A network motion capture platform based on synchronized devices

Abstract

The present application relates to the technical field of computer network technology, and is a network motion capture platform based on synchronization devices, comprising an external expansion device group and a network switch, and also comprising a synchronization device connected to the external expansion device group and the network switch; the external expansion device group comprises at least one external expansion device, and each of the external expansion devices is connected to the synchronization device using its own corresponding synchronization signal; the network switch is connected to at least one network motion capture camera. Through the solution of the embodiment of the present disclosure, the four devices can adopt different software synchronization interfaces, so that the collected information can be synchronized in their respective subsystems, thereby solving the need for information data synchronization between the network motion capture camera and other equipment such as audio and video equipment, active markers, force platforms, electromyographs, etc., to improve the synchronization accuracy and application scope of the overall system.

Description

Technical Field

[0001] The present application relates to the technical field of computer network technology, and in particular to a network motion capture platform based on synchronization equipment. Background Art

[0002] In current networked motion capture camera applications, the IEEE 1588 standard PTP (Precision Time Protocol) is widely used to achieve high-precision time synchronization between cameras. This protocol, which transmits UDP packets over Ethernet networks, effectively ensures time consistency within the camera's internal systems. However, as motion capture technology becomes more diversified and integrated, networked motion capture cameras often need to collaborate with a variety of external devices, such as electromyographs, force plates, audio and video equipment, and active markers. This presents a significant synchronization challenge.

[0003] Due to their hardware characteristics, electromyographs and force plates typically use periodic level pulse signals as a synchronization reference. Audiovisual equipment relies on time code information output by time code generators to accurately capture and record video and sound. Active markers, due to their compact size and battery operation, can only receive synchronization control instructions via wireless data packets. These devices differ significantly in their synchronization methods and software and hardware interfaces. As a result, while subsystem-level synchronization can be achieved within each device (system), when integrated with network motion capture cameras, the lack of a unified synchronization adaptation mechanism prevents the devices from outputting or acquiring consistent synchronization information data. This inconsistency in time synchronization severely limits the effectiveness of network motion capture cameras in multi-device applications, significantly reducing data acquisition accuracy and overall system efficiency.

[0004] Therefore, how to break the synchronization barriers between devices, achieve precise time synchronization between network motion capture cameras and external devices such as audio and video equipment, active markers, force plates, and electromyographs, and improve the synchronization accuracy and application scope of the entire system has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In order to break the synchronization barriers between devices, achieve precise time synchronization between network motion capture cameras and external devices such as audio and video equipment, active markers, force platforms, electromyographs, etc., and improve the synchronization accuracy and application scope of the overall system, this application provides a network motion capture platform based on synchronization devices.

[0006] In the first aspect, the present application provides a network motion capture platform based on synchronization equipment, which adopts the following technical solutions:

[0007] A network motion capture platform based on synchronization equipment, comprising an external expansion equipment group and a network switch, and also comprising a synchronization equipment connected to the external expansion equipment group and the network switch;

[0008] The external expansion device group includes at least one external expansion device, and each of the external expansion devices is connected to the synchronization device using a corresponding synchronization signal;

[0009] The network switch is connected to at least one network motion capture camera;

[0010] The synchronization device adapts the synchronization signal corresponding to the external expansion device to the PTP synchronization protocol of the network motion capture camera to obtain accurate PTP synchronization protocol time, thereby realizing clock synchronization calibration between the network motion capture camera and different external expansion devices, and ensuring the consistency of timestamps of data collected by each device;

[0011] Among them, based on the acquisition, processing and calculation matching of the synchronization signal of the external expansion device by the synchronization device with the PTP protocol time, it specifically includes: generating the corresponding synchronization signal according to the PTP synchronization protocol time of the network motion capture camera and the pre-configured frame rate parameters, or analyzing and calculating the synchronization signal output by the external device and injecting the PTP event message to achieve clock synchronization.

[0012] Optionally, the external expansion device group includes an electromyograph, and the output form of the electromyograph is a pulse synchronous output signal;

[0013] For the electromyograph, the process of the synchronization device implementing the clock synchronization includes:

[0014] The synchronization device collects the pulse synchronization output signal of the electromyograph:

[0015] The synchronization device analyzes the pulse synchronization output signal and uses a sliding window algorithm to calculate the frame period multiple times and conversion time , and perform weighted average on the calculation results:

[0016] ;

[0017] ;

[0018] in, is the frame period after weighted averaging, is the weighted average conversion time, and are the frame period and conversion duration calculated for the i-th time, is the weight of the i-th calculation result, and n is the number of calculations in the sliding window;

[0019] The synchronization device generates accurate system time according to the calculated frame period and conversion duration;

[0020] The synchronization device adds the generated system time to the PTP event message;

[0021] When the network motion capture camera receives the PTP event message, the network motion capture camera synchronizes the PTP synchronization protocol time used by the network motion capture camera with the system time;

[0022] The PTP synchronization protocol time format includes 32-bit integer seconds and 32-bit integer nanoseconds.

[0023] Optionally, the external expansion device group includes a force platform, and the input form of the force platform is a pulse synchronization input signal; for the force platform, the process of the synchronization device implementing the clock synchronization includes:

[0024] The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera;

[0025] According to the current PTP synchronization protocol time and specific required frame rate , the synchronization device generates a corresponding pulse synchronization input signal; the pulse synchronization input signal includes a frame period and conversion duration information; among them, ;

[0026] The specific required frame rate is pre-set by the synchronization device according to application requirements;

[0027] The generated pulse synchronous input signal is output to the force measuring platform device; the force measuring platform performs synchronous data acquisition according to the received pulse synchronous input signal.

[0028] Optionally, the external expansion device group includes at least one audio-visual device and an associated time code generator; and for the audio-visual device, the process of the synchronization device implementing the clock synchronization includes:

[0029] The time code acquisition module included in the synchronization device acquires time code information from the time code generator;

[0030] The collected time code information is converted into the PTP synchronization protocol time format; during the conversion process, the time corresponding to the time code information is , converted PTP synchronization protocol time ;

[0031] in, It is the reference time of the PTP synchronization protocol. It is the time offset of the time code information relative to the reference time;

[0032] The converted PTP synchronization protocol time is added to the PTP event message of the network motion capture camera.

[0033] Optionally, the external expansion device group includes active marking points; and for the active marking points, the process of the synchronization device implementing the clock synchronization includes:

[0034] The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera;

[0035] Synchronous devices set the specified frame rate according to application requirements and duty cycle D;

[0036] The specified frame rate represents the number of times the active marker changes per second, and the duty cycle represents the ratio of the light and dark time of the active marker. The received PTP synchronization protocol time is converted into the active marker system time;

[0037] The calculation formulas for the light-on time and light-off time are:

[0038] ;

[0039] ;

[0040] Add the specified frame rate and duty cycle data to form a complete device data message;

[0041] The generated device data message is sent to each active marking point through the wireless module, and the active marking point performs light and dark control according to the received device data message.

[0042] Optionally, the synchronization device performs filtering processing on the received synchronization signal, and adopts a median filtering algorithm to remove noise interference, including:

[0043]

[0044] in, is the synchronization signal value at the kth moment after filtering, is the value of the original synchronization signal at the kth moment, and m is the radius of the median flow window.

[0045] Optionally, the synchronization device has a fault-tolerant mechanism. When an abnormal synchronization signal of an external expansion device is detected, the synchronization time with the network motion capture camera is recalculated using the following formula:

[0046] ;

[0047] in, is the recalculated synchronization time, is the synchronization time between the jth external expansion device and the network motion capture camera, and s is the number of external expansion devices that are working normally.

[0048] In summary, this application includes at least one of the following beneficial technical effects:

[0049] 1. The present invention uses the network motion capture platform based on the synchronization device described in the present invention. By adapting the synchronization device to the synchronization signal of the external expansion device and the PTP synchronization protocol of the network motion capture camera, precise clock synchronization is achieved, ensuring that the motion capture data and the external device data are accurately corresponding in time, significantly improving the accuracy and coordination of the system data processing, and adopting differentiated synchronization methods for different types of external devices. This can effectively solve the synchronization problem of various types of devices and network motion capture cameras, greatly broaden the range of compatible devices of the system, and enhance the control and synchronization capabilities of devices with different functions.

[0050] 2. The present invention ensures stable operation of the equipment and stable power supply transmission through the specific hardware combination of the synchronization device main control board and the embedded Linux operating system, as well as the rich interface design of the interface board, significantly improving the system scalability and compatibility; the synchronization signal line uses shielded cables to reduce electromagnetic interference and further improve the accuracy of clock synchronization. In addition, the signal filtering processing and fault-tolerant mechanism of the synchronization device can effectively remove noise, respond to signal anomalies, and ensure the overall synchronization performance and stability of the platform; the real-time task scheduling function of the embedded Linux operating system ensures that the synchronization operation responds promptly and accurately, providing strong support for the efficient operation of the network motion capture platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the system architecture of a network motion capture platform based on synchronized devices;

[0052] Figure 2 It is a module diagram of the synchronization device;

[0053] Figure 3 This is a flow chart of pulse input;

[0054] Figure 4 Schematic diagram of the time code input process. DETAILED DESCRIPTION

[0055] Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings.

[0056] Throughout this specification, reference to the terms "certain embodiments," "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0057] The present application embodiment discloses a network motion capture platform based on synchronization equipment, referring to Figure 1 , with synchronization equipment as the key hub, its main architecture is jointly built by external expansion equipment groups, network switches and synchronization equipment. The external expansion equipment groups are rich in variety, covering a variety of devices with different functions. Each external expansion device is connected to the synchronization equipment through a specific and exclusive synchronization signal. The network switch is connected to at least one network motion capture camera, just like a transportation hub in the network, responsible for the efficient transmission of data. The synchronization equipment plays a core role in the entire platform. Its key task is to cleverly adapt the synchronization signal generated by the external expansion device to the format required by the PTP synchronization protocol followed by the network motion capture camera, thereby achieving precise time synchronization between the network motion capture camera and various external expansion devices. This is like calibrating the time in different time zones so that the entire system can work together in an orderly manner.

[0058] A network motion capture platform based on synchronization equipment, comprising an external expansion equipment group and a network switch, and also comprising a synchronization equipment connected to the external expansion equipment group and the network switch;

[0059] The external expansion device group includes at least one external expansion device, and each of the external expansion devices is connected to the synchronization device using a corresponding synchronization signal;

[0060] The network switch is connected to at least one network motion capture camera;

[0061] The synchronization device adapts the synchronization signal corresponding to the external expansion device to the PTP synchronization protocol of the network motion capture camera to obtain accurate PTP synchronization protocol time, thereby realizing clock synchronization calibration between the network motion capture camera and different external expansion devices, and ensuring the consistency of timestamps of data collected by each device;

[0062] Among them, based on the acquisition, processing and calculation matching of the synchronization signal of the external expansion device by the synchronization device with the PTP protocol time, it specifically includes: generating the corresponding synchronization signal according to the PTP synchronization protocol time of the network motion capture camera and the pre-configured frame rate parameters, or analyzing and calculating the synchronization signal output by the external device and injecting the PTP event message to achieve clock synchronization.

[0063] Optionally, the external expansion device group includes an electromyograph, and the output form of the electromyograph is a pulse synchronous output signal;

[0064] For the electromyograph, the process of the synchronization device implementing the clock synchronization includes:

[0065] The synchronization device collects the pulse synchronization output signal of the electromyograph:

[0066] The synchronization device analyzes the pulse synchronization output signal and uses a sliding window algorithm to calculate the frame period multiple times and conversion time , and perform weighted average on the calculation results:

[0067] ;

[0068] ;

[0069] in, is the frame period after weighted averaging, is the weighted average conversion time, and are the frame period and conversion duration calculated for the i-th time, is the weight of the i-th calculation result, and n is the number of calculations in the sliding window;

[0070] The synchronization device generates accurate system time according to the calculated frame period and conversion duration;

[0071] The synchronization device adds the generated system time to the PTP event message;

[0072] When the network motion capture camera receives the PTP event message, the network motion capture camera synchronizes the PTP synchronization protocol time used by the network motion capture camera with the system time;

[0073] The PTP synchronization protocol time format includes 32-bit integer seconds and 32-bit integer nanoseconds.

[0074] Optionally, the external expansion device group includes a force platform, and the input form of the force platform is a pulse synchronization input signal; for the force platform, the process of the synchronization device implementing the clock synchronization includes:

[0075] The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera;

[0076] According to the current PTP synchronization protocol time and specific required frame rate , the synchronization device generates a corresponding pulse synchronization input signal; the pulse synchronization input signal includes a frame period and conversion duration information; among them, ;

[0077] The specific required frame rate is pre-set by the synchronization device according to application requirements;

[0078] The generated pulse synchronous input signal is output to the force measuring platform device; the force measuring platform performs synchronous data acquisition according to the received pulse synchronous input signal.

[0079] Optionally, the external expansion device group includes at least one audio-visual device and an associated time code generator; and for the audio-visual device, the process of the synchronization device implementing the clock synchronization includes:

[0080] The time code acquisition module included in the synchronization device acquires time code information from the time code generator;

[0081] The collected time code information is converted into the PTP synchronization protocol time format; during the conversion process, the time corresponding to the time code information is , converted PTP synchronization protocol time ;

[0082] in, It is the reference time of the PTP synchronization protocol. It is the time offset of the time code information relative to the reference time;

[0083] The converted PTP synchronization protocol time is added to the PTP event message of the network motion capture camera.

[0084] Optionally, the external expansion device group includes active marking points; and for the active marking points, the process of the synchronization device implementing the clock synchronization includes:

[0085] The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera;

[0086] Synchronous devices set the specified frame rate according to application requirements and duty cycle D;

[0087] The specified frame rate represents the number of times the active marker changes per second, and the duty cycle represents the ratio of the light and dark time of the active marker. The received PTP synchronization protocol time is converted into the active marker system time;

[0088] The calculation formulas for the light-on time and light-off time are:

[0089] ;

[0090] ;

[0091] Add the specified frame rate and duty cycle data to form a complete device data message;

[0092] The generated device data message is sent to each active marking point through the wireless module, and the active marking point performs light and dark control according to the received device data message.

[0093] Optionally, the synchronization device performs filtering processing on the received synchronization signal, and adopts a median filtering algorithm to remove noise interference, including:

[0094] ;

[0095] in, is the synchronization signal value at the kth moment after filtering, is the value of the original synchronization signal at the kth moment, and m is the radius of the median flow window.

[0096] Optionally, the synchronization device has a fault-tolerant mechanism. When an abnormal synchronization signal of an external expansion device is detected, the synchronization time with the network motion capture camera is recalculated using the following formula:

[0097] ;

[0098] in, is the recalculated synchronization time, is the synchronization time between the jth external expansion device and the network motion capture camera, and s is the number of external expansion devices that are working normally.

[0099] Among them, the synchronous operation of external expansion equipment, electromyograph (pulse synchronization signal output type), the output form of this type of equipment is pulse synchronization output signal, the specific process of the synchronization device to achieve clock synchronization for this type of equipment is as follows:

[0100] Signal acquisition: Synchronization equipment acts like a keen observer, accurately collecting pulse synchronous output signals from electromyographs. For example, in industrial automation production lines, certain sensor devices periodically output pulse synchronous output signals, and synchronization equipment can quickly capture these signals.

[0101] Parameter calculation: The synchronization device uses a sliding window algorithm to conduct in-depth analysis of the collected pulse synchronization output signal. The sliding window algorithm is like a movable observation window, sliding multiple times in the signal stream, and each time calculating the frame period of the signal in the current window, that is, the time interval between each frame, just like the time difference and transition duration between each frame in a movie, the duration of the signal from the start to the end, such as the time from the beginning of a pulse to its disappearance. To make the calculation result more accurate and reliable, the synchronization device will perform a weighted average of multiple calculation results. For example, in multiple calculations, the most recent calculation result may have a greater impact on the final result, so it is given a higher weight. This can effectively improve the calculation accuracy and stability. Same as system time generation: Based on the frame period and transition duration calculated previously, the synchronization device is like a precise clock regulator, generating accurate system time. This system time is an important basis for subsequent synchronization operations;

[0102] Message integration: The synchronization device cleverly adds the generated system time to the PTP event message; the PTP event message acts as an information carrier to transmit the system time to the network motion capture camera;

[0103] Camera synchronization: After receiving a PTP event message, the network motion capture camera quickly synchronizes its own PTP synchronization protocol time with the system time in the message. The PTP synchronization protocol time format contains 32-bit integer seconds and 32-bit integer nanoseconds. This high-precision time format can achieve extremely accurate timing, just like an atomic clock, ensuring high time synchronization between the network motion capture camera and the electromyograph.

[0104] Force measuring platform (pulse synchronous signal input type), the input form of the force measuring platform is pulse synchronous input signal, the synchronization process of the synchronization device for this type of equipment is as follows:

[0105] Time reception: The synchronization device obtains the current PTP synchronization protocol time from the network motion capture camera, just like obtaining accurate time from a clock source. For example, on a film and television set, the network motion capture camera records the actor's movements in real time, and the synchronization device obtains the current PTP synchronization protocol time from it;

[0106] Signal generation: Based on the current PTP synchronization protocol time and the pre-set specific required frame rate, which is determined by actual application requirements. For example, in virtual reality game development, a higher frame rate may be set to achieve smooth motion capture effects. The synchronization device generates a pulse synchronization input signal containing frame period and conversion duration information. This is like generating a pulse signal that meets the requirements based on the target time and rhythm.

[0107] Device synchronization: The synchronization device outputs the generated pulse synchronization input signal to the force plate. The force plate acts as an executor that receives the instruction and performs synchronous data acquisition based on the received pulse synchronization input signal. For example, in the data acquisition device, the synchronization signal is used to accurately collect data at a specific time point, ensuring that the collected data is consistent with the timing of the network motion capture camera.

[0108] Audio and video equipment and time code generators. Audio and video equipment in the external expansion device group is associated with a time code generator. The process of the synchronization device to achieve clock synchronization for such equipment is as follows:

[0109] Time code acquisition: The time code acquisition module in the synchronization device acts as an information collector, collecting time code information from the time code generator. In film and television production, the time code generator will add time code to the captured video or audio, and the synchronization device can collect this code information;

[0110] Format conversion: The synchronization device cleverly converts the collected time code information into the PTP synchronization protocol time format, which is like translating one language into another, so that the time code information can be understood by the network motion capture camera;

[0111] Message Add: Add the converted PTP synchronization protocol time to the PTP event message of the network motion capture camera, thereby achieving clock synchronization between the audio and video equipment and the network motion capture camera. In this way, in film and television post-production, it can ensure that the motion capture data and audio and video materials are perfectly matched in time.

[0112] Active marking points: For active marking points, the synchronization operations of the synchronization device are as follows:

[0113] Time acquisition: The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera to obtain an accurate time reference. For example, in a stage lighting control scenario, the synchronization device obtains time information from the network motion capture camera responsible for capturing the actor's movements.

[0114] Parameter setting: Set the specified frame rate (indicates the number of times the active marker changes per second, such as the number of times a stage light flashes per second) and duty cycle (the ratio of the active marker's on and off time, such as the ratio of the light's on time to the total time) according to application requirements. This is like designing a unique flashing rhythm and light-to-dark ratio for stage lighting.

[0115] Message generation: Converts the PTP synchronization protocol time to the active mark point system time and adds the specified frame rate and duty cycle data to form a complete device data message. This message is like a detailed instruction list, including all the time and control parameters required for the active mark point.

[0116] Data transmission: Device data messages are sent to each active marker via a wireless module. The active marker then controls the brightness of the light based on the received message. For example, during a stage performance, the lighting equipment accurately adjusts the brightness according to the set frame rate and duty cycle based on the received message, achieving perfect synchronization with the actor's movements.

[0117] Reference Figure 2 , the synchronization device consists of a main control board and an interface board:

[0118] Main control board: The main control board uses Zynq+DDR3+Flash memory chips to build a hardware system, which is like a powerful "brain" for the synchronization device. It runs an embedded Linux operating system with real-time task scheduling capabilities. This operating system can prioritize tasks related to the PTP protocol and underlying hardware configuration tasks, ensuring that the synchronization device responds promptly and accurately to synchronization operations with external expansion devices and network motion capture cameras. The application software supports the PTP protocol, underlying hardware configuration, and user interface functions, making it easy for users to set up and manage the synchronization device.

[0119] Interface board: The interface board integrates a PoE network interface, a pulse synchronization input circuit, a pulse synchronization output circuit, a time code synchronization input circuit, a wireless module, a power supply circuit, and a data interface. It is like a multi-functional connection hub. The PoE network interface facilitates the simultaneous transmission of data and power via Ethernet cables; the pulse synchronization input / output circuit is responsible for interacting with pulse synchronization signals from external devices; the time code synchronization input circuit is used to receive time code information; the wireless module realizes wireless data transmission; the power supply circuit provides stable power for the entire interface board; and the data interface is used to connect various external expansion devices and network motion capture cameras to achieve efficient signal transmission and interaction.

[0120] To safeguard the transmission of synchronous signals, in order to reduce the impact of external electromagnetic interference on the transmission of synchronous signals, all synchronous signal lines connecting external expansion devices to synchronous devices use shielded cables. Shielded cables are like a layer of protective clothing for the synchronous signals, which can effectively block external electromagnetic interference and ensure that the synchronous signals are accurately transmitted to the synchronous devices. This is crucial to ensuring the synchronization accuracy and stability of the entire network motion capture platform, just like the importance of a solid foundation to a high-rise building. Only when the synchronous signals are transmitted stably can the entire platform operate normally and efficiently.

[0121] Reference Figure 3 , the pulse input synchronization mode flow chart is explained: Initialization phase: After starting the pulse input synchronization mode, the synchronization period Tp is first initialized, and the pulse high level time and pulse low level time are both set to 0. This step is to prepare for the subsequent accurate measurement of pulse related parameters;

[0122] Edge detection link: Enter the edge detection step to judge the current signal level. If it is not a specific edge (not clearly specified here, but generally refers to the rising edge or falling edge), then according to the level, the unit time is calculated or accumulated. This is to continuously monitor the high and low level duration of the pulse signal. Therefore, the pulse high level time is Th, the pulse low level time is Ti, and the calculated period value is Tp=Th+Ti;

[0123] Rising edge judgment: After detecting an edge, further judge whether it is a rising edge. If it is not a rising edge, return to continue edge detection; if it is a rising edge, proceed to the next step;

[0124] Parameter calculation and system time processing: After detecting the rising edge, the period value and the duty cycle are calculated, and then these calculation results are used to update and calibrate the system time. This step adjusts the system time by obtaining the pulse period and duty cycle information to achieve synchronization;

[0125] Reset phase: After completing the calculation and system time calibration, reset the sum to 0, return to the edge detection step, and continue monitoring the next pulse cycle.

[0126] Reference Figure 4 , explain the time code input synchronization mode flow chart:

[0127] Initialization stage: When the time code input synchronization mode starts, the time code is initialized to 00:00:00, and the bit counter Cnt and shift register Reg64 are also initialized. This is to lay the foundation for correctly receiving and processing the time code information;

[0128] Synchronous word matching link: Perform the synchronous word matching operation to determine whether the received signal matches the preset synchronous word; if not, perform the bit receiving operation to continue receiving the signal; if it matches, proceed to the next step;

[0129] Reset operation: When the synchronization word is successfully matched, the bit count Cnt is reset to 0, and the shift register Reg64 is also reset to 0; this is to start correctly receiving and storing subsequent time code data;

[0130] Bit receiving step: perform bit receiving operation, each time a bit of data is received, the bit count Cnt is increased by 1, and Reg64 is shifted left by 1 bit, and the received data is stored in the shift register;

[0131] Determine whether the reception is complete: Determine whether the bit count Cnt has reached 64. If not, continue to receive the bit; if it has reached 64, it means that 64 bits of data have been completely received and go to the next step;

[0132] Time code separation: When Cnt=64, the time code sequence is separated from the shift register Reg64 in the format of hh:mm:ss:ff (hours:minutes:seconds:frames), completing the time code extraction and realizing time code input synchronization.

[0133] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A network motion capture platform based on synchronization equipment, including an external expansion equipment group and a network switch, characterized in that: Also included is a synchronization device connected to the external expansion device group and the network switch; The external expansion device group includes at least one external expansion device, and each of the external expansion devices is connected to the synchronization device using a corresponding synchronization signal; The network switch is connected to at least one network motion capture camera; The synchronization device adapts the synchronization signal corresponding to the external expansion device to the PTP synchronization protocol of the network motion capture camera to obtain accurate PTP synchronization protocol time, thereby realizing clock synchronization calibration between the network motion capture camera and different external expansion devices, and ensuring the consistency of timestamps of data collected by each device; Among them, based on the acquisition, processing and calculation matching of the synchronization signal of the external expansion device by the synchronization device with the PTP protocol time, it specifically includes: generating the corresponding synchronization signal according to the PTP synchronization protocol time of the network motion capture camera and the pre-configured frame rate parameters, or analyzing and calculating the synchronization signal output by the external device and injecting the PTP event message to achieve clock synchronization.

2. The network motion capture platform based on synchronization equipment according to claim 1, characterized in that: The external expansion equipment group includes an electromyograph, and the output form of the electromyograph is a pulse synchronous output signal; For the electromyograph, the process of the synchronization device implementing the clock synchronization includes: The synchronization device collects the pulse synchronization output signal of the electromyograph: The synchronization device analyzes the pulse synchronization output signal and uses a sliding window algorithm to calculate the frame period multiple times and conversion time , and perform weighted average on the calculation results: ； ； in, is the frame period after weighted averaging, is the weighted average conversion time, and are the frame period and conversion duration calculated for the i-th time, is the weight of the i-th calculation result, and n is the number of calculations in the sliding window; The synchronization device generates accurate system time according to the calculated frame period and conversion duration; The synchronization device adds the generated system time to the PTP event message; When the network motion capture camera receives the PTP event message, the network motion capture camera synchronizes the PTP synchronization protocol time used by the network motion capture camera with the system time; The PTP synchronization protocol time format includes 32-bit integer seconds and 32-bit integer nanoseconds.

3. The network motion capture platform based on synchronization equipment according to claim 2, characterized in that: The external expansion equipment group includes a force measuring platform, and the input form of the force measuring platform is a pulse synchronous input signal; For the force measuring platform, the process of the synchronization device achieving the clock synchronization includes: The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera; According to the current PTP synchronization protocol time and specific required frame rate , the synchronization device generates a corresponding pulse synchronization input signal; the pulse synchronization input signal includes a frame period and conversion duration information; among them, ; The specific required frame rate is pre-set by the synchronization device according to application requirements; The generated pulse synchronous input signal is output to the force measuring platform device; the force measuring platform performs synchronous data acquisition according to the received pulse synchronous input signal.

4. The network motion capture platform based on synchronization equipment according to claim 2, characterized in that: The external expansion device group includes at least one audio-visual device and an associated time code generator; For the audio-visual device, the process of the synchronization device implementing the clock synchronization includes: The time code acquisition module included in the synchronization device acquires time code information from the time code generator; The collected time code information is converted into the PTP synchronization protocol time format; during the conversion process, the time corresponding to the time code information is , converted PTP synchronization protocol time ; in, It is the reference time of the PTP synchronization protocol. It is the time offset of the time code information relative to the reference time; The converted PTP synchronization protocol time is added to the PTP event message of the network motion capture camera.

5. The network motion capture platform based on synchronization equipment according to claim 2, characterized in that: The external expansion device group includes active marking points; for the active marking points, the process of the synchronization device implementing the clock synchronization includes: The synchronization device receives the current PTP synchronization protocol time from the network motion capture camera; Synchronous devices set the specified frame rate according to application requirements and duty cycle D; The specified frame rate represents the number of times the active marker changes per second, and the duty cycle represents the ratio of the light and dark time of the active marker. The received PTP synchronization protocol time is converted into the active marker system time; The calculation formulas for the light-on time and light-off time are: ； ； Add the specified frame rate and duty cycle data to form a complete device data message; The generated device data message is sent to each active marking point through the wireless module, and the active marking point performs light and dark control according to the received device data message.

6. The network motion capture platform based on synchronization equipment according to claim 1, characterized in that: The synchronization device performs filtering processing on the received synchronization signal and adopts a median filtering algorithm to remove noise interference, including: ； in, is the synchronization signal value at the kth moment after filtering, is the value of the original synchronization signal at the kth moment, and m is the radius of the median flow window.

7. The network motion capture platform based on synchronization equipment according to claim 1, characterized in that: The synchronization device has a fault-tolerant mechanism. When an abnormal synchronization signal is detected from an external expansion device, the synchronization time with the network motion capture camera is recalculated using the following formula: ； in, is the recalculated synchronization time, is the synchronization time between the jth external expansion device and the network motion capture camera, and s is the number of external expansion devices that are working normally.

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