Millimeter wave detection complex scene analysis method and system

Abstract

The invention discloses a millimeter wave detection complex scene analysis method and a millimeter wave detection complex scene analysis system, relates to the technical field of millimeter wave analysis, and is used for solving the problem that the probability of misjudging a target state by a system is increased due to a target speed identification error. Calculating a radial speed of a target object; acquiring acceleration and tension data of a conveyor belt; calculating acceleration power spectral density and tension change rate; evaluating the running state of the conveyor belt; and finally, the target actual speed is obtained by combining the correction speed and the impact factor, the object state is judged according to the minimum speed resolution threshold value of the millimeter wave radar, a conveyor belt control instruction is output, and stable operation of the system is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of millimeter wave analysis, and more particularly, to a millimeter wave detection complex scene analysis method and system. BACKGROUND

[0002] In logistics, sorting and industrial automation scenarios, conveyor belts are widely used for conveying and unloading operations of goods. In order to realize accurate monitoring of the running state of the conveyor belt and the behavior of the goods, millimeter wave radars are gradually introduced into the conveyor belt system to realize real-time monitoring of moving targets due to their non-contact, high-precision and all-weather detection capabilities; in the prior art, the millimeter wave radar is usually used to collect the echo signal of the goods, and the radial velocity of the goods is calculated by time domain or frequency domain analysis to realize tracking and identification of the motion behavior of the goods.

[0003] The prior art has the following disadvantages: At present, in actual industrial scenarios, due to significant acceleration fluctuations and tension changes during high-speed operation or frequent start-stop of the conveyor belt system, the millimeter wave radar echo signal is easily disturbed, resulting in a decrease in detection accuracy, and the conveyor belt may have impact fluctuations caused by driving changes during the unloading stage. Such impact characteristics are not fully modeled or compensated, further exacerbating target speed identification errors, resulting in an increase in system misjudgment of target state probability. Therefore, a millimeter wave detection complex scene analysis method and system are proposed.

[0004] The above information disclosed in the background section is only intended to enhance the understanding of the background of the present disclosure, and therefore it can include information that does not constitute the prior art known to those of ordinary skill in the art. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, embodiments of the present application provide a millimeter wave detection complex scene analysis method and system, which solves the problems proposed in the above background by using Doppler shift analysis, acceleration spectrum modeling and unloading impact factor fusion evaluation technology.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme, a millimeter wave detection complex scene analysis method, comprising the following steps: Step S1: obtaining the time domain echo signal detected by the millimeter wave radar, performing Fourier transform on the time domain echo signal to obtain the Doppler shift of the millimeter wave radar, calculating the center frequency of the millimeter wave radar to obtain the millimeter wave wavelength, and analyzing the radial velocity of the target goods on the conveyor belt in combination with the Doppler shift; Step S2: detecting the acceleration data and tension data of the conveyor belt, calculating the acceleration power spectral density and tension variation rate according to the acceleration data and tension data, and evaluating the running state of the conveyor belt in combination with the acceleration power spectral density and tension variation rate; Step S3: Obtain the preliminary corrected speed of the target item by the radial speed of the target item and the running status of the conveyor belt, retrieve the unloading time of the conveyor belt, detect the driving characteristics of the conveyor belt and the frequency domain characteristics of the radar during the unloading time, and evaluate the unloading impact factor by combining the driving characteristics of the conveyor belt and the frequency domain characteristics of the radar. Step S4: Combine the preliminary corrected speed and the unloading impact factor to analyze the actual speed of the target item, retrieve the minimum speed resolution threshold of the millimeter-wave radar, determine the status of the target item based on its actual speed, and output different conveyor belt control commands.

[0007] In a preferred embodiment, in step S1, the millimeter-wave radar detects and receives time-domain echo signals, and converts the time-domain echo signals into frequency-domain signals through Fourier transform. Based on the Doppler effect, the frequency domain signal is treated as the Doppler frequency shift; The center frequency and speed of light of the millimeter-wave radar are detected, and the ratio of the speed of light to the center frequency is calculated to obtain the millimeter-wave wavelength. Half of the product of the Doppler shift and the millimeter-wave wavelength is taken as the radial velocity of the target object.

[0008] In a preferred embodiment, in step S2, a collection time window is set and divided into a fixed number of time intervals. Within the collection time window, the conveyor belt acceleration signal and tension signal are collected for each time interval, and the acceleration signal and tension signal are converted into acceleration frequency domain signal and tension frequency domain signal through Fourier transform. The acceleration power spectral density is obtained by dividing the square of the absolute value of the acceleration frequency domain signal by the total duration of the acquisition time window. The difference between two tension frequency domain signals within each adjacent time interval is calculated to obtain the tension change.

[0009] In a preferred embodiment, in step S2, the ratio of the tension change in each time interval to the time interval is calculated and the average value is taken to obtain the tension variation rate. When the peak value of the acceleration power spectral density exceeds the preset spectral peak threshold, the conveyor belt operation status will be judged as abnormal operation; A preset tension variation rate threshold is set. When the tension variation rate exceeds the tension variation rate threshold, it is determined that an abnormality has occurred in the conveyor belt.

[0010] In a preferred embodiment, in step S3, the linear speed of the conveyor belt is calculated based on the diameter of the conveyor belt rollers. Calculate the initial corrected speed of the target item based on the radial speed of the target item and the linear speed of the conveyor belt; The initial corrected speed of the target item is obtained by vector summing the radial velocity of the target item and the linear velocity of the conveyor belt.

[0011] In a preferred embodiment, in step S3, the unloading time of the conveyor belt is obtained by calculating the ratio of the length of the target item to the linear speed of the conveyor belt. During the unloading time of the conveyor belt, the peak current, current change rate, impact frequency energy, and peak impact frequency of the conveyor belt are monitored in real time. The conveyor belt drive characteristics are obtained by combining the peak current and the rate of change of current. The radar frequency domain characteristics are obtained by comprehensively calculating the impact frequency energy and the impact frequency peak value. The unloading impact factor is obtained by weighted averaging of the conveyor belt drive characteristics and radar frequency domain characteristics.

[0012] In a preferred embodiment, in step S4, the actual speed of the target item is calculated by adding the preliminary corrected speed to the unloading impact factor; The minimum velocity resolution of the millimeter-wave radar is used as the minimum velocity resolution threshold. When the actual speed of the target item is greater than or equal to the minimum speed resolution threshold, the target item is considered to be in normal condition.

[0013] In a preferred embodiment, in step S4, when the actual speed of the target item is less than the minimum speed resolution threshold, the state of the target item is determined to be abnormal. If the target item is determined to be in a normal state, output a normal operation control command to maintain the current actual speed; If the target item is determined to be in an abnormal state, output a deceleration command and a stop command.

[0014] A millimeter-wave detection system for analyzing complex scenes includes a signal processing module, a state assessment module, a velocity correction module, and a judgment and control module. The signal processing module is responsible for processing the time-domain echo signal detected by the millimeter-wave radar, obtaining the frequency-domain signal through Fourier transform, and then analyzing the Doppler frequency shift and calculating the radial velocity of the target object. The condition assessment module is used to collect and process the acceleration and tension data of the conveyor belt, calculate the acceleration power spectral density and tension variation rate, and assess the operating status of the conveyor belt. The speed correction module calculates the initial corrected speed of the target item based on its radial speed and the operating status of the conveyor belt. It also evaluates the unloading impact factor by analyzing the driving characteristics and radar frequency domain characteristics during the unloading time of the conveyor belt. The judgment and control module integrates the initial correction speed and unloading impact factor, analyzes the actual speed of the target item, compares it with the minimum speed resolution threshold of the millimeter-wave radar, judges the state of the target item, and outputs corresponding control commands.

[0015] The technical effects and advantages of this invention are as follows: This invention acquires time-domain echo signals detected by millimeter-wave radar and analyzes these signals using Fourier transform to obtain the Doppler frequency shift, thereby calculating the radial velocity of the target item. Next, the millimeter-wave radar detection system detects the acceleration and tension data of the conveyor belt, and evaluates the operating status of the conveyor belt by calculating the acceleration power spectral density and tension variation rate, further providing a reference for the dynamic motion state of the target item. Combining the radial velocity of the target item with the operating status of the conveyor belt, the millimeter-wave radar detection system calculates the preliminary corrected velocity of the target item. Based on the unloading time of the conveyor belt, it detects the driving characteristics of the conveyor belt and the radar frequency domain characteristics, and comprehensively analyzes to obtain the unloading impact factor. Finally, the system combines the preliminary corrected velocity with the unloading impact factor to further analyze the actual velocity of the target item, and judges the state of the target item based on the minimum velocity resolution threshold of the millimeter-wave radar, thereby outputting corresponding conveyor belt control commands to ensure the normal operation or adjustment of the conveyor belt. This achieves accurate identification and dynamic control of the target item's motion state under complex operating conditions. Attached Figure Description

[0016] Figure 1 This is a flowchart of a millimeter-wave detection method for analyzing complex scenes according to the present invention.

[0017] Figure 2 This is a schematic diagram of a millimeter-wave detection system for analyzing complex scenes according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention acquires time-domain echo signals detected by millimeter-wave radar and analyzes these signals using Fourier transform to obtain the Doppler frequency shift, thereby calculating the radial velocity of the target item. Next, the millimeter-wave radar detection system detects the acceleration and tension data of the conveyor belt, and evaluates the operating status of the conveyor belt by calculating the acceleration power spectral density and tension variation rate, further providing a reference for the dynamic motion state of the target item. Combining the radial velocity of the target item with the operating status of the conveyor belt, the millimeter-wave radar detection system calculates the preliminary corrected velocity of the target item. Based on the unloading time of the conveyor belt, it detects the driving characteristics of the conveyor belt and the radar frequency domain characteristics, and comprehensively analyzes to obtain the unloading impact factor. Finally, the system combines the preliminary corrected velocity with the unloading impact factor to further analyze the actual velocity of the target item, and judges the state of the target item based on the minimum velocity resolution threshold of the millimeter-wave radar, thereby outputting corresponding conveyor belt control commands to ensure the normal operation or adjustment of the conveyor belt.

[0020] Example 1: A method for analyzing complex scenes using millimeter-wave detection, such as... Figure 1 As shown, it includes the following steps: Step S1: Obtain the time-domain echo signal detected by the millimeter-wave radar, perform Fourier transform on the time-domain echo signal to obtain the Doppler frequency shift of the millimeter-wave radar, detect the center frequency of the millimeter-wave radar to calculate the millimeter-wave wavelength, and analyze the radial velocity of the target item on the conveyor belt in combination with the Doppler frequency shift. Step S2: Detect the acceleration and tension data of the conveyor belt, calculate the acceleration power spectral density and tension variation rate based on the acceleration and tension data, and evaluate the operating status of the conveyor belt by combining the acceleration power spectral density and tension variation rate. Step S3: Obtain the preliminary corrected speed of the target item by the radial speed of the target item and the running status of the conveyor belt, retrieve the unloading time of the conveyor belt, detect the driving characteristics of the conveyor belt and the frequency domain characteristics of the radar during the unloading time, and evaluate the unloading impact factor by combining the driving characteristics of the conveyor belt and the frequency domain characteristics of the radar. Step S4: Combine the preliminary corrected speed and the unloading impact factor to analyze the actual speed of the target item, retrieve the minimum speed resolution threshold of the millimeter-wave radar, determine the status of the target item based on its actual speed, and output different conveyor belt control commands.

[0021] The specific implementation is as follows: In step S1, the millimeter-wave radar detects the emitted electromagnetic waves, which are reflected upon encountering the target object on the conveyor belt. The millimeter-wave radar detects and receives the reflected electromagnetic wave signal, which is the time-domain echo signal. The time-domain echo signal is converted into a frequency-domain signal through Fourier transform, and the transformation expression is as follows: ; Where, x For time-domain echo signals, It is a frequency domain signal.

[0022] According to the Doppler effect, the frequency domain signal that is shifted when reflected back is called the Doppler frequency shift.

[0023] The center frequency and speed of light of a millimeter-wave radar are detected, and the ratio of the speed of light to the center frequency is calculated to obtain the millimeter-wave wavelength.

[0024] The radial velocity of the target object is calculated based on the Doppler frequency shift and millimeter-wave wavelength, using the following formula: ; Where v is the radial velocity of the target object, For Doppler frequency shift, It is the wavelength of millimeter waves.

[0025] It should be noted that the Fourier transform is a mathematical tool for converting time-domain echo signals to frequency-domain signals, used to analyze the composition of different frequency components in a signal; the Doppler effect refers to the phenomenon that the received wavelength changes when the relative motion between the wave source and the observer changes.

[0026] In step S2, a data acquisition time window is set and divided into a fixed number of time intervals. Within the data acquisition time window, the acceleration signal and tension signal of the conveyor belt at each time interval are acquired in real time by the acceleration sensor and tension sensor installed on the conveyor belt. The acceleration time-domain echo signal is converted into an acceleration frequency-domain signal using Fourier transform, and the acceleration power spectral density is further calculated using the following formula: ; in, For acceleration power spectral density, The signal is in the frequency domain of acceleration, and T is the total duration of the acquisition time window.

[0027] The tension time-domain echo signal is converted into a tension frequency-domain signal by Fourier transform. The tension variation rate is obtained by calculating the ratio of each tension change in each time interval to the time interval and taking the average value.

[0028] Among them, tension change refers to the difference between two tension data within each adjacent time interval. It is an indicator that describes the rate of tension change of the conveyor belt during operation and is used to evaluate the operating status of the conveyor belt, such as load changes, slack or overload.

[0029] Acceleration power spectral density reflects the vibration state and impact characteristics of the conveyor belt vibration signal at different frequencies. After obtaining the acceleration power spectral density, the maximum value of each frequency band in the spectrum is collected, and the maximum value of the frequency band is taken as the peak value of the acceleration power spectral density. A preset peak value threshold is set, and the peak value of the acceleration power spectral density and the peak value threshold of the spectrum are standardized to keep them under the same dimension.

[0030] When the peak value of the acceleration power spectral density exceeds the peak value threshold of the spectrum, the millimeter-wave radar monitoring system will determine that the conveyor belt is operating abnormally. Under normal operating conditions, the conveyor belt runs smoothly at a stable speed, the vibration of the conveyor belt should be uniform and gentle, and the peak value of the acceleration power spectral density will not be too high.

[0031] A preset tension variation rate threshold is set. When the tension variation rate exceeds the tension variation rate threshold, it is determined that an abnormality has occurred in the conveyor belt.

[0032] The tension variation rate reflects the tension change of the conveyor belt and can indicate whether there are problems such as load changes, slack or overload during the operation of the conveyor belt. Under normal operating conditions, the tension variation rate remains within the normal range and the tension variation rate is small.

[0033] When the acceleration power spectral density peak has no significant peak and the tension variation rate is less than the tension variation rate threshold, the conveyor belt is judged to be operating normally. When the acceleration power spectral density peak has a significant peak and the tension variation rate is greater than or equal to the tension variation rate threshold, the conveyor belt is judged to be operating abnormally. It should be noted that an accelerometer is an electronic device that measures the acceleration force of an object; a tension sensor is an electronic device used to measure the tensile force or tension acting on an object; the peak spectral threshold and the tension variation rate threshold are determined by professionals based on the actual system's operating characteristics and design standards through experiments and data analysis, and will not be elaborated upon here.

[0034] In step S3, the preliminary corrected speed of the target item is calculated based on the radial speed of the target item and the running state of the conveyor belt, where the running state of the conveyor belt is the linear speed of the conveyor belt.

[0035] The linear speed of the conveyor belt can be calculated using the diameter of the conveyor belt rollers. The formula is as follows: ; in, The linear speed of the conveyor belt, The diameter of the drum is measured directly with vernier calipers. Multiple measurements are taken and the average value is taken to reduce errors. The rotational speed of the drum is measured by placing the probe of a mechanical tachometer vertically against the center hole at the end of the drum shaft. The speed value is read directly by driving the internal gear mechanism of the tachometer through friction transmission.

[0036] The initial correction speed of the target item is obtained by summing its radial velocity and the linear velocity vector of the conveyor belt, as shown in the following formula: ; in, The initial correction speed for the target item. Radial velocity, This represents the linear speed of the conveyor belt.

[0037] Retrieve the conveyor belt unloading time, which refers to the time interval between the target item being unloaded from the conveyor belt and completely leaving the conveyor belt.

[0038] The length of the target object is measured, and the unloading time of the conveyor belt is calculated by the ratio of the length of the target object to the linear speed of the conveyor belt. During the unloading time, the conveyor belt drive characteristics and radar frequency domain characteristics are detected in real time.

[0039] Conveyor belt drive characteristics refer to the set of parameters reflecting the operating status of the conveyor belt motor, including peak current and rate of change of current. Radar frequency domain characteristics refer to the vibration energy and main frequency parameters of the interaction between the target object and the conveyor belt extracted through spectrum analysis, including impact frequency energy and impact frequency peak.

[0040] The preset acquisition time is N times the unloading time. The acquisition time is divided into multiple time intervals. The current signal is acquired by the current sensor at a acquisition rate of 1 second. The acquired current signal is a continuous signal that changes with time. The maximum instantaneous current value within this time interval is selected as the current peak value.

[0041] The data acquisition time should be N times the unloading time. If the acquisition time is too short, the signal will be incomplete. Ensure that the data acquisition window is long enough to capture the complete signal changes after the target item is unloaded, and prevent the high-frequency signals or current changes caused by the unloading impact from being missed.

[0042] The current time series data of the conveyor belt motor is collected by the current sensor. The current sample value at any time is selected in the time series data, and the current sample value at the next adjacent time is selected. The current difference is obtained by the difference between the current sample values ​​of these two adjacent sampling points, and then compared with the time interval to obtain the current change rate during this time period.

[0043] The impact frequency energy characteristic of radar frequency domain features represents the vibration energy generated by the interaction between the target item and the conveyor belt during unloading. This feature is extracted from spectrum analysis to analyze the energy distribution of the signal in the frequency domain.

[0044] Radar echo signals are acquired using an accelerometer. The time-domain echo signal is converted to a frequency-domain signal using Fourier transform. The energy spectrum is obtained by squaring the absolute value of the frequency-domain signal. The impact frequency energy is then calculated based on the energy spectrum. ; in, and It is the frequency range of the impact frequency. It is the energy spectrum of that frequency band. Energy at the impact frequency.

[0045] The frequency range of the impact frequency is set based on experience. and .

[0046] Within a known impulse frequency range, the frequency domain signal is treated as spectral data, and the spectral data is divided into many frequency points. For each frequency point Calculate the energy spectrum Compare the energy spectrum at each frequency point The frequency point corresponding to the maximum value is the peak value of the impact frequency.

[0047] Calculate the conveyor belt drive characteristics by combining peak current and rate of change of current: ; in, For conveyor belt drive features, This is the peak current. Let x be the rate of change of current, and y be the weighting coefficients.

[0048] Calculate radar frequency domain characteristics by combining impact frequency energy and impact frequency peak value: ; in, Radar frequency domain characteristics, For impact frequency energy, denoted as the peak impulse frequency, and z and w as radar weighting coefficients, representing the degree of contribution of different radar characteristics to the impulse factor.

[0049] The unloading impact factor is obtained by weighted averaging of conveyor belt drive characteristics and radar frequency domain characteristics.

[0050] ; in, For unloading impact factors, This is the impact weighting coefficient.

[0051] The unloading impact factor is a quantitative parameter representing the impact caused by factors such as interaction, collision, friction, and vibration between the item and the conveyor belt during the unloading process. During the unloading process, if the initial correction speed of the target item is too high, the target item will be impacted by the conveyor belt or other items. A preset impact threshold is set. When the initial correction speed of the target item is greater than or equal to the impact threshold, it means that there is an impact during the unloading process, triggering an alarm or control command. Otherwise, there is no impact.

[0052] It should be noted that x, y, z, w The impact threshold is adjusted based on practical application through experiments or experience. A current sensor is a device used to detect the magnitude of current in a circuit and convert it into a measurable, transmittable, or processable electrical signal or other form of information.

[0053] In step S4, the actual velocity of the target item is calculated by initially correcting the velocity and the unloading impact factor: ; in, The actual speed of the target item. For the initial speed correction, C is the unloading impact factor.

[0054] When the unloading impact factor is positive, it indicates that the target item was impacted during the unloading process, and the actual speed will increase. When the unloading impact factor is negative, it indicates that the unloading process has little impact on the target item, and the actual speed will be close to the initial corrected speed.

[0055] Every millimeter-wave radar has a fixed minimum hardware velocity resolution, which is a fixed constant determined by the radar hardware parameters. It refers to the minimum velocity difference that the radar system can detect and distinguish, that is, the velocity difference between two objects that the system can distinguish without producing errors. It is provided directly by the manufacturer in the product specification and can accurately measure the minimum velocity variation range of the radar system.

[0056] Use this minimum velocity resolution as the minimum velocity resolution threshold. .

[0057] when Greater than or equal to When the actual speed of the target item is within the effective measurement range of the radar, the radar can detect the movement of the target item, the conveyor belt system determines that the state of the target item is normal, and maintains the current actual speed of the conveyor belt. when Less than When the actual speed of the target item is outside the effective measurement range of the radar, the radar cannot detect the movement of the target item. The conveyor belt system determines that the state of the target item is abnormal and will automatically slow down or stop the conveyor belt system. Based on the actual speed and state of the target item, the conveyor belt system determines to output different conveyor belt control commands to adapt to the current operating conditions: If the conveyor belt system is in normal condition, it will output a normal operation control command. At this time, the conveyor belt will maintain its current actual speed to ensure stable transport of the target item. If the conveyor belt system is in abnormal condition, it will output a deceleration command to prevent damage caused by system failure or the target item not being detected correctly.

[0058] When an abnormal state of the target item is continuously detected, the system will prioritize the shutdown command to ensure the safety of the system and prevent physical damage to the item due to incorrect detection. The deceleration command is triggered when the target item is in a slightly abnormal state, but if the item has been found to be unable to be detected normally, the shutdown command should be output directly to avoid further operation.

[0059] Example 2: Based on a millimeter-wave detection system for analyzing complex scenes, such as... Figure 2 As shown, a method for analyzing complex scenarios in millimeter-wave detection is used, including a signal processing module, a state evaluation module, a velocity correction module, and a judgment and control module.

[0060] The signal processing module is responsible for processing the time-domain echo signal detected by the millimeter-wave radar, obtaining the frequency-domain signal through Fourier transform, and then analyzing the Doppler frequency shift and calculating the radial velocity of the target object. The condition assessment module is used to collect and process the acceleration and tension data of the conveyor belt, calculate the acceleration power spectral density and tension variation rate, and assess the operating status of the conveyor belt. The speed correction module calculates the initial corrected speed of the target item based on its radial speed and the operating status of the conveyor belt. It also evaluates the unloading impact factor by analyzing the driving characteristics and radar frequency domain characteristics during the unloading time of the conveyor belt. The judgment and control module integrates the initial correction speed and unloading impact factor, analyzes the actual speed of the target item, compares it with the minimum speed resolution threshold of the millimeter-wave radar, judges the state of the target item, and outputs corresponding control commands.

[0061] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0062] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and inventive constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0063] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0064] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0065] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for analyzing complex scenes using millimeter-wave detection, characterized in that: Includes the following steps: Step S1: Obtain the time-domain echo signal detected by the millimeter-wave radar, perform Fourier transform on the time-domain echo signal to obtain the Doppler frequency shift of the millimeter-wave radar, detect the center frequency of the millimeter-wave radar to calculate the millimeter-wave wavelength, and analyze the radial velocity of the target item on the conveyor belt in combination with the Doppler frequency shift. Step S2: Detect the acceleration and tension data of the conveyor belt, calculate the acceleration power spectral density and tension variation rate based on the acceleration and tension data, and evaluate the operating status of the conveyor belt by combining the acceleration power spectral density and tension variation rate. Step S3: Obtain the preliminary corrected speed of the target item by the radial speed of the target item and the running status of the conveyor belt, retrieve the unloading time of the conveyor belt, detect the driving characteristics of the conveyor belt and the frequency domain characteristics of the radar during the unloading time, and evaluate the unloading impact factor by combining the driving characteristics of the conveyor belt and the frequency domain characteristics of the radar. Step S4: Combine the preliminary corrected speed and the unloading impact factor to analyze the actual speed of the target item, retrieve the minimum speed resolution threshold of the millimeter-wave radar, determine the status of the target item based on its actual speed, and output different conveyor belt control commands.

2. The method for analyzing complex scenes using millimeter-wave detection according to claim 1, characterized in that: In step S1, the millimeter-wave radar detects and receives time-domain echo signals, and converts the time-domain echo signals into frequency-domain signals through Fourier transform; Based on the Doppler effect, the frequency domain signal is treated as the Doppler frequency shift; The center frequency and speed of light of the millimeter-wave radar are detected, and the ratio of the speed of light to the center frequency is calculated to obtain the millimeter-wave wavelength. Half of the product of the Doppler shift and the millimeter-wave wavelength is taken as the radial velocity of the target object.

3. The method for analyzing complex scenes using millimeter-wave detection according to claim 1, characterized in that: In step S2, a collection time window is set and divided into a fixed number of time intervals. Within the collection time window, the conveyor belt acceleration signal and tension signal are collected for each time interval. The acceleration signal and tension signal are then converted into acceleration frequency domain signal and tension frequency domain signal through Fourier transform. The acceleration power spectral density is obtained by dividing the square of the absolute value of the acceleration frequency domain signal by the total duration of the acquisition time window. The difference between two tension frequency domain signals within each adjacent time interval is calculated to obtain the tension change.

4. The method for analyzing complex scenes using millimeter-wave detection according to claim 3, characterized in that: In step S2, the ratio of the tension change in each time interval to the time interval is calculated and the average value is taken to obtain the tension variation rate. When the peak value of the acceleration power spectral density exceeds the preset spectral peak threshold, the conveyor belt operation status will be judged as abnormal operation; A preset tension variation rate threshold is set. When the tension variation rate exceeds the tension variation rate threshold, it is determined that an abnormality has occurred in the conveyor belt.

5. The method for analyzing complex scenes using millimeter-wave detection according to claim 2, characterized in that: In step S3, the linear speed of the conveyor belt is calculated based on the diameter of the conveyor belt rollers. Calculate the initial corrected speed of the target item based on the radial speed of the target item and the linear speed of the conveyor belt; The initial corrected speed of the target item is obtained by vector summing the radial velocity of the target item and the linear velocity of the conveyor belt.

6. The method for analyzing complex scenes using millimeter-wave detection according to claim 5, characterized in that: In step S3, the ratio of the length of the target item to the linear speed of the conveyor belt is calculated to obtain the unloading time of the conveyor belt; During the unloading time of the conveyor belt, the peak current, current change rate, impact frequency energy, and peak impact frequency of the conveyor belt are monitored in real time. The conveyor belt drive characteristics are obtained by combining the peak current and the rate of change of current. The radar frequency domain characteristics are obtained by comprehensively calculating the impact frequency energy and the impact frequency peak value. The unloading impact factor is obtained by weighted averaging of the conveyor belt drive characteristics and radar frequency domain characteristics.

7. The method for analyzing complex scenes using millimeter-wave detection according to claim 6, characterized in that: In step S4, the actual speed of the target item is calculated by adding the preliminary corrected speed to the unloading impact factor; The minimum velocity resolution of the millimeter-wave radar is used as the minimum velocity resolution threshold. When the actual speed of the target item is greater than or equal to the minimum speed resolution threshold, the target item is considered to be in normal condition.

8. The method for analyzing complex scenes using millimeter-wave detection according to claim 7, characterized in that: In step S4, when the actual speed of the target item is less than the minimum speed resolution threshold, the state of the target item is determined to be abnormal. If the target item is determined to be in a normal state, output a normal operation control command to maintain the current actual speed; If the target item is determined to be in an abnormal state, output a deceleration command and a stop command.

9. A millimeter-wave detection complex scene analysis system, used to implement the millimeter-wave detection complex scene analysis method according to any one of claims 1-8, characterized in that: It includes a signal processing module, a state evaluation module, a speed correction module, and a judgment and control module; The signal processing module is responsible for processing the time-domain echo signal detected by the millimeter-wave radar, obtaining the frequency-domain signal through Fourier transform, and then analyzing the Doppler frequency shift and calculating the radial velocity of the target object. The condition assessment module is used to collect and process the acceleration and tension data of the conveyor belt, calculate the acceleration power spectral density and tension variation rate, and assess the operating status of the conveyor belt. The speed correction module calculates the initial corrected speed of the target item based on its radial speed and the operating status of the conveyor belt. It also evaluates the unloading impact factor by analyzing the driving characteristics and radar frequency domain characteristics during the unloading time of the conveyor belt. The judgment and control module integrates the initial correction speed and unloading impact factor, analyzes the actual speed of the target item, compares it with the minimum speed resolution threshold of the millimeter-wave radar, judges the state of the target item, and outputs corresponding control commands.

Images