.

[0048] In the embodiments of the present application, the acquired induction value in the correction acquisition time period in the current correction period is used to update the detection reference value in the adjacent next correction period, and the detection reference value is the reference value (or basis) for the metal detection device to determine whether there is a target metal. Here, the target metal refers to a metal object that needs to be detected by the metal detection device, such as a controlled knife carried by a passenger. When the ending time of the correction acquisition time period is the same as the ending time of the correction period, the timeliness of the induction value is better, so that the detection reference value updated according to the induction value is more accurate.

[0049] It should be understood that the length of the correction period and the length of the correction acquisition time period can be preset according to the actual application requirements of the metal detection device; or the length of the correction period can be adjusted according to the working state of the metal detection device. For example, when the working intensity of the metal detection device is large (i.e., when the passenger flow is large), the length of the correction period is made longer (which can be 10 minutes, 20 minutes, etc.), and when the working intensity of the metal detection device is small (i.e., when the passenger flow is small), the length of the correction period is made shorter (which can be 1 minute, 2 minutes, etc.).

[0050] Optionally, the sensed value can be a voltage value, a current value, the frequency, amplitude, phase, or other values ​​of a signal. The sensed value can be obtained based on the principle of electromagnetic induction or other induction principles (such as microwaves), and this application does not impose any limitations on this. When a metal object appears within the detection range of the metal detection device, the sensed value will change.

[0051] Optionally, in step S101, the acquired sensing value can be one or multiple. Acquiring multiple sensing values ​​can avoid the problem of inaccurate detection reference value caused by inaccurate single data.

[0052] Optionally, the number of sensing values ​​within a calibration acquisition period can be 2, 4, 8, or 10, etc., and this application does not impose any restrictions on this.

[0053] Step S102: Determine whether the metal detection device detected metal during the calibration collection period based on the sensing value.

[0054] like Figure 2 Taking the first calibration cycle as an example, with the start and end times of the first calibration cycle being 0 and 5 minutes respectively, and the duration of the calibration acquisition time period being 5 seconds, step S102 determines whether the metal detection device detects metal within the time period of 4 minutes and 55 seconds to 5 minutes.

[0055] If not, i.e., if it is determined that the metal detection device did not detect any metal during the calibration acquisition period, then step S103 is executed to update the detection reference value for the next adjacent calibration cycle based on the sensing value. That is, at the end of the current calibration cycle, the detection reference value is updated, and this updated detection reference value is used for the next adjacent calibration cycle.

[0056] If so, that is, when it is determined that the metal detection device detects metal during the calibration collection period, then step S104 is executed, and the detection reference value in the next adjacent calibration cycle is not updated, that is, the detection reference value in the next adjacent calibration cycle is the same as the detection reference value in the current calibration cycle.

[0057] Furthermore, the calibration method 100 provided in this application embodiment further includes: obtaining the measured value within the current detection cycle (this measured value is of the same type as the aforementioned sensing value, for example, both are voltage values, and can be one or more), and determining whether there is a target metal within the current detection cycle based on the measured value and the detection reference value. If so (i.e., it is determined that there is a target metal), then the buzzer sounds or the LED lights up to issue an alarm; if not (i.e., it is determined that there is no target metal), then no alarm is issued.

[0058] Exemplarily, the length of the detection period can be 0.5 seconds, 1 second, 2 seconds, etc., which is not limited in the present application. Assuming that the length of the detection period is 2 seconds, the metal detection device performs the judgment of whether there is a target metal every 2 seconds when performing the above steps of the correction method 100.

[0059] It should be understood that the detection period and the correction period (including the correction acquisition time period) are independent of each other, that is, the judgment of whether there is a target metal in the detection period and the judgment of whether there is a metal in the correction acquisition time period are independent of and do not affect each other. Specifically, the length of one correction period is greater than the length of one detection period, and the detection process (detection period) of the target metal can be continuously performed in one correction period, which can be performed once, twice, or even five times. The judgment processes in the detection period and the correction period do not interfere with each other, and only the judgment of the target metal in the detection period uses the detection reference value in the correction period. Among them, the judgment result of whether there is a target metal in the detection period is used to judge whether the alarm needs to be sounded to remind the security personnel; and the judgment result of whether there is a metal in the correction acquisition time period is further used to judge whether the detection reference value needs to be updated, and this judgment result is not used as a basis for whether the alarm needs to be sounded, and the updated detection reference value is used as a basis for judging whether there is a target metal in the detection period.

[0060] In the embodiments of the present application, for each detection period, the detection reference value in the detection period is determined according to the relationship between the end time of the detection period and the correction period. As shown in Figure 2 For example, the end time of the first two detection periods is before the end time of the first correction period, so the detection reference value in the first two detection periods is the detection reference value in the first correction period, and the end time t of the third detection period is after the end time of the first correction period and before the end time of the second correction period. Therefore, the detection reference value in the third detection period is the detection reference value in the second correction period. In other words, if the detection reference value is updated before the end time of the current detection period, the judgment process of whether there is a target metal in the current detection period is based on the updated detection reference value.

[0061] Optionally, the correction method 100 provided in the embodiments of the present application further comprises: after the metal detection device is started, obtaining a plurality of measurement values (the type of the measurement value is the same as the type of the induction value, for example, both are voltage values) in a preset time period, and taking the arithmetic mean of the plurality of measurement values as the detection reference value in the first correction period.

[0062] As shown in Figure 2As shown, the starting moment of the preset time period is the starting moment of the metal detection device, and the starting moment of the first correction period and the first detection period is the next moment adjacent to the ending moment of the preset time period. That is, when the metal detection device applies the correction method 100, the detection of the target metal is not performed in the preset time period after the starting, and the correction of the detection reference value is not started, but after the detection reference value in the first correction period, that is, the detection reference value in the first detection period, is determined according to the plurality of measurement values obtained in the preset time period (the detection reference value here is the initial detection reference value), the detection of the target metal and the correction process of the detection reference value are started.

[0063] Exemplarily, the length of the preset time period can be 5 seconds, 10 seconds, 20 seconds, etc., and the number of measurement values can be 5, 10, 20, etc., which are not limited in the present application.

[0064] Through the above steps, the detection reference value in the first correction period (also in the first detection period) is determined according to the plurality of measurement values obtained in the preset time period after the starting of the metal detection device, which can exclude some non-target metals (hereinafter referred to as environmental metals) in the environment where the metal detection device is located, such as the security X-ray machine, liquid detector, explosive detector, etc. placed beside the security door, so as not to affect the detection of the target metal by the metal detection device, and can avoid the situation that the metal detection device always alarms by misjudging the environmental metal as the target metal, thereby reducing the false alarm rate.

[0065] Optionally, the detection reference value in the first correction period can also be a pre-set value, that is, the metal detection device directly performs the first detection period and the first correction period after the starting.

[0066] Further, the correction method provided by the embodiment of the present application further comprises: performing a reset operation before the starting moment of the preset time period after the starting of the metal detection device, so as to clear the inductance value, detection reference value and other data stored in the last use, thereby not affecting the normal use of the metal detection device after the starting.

[0067] The correction method 100 provided by the embodiments of the present application acquires the induction value in the correction acquisition time period in the current correction period, and updates the detection reference value in the adjacent next correction period according to the induction value when it is determined that the metal detection device does not detect metal in the correction acquisition time period according to the induction value. If the metal detection device does not detect metal in the correction acquisition time period, the change of the induction value is not disturbed by the metal. At this time, the change of the induction value reflects the change of the components in the circuit of the metal detection device. The embodiments of the present application update the detection reference value in the next correction period according to the induction value reflecting the change of the circuit, which can reduce or even eliminate the error caused by the instability of the circuit, so that the accuracy of the updated detection reference value is higher, and the metal detection device can have a higher detection rate and a lower false alarm rate when detecting the target metal according to the updated detection reference value. When the metal detection device executes the correction method 100, the foregoing steps are repeated periodically, so that the metal detection device can be self-corrected by periodically judging whether the detection reference value can be updated and updating the detection reference value when the condition is met during the entire running time period from starting to closing, without manual intervention, which is more intelligent.

[0068] In addition, the correction method 100 provided by the embodiments of the present application does not need to use new hardware, that is, the hardware circuit of the metal detection device does not need to be improved, the complexity of the circuit design is low, the cost is also low, and new errors are not introduced.

[0069] In a possible embodiment, Figure 3 is a schematic flowchart of an embodiment of the correction method provided by the embodiments of the present application, as Figure 3 shown, determining whether the metal detection device detects metal in the correction acquisition time period according to the induction value includes: when the absolute value of the difference between the first average value and the detection reference value in the current correction period is less than the first threshold value, determining that the metal detection device does not detect metal in the correction acquisition time period, wherein the first average value is the arithmetic average value of the induction value.

[0070] updating the detection reference value in the adjacent next correction period according to the induction value includes: updating the detection reference value in the adjacent next correction period to the first average value.

[0071] Further, when the absolute value of the difference between the first average value and the detection reference value in the current correction period is greater than the first threshold value, it is determined that the metal detection device detects metal in the correction acquisition time period, and the detection reference value in the adjacent next period is not updated, that is, the detection reference value remains unchanged.

[0072] It should be understood that when the metal detection device executes the correction method 100, the foregoing steps are repeated periodically. Figure 3 The flow steps shown.

[0073] In the present embodiment, by comparing the absolute value of the difference between the first average value (i.e. the arithmetic average of the induction values, at this time, there are multiple induction values) and the detection reference value in the current correction period and the size of the first threshold value, it can be determined whether the metal detection device detects metal in the correction collection time period. When the absolute value of the difference between the first average value and the detection reference value in the current correction period is less than the first threshold value, in other words, when the absolute value of the difference between the first average value and the current detection reference value is small, the change of the induction value is caused by the error of the instability of the self-circuit, rather than being affected by the presence of metal. Therefore, only when it is determined that the metal detection device does not detect metal in the correction collection time period, the detection reference value is updated, which is more reasonable, and the accuracy of the updated detection reference value is higher, which will not affect the subsequent detection process of the target metal, and can also improve the detection rate of the metal detector and reduce the false alarm rate.

[0074] It should be understood that the first threshold value is a preset value and is positive, and the first threshold value can be determined according to the actual use scene of the metal detection device.

[0075] In a possible embodiment, according to the obtained measured value in the current detection period and the detection reference value, it is determined whether there is a target metal in the current detection period, comprising: when the absolute value of the difference between the third average value and the detection reference value in the current detection period is less than the fourth threshold value, it is determined that the metal detection device does not detect the target metal in the current detection period; when the absolute value of the difference between the third average value and the detection reference value in the current detection period is greater than or equal to the fourth threshold value, it is determined that the metal detection device detects the target metal in the current detection period, and then an alarm operation can be performed. Wherein, the third average value is the arithmetic average of the multiple measured values.

[0076] Here, the fourth threshold value represents the detection sensitivity of the metal detection device, and the user can change the size of the fourth threshold value by adjusting the hardware circuit when using the metal detection device, and thus the sensitivity of the metal detection device can be changed, so that the metal detection device can be applied to different use scenes.

[0077] In other embodiments, when there are multiple induction values, the step of determining whether the metal detection device detects metal in the correction collection time period according to the multiple induction values can be performed by other statistical calculation methods, as long as the deviation degree of the multiple induction values as a whole from the detection reference value in the current correction period can be measured. Illustratively, the deviation absolute value of each induction value corresponding to the induction value and the detection reference value in the current correction period is determined, and the arithmetic average of the multiple deviation absolute values is calculated, and then the arithmetic average of the multiple deviation absolute values and a threshold value are compared to determine whether metal is detected.

[0078] Optionally, the determination of whether there is a target metal in the detection period can adopt the same determination logic as the above embodiment.

[0079] Optionally, when only one induction value is obtained, the first average value is the induction value itself.

[0080] Further, Figure 4 is a schematic flow chart of an embodiment of the correction method provided by the present application, as Figure 4 indicated, the correction method 100 provided by the present application further includes:

[0081] If it is determined that metal is detected in each of the M consecutive correction acquisition time periods, wherein M is a positive integer greater than or equal to 2;

[0082] According to the first average value corresponding to each of the M correction acquisition time periods in the M correction periods, the detection reference value in the M+1 correction period is updated.

[0083] It should be understood that the value of M can be set according to the actual use of the metal detection device. For example, M can be 10, 20, 50, or even 100, etc. In actual application, M can be taken to be larger.

[0084] As Figure 2 indicated, in Figure 2 the M consecutive correction periods (i.e., the M correction periods are consecutive in time), that is, there are M consecutive correction acquisition time periods (for the correction acquisition time period, consecutive does not mean consecutive in time), if it is determined that metal is detected in each of the M correction acquisition time periods, M first average values can be obtained, and then the detection reference value in the M+1 correction period can be updated according to the M first average values. As Figure 2 indicated, the M+1 correction period is the adjacent next correction period of the last correction period in the M consecutive correction periods.

[0085] In the M consecutive correction periods, if one of the correction time periods is determined to not detect metal, the first average value corresponding to this correction acquisition time period is discarded (which can also be understood as deleted, not stored), so that the first average value corresponding to this correction acquisition time period cannot be obtained, and the subsequent step of "updating the detection reference value in the M+1 correction period according to the first average value corresponding to each of the M correction acquisition time periods in the M correction periods" cannot be performed.

[0086] If it is determined that metal is detected in each of the M consecutive correction collection time periods, it indicates that there is a metal in the detection range of the metal detection device for a long time. If the metal exists in the environment for a long time (it can be understood that the security personnel know the existence of the metal), the metal detection device does not need to alarm every detection period, which may cause interference to the detection of other new metals and may cause false alarm, which is not conducive to the judgment of the security personnel. The application can divide the metal that exists in the environment for a long time into an environmental metal, and the interference caused by the environmental metal is considered when updating the detection reference value, so that the subsequent detection of the target metal can be more accurate. Through the above setting, the correction method provided by the application can reduce or even eliminate the continuous interference of the external environment on the detection process (for example, a metal exists for a long time, or a metal exists in the detection range of the metal detection device for a long time and leaves the detection range at a certain moment), and the detection reference value is updated according to the change of the metal in the environment, so that the detection rate can be improved and the false alarm rate can be reduced.

[0087] Optionally, the M consecutive correction periods in which metal is detected in each of the M consecutive correction collection time periods are located in a preset time interval. For example, after the metal detection device is started, the starting time of the first correction period is 0, the length of the preset time interval is T1, and the ending time of the first time interval is T1. The above M consecutive correction periods are located in the first time interval [0-T1], or the second time interval [T1-2T1], or the pth time interval [(p-1)T1-pT1], and only then can the next step of "updating the detection reference value in the M+1th correction period according to the first average value corresponding to each correction collection time period in the M correction periods" be performed.

[0088] Through the above steps, the preconditions for performing the step of "updating the detection reference value" are more stringent, so that the interference caused by uncertain factors in the environment can be minimized, and the accuracy of the detection reference value can be improved.

[0089] As shown in Figure 4 updating the detection reference value in the M+1th correction period according to the first average value corresponding to each correction collection time period in the M correction periods, comprises:

[0090] updating the detection reference value in the M+1th correction period according to N qualified values in the M first average values, wherein the absolute value of the difference between each qualified value and the second average value is less than the second threshold value, the second average value is the arithmetic average of the M first average values, and N is a positive integer less than or equal to M.

[0091] Specifically, the N qualified values are determined from the M first average values, wherein only the first average values satisfying the condition that the absolute value of the difference from the second average value is less than the second threshold value are stored and determined as the qualified values, and the first average values not satisfying the condition (which can be understood as obvious outliers) are deleted, so that the fluctuation range of the N qualified values is small, and it can be considered that the N qualified values represent the changes caused by the same metal. Since the authenticity of the arithmetic mean is easily affected by extreme values (i.e., the aforementioned obvious outliers), by deleting some obvious outliers and updating the detection reference value in the M+1 correction period according to the remaining qualified values, the accuracy of the updated detection reference value can be higher.

[0092] Optionally, the detection reference value in the M+1 correction period can be updated as the arithmetic mean of the N qualified values.

[0093] Optionally, the second threshold value can be the standard deviation of the M first average values, and the second threshold value can also be 2 times, 3 times, etc. of the standard deviation, or any value preset according to the actual application scenario.

[0094] Specifically, the N qualified values can be all or part of the M first average values. When N is equal to M, it means that all the M first average values satisfy the above condition and can be used as qualified values.

[0095] Further, as shown in Figure 4 updating the detection reference value in the M+1 correction period according to the N qualified values of the M first average values, comprising:

[0096] If N is greater than or equal to the third threshold value, the detection reference value in the M+1 correction period is updated as the arithmetic mean of the N qualified values.

[0097] Here, the third threshold value is a positive integer, and the third threshold value can be a certain percentage of M, such as 100%, 95%, 90%, 70%, 50%, etc. For example, M is 50, and the third threshold value can be 45, 40, 35, etc. For another example, M is 100, and the third threshold value can be 80, 70, etc. Illustratively, M is 100, and the third threshold value is 80. Only when the total number N of qualified values is greater than or equal to 80 (for example, N is 85, 90, 92, etc.) will the detection reference value in the M+1 correction period be updated as the arithmetic mean of the N qualified values. When N is 20, 60, 70, etc., the representativeness of the N qualified values can not be enough, and the detection reference value in the M+1 correction period is not updated.

[0098] By the above steps, the precondition of updating the detection reference value in the M+1th correction period to the arithmetic mean of the N qualified values is more strict, so that some interference in the environment can be reduced, the accuracy of the updated detection reference value is improved, and then the detection rate of the metal detection device can be improved and the false positive rate can be reduced.

[0099] The embodiment of the present application also provides a metal detection device 200, Figure 5 is a schematic block diagram of the metal detection device provided by the embodiment of the present application, as Figure 5 shown, the metal detection device 200 includes an acquisition unit 210, a judgment unit 220 and an updating unit 230.

[0100] The acquisition unit 210 is configured to acquire an induction value in a correction collection time period in a current correction period; the judgment unit 220 is configured to judge whether the metal detection device detects metal in the correction collection time period according to the induction value; and the updating unit 230 is configured to update a detection reference value in an adjacent next correction period according to the induction value if the metal detection device does not detect metal in the correction collection time period.

[0101] Further, the judgment unit 220 is specifically configured to: when an absolute value of a difference between a first average value and the detection reference value in the current correction period is less than a first threshold value, determine that the metal detection device does not detect metal in the correction collection time period, wherein the first average value is an arithmetic mean of the induction value; and the updating unit 230 is specifically configured to: update the detection reference value in the adjacent next correction period to the first average value.

[0102] The embodiment of the present application also provides a metal detection device 300, Figure 6 is a structural schematic diagram of the metal detection device provided by the embodiment of the present application, as Figure 6 shown, the metal detection device 300 includes a processor 310, a memory 320 and a computer program 330 stored in the memory 320 and executable on the processor. The processor 310 implements various possible embodiments of the above correction method 100 when executing the computer program 330.

[0103] Optionally, the metal detection device 300 provided by the embodiment of the present application can be a security door, a handheld security instrument or the like.

[0104] When the processor 310 in the metal detection device 300 provided by the embodiments of the present application executes the computer program 330 to implement various possible embodiments of the above-mentioned correction method 100, the operation speed of the processor 310 is very fast, and thus the speed of updating the detection reference value is also very fast, which is equivalent to real-time correction updating and does not affect the detection, alarm and other operations of the metal detection device 300 on the target metal.

[0105] The embodiments of the present application also provide a computer readable storage medium, and the computer readable storage medium stores a computer program. When the computer program is executed by a processor, various possible embodiments of the above-mentioned correction method 100 are implemented.

[0106] Optionally, the computer readable storage medium can be a random access memory (RAM), a memory, a read only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable magnetic disk, a CD-ROM, or any other form of storage medium known in the technical field.

[0107] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, and all the changes or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A calibration method of a metal detection apparatus, characterized by, The method comprises: obtaining an induction value in a correction acquisition time period in a current correction period; determining whether the metal detection device detects metal in the correction acquisition time period according to the induction value; if not, it is indicated that the change of the induction value is not disturbed by the metal, and the detection reference value in an adjacent next correction period is updated according to the induction value, wherein the change of the induction value reflects the change of the components in the circuit of the metal detection device itself; the determination whether the metal detection device detects metal in the correction acquisition time period according to the induction value comprises: when the absolute value of the difference between the first average value and the detection reference value in the current correction period is less than the first threshold value, it is determined that the metal detection device does not detect metal in the correction acquisition time period, wherein the first average value is the arithmetic average value of the induction value; the updating of the detection reference value in the adjacent next correction period according to the induction value comprises: updating the detection reference value in the adjacent next correction period as the first average value; the correction method further comprises: obtaining a measured value in a current detection period, and determining whether there is target metal in the current detection period according to the measured value and the detection reference value, and if there is, alarming; the determination whether there is target metal in the current detection period according to the measured value and the detection reference value in the current detection period comprises: when the absolute value of the difference between the third average value and the detection reference value in the current detection period is greater than or equal to the fourth threshold value, it is determined that the metal detection device detects target metal in the current detection period, wherein the third average value is the arithmetic average value of the plurality of measured values; the correction method further comprises: if it is determined that metal is detected in each correction acquisition time period in the continuous M correction periods, wherein M is a positive integer greater than or equal to 2; updating the detection reference value in the M+1 correction period according to the first average value corresponding to each correction acquisition time period in the M correction periods.

2. The correction method of claim 1, wherein the updating of the detection reference value in the M+1 correction period according to the first average value corresponding to each correction acquisition time period in the M correction periods comprises: updating the detection reference value in the M+1 correction period according to N qualified values in the M first average values, wherein the absolute value of the difference between each qualified value and the second average value is less than the second threshold value, the second average value is the arithmetic average value of the M first average values, and N is a positive integer less than or equal to M.

3. The correction method of claim 2, wherein, the updating of the detection reference value in the M+1 correction period according to N qualified values in the M first average values comprises: if N is greater than or equal to the third threshold value, updating the detection reference value in the M+1 correction period as the arithmetic average value of the N qualified values.

4. The correction method according to any one of claims 1 to 3, characterized in that, the correction method further comprises: after the metal detection device is started, a plurality of measurement values in a preset time period are obtained, and the arithmetic average value of the plurality of measurement values is taken as the detection reference value in the first correction period.

5. The correction method according to any one of claims 1 to 3, characterized in that, the end time of the correction acquisition time period in the current correction period is the same as the end time of the current correction period.

6. A metal detection apparatus characterized by, ​ An acquisition unit is configured to acquire a sensing value in a correction acquisition time period in a current correction period; A determination unit is configured to determine whether the metal detection device detects metal in the correction acquisition time period according to the sensing value; An updating unit is configured to update a detection reference value in a next correction period adjacent to the current correction period according to the sensing value if the metal detection device does not detect metal in the correction acquisition time period, wherein the change of the sensing value reflects the change of components in the circuit of the metal detection device itself. The determination unit is specifically configured to determine that the metal detection device does not detect metal in the correction acquisition time period when an absolute value of a difference between a first average value and the detection reference value in the current correction period is less than a first threshold value, wherein the first average value is an arithmetic average value of the sensing value. The updating unit is specifically configured to update the detection reference value in the next correction period adjacent to the current correction period as the first average value. The metal detection device is further configured to acquire a measured value in a current detection period, and determine whether there is target metal in the current detection period according to the measured value and the detection reference value, and alarm if there is target metal. Determining whether there is target metal in the current detection period according to the measured value and the detection reference value in the current detection period includes: Determining that the metal detection device detects target metal in the current detection period when an absolute value of a difference between a third average value and the detection reference value in the current detection period is greater than or equal to a fourth threshold value, wherein the third average value is an arithmetic average value of a plurality of measured values. The metal detection device is further configured to determine that metal is detected in each of the correction acquisition time periods in M consecutive correction periods, wherein M is a positive integer greater than or equal to 2. Updating the detection reference value in an M+1 correction period according to a first average value corresponding to each of the correction acquisition time periods in the M correction periods.

7. A metal detection apparatus characterized by, The memory is configured to store a computer program. The processor is configured to execute the computer program to implement the steps of the correction method in any one of claims 1-5. The computer program stored on the computer readable storage medium is executed by the processor to implement the steps of the correction method in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, ​

Images