CN116211559A - Wireless flexible myoelectricity acquisition system for artificial limb control - Google Patents

Abstract

The invention discloses a wireless flexible myoelectricity acquisition system for artificial limb control, which relates to the field of rehabilitation aids and comprises a host machine and a slave machine, wherein the host machine is arranged on an artificial limb; the slave is attached to the skin surface through an adhesive layer; the slave comprises a silica gel shell, an adhesive layer, a slave circuit board and a myoelectricity electrode; the slave circuit board comprises a myoelectricity acquisition module, a slave Bluetooth module, a slave rectification voltage stabilizing module and a secondary coil; the host comprises a host Bluetooth module, a host control module, a power management module, a lithium battery and a primary coil; the slave Bluetooth module sends the digitized myoelectricity data to the host Bluetooth module; and the host control module decodes myoelectricity data and controls the prosthetic hand to make corresponding gestures according to decoding results. The slave is attached to the skin surface through the adhesive layer, acquires electric energy from the host in a wireless mode and wirelessly communicates with the host, so that electrode displacement caused by putting on and taking off of the artificial limb is avoided, retraining frequency is reduced, and user load is greatly reduced.

Description

A wireless flexible EMG acquisition system for prosthetic control

technical field

The invention relates to the field of rehabilitation aids, in particular to a wireless flexible myoelectric collection system oriented to artificial limb control.

Background technique

There are a large number of physically handicapped people in my country, and a considerable number of them are upper limb amputee. Restoring hand function with a prosthetic hand for upper limb amputees would greatly improve the quality of life and benefit recovery from trauma.

Among upper limb prostheses, extracorporeal force-generating prostheses have the greatest potential to restore hand function. Extracorporeal prosthetics are prosthetics powered by external sources of power, such as electric or pneumatic. For intuitive and natural control of external force source prostheses, the human-machine interface is the first choice. Because surface electromyography has the advantages of being non-invasive and rich in neural control information, a large number of commercial prosthetics currently use surface electromyography as a signal source for man-machine interface control prostheses.

Most of the existing commercial and research prostheses are dry electrodes made of metal for the convenience of wearing and dismounting, and to ensure that the electrodes have a long service life. These electrodes are usually installed on the inside of the socket along the circumferential direction, and collect surface electromyography signals through close contact with the skin at the end of the user's residual limb. This faces challenges in practical applications and seriously affects the enthusiasm of patients to use prostheses. On the one hand, wearing and taking off the prosthesis causes electrode displacement, and the data initially used to train the EMG decoding model is collected at a specific electrode position, which reduces the accuracy of the EMG decoding model used for prosthetic control. In order to overcome the influence of electrode displacement, a common method is to retrain each time before using the prosthesis, that is, to collect a part of new myoelectric data to train a classifier model applicable to the current electrode position. Frequent retraining greatly increases the burden on the user. On the other hand, the difference between the Young's modulus of the metal electrode and the skin is large, which makes the user prone to discomfort when wearing the prosthesis for a long time; at the same time, it cannot achieve conformal contact with the skin, resulting in a high skin-electrode interface impedance. adversely affect the quality of EMG signals.

Therefore, those skilled in the art are committed to developing a wireless flexible myoelectric acquisition system for prosthesis control, which can separate the myoelectric electrode from the prosthesis, and can be attached to the skin surface stably for a long time; Myoelectric electrodes, which can be reused at the same time.

Contents of the invention

In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to avoid electrode displacement caused by wearing and taking off of the prosthesis, and how to realize the conformal contact between the electrode and the skin.

To achieve the above object, the present invention provides a wireless flexible myoelectric acquisition system oriented to prosthesis control, including a host and a slave, wherein the host is installed on the prosthesis; the slave is attached to the skin through an adhesive layer surface; the slave includes a silica gel shell, an adhesive layer, a slave circuit board, and an electromyographic electrode; the slave circuit board uses PI as a flexible substrate, and includes a myoelectric acquisition module, a slave Bluetooth module, and a slave rectifier stabilizer pressure module, secondary coil; the host includes a host bluetooth module, a host control module, a power management module, a lithium battery, and a primary coil; the myoelectric collection module collects surface myoelectric signals through the myoelectric electrodes and performs filtering , amplification and analog-to-digital conversion; the slave bluetooth module sends digitized myoelectric data to the host bluetooth module; the host bluetooth module receives myoelectric data and sends it to the host control module; the host control module Decode the EMG data, and control the prosthetic hand to make corresponding gestures according to the decoding result.

Further, the silicone shell is made by casting or 3D printing, and is used to protect the circuit in the slave; the adhesive layer is made of viscous silicone casting.

Further, the EMG acquisition module uses ADS1298 as an analog front-end, with a built-in differential amplifier and an analog-to-digital converter to collect surface EMG signals of 8 differential channels, and an RC high-pass filter is provided at the front stage of the analog front-end.

Further, the form of the myoelectric electrode is two gold-plated copper electrodes on a piece of FPC, which are used for the differential input of an acquisition channel; when the myoelectric electrode is attached, the two electrodes of the same channel are consistent with the direction of the muscle .

Further, the myoelectric electrode is connected to the slave circuit board through an FPC connection wire.

Further, the slave rectification and voltage stabilization module rectifies and filters the AC voltage generated by electromagnetic induction in the secondary coil to provide 3.3V DC voltage for other modules of the slave.

Further, the secondary coil is in the form of a flexible circuit printed on the slave circuit board.

Further, the master control module controls the power management module to wirelessly supply power to the slave.

Further, the power management module provides a 3.3V DC voltage for the host Bluetooth module and the host control module through an LDO regulator; the power management module outputs a 5V DC voltage through a DC-DC converter, which is an NFC The transceiver supplies power; the NFC transceiver inverts the 5V DC voltage into a 13.56MHz AC voltage, and wirelessly transmits electric energy to the slave through the inductive coupling between the primary coil and the secondary coil.

Further, the primary coil is installed outside the socket of the prosthetic limb, aligned with the slave, and connected to the master through wires.

Compared with the prior art, the present invention has at least the following beneficial technical effects:

1. The slave machine of the present invention is attached to the skin surface through an adhesive layer made of self-adhesive materials such as viscous silica gel. At the same time, the slave machine obtains electric energy from the host computer on the prosthesis by wireless means and communicates with it wirelessly, avoiding the prosthesis from being put on and off The resulting electrode displacement reduces the frequency of retraining and greatly reduces the burden on users;

2. The slave machine of the present invention is made with flexible electronic technology, and its thickness is small, and its Young’s modulus is equivalent to that of the skin, even much smaller than that of the skin, which improves the comfort of the electromyographic electrode and realizes the conformal contact between the electrode and the skin, and the signal Better quality than rigid electrodes used in common prosthetics.

The idea, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

Description of drawings

Fig. 1 is the structural representation of a preferred embodiment of the present invention;

Fig. 2 is a system schematic diagram of a preferred embodiment of the present invention;

Fig. 3 is a flow chart of myoelectric signal processing and decoding in a preferred embodiment of the present invention.

Among them, 10-slave; 11-silicone shell; 12-adhesive layer; 13-slave circuit board; 14-EMG electrode; 15-FPC connection line; 20-host; 21-primary coil; cavity; 40 - forearm stump; 41 - skin surface.

Detailed ways

The following describes several preferred embodiments of the present invention with reference to the accompanying drawings, so as to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned herein.

In the drawings, components with the same structure are denoted by the same numerals, and components with similar structures or functions are denoted by similar numerals. The size and thickness of each component shown in the drawings are shown arbitrarily, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of parts is appropriately exaggerated in some places in the drawings.

The application scenario of this embodiment is forearm prosthesis control, as shown in Figure 1, which is a schematic structural diagram of a preferred embodiment of the present invention, including two parts, the slave 10 and the host 20, and the slave 10 is attached to the user's forearm stump On the skin surface 41 of 40, the primary coil 21 is installed on the outside of the prosthesis socket 30, aligned with the slave 10 on the inside, and connected to the host 20 installed on the prosthesis through wires. The structure of the slave 10 includes a silicone shell 11 , an adhesive layer 12 , a slave circuit board 13 , myoelectric electrodes 14 and FPC connecting wires 15 . The silicone shell 11 is made by casting or 3D printing, and is used to protect the circuit in the slave 10 . The adhesive layer 12 is made of viscous silica gel and is used for stably attaching to the skin surface 41 . The slave circuit board 13 uses PI as a flexible substrate, and includes a myoelectric acquisition module, a slave Bluetooth module, and a slave rectification and voltage stabilization module. The material and structure of the silicone shell 11 , the adhesive layer 12 and the slave circuit board 13 ensure that the slave 10 has a small thickness and has similar mechanical properties to the skin, which is conducive to the long-term and stable attachment of the slave 10 to the skin surface 41 .

The host 20 includes a host Bluetooth module, a host control module, a power management module, a lithium battery, and a primary coil 21 .

Preferably, the secondary coil is in the form of a flexible circuit printed on the slave circuit board 13 ; the primary coil 21 can also be printed on the FPC so as to better fit the outer curved surface of the prosthetic socket 30 .

Preferably, the myoelectric electrode 14 is connected to the slave circuit board 13 through an FPC connection line 15 .

As shown in FIG. 2, it is a schematic diagram of the system of this embodiment. The EMG collection module collects surface EMG signals (sEMG) through the EMG electrodes 14, and performs filtering, amplification and analog-to-digital conversion. The slave bluetooth module includes a bluetooth SoC, responsible for sending digitized myoelectric data to the host 20 via bluetooth. The slave machine rectification and voltage stabilization module rectifies and filters the AC voltage generated by electromagnetic induction in the secondary coil, and provides 3.3V DC voltage for other modules of the slave machine 10 .

The host bluetooth module contains a bluetooth SoC, which is used to receive the myoelectric data sent by the slave bluetooth module and transmit it to the host control module. The host control module includes a microcontroller (MCU) for decoding myoelectric data, and controls the prosthetic hand to make corresponding gestures according to the decoding result, and at the same time controls the power management module to supply wireless power to the slave 10 . The power management module converts the 3.7V DC voltage input by the lithium battery into different voltages for use by other modules of the host computer 20 . The lithium battery simultaneously supplies power to the host computer 20 and the prosthetic hand.

Preferably, the EMG acquisition module uses ADS1298 as the analog front end, with a built-in differential amplifier and an analog-to-digital converter (ADC), which can collect sEMG of 8 differential channels; the front stage of the analog front end also has an RC high-pass filter.

Preferably, the form of the myoelectric electrode 14 is two gold-plated copper electrodes on a piece of FPC, which are used for differential input of one acquisition channel; when attaching the myoelectric electrode 14, the two electrodes of the same channel should be consistent with the direction of the muscle.

Preferably, the voltage conversion scheme of the power management module is as follows: provide 3.3V DC voltage for the host Bluetooth module and the host control module through the LDO voltage regulator; at the same time output 5V DC voltage through the DC-DC converter to supply power for an NFC transceiver; The NFC transceiver inverts the 5V DC voltage into a 13.56MHz AC voltage, and wirelessly transmits electric energy to the slave 10 through the inductive coupling between the primary coil 21 and the secondary coil.

As shown in FIG. 3 , it is a flow chart of the processing and decoding of the electromyographic signal realized in this embodiment. The sEMG recorded by the electromyography electrode 14 first passes through the RC high-pass filter in the electromyography acquisition module, then passes through the built-in EMI filter, differential amplification and anti-aliasing filter of the analog front end, and then obtains digitized electromyographic data through analog-to-digital conversion. The MCU of the host control module performs band-pass filtering on the myoelectric data, extracts signal features, and inputs the features into the myoelectric decoding model, and finally outputs control signals for the prosthetic hand.

Preferably, the cut-off frequency of the RC high-pass filter of the myoelectric acquisition module is 10 Hz, which is used to suppress noise such as low-frequency motion artifacts; the differential gain of the analog front-end is 6, the sampling rate of the analog-to-digital conversion is 1 kHz, and the resolution is 24 bits.

Preferably, the MCU on the host control module realizes the software filtering of electromyographic signals, including a bandpass filter of 20 to 450 Hz and a notch filter of 50 Hz; the selected electromyographic decoding model is linear discriminant analysis (LDA ) model for gesture classification.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (10)

1. A wireless flexible myoelectric acquisition system for prosthetic control, characterized in that it comprises a host and a slave, wherein the host is installed on the prosthesis; the slave is attached to the skin surface by an adhesive layer; The slave machine includes a silica gel shell, an adhesive layer, a slave machine circuit board, and an electromyographic electrode; the slave machine circuit board uses PI as a flexible substrate, and includes a myoelectric acquisition module, a slave machine Bluetooth module, a slave machine rectification and voltage stabilization module, secondary coil; the host includes a host bluetooth module, a host control module, a power management module, a lithium battery, and a primary coil; the myoelectric acquisition module collects surface electromyography signals through the electromyography electrodes, and performs filtering, amplification and Analog-to-digital conversion; the slave bluetooth module sends digitized myoelectric data to the host bluetooth module; the host bluetooth module receives the myoelectric data and sends it to the host control module; the host control module decodes the myoelectric data, and control the prosthetic hand to make corresponding gestures according to the decoded results. 2. The wireless flexible myoelectric acquisition system oriented to prosthesis control as claimed in claim 1, wherein the silicone shell is made by casting or 3D printing to protect the circuit in the slave; the adhesive The attached layer is poured with viscous silicone. 3. The wireless flexible myoelectric acquisition system facing prosthesis control as claimed in claim 1, wherein the myoelectric acquisition module uses ADS1298 as an analog front end, and has a built-in differential amplifier and an analog-to-digital converter to collect 8 differential channels The surface electromyographic signal of the analog front-end has an RC high-pass filter. 4. the wireless flexible myoelectric acquisition system facing prosthesis control as claimed in claim 1, is characterized in that, the form of described electromyography electrode is 2 gold-plated copper electrodes on a piece of FPC, is used for the differential input of an acquisition channel ; When the myoelectric electrodes are attached, the two electrodes of the same channel are in the same direction as the muscles. 5. The wireless flexible myoelectric acquisition system oriented to prosthesis control as claimed in claim 1, wherein the myoelectric electrode is connected with the slave circuit board through an FPC connection line. 6. The wireless flexible myoelectric acquisition system facing prosthesis control as claimed in claim 1, wherein the slave rectification and voltage stabilization module rectifies and filters the AC voltage generated by electromagnetic induction in the secondary coil, Provide 3.3V DC voltage for other modules of the slave. 7. The wireless flexible myoelectric acquisition system oriented to prosthesis control according to claim 1, wherein the secondary coil is in the form of a flexible circuit printed on the slave circuit board. 8. The wireless flexible myoelectric acquisition system oriented to prosthesis control according to claim 1, wherein the host control module controls the power management module to wirelessly supply power to the slave. 9. The wireless flexible myoelectric acquisition system facing prosthesis control as claimed in claim 1, wherein the power management module provides 3.3V direct current for the host bluetooth module and the host control module through an LDO voltage regulator voltage; the power management module outputs a 5V DC voltage through a DC-DC converter to supply power for an NFC transceiver; the NFC transceiver inverts the 5V DC voltage into a 13.56MHz AC voltage, and passes through the primary coil and the Inductive coupling between the secondary coils wirelessly transfers power to the slave. 10. The wireless flexible EMG acquisition system oriented to prosthesis control according to claim 1, wherein the primary coil is installed outside the socket of the prosthesis, aligned with the slave, and connected to the host through a wire.

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