A method and system for capturing key frames of a race walking video based on surface acoustic wave

Abstract

The present invention provides a method for capturing key frames of a race walking video based on surface acoustic waves, including: acquiring real-time motion videos through a video information acquisition system; performing pressure detection through a surface acoustic wave sensor set at a specific position; sampling the real-time output signal of the surface acoustic wave sensor through a frequency selection circuit, and determining the landing state of the foot through frequency comparison; sending data to a single-chip microcomputer through a signal transmitting end and a signal receiving end, and the single-chip microcomputer sending the data to a computer; the present invention can automatically capture key frames in the race walking video based on the surface acoustic wave sensor, avoiding the cumbersome process of manually marking key points and the adverse effects of human subjective factors on the results.

Description

Technical Field

[0001] The present invention relates to the technical field of data acquisition and processing, and particularly to a method and system for capturing key frames of a race walking video based on surface acoustic waves. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Race walking is an international competitive event. Some athletes are good at taking small steps with high frequency, while some athletes prefer to take big steps with high frequency, which leads to some athletes being penalized for fouls many times in major competitions. Therefore, it is particularly important to use scientific methods to capture race walking postures to help athletes correct their race walking postures.

[0004] When capturing the race walking postures of athletes, multiple cameras are usually used to synchronously collect images of the athletes' race walking process from different angles, and then the collected images are manually analyzed offline. When analyzing the data, generally, operators find each key point frame by frame in the collected video, and then the terminal analyzes the speed and angle of the key points. Usually, the key points appear when the athlete's foot touches the ground. Since it is necessary to manually find the key points when the athlete's foot touches the ground frame by frame in the video, the efficiency and accuracy are relatively low. Summary of the Invention [[ID=)18]]

[0005] In order to solve the above problems, the present invention proposes a method and system for capturing key frames of a race walking video based on surface acoustic waves. The present invention can overcome the problem of low efficiency in analyzing race walking postures caused by manually finding key frames of the video in related technologies.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] A method for capturing key frames of a race walking video based on surface acoustic waves, comprising:

[0008] Obtaining a real-time motion video through a video information acquisition system;

[0009] Performing pressure detection through a surface acoustic wave sensor set at a specific position;

[0010] Sampling the real-time output signal of the surface acoustic wave sensor through a frequency selection circuit, and determining the landing state of the foot by frequency comparison;

[0011] Sending data to a single-chip microcomputer through a signal transmitter and a signal receiver, and the single-chip microcomputer sends the data to a computer;

[0012] Capturing key frames in the real-time motion video through a computer, and further obtaining training data.

[0013] Further, the surface acoustic wave sensor is disposed under the insole of the athlete, and a frequency selection circuit is installed under the insole.

[0014] Further, the reference frequency of the frequency selection circuit is set to the frequency of the electrical signal output by the surface acoustic wave sensor after the foot lands.

[0015] Further, the video acquisition system and the time acquisition system are clock synchronized by pre-running the system.

[0016] Further, the surface acoustic wave sensor receives electromagnetic waves through a microstrip patch antenna, and the signal transmitting end is powered by a battery.

[0017] Further, the frequency selection circuit samples the real-time output signal of the surface acoustic wave sensor, and the sampling frequency is set to be greater than the frame rate of the camera in the video acquisition system.

[0018] A race walking video key frame grabbing system based on surface acoustic wave, comprising:

[0019] A video information acquisition system for acquiring video information of the race walking process;

[0020] A time information acquisition system for grabbing key frames of the video;

[0021] Further, the time information acquisition system includes:

[0022] A surface acoustic wave sensor for detecting the sole pressure;

[0023] A frequency selection circuit installed under the insole to determine whether the foot landing state is "yes" or "no";

[0024] A signal transmitting and processing module, including an antenna and a signal transmitting chip, installed under the insole for signal processing and transmission.

[0025] Further, the time information acquisition system further includes:

[0026] A signal receiving and processing module, including a signal receiving chip and a single-chip microcomputer, for receiving and processing signals.

[0027] Further, the time information acquisition system further includes:

[0028] A race walking video key frame grabbing module for recording the foot landing moment and grabbing key frames.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] The present invention can automatically capture key frames in a race walking video based on a surface acoustic wave sensor, avoiding the cumbersome process of manually annotating key points and the adverse effects of human subjective factors on the results. It not only improves the annotation efficiency but also the annotation accuracy. At the same time, the surface acoustic wave sensor has higher sensitivity, linearity, and stability compared to piezoelectric substrates or other sensors, which can ensure high annotation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application.

[0032] Figure 1 is the flowchart of Embodiment 1;

[0033] Figure 2 is the framework diagram of Embodiment 2;

[0034] Figure 3 is the schematic diagram of the installation position of the surface acoustic wave sensor in Embodiment 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanations of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Embodiment 1.

[0039] As Figure 1 shown, the clock synchronization of the video acquisition system and the time acquisition system is performed by pre-running the system. The surface acoustic wave sensor receives electromagnetic waves through a microstrip patch antenna, and the signal transmitter is powered by a battery;

[0040] The pressure is detected by installing a surface acoustic wave sensor under the insole at the heel of the athlete;

[0041] A frequency selection circuit is installed under the insole at the heel of the athlete;

[0042] Set the reference frequency of the frequency selection circuit to the frequency of the electrical signal output by the surface acoustic wave sensor after the foot touches the ground;

[0043] The frequency selection circuit samples the real-time output signal of the surface acoustic wave sensor, and determines whether the landing state of the foot is "yes" or "no" by frequency comparison;

[0044] When the frequency selection circuit determines "yes", the signal transmitter under the insole sends an indication signal of foot landing through the antenna;

[0045] After receiving the landing indication signal, the receiving end sends data to the single-chip microcomputer, and the single-chip microcomputer immediately sends the data to the computer after receiving it;

[0046] The computer records the moment when the data is received, which is the moment when the foot touches the ground;

[0047] After obtaining the race walking video, the supporting software in the computer grabs the key frames in the video according to the moments recorded previously, and analyzes and processes the obtained key frames to obtain the training data of the athlete.

[0048] In one possible implementation manner, the clock synchronization of the video acquisition system and the time acquisition system by pre-running the system, and the surface acoustic wave sensor receives electromagnetic waves through a microstrip patch antenna, and the signal transmitter is powered by a battery includes:

[0049] The system pre-runs before formal operation, and the clocks inside each key device will record the behavior of the system and the time when it occurs, and the internal error of the system is reduced by this method;

[0050] The surface acoustic wave sensor receives electromagnetic waves through a microstrip patch antenna to obtain the required electrical signal;

[0051] The signal transmitter is provided with stable energy by a battery;

[0052] In one possible implementation manner, the detection of pressure by installing a surface acoustic wave sensor under the insole at the heel of the athlete includes:

[0053] The surface acoustic wave sensor receives electromagnetic waves through a microstrip patch antenna, and the interdigital transducer converts the electrical signal into a surface acoustic wave through the inverse piezoelectric effect. The surface acoustic wave propagates on the surface of the piezoelectric substrate material. When there is pressure, the propagation speed of the surface acoustic wave will change, and finally the frequency of the electrical signal output by the receiving transducer will shift, and the output electrical signal is transmitted to the next module;

[0054] In one possible implementation manner, the setting of the reference frequency of the frequency selection circuit to the frequency of the electrical signal output by the surface acoustic wave sensor after the foot touches the ground includes:

[0055] Measure the frequency of the output electrical signal of the surface acoustic wave sensor when the foot touches the ground, and set this frequency as the reference frequency of the frequency selection circuit;

[0056] In one possible implementation, the frequency selection circuit samples the real-time output signal of the surface acoustic wave sensor, and determines whether the foot landing state is "yes" or "no" through frequency comparison, including:

[0057] Set the sampling frequency to be greater than the frame rate of the camera in the video acquisition system;

[0058] The frequency comparison is to compare the frequency of the sampling signal with the reference frequency, and determine whether the foot landing state is "yes" or "no" by analyzing whether the frequency difference is less than the threshold value:

[0059] Case 1: If the frequency difference is less than the threshold value, it is determined that the foot landing state is "yes";

[0060] Case 2: If the frequency difference is greater than or equal to the threshold value, it is determined that the foot landing state is "no";

[0061] In one possible implementation, when the frequency selection circuit determines "yes", the signal transmitting end sends an indication signal of foot landing through the antenna; after the receiving end receives the landing indication signal, it sends data to the single-chip microcomputer, and after the single-chip microcomputer receives it, it immediately sends data to the computer, including:

[0062] The content of the landing indication signal does not affect the judgment of the landing moment. For simplicity, the landing indication signal of the foot is set as a single character "1", the data sent by the receiving end to the single-chip microcomputer is a single character "1", and the data sent by the single-chip microcomputer to the computer is a single character "1".

[0063] In one possible implementation, when the single-chip microcomputer receives the character sent by the receiving end and sends the character 1 to the computer, including:

[0064] After the single-chip microcomputer receives the character, it immediately sends the character 1 to the computer through the USB interface;

[0065] In one possible implementation, after obtaining the race walking video, the supporting software in the computer grabs the key frames in the video according to the previously recorded time, and analyzes and processes the obtained key frames to obtain training data, including:

[0066] Since clock synchronization has been performed in advance, through relevant programs, the key frames of the foot landing in the video can be found according to the previously recorded time, and the training data of the athlete can be obtained by analyzing the key frames in combination with other technologies (such as artificial intelligence);

[0067] Specifically,

[0068] As shown Figure 1 in the figure, the key frame extraction method for race walking videos provided in this embodiment includes:

[0069] S101. Install a surface acoustic wave sensor at the heel of the athlete to detect pressure;

[0070] S102. Use a frequency selection circuit to compare the frequencies of the real-time output signals of the sensor;

[0071] S103. When the frequency selection circuit determines "yes", the transmitting end sends an indication signal of foot landing;

[0072] S104. After receiving the landing indication signal, the receiving end sends data to the single-chip microcomputer;

[0073] S105. After receiving the data, the single-chip microcomputer immediately sends the data to the computer;

[0074] S106. The computer records the moment when the data is received, which is the moment of foot landing;

[0075] S107. Grab the key frame of the video according to the landing moment;

[0076] Cameras can be pre-installed in the set area of the race walking path of the race walker. Specifically, four high-frequency cameras can be used. The four cameras collect race walking information from multiple angles in a frame synchronization manner, and the cameras are turned on when the athlete starts race walking.

[0077] In step S101, a small surface acoustic wave sensor is pre-placed at the insole of the athlete's rear heel. The pressure generated when the foot lands causes a change in the velocity v of the surface acoustic wave. The change in v ultimately leads to a change in the frequency of the electrical signal output by the output transducer; when the substrate of the sensor is stressed and undergoes a strain δ, v can be expressed as follows:

[0078] v(δ) = (1 + kδ)v0

[0079] v(δ) is the surface acoustic wave velocity when there is pressure; v0 is the surface acoustic wave velocity when there is no pressure, k is the material constant, and δ is the substrate strain; then the corresponding relationship between the resonance frequency f and the substrate strain δ is:

[0080]

[0081] As shown in the formula, when the athlete's foot lands during race walking, a pressure is applied to the surface acoustic wave sensor, causing a change in the frequency of the electrical signal output by the surface acoustic wave sensor. Set the reference frequency of the frequency selection circuit to the frequency of the electrical signal output by the surface acoustic wave sensor after foot landing, then the frequency selection circuit can determine whether the foot landing state is "yes" or "no" through frequency comparison.

[0082] In step S102, the electrical signal output by the surface acoustic wave sensor is passed through a frequency selection circuit. By comparing frequencies, it is determined whether the landing state of the foot is "yes" or "no". The frequency comparison is to compare the frequency of the sampled signal with the reference frequency. By analyzing whether the frequency difference is less than the threshold value, it is determined whether the landing state of the foot is "yes" or "no".

[0083] In step S103, when the frequency selection circuit determines "yes", the signal transmitter sends an indication signal of foot landing through the antenna. The content of the landing indication signal does not affect the judgment of the landing moment. For simplicity, the landing indication signal of the foot is set as a single character "1".

[0084] In one possible implementation, the Zigbee wireless communication technology is selected. The Zigbee wireless communication technology is a short-range, low-power, low-cost, and low-transmission-rate wireless communication technology. And the amount of data transmitted each time is very small, and the required transmission rate is not high. Therefore, the Zigbee wireless communication technology is selected, and the transmitting chip is a 2.4GHz radio frequency transmitting chip.

[0085] In step S104, after receiving the landing indication signal, the receiving end sends data to the single-chip microcomputer. The content of the sent data does not affect the judgment of the landing moment. For simplicity, the sent data is set as a single character "1".

[0086] In the specific implementation process, a CC2420 2.4GHz radio frequency receiving chip is selected. The receiving chip sends the single character 1 to the corresponding pin of the single-chip microcomputer through the bus interface.

[0087] In step S105, after receiving the data, the single-chip microcomputer immediately sends data to the computer. The content of the sent data does not affect the judgment of the landing moment. For simplicity, the sent data is set as a single character "1".

[0088] In step S106, after receiving the data, the computer immediately records the current moment, which is the moment when the foot lands. Since the starting moment of each camera shooting has been pre-recorded, combined with the moment recorded by the computer, the key frame when the athlete's foot lands can be directly found in the video without the need for manual frame-by-frame search, improving the efficiency and accuracy.

[0089] In step S107, a race walking key frame grabbing program has been configured in the computer, and the key frame when the athlete's foot lands can be directly found in the video according to the moment recorded by the computer;

[0090] This embodiment also provides a race walking video key frame grabbing system for executing the steps in the above method embodiment. The system includes:

[0091] A camera for collecting video information of the race walking process;

[0092] A surface acoustic wave sensor is installed under the insole at the heel of the athlete to detect pressure;

[0093] A frequency selection circuit is installed under the athlete's insole to determine whether the foot landing state is "yes" or "no";

[0094] A signal transmitting and processing module is installed under the insole to process and transmit signals;

[0095] A signal receiving and processing module is used to receive signals and send data to a computer through a single-chip microcomputer;

[0096] A computer is used to record the moment when the athlete's foot lands in order to find the key frames in the race walking video;

[0097] Among them, the computer has been configured to implement the method in the foregoing embodiment.

[0098] The corresponding method in the embodiment can be completed by the integrated logic circuit of the hardware in the single-chip microcomputer or the instructions in the form of software.

[0099] The signal transmitting and processing module and the signal receiving and processing module may mainly include a single-chip microcomputer and a wireless radio frequency transceiver chip.

[0100] The above single-chip microcomputer can be PIC18F4620, which mainly includes a crystal oscillator circuit, a reset circuit, a power supply circuit, and an in-circuit programming and debugging circuit. The crystal oscillator circuit uses a stable quartz crystal oscillator, the reset circuit uses a simple resistor-capacitor reset, low-valid, and the in-circuit debugging and programming of the single-chip microcomputer use the unique in-circuit serial programming pins of MICROCHIP. These pins can connect the single-chip microcomputer to a third-party debugger for real-time in-circuit programming and debugging.

[0101] The above wireless radio frequency transceiver chip can be a Zigbee transceiver chip CC2420. Its peripheral circuit includes three parts: a crystal oscillator clock circuit, a radio frequency input / output matching circuit, and a single-chip microcomputer interface circuit. The chip clock signal can be provided either by an external active crystal or by an internal circuit. The radio frequency input / output matching circuit is mainly used to match the input and output impedance of the chip, and at the same time provide a DC bias for the PA and LNA inside the chip.

[0102] CC2420 performs data transmission, etc. through a 4-wire serial SPI bus interface. The sending and receiving buffers are set by controlling the states of the FIFO and FIFOP pin interfaces, and the input of the clock / timing information can be controlled by setting the state of the SFD pin. Connecting the above interfaces to the corresponding pins of the single-chip microcomputer can implement the method in the above embodiment.

[0103] Embodiment 2.

[0104] A key frame grabbing system for race walking videos based on surface acoustic waves, comprising:

[0105] A video information acquisition system for acquiring video information during race walking;

[0106] A time information acquisition system for grabbing key frames of the video;

[0107] Furthermore, the time information acquisition system includes:

[0108] A surface acoustic wave sensor for detecting the sole pressure;

[0109] A frequency selection circuit installed under the insole to determine whether the foot landing state is "yes" or "no";

[0110] A signal transmitting and processing module, including an antenna and a signal transmitting chip, installed under the insole for signal processing and transmission.

[0111] The time information acquisition system further includes:

[0112] A signal receiving and processing module, including a signal receiving chip and a single-chip microcomputer, for signal reception and processing.

[0113] The time information acquisition system further includes:

[0114] A key frame grabbing module for race walking videos to record the moment of foot landing and grab key frames.

[0115] Specifically,

[0116] In one possible implementation, the video information acquisition system for acquiring video information during race walking includes:

[0117] Four cameras for acquiring video information during race walking from four directions of the front, back, left, and right of the athlete;

[0118] Video processing software for collecting and analyzing video information;

[0119] In one possible implementation, the time information acquisition system for grabbing key frames of the video includes:

[0120] A surface acoustic wave sensor for detecting the sole pressure of the athlete;

[0121] A frequency selection circuit installed under the athlete's insole to determine whether the foot landing state is "yes" or "no";

[0122] A signal transmitting and processing module, including components such as an antenna and a signal transmitting chip, installed under the athlete's insole for signal processing and transmission;

[0123] The signal receiving and processing module, including components such as a signal receiving chip and a single-chip microcomputer, receives and processes signals;

[0124] The race walking video key frame capturing software records the moment when the foot touches the ground and captures key frames;

[0125] In one possible implementation, there are four cameras, which are used to synchronously collect video information of the race walking process from four angles of front, back, left and right;

[0126] In one possible implementation, the video processing software is located in a computer and is used to process the obtained video;

[0127] In one possible implementation, the surface acoustic wave sensor mainly includes:

[0128] Microstrip patch antenna, interdigital transducer;

[0129] In one possible implementation, the signal transmitting and processing module includes:

[0130] A transmitting chip, which is used for protocol conversion and sending work;

[0131] An antenna, which is used to send signals;

[0132] In one possible implementation, the signal receiving and processing module includes:

[0133] An antenna, which is used to receive signals;

[0134] A receiving chip, which is used for signal receiving and processing and other work;

[0135] A single-chip microcomputer, which is used to receive data and send data to a computer;

[0136] In one possible implementation, the race walking key frame capturing software is located in a computer and is used to record the moment when the foot touches the ground and capture key frames for the video obtained by the video processing software, and save the obtained data to a database;

[0137] In one possible implementation, a computer is used to run the video processing software and the race walking key frame capturing software, store data, and collect training data;

[0138] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0139] The present application is described by referring to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0140] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0141] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A method for capturing key frames of a walking race video based on surface acoustic waves, characterized in that: include: Acquire real-time motion video through the video information acquisition system; Before the official operation, the clock inside each key device will record the system behavior and its occurrence time. The clock of the video acquisition system and the time acquisition system will be synchronized by the pre-operation system. Pressure detection is performed by a surface acoustic wave sensor disposed under the insole at the athlete's heel; a frequency selection circuit is also installed under the insole at the athlete's heel; The pressure generated when the foot lands causes the surface acoustic wave velocity v to change. The change in v causes the frequency of the output electrical signal of the output transducer to change. When the sensor substrate is subjected to a force and a strain δ occurs, v is expressed as follows: v(δ)=(1+kδ)v0 v(δ) is the surface acoustic wave velocity under pressure; v0 is the surface acoustic wave velocity under no pressure, k is the material constant, and δ is the substrate strain. The corresponding relationship between the resonant frequency f and the substrate strain δ is: The real-time output signal of the surface acoustic wave sensor is sampled through a frequency selection circuit, and the sampling frequency is set to be greater than the frame rate of the camera in the video acquisition system. The landing state of the foot is determined by frequency comparison; the reference frequency of the frequency selection circuit is set to the frequency of the electrical signal output by the surface acoustic wave sensor after the foot lands; The frequency comparison is to compare the frequency of the sampled signal with the reference frequency, and to determine whether the foot has landed, by analyzing whether the frequency difference is less than a threshold value. Specifically, When the frequency difference is less than the threshold value, the foot landing state is determined to be "yes"; When the frequency difference is greater than or equal to the threshold value, the foot landing status is determined to be "no"; Data is sent to the single-chip microcomputer through the signal transmitting end and the signal receiving end, and the single-chip microcomputer sends the data to the computer; wherein, when the frequency selection circuit determines that the foot has touched the ground, the signal transmitting end sends an indication signal of the foot touching the ground through the antenna; after receiving the indication signal of the foot touching the ground, the receiving end sends data to the single-chip microcomputer, and the single-chip microcomputer immediately sends the data to the computer after receiving the data; The training data is obtained by capturing key frames in real-time sports videos through a computer. After receiving the data, the computer immediately records the current moment, which is the moment when the foot touches the ground. Since the moment when each camera starts shooting has been recorded in advance, combined with the moment when the foot touches the ground recorded by the computer, the key frame of the athlete's foot touching the ground can be directly found in the video.

2. The method for capturing key frames of a walking race video based on surface acoustic waves according to claim 1, wherein: The surface acoustic wave sensor receives electromagnetic waves through a microstrip patch antenna and supplies energy to a signal transmitting end through a battery.

3. A walking race video key frame capture system based on surface acoustic wave, characterized in that: include: Video information acquisition system, used to collect video information of the race walking process; Time information acquisition system, used to capture video key frames; Before the official operation, the clock inside each key device will record the system behavior and its occurrence time. The clock of the video acquisition system and the time acquisition system will be synchronized by the pre-operation system. The time information acquisition system includes: The surface acoustic wave sensor detects sole pressure and is placed under the insole at the athlete's heel. The pressure generated when the foot lands causes the surface acoustic wave velocity v to change, and this change in v causes a change in the frequency of the electrical signal output by the output transducer. When the sensor substrate is subjected to a force and produces a strain δ, v is expressed as follows: v(δ)=(1+kδ)v0 v(δ) is the surface acoustic wave velocity under pressure; v0 is the surface acoustic wave velocity under no pressure, k is the material constant, and δ is the substrate strain. The corresponding relationship between the resonant frequency f and the substrate strain δ is: The frequency selection circuit is installed under the insole at the athlete's heel. The reference frequency of the frequency selection circuit is set to the frequency of the electrical signal output by the surface acoustic wave sensor after the foot lands. The real-time output signal of the surface acoustic wave sensor is sampled by the frequency selection circuit. The sampling frequency is set to be greater than the frame rate of the camera in the video acquisition system. The frequency of the sampled signal is then compared with the reference frequency. By analyzing whether the frequency difference is less than a threshold value, it is determined whether the foot has landed. Specifically, When the frequency difference is less than the threshold value, the foot landing state is determined to be "yes"; When the frequency difference is greater than or equal to the threshold value, the foot landing status is determined to be "no"; The signal transmission and processing module, including an antenna and a signal transmission chip, is installed under the insole to process and transmit signals. When the frequency selection circuit determines "yes", the signal transmission chip sends a foot-landing indication signal through the antenna. The module also includes a signal receiving chip and a single-chip microcomputer to receive and process the signal. After receiving the foot-landing indication signal, the signal receiving chip sends data to the single-chip microcomputer, which immediately sends the data to the computer. The race walking video key frame capture module records the moment when the foot touches the ground and captures the key frames.

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