CN113242527B - Communication system based on wireless somatosensory inertial measurement module - Google Patents
Communication system based on wireless somatosensory inertial measurement module Download PDFInfo
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/30—Services specially adapted for particular environments, situations or purposes
- H04W4/38—Services specially adapted for particular environments, situations or purposes for collecting sensor information
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- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
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- H—ELECTRICITY
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Abstract
The application discloses a communication system based on wireless somatosensory inertial measurement module, including a plurality of inertial measurement modules, data coordinator and PC end. The point-to-point networking mode is adopted between the inertia measurement modules and the data coordinators, the corresponding data transceivers in each inertia measurement module and the data coordinators carry out point-to-point data transmission, each pair of the inertia measurement modules and the data transceivers communicate and share a wireless communication channel, each data transceiver has own transmission frequency point, the mutual influence is avoided, the signal crosstalk of adjacent channels is effectively avoided, and the real-time performance and the reliability of the communication system are ensured. In addition, when the system is powered on, the data coordinator and each inertial measurement module are subjected to time synchronization, and in the data transmission process, the time deviation of the inertial measurement modules is compensated through the ACK signals carrying time information returned by the data coordinator, so that the time of each inertial measurement module is effectively synchronized, and the instantaneity and synchronism of the whole communication system are ensured.
Description
Technical Field
The present disclosure relates to the field of wireless communications technologies, and in particular, to a communication system based on a wireless somatosensory inertial measurement module.
Background
Inertial measurement is a technology for measuring actions of a human body or other objects by using an inertial sensor, and the technology has the advantages of being free from site limitation, convenient to wear and the like, and is widely applied to a plurality of fields such as physical exercise, medical treatment, military, telecine and the like. For example, people can use the technology to realize a motion health system for body feeling to help people to do physical exercise, so that physical exercise can still be performed without being influenced by outdoor places, and the health of people is promoted. Therefore, the design of the inertial measurement module software and hardware system has certain commercial value, and the realization of the inertial measurement module software and hardware system with excellent performance requires the real-time performance and reliability of motion capture data transmitted wirelessly. Therefore, it is also necessary to design a wireless sensor network communication method with high real-time performance, reliability and synchronism.
The prior art discloses a method for acquiring attitude data such as acceleration, angular velocity and the like based on an MEMS sensor. The inertial measurement module in the method has no wireless transmission unit, is large in size and high in power consumption, and therefore the requirement of wireless transmission at present is not met.
The prior art discloses an active RFID low-power consumption system based on an inertial measurement module, which does not build a wireless sensor network, does not design a communication method of the wireless sensor network, and cannot guarantee the real-time performance and reliability of the wireless sensor network. And the inertial measurement module of the system does not perform electromagnetic shielding treatment, and the anti-interference capability of the inertial sensor is small, so that the system cannot be applied to the current scene.
The prior art discloses a human motion capture system based on an inertial measurement module, which comprises a plurality of inertial sensors, temperature sensors, a Bluetooth module, a data coordinator and a data fusion module, wherein the inertial sensors are responsible for collecting data. In the system, data are connected with all inertial measurement modules through Bluetooth 4.0 protocol, and uploading of data collected by each inertial measurement module is achieved in a polling scanning mode. It can be seen that in such a communication manner, if the data transmission rate of the inertial measurement module is too high, a phenomenon such as packet loss is likely to occur. And the time synchronization processing is not performed, and under the condition that the working time of the inertial measurement module is too long, the phenomena of data packet confusion and data transmission conflict are easily caused by factors such as clock drift, so that the current design requirement is not met.
In summary, how to provide a wireless sensor network communication scheme with high real-time performance, reliability and synchronization is a problem to be solved by those skilled in the art.
Disclosure of Invention
The purpose of the application is to provide a communication system based on wireless somatosensory inertial measurement module, in order to solve the problem that the communication scheme of present inertial measurement module is lower in reliability, poor in instantaneity and unsatisfactory in synchronism.
In order to solve the technical problems, the application provides a communication system based on a wireless somatosensory inertial measurement module, which comprises a plurality of inertial measurement modules, a data coordinator and a PC (personal computer) end, wherein the data coordinator comprises a main controller and a plurality of data transceivers, the data transceivers are in one-to-one correspondence with the inertial measurement modules, and transmission frequency points of the data transceivers are different;
when the system is powered on, the data coordinator is used for sending time synchronization calibration commands to each inertia measurement module so as to trigger a time synchronization calibration process; in the time synchronization calibration process, each inertia measurement module determines the transmission time and the time deviation of the inertia measurement module compared with the data coordinator;
in the data transmission process, the inertial measurement module is used for transmitting inertial data to a corresponding data transceiver in a wireless transmission mode; the data transceiver is used for sending the inertial data to the main controller through an SPI bus after receiving the inertial data, and is also used for feeding back an ACK signal to the inertial measurement module, wherein the ACK signal carries time information of the data transceiver receiving the inertial data; the main controller is used for integrating the received inertial data and sending the integration result to the PC end; and the inertia measurement module is used for correcting the time deviation according to the ACK signals received in the front and the back.
Preferably, the PC side is configured to send a control command to the inertial measurement module via the data coordinator, so as to implement a control operation on the inertial measurement module.
Preferably, the control operation includes any one or more of: and starting data acquisition, stopping data acquisition, entering a calibration mode, modifying an uploading period, and modifying a module ID.
Preferably, the IO pin of the data transceiver is in an output mode, and outputs a low level by default; after receiving the inertial data sent by the inertial measurement module, the IO pin of the data transceiver outputs a high level, and triggers an interrupt service function to update flag bit data, wherein each bit in the flag bit data represents the state of the corresponding data transceiver; the main controller circularly detects the zone bit data and reads the inertia data from the corresponding data transceiver according to the zone bit data.
Preferably, the inertial measurement module is configured to: and transmitting the data packet carrying the inertial data to a corresponding data transceiver in a wireless transmission mode, waiting for an ACK signal transmitted by the data transceiver, and if the ACK signal transmitted by the data transceiver is not received after exceeding a preset time threshold, transmitting the data packet to the data transceiver again until the transmission times reach the maximum transmission times.
Preferably, when the number of transmissions reaches the maximum number of transmissions, the inertial measurement module is configured to detect whether a communication channel of another inertial measurement module is idle, and if so, transmit a data packet to the data transceiver through the communication channel of the other inertial measurement module.
Preferably, the inertial measurement module comprises a power management unit, an inertial sensor unit, a baseband and radio frequency processing unit and an external crystal oscillator source.
Preferably, the circuit board of the inertial measurement module adopts a four-layer board design scheme, and comprises a top surface signal layer, an intermediate power layer, a ground layer and a bottom surface signal layer.
Preferably, in the inertial measurement module, copper-clad is disposed around the inertial sensor unit, and a tin foil material is disposed on the upper surface of the power management unit.
Preferably, the system further comprises a magnetic field calibration upper computer, wherein the magnetic field calibration upper computer is connected with the data coordinator through a USB interface and is used for collecting magnetic field data of the inertial measurement module and issuing magnetic field data compensation values to the inertial measurement module.
The application provides a communication system based on wireless somatosensory inertial measurement module, including a plurality of inertial measurement modules, data coordinator and PC end, wherein, data coordinator includes main control unit and a plurality of data transceiver, and data transceiver and inertial measurement module one-to-one, and the transmission frequency point of different data transceiver is different. When the system is powered on, the data coordinator sends time synchronization calibration commands to each inertia measurement module so as to trigger a time synchronization calibration process; during the time synchronization calibration process, each inertial measurement module determines the time of transmission and its own time offset compared to the data coordinator. In the data transmission process, the inertia measurement module is used for transmitting inertia data to the corresponding data transceiver in a wireless transmission mode; the data transceiver is used for transmitting the inertial data to the main controller through the SPI bus after receiving the inertial data, and is also used for feeding back an ACK signal to the inertial measurement module, wherein the ACK signal carries time information of the inertial data received by the data transceiver; the main controller is used for integrating the received inertial data and sending the integration result to the PC end; the inertia measurement module is used for correcting the time deviation according to the ACK signals received in the front and the back.
Therefore, in the system, a point-to-point networking mode is adopted between the inertia measurement module and the data coordinator, the corresponding data transceivers in each inertia measurement module and the data coordinator carry out point-to-point data transmission, each pair of the inertia measurement module and the data transceivers communicate and share a wireless communication channel, each data transceiver has own transmission frequency point, the mutual influence is avoided, signal crosstalk of adjacent channels is effectively avoided, the phenomenon that data transmission delay is too high due to insufficient channel resources or channel competition occurs when data is transmitted at high speed is avoided, and the instantaneity and reliability of the communication system are ensured. In addition, when the system is powered on, the data coordinator and each inertial measurement module are subjected to time synchronization, and in the data transmission process, the time deviation of the inertial measurement modules is compensated through the ACK signals carrying time information returned by the data coordinator, so that the time of the data coordinator and each inertial measurement module is effectively synchronized, and the real-time performance and the synchronism of the whole communication system are ensured.
Drawings
For a clearer description of embodiments of the present application or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description that follow are only some embodiments of the present application, and that other drawings may be obtained from these drawings by a person of ordinary skill in the art without inventive effort.
FIG. 1 is a block diagram of a first embodiment of a communication system based on a wireless somatosensory inertial measurement module provided herein;
fig. 2 is a schematic diagram of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application;
fig. 3 is a block diagram of an internal design of a data coordinator of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application;
fig. 4 is a schematic diagram of time synchronization calibration of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application;
fig. 5 is a schematic diagram of time offset compensation of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module according to the present application;
fig. 6 is a schematic diagram of an internal bus of a data coordinator of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application;
fig. 7 is a schematic hardware design diagram of an inertial measurement module of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application;
fig. 8 is a schematic diagram of a magnetic field calibration host computer of a second embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application.
Detailed Description
In order to provide a better understanding of the present application, those skilled in the art will now make further details of the present application with reference to the drawings and detailed description. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
The traditional physical exercise is limited by places or people, so that sports fans cannot enjoy sports at any time to bring health promotion effects. Current wireless sensor networks generally use wireless communication technologies such as bluetooth, WIFI, zigbee, and the like. In general, in the bluetooth communication scheme, a master device is connected to seven slave devices at most, which is insufficient in networking capability. Although there are 13 WIFI wireless network channels, there are only three channels of 1, 6, 11 (or 13) that are not overlapped, that is, the selection of two channels has overlapping portions, so improvement is needed in terms of instantaneity, stability, and the like, and the power consumption of WIFI devices is higher. Although the Zigbee has low power consumption and poor networking capability, the transmission rate is too slow, which does not meet the requirements of the current scenario.
In view of the above problems, the present application provides a communication system based on a wireless motion sensing inertial measurement module, where the inertial measurement module can capture the gesture motion information of the whole body to obtain inertial data, and transmit the inertial data to a data coordinator through wireless, and finally send the inertial data to a PC end. The data transceivers in the inertia measurement module and the data coordinator adopt a point-to-point networking mode, each pair of the inertia measurement module and the data transceivers are communicated to share a wireless communication channel, each data transceiver has own transmission frequency point, the mutual influence is avoided, signal crosstalk of adjacent channels is effectively avoided, the condition that channel resources are insufficient or channel competition occurs is avoided, and the real-time performance and reliability of a communication system are ensured. Under the sports scene, the system enables sports lovers to complete own moving targets indoors, so that the physical health of people is promoted.
In the following, a first embodiment of a communication system based on a wireless somatosensory inertial measurement module provided in the present application is described, referring to fig. 1, where the first embodiment includes: the system comprises a plurality of inertia measurement modules, a data coordinator and a PC (personal computer) end, wherein the data coordinator comprises a main controller and a plurality of data transceivers, the data transceivers are in one-to-one correspondence with the inertia measurement modules, and the transmission frequency points of different data transceivers are different.
When the system is powered on, the data coordinator is used for sending time synchronization calibration commands to each inertia measurement module so as to trigger a time synchronization calibration process; during the time synchronization calibration process, each inertial measurement module determines the time of transmission and its own time offset compared to the data coordinator.
In the data transmission process, the inertia measurement module is used for transmitting inertia data to the corresponding data transceiver in a wireless transmission mode; the data transceiver is used for transmitting the inertial data to the main controller through the SPI bus after receiving the inertial data, and is also used for feeding back an ACK signal to the inertial measurement module, wherein the ACK signal carries time information of the inertial data received by the data transceiver; the main controller is used for integrating the received inertial data and sending the integration result to the PC end; the inertia measurement module is used for correcting the time deviation according to the ACK signals received in the front and the back.
In addition, the PC side is used for sending a control command to the inertial measurement module through the data coordinator so as to realize control operation of the inertial measurement module. In practical applications, the control operation includes any one or more of the following: and starting data acquisition, stopping data acquisition, entering a calibration mode, modifying an uploading period, and modifying a module ID.
In order to avoid the problem of packet loss, as a specific implementation manner, the inertial measurement module sends the data packet carrying the inertial data to the corresponding data transceiver in a wireless transmission mode, waits for an ACK signal sent by the data transceiver, and if the ACK signal sent by the data transceiver is not received after exceeding a preset time threshold, sends the data packet to the data transceiver again until the sending frequency reaches the maximum sending frequency.
Specifically, after the number of transmissions reaches the maximum number of transmissions, if the ACK signal transmitted by the data transceiver is still not received, it indicates that a problem occurs in the communication channel between the current inertial measurement module and the data transceiver, and at this time, the inertial measurement module may detect whether the communication channel of the other inertial measurement module is idle, and if so, transmit the data packet to the data transceiver through the communication channel of the other inertial measurement module. For example, assuming that the inertial measurement module 1 corresponds to the data transceiver 1 and the inertial measurement module 2 corresponds to the data transceiver 2, when a problem arises in communication between the inertial measurement module 1 and the data transceiver 1, the inertial measurement module 1 may temporarily transmit data packets to the data transceiver 1 using a communication channel between the inertial measurement module 2 and the data transceiver 2.
As a preferred implementation manner, the embodiment may further include a magnetic field calibration upper computer. The magnetic field calibration upper computer is connected with the data coordinator through a USB interface and is used for collecting magnetic field data of the inertial measurement module and issuing magnetic field data compensation values to the inertial measurement module.
The communication system based on the wireless somatosensory inertial measurement module provided by the embodiment comprises a plurality of inertial measurement modules, a data coordinator and a PC (personal computer) terminal. In the system, a point-to-point networking mode is adopted between the inertia measurement module and the data coordinator, the corresponding data transceivers in each inertia measurement module and the data coordinator carry out point-to-point data transmission, each pair of the inertia measurement module and the data transceivers communicate and share a wireless communication channel, each data transceiver has own transmission frequency point, mutual influence is avoided, signal crosstalk of adjacent channels is effectively avoided, and when data is transmitted at a high speed, data transmission delay is too high due to insufficient channel resources or channel competition, and real-time performance and reliability of a communication system are ensured. In addition, when the system is powered on, the data coordinator and each inertial measurement module are subjected to time synchronization, and in the data transmission process, the time deviation of the inertial measurement modules is compensated through the ACK signals carrying time information returned by the data coordinator, so that the time of the data coordinator and each inertial measurement module is effectively synchronized, and the real-time performance and the synchronism of the whole communication system are ensured.
The second embodiment of the communication system based on the wireless motion sensing inertial measurement module provided by the application is implemented based on the first embodiment, and is expanded to a certain extent based on the first embodiment. Specifically, the second embodiment describes the process of time synchronization calibration in detail, and also describes the hardware structure and software design of the inertial measurement module.
As shown in fig. 2 and 3, the communication system based on the wireless somatosensory inertial measurement module provided in the present embodiment includes a plurality of inertial measurement modules, a data coordinator and a PC terminal. The inertial measurement module sends inertial data or state information to the data coordinator in a 2.4G wireless transmission mode, and after the 2.4G data transceiver in the data coordinator receives the data, the data is sent to the main controller in an SPI bus mode, and the main controller integrates the data and uploads the data to the PC through the USB interface. The PC computer can also issue a command to the data coordinator through the upper computer software, so that the command is issued to the appointed inertial measurement module, and the control operation of the inertial measurement module, such as parameter modification or checking, is completed, so that the wireless sensing network which can upload data to the PC computer and issue the command to control the inertial measurement module is obtained.
The following describes a communication system based on a wireless somatosensory inertial measurement module in five parts: the method comprises the steps of communication between an inertial measurement module and a data coordinator, communication between a data transceiver and a main controller, hardware design of the inertial measurement module, software design of the inertial measurement module and a magnetic field calibration process of the inertial measurement module.
The first part, the inertial measurement module communicates with the data coordinator.
In this embodiment, a peer-to-peer networking manner based on a 2.4G active RFID transceiver is adopted between the inertial measurement module and the data coordinator, and each inertial measurement module and the corresponding 2.4G data transceiver in the data coordinator perform peer-to-peer data transmission. Each data transceiver has own transmission frequency point, and the transmission frequency points are not mutually influenced. Each pair of inertial measurement module and data transceiver shares a single wireless communication channel, 14 channels each with a bandwidth of 2MHZ. In order to avoid signal crosstalk of adjacent channels and better avoid overlapping of WIFI channels, each channel adopts fixed frequency points for transmission, and the frequency points are respectively: 2402MHz,2405MHz,2408MHz,2489MHz,2492MHz,2495MHz,2498MHz,2501MHz,2504MHz,2507MHz, 2513MHz,2518MHz,2523MHz. Therefore, the data transmission delay is prevented from being too high due to insufficient channel resources or channel competition during high-speed data transmission, and the instantaneity and the reliability in the wireless sensor network are improved. It can be understood that in practical application, the number of channels, the bandwidth of channels, and the transmission splice point can be set or adjusted according to the practical application scenario, which is not limited in this embodiment.
The 2.4G data transceiver in the data coordinator replies an ACK signal each time a data packet is received. If the inertial measurement module does not receive the ACK signal within a certain time after transmitting the data packet, the data packet is retransmitted, if the continuous transmission is unsuccessful for ten times, the inertial measurement module detects whether other communication channels of the inertial measurement module are idle, and if the communication channels are idle, the data packet is transmitted by using the communication channels until the transmission is successful. Therefore, the packet loss phenomenon of 2.4G wireless transmission is avoided, and the reliability of the wireless sensor network is greatly improved.
In order to improve the real-time performance of the wireless sensor network, the time of the inertia measurement modules is synchronized, and the time disorder of each inertia measurement module caused by clock drift is avoided. The embodiment uses a synchronization time algorithm based on TPSN, firstly, time synchronization is carried out on the data coordinator and each inertial measurement module, and then the inertial measurement modules are compensated by the ACK signals which are returned by the data coordinator and carry time information. The specific process is as follows:
after the wireless sensor network is electrified, the data coordinator sends a time synchronization calibration command to the inertial measurement module, the inertial measurement module receives the command after the beta time passes, and a data packet 1 carrying time information T1 is sent to the data coordinator at the moment T1. At time T2, the data coordination transceiver receives the data packet 1, and sends the data packet 2 to the inertial measurement module at time T3, where the data packet 2 includes T1, T2, and T3 information. At time T4, the inertial measurement module receives data packet 2. The process is shown in fig. 4, where T2-t1=delta+d, and T4-t3=d-delta, where delta is the time offset between the inertial measurement module and the data transceiver and d is the propagation delay of the time synchronization pulse packet. Therefore, the time deviation delta= [ (T2-T1) - (T4-T3) ]/2, the transmission time d= [ (T2-T1) + (T4-T3) ]/2. After Delta and d are obtained, the inertial measurement module can calculate the time information vcoordatostime=Tick+delta+d of the data coordinator, where Tick is the current time of the inertial measurement module. Similarly, other inertia measurement modules operate sequentially, and can respectively obtain the delta and d of the inertia measurement modules, and the delta and d of the inertia measurement modules can respectively compensate the self-sending data packet timer, so that the synchronization effect is achieved.
In the transmission work of the wireless sensor network, as the crystal oscillator of the inertia measurement module has drift, the larger the drift is, the delta value is insufficient to compensate the drift value. Therefore, the data coordinator needs to return an ACK signal after receiving the data packet each time, the ACK signal carries time information of the moment when the data coordinator receives the data packet, and delta value is compensated according to the ACK signal. As shown in fig. 5, the data coordinator is configured to load ACK data ACK at the moment of receiving mode, the inertial measurement module sends a data packet 1, the data coordinator receives the data packet and records the current time t0, and returns ACK data ACK to the inertial measurement module, loads ACK data record time t0 again, and waits for the arrival of the next data packet; the inertial measurement module sends a data packet 2, the data coordinator receives the data packet and records the current time t1 at the same time, and returns ACK data t0 to the inertial measurement module and loads the ACK data t1; the inertial measurement module obtains time information t0 of the coordinator, subtracts propagation delay d, then subtracts the propagation delay d from the data packet sending time Vcoordatosime to obtain diff, and finally updates Delta=Delta+diff.
The second part, the data transceiver communicates with the master controller.
The communication between the 2.4G data transceiver and the main controller adopts a wired SPI bus mode, and four wires are shared by the SPI interface: MISO, MOSI, CLK, CS, as shown in fig. 6. The MCU is used as a host, the 2.4G transceivers are used as slaves, and one MCU is provided with 15 2.4G transceiver slaves.
In order to improve the response rate of the MCU to the 2.4G transceiver slaves, each 2.4G transceiver slave has a common IO pin connected with the IO pin of the MCU. The IO pin of the slave is configured into an output mode, the general state outputs a low level, and the MCU pin connected with the slave is configured into an external interrupt input mode. Whenever the 2.4G transceiver slave receives a data packet of the inertial measurement module, the IO pin of the slave outputs a high level, and the MCU enters an interrupt service function. In this function, the value of the data IfDatFlg will be changed. IfDatFlg is an unsigned integer of 32 bits of data in which each bit represents the state of a 2.4G transceiver slave. The corresponding position 1 of the IfDatFlg indicates that the corresponding transceiver slave receives data, and prompts the MCU to read the data. The MCU continuously judges whether the IfDatFlg is 0 or not to judge whether a transceiver receives the data packet or not, so that the data can be read in time, and the requirements of instantaneity and reliability are met.
Third, hardware design of inertial measurement module.
As shown in fig. 7, the inertial measurement module includes a power management unit, an inertial sensor unit, a baseband plus radio frequency processing unit, and an external crystal oscillator source. The power management unit is positioned at the bottom layer of the circuit board, and the gesture data acquisition unit, the baseband and radio frequency processing unit and the external crystal oscillator source are positioned at the top layer of the circuit board.
In the design of the high-speed circuit board, in order to avoid the interference of electromagnetic signals inside and outside the circuit board on the gesture data acquisition unit and ensure that the signals of the hardware system are more stable, the design of the node circuit board of the embodiment adopts a four-layer board design scheme, and comprises a top surface signal layer, a middle power layer, a ground layer and a bottom surface signal layer. And copper coating processing is performed around the inertial sensor, and insulation processing is performed on the gesture data acquisition unit and the lithium battery by using a tin foil material, so that the electromagnetic interference capability of the MPU9250 chip is improved.
The baseband and radio frequency processing unit is the core of the whole inertial measurement module and mainly comprises an NRF24L01P chip and an MCU of NORDIC company. The NRF24L01P is a 2.4G transceiver chip, an embedded baseband protocol engine (enhanced clock) is integrated, the NRF24L01P supports air rates of 250kbps, 1Mbps and 2Mbps, the wireless transceiver chip is suitable for ultra-low power wireless application, has excellent wireless receiving sensitivity and anti-interference performance, and other suitable chips can be selected in practical application. NRF24L01P configuration registers may be accessed in all modes of operation by Serial Peripheral Interface (SPI) operation and configuration NRF24L 01P. In order to ensure the normal operation of the module, the MCU uses on-chip resources such as a TIM2 timer, an analog I2C interface, an SPI interface, an ADC converter and the like. The analog I2C interface is used for communicating with the inertial sensor unit, acquiring motion gesture data, the MCU can perform data fusion processing, and finally, the data packet is packaged and sent to the data coordinator through the radio frequency unit. The ADC is used for collecting power information of the lithium battery and monitoring electric quantity information of the lithium battery in real time. The SPI interface is used for configuration of NRF24L01P and transmission and reception of data. The TIM2 timer is used for timing and generating an interrupt signal, when the inertial measurement module is started, the MCU sends a frame of data packet to the data coordinator every time an interrupt occurs, and in order to reduce clock drift, the clock source of the TIM2 adopts an external crystal oscillator source.
The inertial sensor unit is used for capturing motion attitude information of the inertial measurement module. The inertial sensor is MPU9250 chip of invente company, and has accelerometer sensor, gyroscope sensor and magnetometer sensor integrated thereon. The acceleration sensor is used for capturing the acceleration information of the racket, the gyroscope is used for capturing the angle and angular speed information of the racket, and the magnetometer is used for measuring the magnetic field intensity and direction of the current position of the racket. It will be appreciated that other chips may be selected as inertial sensors in practical applications, and this embodiment is not limited thereto.
The power management unit is connected with each power supply and stably supplies power for each unit by 3.3V. The unit mainly comprises a 4.2V lithium battery, a USB charging management chip TC4045P, LDO, a switch, a field effect transistor and the like. The USB charging management chip is used for managing USB charging current and placing damage to the lithium battery or the module caused by overcharge. The field effect tube is matched with the switch to control the on/off of the inertial measurement module, and the use of the field effect tube effectively prevents huge voltage loss caused by poor contact of the switch. The LDO is used for stabilizing the power supply voltage of the other units to be 3.3V.
And the fourth part, software design of the inertia measurement module.
First, the command process from the host computer to the inertial measurement module will be described. The PC computer is connected with the data coordinator through the USB interface, the PC upper computer firstly transmits the command to the data coordinator, and the data coordinator transmits the command to the inertia measurement module through the 2.4G transceiver. After receiving the command, the inertial sensor analyzes the command information and completes the corresponding action. The command format and the functions from the upper computer to the inertia measurement module are as follows:
TABLE 1
And the first inertial measurement module is powered on in a default mode, and state information such as a module ID number, lithium battery electricity quantity information, acquisition data frequency and the like of the inertial measurement module is sent in the default mode, and the upper computer waits for sending a command and enters a command mode. In the command mode, the data acquisition function of the inertial measurement module, the acquisition of the stop module, the change of the module ID number and other functions can be started. After the inertial measurement module is started to collect data, the TIM2 timer in NRFL24E1 will start the timer interrupt function, generate an interrupt every 33ms, and send a data packet.
Referring now to the inertial measurement module to the host computer data format, it includes:
BYTE1: device IDs (1-20);
BYTE2：0；
BYTE3:2, the terminal sends dynamic data to the service program;
BYTE4: N/A, independent value;
BYTE5: transmission sequence number 1 (0-255 cycles);
BYTE6: transmitting sequence number 2 (0-255 cycles, after each dynamic data frame is transmitted [ transmitting sequence number 2 ] +1, after upward carry [ transmitting sequence number 1 ] +1);
BYTE7-BYTE10: 32-bit shaping number, which represents the number of milliseconds up to the present after the instruction is started;
BYTE11-BYTE36: the sensor data, as shown in the following table, includes four parts.
TABLE 2
| Quaternion | Q0L | Q0H | Q1L | Q1H | Q2L | Q2H | Q3L | Q3H |
| Acceleration of | AxL | AxH | AyL | AyH | AzL | AzH | ||
| Angular velocity of | WxL | WxH | WyL | WyH | WzL | WzH | ||
| Magnetic field | HxL | HxH | HyL | HyH | HzL | HzH |
BYTE11-BYTE18: representing quaternion, specifically as follows:
Q0＝((Q0H<<8)|Q0L)/32768
Q1＝((Q1H<<8)|Q1L)/32768
Q2＝((Q2H<<8)|Q2L)/32768
Q3＝((Q3H<<8)|Q3L)/32768
BYTE19-BYTE24: the acceleration is expressed as follows:
ax= ((AxH < < 8) | AxL)/32768 x 16g (g is gravity acceleration, preferably 9.8m/s 2)
ay= ((AyH < < 8) | AyL)/32768 x 16g (g is gravitational acceleration, preferably 9.8m/s 2)
az= ((AzH < < 8) | AzL)/32768 x 16g (g is gravitational acceleration, preferably 9.8m/s 2)
BYTE25-BYTE30: the angular velocity is expressed as follows:
wx＝((wxH<<8)|wxL)/32768*2000(°/s)
wy＝((wyH<<8)|wyL)/32768*2000(°/s)
wz＝((wzH<<8)|wzL)/32768*2000(°/s)
BYTE31-BYTE36: the magnetic field is represented as follows:
magnetic field (x-axis) hx= ((HxH < < 8) | HxL)
Magnetic field (y axis) hy= ((HyH < < 8) | HyL)
Magnetic field (z-axis) hz= ((Hz < < 8) | HzL)
And fifth part, magnetic field calibration process of the inertial measurement module.
FIG. 8 is a magnetic field calibration host computer of the inertial measurement module, which is programmed based on the QT5.4 platform. The upper computer is connected with the data coordinator through the USB interface, and can complete the functions of collecting magnetic field data of the inertial measurement module, issuing compensation magnetic field data values to the inertial measurement module and the like.
The upper computer code mainly comprises main, myapp, mythread, widget, and other files. The myapp.cpp file mainly realizes the design of a UI interface, connects various slot functions, and creates and uses serial threads. The mythread.cpp file mainly realizes the initialization of the serial port, realizes the functions of receiving and sending serial port data, and is connected with a groove function for drawing. The widget.h file mainly realizes the function of drawing tables and points in the widget window.
It can be seen that the present embodiment relates to the field of wireless sensing technology and the field of human motion sensing technology, and in particular, to wireless sensing communication based on inertial measurement of body sensing of a mems technology sensor. The embodiment provides a wireless sensor network communication method with high real-time performance, reliability and synchronization time, and a small-size and low-power-consumption somatosensory inertial measurement module design. Not only can meet the requirements of physical exercise of ordinary sports lovers, but also can be in butt joint with a somatosensory game, correct the sports posture for professional athletes, and improve the skills of the professional athletes. In summary, the present embodiment has at least the following advantages:
1. by adopting a point-to-point networking mode based on the 2.4G active RFID transceiver, each inertial measurement module and the corresponding 2.4G transceiver in the data coordinator transmit data point-to-point, and each 2.4G transceiver receives one data packet, an ACK signal can be returned to a sender, so that the wireless sensing network has higher real-time performance and better reliability.
2. In the design of the high-speed circuit board, a four-layer board design scheme is adopted. And copper coating processing is performed around the inertial sensor, and tin foil materials are used for isolating processing on the gesture data acquisition unit and the lithium battery, so that the interference of electromagnetic signals inside and outside the circuit board on the gesture data acquisition unit is avoided, and the stability of hardware system signals is improved.
3. The MEMS inertial sensor is adopted to collect data, related attitude data such as quaternion and the like are obtained through data fusion by the MCU, and finally the data are uploaded to the data coordinator in a wireless transmission mode, and the PC upper computer can also issue a command to calibrate the magnetic field of the inertial measurement module.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The foregoing has outlined rather broadly the more detailed description of the present application and the principles and embodiments of the present application have been presented in terms of specific examples, which are provided herein to assist in the understanding of the method and core concepts of the present application; meanwhile, as those skilled in the art will have modifications in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Claims (9)
1. The communication system based on the wireless somatosensory inertial measurement module is characterized by comprising a plurality of inertial measurement modules, a data coordinator and a PC end, wherein the data coordinator comprises a main controller and a plurality of data transceivers, the data transceivers are in one-to-one correspondence with the inertial measurement modules, and the transmission frequency points of the data transceivers are different;
when the system is powered on, the data coordinator is used for sending time synchronization calibration commands to each inertia measurement module so as to trigger a time synchronization calibration process; in the time synchronization calibration process, each inertia measurement module determines the transmission time and the time deviation of the inertia measurement module compared with the data coordinator;
in the data transmission process, the inertial measurement module is used for transmitting inertial data to a corresponding data transceiver in a wireless transmission mode; the data transceiver is used for sending the inertial data to the main controller through an SPI bus after receiving the inertial data, and is also used for feeding back an ACK signal to the inertial measurement module, wherein the ACK signal carries time information of the data transceiver receiving the inertial data; the main controller is used for integrating the received inertial data and sending the integration result to the PC end; the inertia measurement module is used for correcting the time deviation according to the ACK signals received in the front and the back;
the IO pin of the data transceiver is in an output mode, and outputs a low level by default; after receiving the inertial data sent by the inertial measurement module, the IO pin of the data transceiver outputs a high level, and triggers an interrupt service function to update flag bit data, wherein each bit in the flag bit data represents the state of the corresponding data transceiver; the main controller circularly detects the zone bit data and reads the inertia data from the corresponding data transceiver according to the zone bit data.
2. The communication system based on a wireless somatosensory inertial measurement module according to claim 1, wherein the PC side is configured to send a control command to the inertial measurement module via the data coordinator to implement a control operation of the inertial measurement module.
3. The wireless somatosensory inertial measurement module-based communication system of claim 2, wherein the control operations comprise any one or more of: and starting data acquisition, stopping data acquisition, entering a calibration mode, modifying an uploading period, and modifying a module ID.
4. The wireless somatosensory inertial measurement module-based communication system of claim 1, wherein the inertial measurement module is to: and transmitting the data packet carrying the inertial data to a corresponding data transceiver in a wireless transmission mode, waiting for an ACK signal transmitted by the data transceiver, and if the ACK signal transmitted by the data transceiver is not received after exceeding a preset time threshold, transmitting the data packet to the data transceiver again until the transmission times reach the maximum transmission times.
5. The wireless somatosensory inertial measurement module-based communication system of claim 4, wherein the inertial measurement module is configured to detect whether a communication channel of another inertial measurement module is idle when the number of transmissions reaches the maximum number of transmissions, and if so, to transmit a data packet to the data transceiver over the communication channel of the other inertial measurement module.
6. The communication system based on a wireless somatosensory inertial measurement module of claim 1, wherein the inertial measurement module comprises a power management unit, an inertial sensor unit, a baseband plus radio frequency processing unit, and an external crystal oscillator source.
7. The communication system based on wireless somatosensory inertial measurement module according to claim 6, wherein the circuit board of the inertial measurement module adopts a four-layer board design, comprising a top signal layer, an intermediate power layer, a ground layer, and a bottom signal layer.
8. The communication system based on a wireless somatosensory inertial measurement module according to claim 6, wherein in the inertial measurement module, copper-clad is provided around the inertial sensor unit, and a tin foil material is provided on an upper surface of the power management unit.
9. The communication system according to any one of claims 1 to 8, further comprising a magnetic field calibration host computer connected to the data coordinator via a USB interface, for collecting magnetic field data of the inertial measurement module and issuing magnetic field data compensation values to the inertial measurement module.
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