阅读说明：本技术 一种便携的无线穿戴式肌肉运动信号采集系统 (Portable wireless wearable muscle movement signal acquisition system ) 是由 常青 金文光 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种便携的无线穿戴式肌肉运动信号采集系统,包括：采集端,所述采集端包括柔性采集板、核心板和电源板,所述柔性采集板用于采集表面肌肉电信号,并对电信号进行放大、滤波信号处理,所述核心板用于接收处理后的信号,对信号进行模数转换,再将模数转换后的信号与惯性运动信息一起打包发送,其中惯性运动信息包括加速度、角速度和磁场；所述电源板为柔性采集板和核心板提供工作电压；接收端,用于通过低功耗无线蓝牙技术接收打包发送的数据。本系统可应用于手势感知或操控的人机交互系统、人体步态分析的研究、医学中肌肉运动康复的训练等,结构紧凑、穿戴便携、信噪比高、功耗低。(The invention discloses a portable wireless wearable muscle movement signal acquisition system, which comprises: the acquisition end comprises a flexible acquisition board, a core board and a power board, wherein the flexible acquisition board is used for acquiring surface muscle electric signals, amplifying and filtering the electric signals, and the core board is used for receiving the processed signals, performing analog-to-digital conversion on the signals, and packaging and sending the signals after the analog-to-digital conversion and inertial motion information together, wherein the inertial motion information comprises acceleration, angular velocity and a magnetic field; the power panel provides working voltage for the flexible acquisition board and the core board; and the receiving end is used for receiving the data sent by the package through the low-power wireless Bluetooth technology. The system can be applied to a human-computer interaction system for gesture sensing or control, human gait analysis research, muscle movement rehabilitation training in medicine and the like, and has the advantages of compact structure, portability in wearing, high signal-to-noise ratio and low power consumption.)

1. A portable wireless wearable muscle movement signal acquisition system, comprising:

the acquisition terminal (1) comprises a flexible acquisition board (3), a core board (4) and a power board (5), wherein the flexible acquisition board (3) is used for acquiring surface muscle electrical signals, amplifying and filtering the electrical signals, the core board (4) is used for receiving the processed signals, performing analog-to-digital conversion on the signals, and packaging and sending the signals after the analog-to-digital conversion and inertial motion information together, wherein the inertial motion information comprises acceleration, angular velocity and a magnetic field; the power panel (5) provides working voltage for the flexible acquisition board (3) and the core board (4);

and the receiving end (2) is used for receiving the data sent by the package through the low-power wireless Bluetooth technology.

2. The wireless wearable muscle movement signal acquisition system according to claim 1, wherein the flexible acquisition board (3) is made of a flexible circuit board and comprises N groups of electromyographic main electrodes (6) and N groups of electromyographic signal conditioning modules (7), each group of electromyographic main electrodes (6) is connected with the corresponding group of electromyographic signal conditioning modules (7) to form an N-channel surface electromyographic signal acquisition circuit, wherein N is a positive integer.

3. The wireless wearable muscle movement signal acquisition system according to claim 1, wherein the core board (4) is composed of a wireless microcontroller (8) and peripheral circuits thereof, an inertia measurement unit (9) and a vibrator (10), the wireless microcontroller (8) integrates a low-power wireless Bluetooth module (11) and an analog-to-digital conversion module (12), broadcasting, connection and data receiving and transmitting of low-power wireless Bluetooth are completed by operating an embedded real-time operating system (13), and meanwhile, acquisition, storage and start and stop of the vibrator (10) are controlled in response to a command sent from a receiving end (2).

4. The wireless wearable muscle movement signal acquisition system according to claim 1, wherein the power board (5) is composed of a power module (14) and a lithium battery (15), the power module (14) comprises a plurality of power chips, a charging circuit and a voltage protection circuit, and the lithium battery (15) with 3.7V is charged through microsusb, so that a stable voltage of ± 2.5V is provided for the acquisition board (3) according to the control of the core board (4), a stable voltage of 2.5V is provided for the core board (4), and power consumption is optimized.

5. The wireless wearable muscle movement signal acquisition system according to claim 2, wherein each group of myoelectric dry electrodes (6) comprises three stainless steel electrodes, two of which are acquisition electrodes with a size of 10mm x 1mm, the other is a reference electrode with a size of 10mm x 4mm x 1mm, and the position of the middle symmetrical point of the two acquisition electrodes is used as a reference ground.

6. The wireless wearable muscle movement signal acquisition system according to claim 2, wherein each group of electromyographic signal conditioning module (7) integrates four operational amplifiers, and performs two-stage amplification, passive high-pass filtering and active low-pass filtering on the surface electromyographic signals, the two-stage amplification is realized by a first-stage differential amplification circuit and a second-stage low-pass amplification circuit, the first-stage differential amplification circuit performs differential amplification on the signals, the second-stage amplification circuit is a fourth-order butterworth low-pass filter, the pass band is-1 dB at 220Hz, the stop band is-20 dB at 500Hz, and the gain of the amplification circuit is 60 dB.

7. A wireless wearable muscle movement signal acquisition system according to claim 3, wherein the wireless microcontroller (8) controls the sampling frequency of the digital-to-analog converter according to the command sent by the user from the receiving terminal (2), so as to change the sampling rates of the electromyographic signal and the inertial measurement unit to meet different application requirements, wherein the sampling rate of the electromyographic signal ranges from 100Hz to 500 Hz.

8. The wireless wearable muscle motion signal acquisition system according to claim 3, wherein the embedded real-time operating system (13) detects whether the system is in motion state through the inertial measurement unit (9), and if the device does not move in a period of time, the embedded real-time operating system judges that the system is not in use, and therefore all resources which are not necessary to be turned on are turned off, and the embedded real-time operating system enters into a very low power consumption sleep mode; if the system is in a motion state, the embedded real-time operating system (13) is awakened, and tasks such as connection of the low-power-consumption Bluetooth and data acquisition are executed.

9. The wireless wearable muscle movement signal acquisition system according to claims 1-8, wherein the flexible acquisition board (3), the core board (4) and the power board (5) adopt an integrated packaging technology, wherein each group of myoelectric dry electrodes (6) and each group of myoelectric signal conditioning modules (7) are welded together through bonding pads, the core board (4) and the power board (5) are connected with the flexible circuit board through micro connectors, and the core board (4), the power board (5) and the flexible acquisition board (2) form a compact structure with upper and lower layers.

10. The wireless wearable muscle movement signal acquisition system according to claim 1, wherein the receiving end (2) receives the electromyographic signals and the inertia measurement data sent by the acquisition end (1) through a low-power wireless Bluetooth technology, and sends the electromyographic signals and the inertia measurement data to the PC through a USB serial port, and the receiving end (2) further sends sampling rate change commands and vibrator control commands sent by the PC to the acquisition end (1) through the low-power wireless Bluetooth technology so as to meet different application requirements.

Technical Field

The invention relates to the technical field of weak signal acquisition, in particular to a portable wireless wearable muscle movement signal acquisition system.

Background

Surface Electromyography (SEMG) is a comprehensive bioelectricity phenomenon produced in the epidermis of the human body by the conduction of electrical signals through the neuromuscular system. It is an electric signal with very small voltage amplitude, the amplitude of the signal is generally in the range of 20 μ V to 300 μ V, and the energy of the signal is mainly concentrated in the range of 50Hz to 220 Hz. By collecting and analyzing the surface electromyographic signal data, the method has the advantages of no harm to human bodies, no pain, simplicity and convenience in operation and the like, and has wide application prospects and considerable economic values in the fields of gesture interaction, gait analysis, rehabilitation medical treatment and the like.

An embedded real-time operating system (RTOS) is an operating system that is capable of receiving data and processing events at a sufficiently fast speed, and the results of the processing can be used to control or make a system respond quickly and coordinate the orderly execution of all real-time tasks in a short time. The operating system is low in cost, small in occupied resource, low in power consumption and strong in reliability, and is widely applied to embedded systems such as small intelligent terminals.

The low-power wireless Bluetooth technology (BLE) adopts the same working frequency as the classic Bluetooth technology (Bluetooth), but the advantage of low power consumption can prolong the service time of the product by several times under the condition of the same electric quantity. It also has the advantages of small volume and low cost, and can play a role in emerging applications in the fields of medical care, sports fitness, beacons, security, home entertainment and the like.

At present, in the field of gesture sensing and control, some products adopt a depth camera (Kinect) to perform gesture recognition, and have the defects of high cost and shielding; other products adopt gesture sensors or bending sensors and the like, a large amount of hardware is needed for recognizing gestures, and the products are high in cost, inconvenient to wear, heavy in visual sense and difficult to popularize and use in actual life. In the field of human gait analysis, acceleration sensors or Inertial Measurement Units (IMUs) are adopted to collect gait data of human motion, and foot pressure distribution data are collected to analyze gait. At present, in the field of muscle movement electric signal acquisition, few devices can complete portable, low-noise and low-power-consumption data acquisition in a wireless state.

Disclosure of Invention

The embodiment of the invention aims to provide a portable wireless wearable muscle movement signal acquisition system, which aims to solve the problems of inconvenient wearing, low signal-to-noise ratio and high power consumption in the prior art.

The embodiment of the invention provides a portable wireless wearable muscle movement signal acquisition system, which comprises:

the acquisition end comprises a flexible acquisition board, a core board and a power board, wherein the flexible acquisition board is used for acquiring surface muscle electric signals, amplifying and filtering the electric signals, and the core board is used for receiving the processed signals, performing analog-to-digital conversion on the signals, and packaging and sending the signals after the analog-to-digital conversion and inertial motion information together, wherein the inertial motion information comprises acceleration, angular velocity and a magnetic field; the power panel provides working voltage for the flexible acquisition board and the core board;

and the receiving end is used for receiving the data sent by the package through the low-power wireless Bluetooth technology.

Furthermore, the flexible collecting board is made of a flexible circuit board and comprises N groups of electromyographic main electrodes and N groups of electromyographic signal conditioning modules, each group of electromyographic main electrodes is connected with one corresponding group of electromyographic signal conditioning modules to form an N-channel surface electromyographic signal collecting circuit, and N is a positive integer.

Furthermore, the core board is composed of a wireless microcontroller and a peripheral circuit thereof, an inertia measurement unit and a vibrator, the wireless microcontroller integrates a low-power wireless Bluetooth module and an analog-to-digital conversion module, broadcasting, connection and data receiving and sending of the low-power wireless Bluetooth are completed by operating an embedded real-time operating system, and meanwhile, the acquisition, storage and starting and stopping of the vibrator are controlled by responding to a command sent from a receiving end.

Further, the power strip comprises power module and lithium cell, power module includes multiple power chip, charging circuit, voltage protection circuit, charges for 3.7V's lithium cell through MicroUSB to for gathering the board and providing 2.5V's regulated voltage according to the control of nuclear core plate, for nuclear core plate provides 2.5V's regulated voltage, and optimize the consumption.

Furthermore, each myoelectricity dry electrode group consists of three stainless steel electrodes, wherein two of the three stainless steel electrodes are acquisition electrodes with the size of 10mm multiplied by 1mm, the distance between the two acquisition electrodes is 20mm, the other stainless steel electrode is a reference electrode with the size of 10mm multiplied by 4mm multiplied by 1mm, and the position of the middle symmetrical point of the two acquisition electrodes is used as a reference ground.

Furthermore, each group of electromyographic signal conditioning module integrates four operational amplifiers, and performs two-stage amplification, passive high-pass filtering and active low-pass filtering processing on the surface electromyographic signals, wherein the two-stage amplification is realized by a first-stage differential amplification circuit and a second-stage low-pass amplification circuit, the first-stage differential amplification circuit performs differential amplification on the signals, the second-stage amplification circuit is a fourth-order Butterworth low-pass filter, the passband is-1 dB at 220Hz, the stopband is-20 dB at 500Hz, and the gain of the amplification circuit is 60 dB.

Further, the wireless microcontroller controls the sampling frequency of the digital-to-analog converter according to a command sent by a user from a receiving end, so that the sampling rates of the electromyographic signal and the inertia measurement unit are changed to meet different application requirements, wherein the sampling rate range of the electromyographic signal is 100Hz to 500 Hz.

Furthermore, the embedded real-time operating system detects whether the system is in a motion state through the inertia measurement unit, and if the device does not move within a period of time, the embedded real-time operating system judges that the system is not in use, so that all resources which are not necessary to be started can be closed, and the embedded real-time operating system enters an extremely low power consumption sleep mode; and if the system is in a motion state, the embedded real-time operating system is awakened, and tasks such as connection of the low-power-consumption Bluetooth, data acquisition and the like are executed.

Furthermore, the flexible collecting board, the core board and the power board adopt an integrated packaging process, wherein each group of the myoelectricity dry electrodes and each group of the myoelectricity signal conditioning modules are welded together through a welding pad, the core board and the power board are connected with the flexible circuit board through a miniature connector, and the core board, the power board and the flexible collecting board form a compact structure with an upper layer and a lower layer.

Furthermore, the receiving end receives the electromyographic signals and the inertia measurement data which are sent by the acquisition end through the low-power-consumption wireless Bluetooth technology and sends the electromyographic signals and the inertia measurement data to the PC through the USB serial port, and the receiving end sends the sampling rate changing and vibrator controlling commands sent by the PC to the acquisition end through the low-power-consumption wireless Bluetooth technology so as to meet different application requirements.

The system structure can be divided into three parts, namely an acquisition board which is responsible for signal acquisition and conditioning, a core board which is responsible for signal analog-to-digital conversion and data transmission, and a receiving end which receives and subsequently processes data. The total amplification factor of the acquisition board to the surface electromyographic signals is 60dB, the acquisition board is amplified in two stages, the gain of the first stage differential amplification circuit is 40dB, and the gain of the second stage fourth-order low-pass filter is 20 dB. The core board MCU adopts a BLE Bluetooth chip, carries ti-rtos, performs 12-bit 8-channel analog-to-digital conversion with the sampling rate of 100 Hz-500 Hz on the electromyographic signals output by the acquisition board, and simultaneously sends surface electromyographic signal data and inertial measurement unit data to a receiving end BLE host computer by the role of a BLE slave computer. The receiving end MCU also adopts a BLE Bluetooth chip, receives data sent by the core board by the role of the BLE host, converts the format of the data, and transmits the data to the PC through the USB for subsequent applications such as electromyographic signal processing and analysis.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic diagram of a portable wireless wearable muscle movement signal acquisition system according to an embodiment of the present invention;

fig. 2 is a system structure design diagram of a portable wireless wearable muscle movement signal acquisition system according to an embodiment of the present invention;

fig. 3 is an outline view of a collecting end of the portable wireless wearable muscle movement signal collecting system according to the embodiment of the invention;

fig. 4 is a physical diagram of a flexible acquisition board of the portable wireless wearable muscle movement signal acquisition system according to the embodiment of the invention;

fig. 5 is a real object diagram of a core board of the portable wireless wearable muscle movement signal acquisition system according to the embodiment of the present invention;

fig. 6 is a core program structure of a portable wireless wearable muscle movement signal acquisition system according to an embodiment of the present invention;

fig. 7 is a process of establishing a bluetooth low energy connection for the portable wireless wearable muscle movement signal acquisition system according to an embodiment of the present invention;

fig. 8 is a test example of a portable wireless wearable muscle movement signal acquisition system according to an embodiment of the present invention.

Detailed Description

The product of the invention is described in further detail below with reference to the accompanying drawings and specific examples.

As shown in fig. 1, the present embodiment provides a portable wireless wearable muscle movement signal acquisition system, including: the system comprises an acquisition end 1, wherein the acquisition end 1 comprises a flexible acquisition board 3, a core board 4 and a power board 5, the flexible acquisition board 3 is used for acquiring surface muscle electrical signals (sEMG) and amplifying and filtering the electrical signals, the core board 4 is used for receiving the processed signals, performing analog-to-digital conversion on the signals, and packaging and sending the signals after the analog-to-digital conversion and inertial motion information together, wherein the inertial motion information comprises acceleration, angular velocity and a magnetic field; the power panel 5 provides working voltage for the flexible acquisition board 3 and the core board 4; and the receiving end 2 is used for receiving the data sent by the package through the low-power wireless Bluetooth technology.

Further, the receiving end can send the data to the PC through the UART so as to perform the processing and application of the next step such as digital filtering, algorithm denoising, detection recognition and the like. The structural design of the system is shown in fig. 2. The design of each section is described in detail in the following subsections. The acquisition board of the system is made of a Flexible Printed Circuit (FPC), mainly comprises stainless steel electrodes, an AD8609 chip and related circuits, and the front and back surfaces of the acquisition board are shown in figure 4. The stainless steel electrodes are 10mm multiplied by 1mm in size, and the distance between the two collecting electrodes is 20 mm. Besides two collecting electrodes, a reference electrode is attached to the middle symmetrical point of each channel, the size of the reference electrode is 10mm multiplied by 4mm multiplied by 1mm, and the reference electrode is used as a reference ground to suppress common mode interference as much as possible.

The AD8609 chip integrates four operational amplifiers, and two-stage amplification is carried out on the surface muscle electrical signals. The first-stage differential amplification circuit performs differential amplification on the signals, and the amplification factor is 40 dB; the second stage of amplification circuit is a fourth-order Butterworth low-pass filter, the pass band is-1 dB at 220Hz, the stop band is-20 dB at 500Hz, and the gain is 20 dB. The flexible collecting board is connected with the power panel and the core board through an FPC connector, and the amplified myoelectric signals are connected into an ADC interface of the core board.

The core board of the system mainly comprises a CC2640R2F chip and a peripheral circuit thereof, an MPU9250 chip and a peripheral circuit thereof, a 2.4GHz antenna and the like, wherein the front and the back surfaces of the core board are shown in figure 5.

The CC2640R2F chip is a wireless microcontroller, is suitable for the application of Bluetooth 5 low energy (BLE), has extremely low active RF and MCU current. The chip main processor is a 32-bit ARM Cortex-M3 kernel, has rich peripheral function sets, comprises a unique ultralow power consumption Sensor Controller (Sensor Controller), and can complete the functions in a TI real-time operating system (TI-RTOS). The MPU9250 is one of the smallest nine-axis motion tracking devices, improving performance while reducing chip size and power consumption. It comprises a three-axis gyroscope, a three-axis accelerometer and a three-axis digital compass (magnetometer).

The system uses a Sensor Controller to realize the functions of controlling acquisition of an ADC, controlling communication between an IIC and an MPU9250, storing data and controlling an IO port, and finishing functions of BLE broadcasting, BLE connection, data extraction, packaging and sending and the like in a main task of a main processor. The core program operation structure is shown in fig. 6.

Firstly, after the acquisition loop end is electrically started, a power supply of a receiving end is simultaneously turned on, and BLE connection is initiated. After connection is completed, the core board BLE slave runs a Sensor Controller, controls the IO port to open a power supply of the acquisition board, defaults to open the ADC to perform analog-to-digital conversion of 8 channels at a sampling rate of 200Hz, defaults to open the IIC to control the inertial measurement unit to sample at a sampling rate of 50Hz, and stores data in the annular cache region. After the stored data reaches a certain threshold, the Sensor Controller will issue an interrupt when the main task is idle without data in the process of sending. And after the main task detects the interruption, taking out the data from the annular cache region, packaging and sending the data to a receiving end, clearing the interruption mark and enabling the interruption again after the sending is finished. If BLE connection is disconnected, the main task can end the Sensor Controller, turn off the ADC, the IIC and the power supply of the acquisition board, enter a low power consumption state and wait for next connection.

In the low-power-consumption state, the system detects whether the acquisition end is in a motion state or not through an accelerometer of the inertia measurement unit. If the acquisition end does not move within a period of time, the acquisition end can be judged not to be used, and then resources which are not needed to be started on the core board are closed, and the core board enters a sleep mode with extremely low power consumption; when the collection end recovers the motion state, the system is awakened, and tasks such as initiating BLE connection and collecting data are executed.

According to the system, a core board and a receiving end carry out data transmission through a low-power Bluetooth technology (BLE), a core board MCU serves as a role of a BLE Slave machine (Slave), a receiving end MCU serves as a role of a BLE host machine (Master), and the process of establishing connection between the BLE Master machine and the BLE Slave machine is shown in figure 7.

The data communication mode between BLE is mainly four types, namely write, read, notify and indicator, wherein the former two are actively written and read to the Slave by the Master, and the latter two are actively transmitted to the Master by the Slave. Among them, the notify scheme is most efficient in transmission rate. The Notify sends data based on the GATT layer, and can rely on a link layer at a lower layer to ensure that the data in the air is not lost, so as long as the rate of Notify is controlled and the Master reads the transmitted data in time, the reliability of data transmission can be ensured. In order to ensure high transmission rate, the Slave of the system adopts a notify mode to transmit surface electromyogram signal data to the Master.

Data are transmitted in a notify mode, a Characteriodic structure body is required to be defined in a BLE slave machine, Value of the Characteriodic structure body is defined as a character array and used for storing surface electromyographic signal data read from a data buffer area, and other attribute parameters are set according to the requirement of the notify mode. Regarding the length of the array, according to the provision of the BLE 5 protocol stack, the system is set to 240 bytes, so that the transmission of 15 frames of 8-channel electromyographic signal data or 12 frames of 8-channel electromyographic signal data and 48 bytes of inertial measurement unit data can be realized. The receiving end BLE host can receive the message sent by the slave after the receiving end BLE host establishes connection with the BLE slave successfully. When the bottom layer of the host receives the message from the slave, the message type can be automatically judged, if the message belongs to notify message, namely surface electromyogram signal data is carried, a data processing function is entered, the data in Value is packaged in a certain format and then sent to a PC through UART.

In addition to transmitting data in a notify mode, the receiving-end BLE host initiates write communication operation to the BLE slave according to needs. And modifying the Characteriodic Characteristic value of the specific service of the BLE slave machine through write operation to complete control commands such as sampling rate modification, vibrator starting and the like initiated by a PC (personal computer), and realize multi-sampling-rate electromyographic signal acquisition and vibration feedback to an arm.

Fig. 8 shows that the subject wears the collecting ring on the abdomen of the forearm muscle and collects the surface electromyogram signals of 8 channels when the palm is opened, wherein the channels 1 to 4 are sequentially arranged from left to right and from top to bottom. Observation shows that surface electromyographic signals of the channel 1, the channel 2 and the channel 4 are very obvious, noise is relatively small, and an acquisition result is ideal; the channel 3 just touches the outer radius of the forearm and is therefore very noisy. After a plurality of tests, the quality of surface electromyographic signal acquisition is related to the contact tightness between the device and the skin and the preparation before the skin test. While good skin pre-measurement preparation can improve signal quality.

In order to be suitable for most people to wear, the collecting ring manufactured by the patent is flexible in circumference and adopts a connection mode with flexible and variable length, as shown in figure 3. The shell is made of resin and is connected by a silica gel bandage. Therefore, the acquisition board in the system uses a customized flexible circuit board, the core board is embedded in the resin shell and connected with the flexible acquisition board, and an independent power supply board is designed to uniformly supply power to the acquisition board and the core board.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.