阅读说明：本技术 一种用于假肢手运动姿态感觉反馈的穿戴式电刺激系统 (Wearable electrical stimulation system for artificial hand motion posture sensory feedback ) 是由 黄河清 吴小鹰 侯文生 赵云 赵威 于 2020-04-14 设计创作，主要内容包括：本发明涉及一种用于假肢手运动姿态感觉反馈的穿戴式电刺激系统,属于假肢电刺激系统技术领域,包括臂环本体、电刺激器；臂环本体上设有对应各个电刺激位点的孔位；电刺激器设置在臂环本体上,包括：微控制器、电源电路、H桥电路、恒流源电路、电极；微控制器读取假肢手手指的实时运动姿态信息,并根据此运动姿态信息发送对应的电刺激控制命令给H桥电路和恒流源电路；电源电路为微控制器、H桥电路和恒流源电路提供工作电压；电极为自粘电极片,负极置于前臂的拇短伸肌、小指伸肌、指伸肌、拇长屈肌、指浅屈肌,正极置于臂环内侧,沿手臂一周排布。本发明安全可靠,工作稳定,能实时将假肢手手指的运动姿态信息以电刺激的方式反馈给用户。(The invention relates to a wearable electrical stimulation system for sensory feedback of the movement posture of an artificial hand, belonging to the technical field of artificial limb electrical stimulation systems, and comprising an arm ring body and an electrical stimulator; hole sites corresponding to the electric stimulation sites are arranged on the arm ring body; the electro stimulator is arranged on the arm ring body and comprises: the device comprises a microcontroller, a power supply circuit, an H-bridge circuit, a constant current source circuit and electrodes; the microcontroller reads the real-time motion attitude information of the artificial limb fingers and sends corresponding electrical stimulation control commands to the H-bridge circuit and the constant current source circuit according to the motion attitude information; the power supply circuit provides working voltage for the microcontroller, the H-bridge circuit and the constant current source circuit; the electrodes are self-adhesive electrode plates, the negative electrode is arranged on extensor hallucis brevis, extensor digitorum minutissima, extensor digitorum longus and flexor digitorum superficialis of the forearm, and the positive electrode is arranged on the inner side of the arm ring and distributed along the circumference of the arm. The invention is safe and reliable, works stably, and can feed back the motion posture information of the artificial hand and the finger to the user in an electric stimulation mode in real time.)

1. A wearable electrical stimulation system for sensory feedback of the motion posture of a prosthetic hand, characterized in that: comprises an arm ring body and an electrical stimulator;

the arm ring body is worn on the forearm and is provided with hole sites corresponding to the electric stimulation sites;

the electro stimulator is arranged on the arm ring body and comprises: the device comprises a microcontroller, a power supply circuit, an H-bridge circuit, a constant current source circuit and electrodes;

the microcontroller reads real-time motion attitude information of the artificial limb fingers and sends corresponding electrical stimulation control commands to the H-bridge circuit and the constant current source circuit according to the motion attitude information;

the power supply circuit is used for converting input voltage into working voltage corresponding to the microcontroller, the H-bridge circuit and the constant current source circuit;

the H-bridge circuit is used for polarity inversion of a stimulation waveform;

the constant current source circuit is used for ensuring that the output current and the stimulation effect are not influenced by the impedance change of the human body;

the electrode is a self-adhesive electrode plate, the negative electrode of the electrode is a stimulating electrode, the positive electrode of the electrode is a reference electrode, the negative electrodes are respectively arranged on extensor hallucis brevis, extensor digitorum minutissima, flexor hallucis longus and flexor hallucis longus of the forearm, and the positive electrodes are arranged on the inner side of the arm ring and distributed along the circumference of the arm.

2. A wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude of a prosthetic of claim 1, wherein: the electrodes are arranged at corresponding positions to stimulate different forearm muscle groups and functional partitions of multi-tendon muscles thereof, and the stimulation current induces corresponding muscle contraction, so that corresponding bending and stretching motion feelings of fingers are formed due to muscle fiber contraction and stimulation of muscle spindle receptors; stimulating extensor hallucis longus to induce a motion sensation of thumb extension; stimulating the extensor muscle of the index finger to induce the motion feeling of the extension of the index finger; stimulating the extensor muscles of the little finger to induce the motion feeling of the little finger extension; stimulating the middle finger area and the ring finger area of the extensor muscles of the fingers to respectively induce the feeling of stretching movement of the middle finger and the ring finger; stimulating the flexor hallucis longus to induce a motor sensation of thumb flexion; stimulating the index finger area, the middle finger area, the ring finger area and the little finger area of the superficial flexor muscles of the fingers to respectively induce the sense of flexion movement of the index finger, the middle finger, the ring finger and the little finger;

the electrodes are used for providing stimulation current to cause contraction of muscle fibers of forearm muscles corresponding to fingers and functional division muscles of the forearm muscles, muscle shuttle receptors form sensory nerve impulses, the target muscle position of an electrical stimulation signal is determined by the gesture action mode of an artificial limb finger participating in movement, and the output mode of the electrical stimulation signal is controlled by the movement time phase and posture of the corresponding artificial limb finger, wherein the output mode comprises start-end time, frequency and intensity of the electrical stimulation signal.

3. A wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude of a prosthetic of claim 1, wherein: the output waveform of the electric stimulator is a biphase square wave; the output frequency range is 10-100Hz, and the precision is 1 Hz; the output amplitude range is 0-15mA, and the precision is 0.1 mA; the output pulse width is fixed at 100-; the number of channels for electrical stimulation output is 8, and parameters of each channel are independently adjusted.

4. A wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude of a prosthetic of claim 1, wherein: and the microcontroller reads the real-time motion attitude information of the artificial hand finger according to the encoder of the motor in the artificial hand finger.

5. A wearable electrical stimulation system for sensory feedback of a hand's motor posture as claimed in claim 3, wherein: the current motion attitude information of the artificial finger comprises the motion direction, the motion speed and the current position of the artificial finger.

6. A wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude of a prosthetic of claim 1, wherein: and the microcontroller selects a corresponding electrical stimulation mode according to the real-time motion attitude information of the artificial limb finger and sends a corresponding control command to realize dynamic regulation and control of electrical stimulation output.

7. The wearable electrical stimulation system for kinetic pose sensory feedback of a prosthetic hand of claim 6, wherein: the electrical stimulation pattern includes: selection of electrical stimulation frequency, selection of electrical stimulation intensity, selection of electrical stimulation channel.

8. The wearable electrical stimulation system for kinetic pose sensory feedback of a prosthetic hand of claim 6, wherein: the dynamic regulation of the electrical stimulation output comprises:

the finger position is defined according to the angle of the metacarpophalangeal joints of the fingers and is divided into three areas, wherein 0-30 degrees is a1 area, 30-60 degrees is a2 area, and 60-90 degrees is a 3 area; the muscle contraction degree of the fingers at different positions is different, the high-frequency signal proportion in the myoelectricity is increased and the low-frequency signal proportion in the myoelectricity is reduced when the muscles contract, so that the positions of the fingers are represented by changing the frequency of the electrical stimulation output waveform, and the stronger the muscle contraction is, the higher the electrical stimulation frequency is; when the fingers do stretching movement, the extensors contract, so that the region 1 corresponds to a mode I with lower frequency, the region 2 corresponds to a mode II with medium frequency, and the region 3 corresponds to a mode III with higher frequency; when the fingers do flexion movement, the flexors contract, and the frequency corresponding to the region 1 is the mode three, the frequency corresponding to the region 2 is the mode two, and the frequency corresponding to the region 3 is the mode one;

dividing the finger motion angular speed into four grades, setting the angular speed as 0 grade when the angular speed is zero, setting the slower speed as 1 grade, setting the medium speed as 2 grade, and setting the faster speed as 3 grade; the increase of the motion speed of the finger can lead the nerve activity of the motor cortex to be enhanced, so that the angular speed of the motion of the finger is reflected by changing the amplitude of the electrical stimulation output, and the electrical stimulation amplitude is higher when the angular speed is higher; the 0-level corresponding amplitude is 0mA, the 1-level corresponding amplitude is a lower amplitude, the 2-level corresponding amplitude is a medium amplitude, and the 3-level corresponding amplitude is a higher amplitude;

selectively activating electrode channels of corresponding muscles according to the motion direction of the finger;

and reading the motion attitude information of the prosthetic hand every 10ms, and if the current motion attitude information is different from the last read motion attitude information, recoding the electrical stimulation mode.

9. A wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude of a prosthetic of claim 1, wherein: the H-bridge circuit controls the selection of the internal channel through the PWM signal output by the singlechip so as to realize the reversal of the polarity of the electrical stimulation waveform.

10. A wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude of a prosthetic of claim 1, wherein: and the signal input end of the constant current source circuit is connected with the output end DAC out of the DAC module in the microcontroller, and constant current irrelevant to the load is obtained according to the resistance value of the internal resistor of the circuit and the voltage value of the DAC out.

Technical Field

The invention belongs to the technical field of artificial limb electrical stimulation systems, and relates to a wearable electrical stimulation system for artificial hand motion posture sensory feedback.

Background

The disabled upper limbs bring much inconvenience to patients, and the study, work and life are greatly affected. The artificial limb is researched to improve the quality of daily life of the patients with limb disabilities. Early intelligent prostheses rely primarily on collecting myoelectric signals from the surface of the user's residual limb muscles and processing them for driving the prosthesis to perform specific actions. Because no feedback information is introduced, the open-loop control mode is very arduous for a user, and the motion posture of the prosthetic hand is sensed mainly by means of the visual feedback of the human body. The prosthetic hand wearer needs to be attentive to the progress of the prosthetic hand movement. Furthermore, the input of the visual information to the output of the prosthetic hand control signal has a certain time delay.

The sensing feedback is introduced into the control of the artificial limb to form a control closed loop, so that the controllability and the flexibility of the artificial limb can be greatly improved, and the artificial limb can better assist an amputee to finish daily activities. Most of the artificial limb sensory feedback systems developed at the present stage are tactile feedback for artificial limb fingers and are used for transmitting gripping contact information to a human body. Pressure information and sliding information of fingertips are collected and are applied to a human body in the form of electric stimulation or vibration stimulation, so that a user feels the gripping condition of the artificial hand, and the artificial hand is controlled more accurately.

Chinese patent CN108733198A proposes an electric stimulation system for generating artificial touch, which fixes a stimulation electrode plate on the skin surface needing to generate artificial touch, receives two-dimensional distribution information and type information of touch intensity from an upper computer according to a microcontroller circuit, adjusts the current output intensity of a constant current output adjusting circuit according to the type information of touch, outputs or recovers current at different moments by selectively activating each electrode site on the skin surface, forms a loop with a human subcutaneous touch receptor, stimulates corresponding neurons to generate action potential, and thereby generates artificial touch.

In the design and research of an intelligent artificial limb grasping system based on vibration feedback in a university of science and technology 2016 of jacobia, a touch sensor is mounted at the tip of an artificial limb finger to acquire the pressure when an object is grasped, the magnitude of the pressure applied to the artificial limb hand during grasping is reflected by the vibration strength of a micro vibration motor attached to the surface of the skin of the back of the hand, and the motor has higher vibration strength when the pressure is higher, so that a user is assisted to grasp the object better.

However, the information on the prosthetic hand end includes information on the state of motion, such as a gripping gesture of the hand, a bending motion of fingers, and the like, in addition to information on the contact object. The existing artificial hand feeling feedback strategy lacks feedback of the artificial hand motion posture information. If the motion attitude information of the artificial hand is added into the closed-loop feedback of the artificial hand, the interactivity of the user and the artificial hand is further enhanced, so that the proprioception of the user on the artificial hand is improved.

The finger motion perception mainly comes from muscle contraction induced muscle twitch receptor nerve afferent of finger motion, the finger motion state (motion speed and flexion and extension posture) directly influences the output mode of the muscle twitch receptor, but the existing artificial limb sensory feedback cannot fully utilize the artificial limb finger motion state to influence the output of the muscle twitch receptor. The technical idea of the invention is that a surface electrode is utilized to provide stimulation current to cause contraction of muscle fibers of forearms corresponding to fingers and functional partitions thereof, muscle shuttle receptors form sensory nerve impulses, the target muscle position of an electric stimulation signal is determined by artificial fingers (gesture action mode) participating in movement, and the output mode (start-end time, frequency, strength and the like of the electric stimulation signal) of the electric stimulation signal is controlled by the movement time phase and posture of the corresponding artificial fingers.

Disclosure of Invention

In view of the above, the present invention provides a wearable electrical stimulation system for the motor posture sensory feedback of a prosthetic hand, which is used to realize the motor posture sensory feedback of the fingers of the prosthetic hand and stimulate the corresponding muscles of the arm of the user in an electrical stimulation feedback manner to generate real-time finger motor feeling feedback.

In order to achieve the purpose, the invention provides the following technical scheme:

a wearable electrical stimulation system for sensory feedback of the movement posture of an artificial hand comprises an arm ring body and an electrical stimulator;

the arm ring body is worn on the forearm and is provided with hole sites corresponding to the electric stimulation sites;

the electro stimulator is arranged on the arm ring body and comprises: the device comprises a microcontroller, a power supply circuit, an H-bridge circuit, a constant current source circuit and electrodes;

the microcontroller reads real-time motion attitude information of the artificial limb fingers and sends corresponding electrical stimulation control commands to the H-bridge circuit and the constant current source circuit according to the motion attitude information;

the power supply circuit is used for converting input voltage into working voltage corresponding to the microcontroller, the H-bridge circuit and the constant current source circuit;

the H-bridge circuit is used for polarity inversion of a stimulation waveform;

the constant current source circuit is used for ensuring that the output current and the stimulation effect are not influenced by the impedance change of the human body;

the electrode is a self-adhesive electrode plate, the negative electrode of the electrode is a stimulating electrode, the positive electrode of the electrode is a reference electrode, the negative electrodes are respectively arranged on extensor hallucis brevis, extensor digitorum minutissima, flexor hallucis longus and flexor hallucis longus of the forearm, and the positive electrodes are arranged on the inner side of the arm ring and distributed along the circumference of the arm.

Furthermore, the electrodes are arranged at corresponding positions to stimulate different forearm muscle groups and functional partitions of multi-tendon muscles thereof, and the stimulation current induces corresponding muscle contraction, so that corresponding bending and stretching motion feelings of fingers are formed due to muscle fiber contraction and muscle spindle receptor excitation; stimulating extensor hallucis longus to induce a motion sensation of thumb extension; stimulating the extensor muscle of the index finger to induce the motion feeling of the extension of the index finger; stimulating the extensor muscles of the little finger to induce the motion feeling of the little finger extension; stimulating the middle finger area and the ring finger area of the extensor muscles of the fingers to respectively induce the feeling of stretching movement of the middle finger and the ring finger; stimulating the flexor hallucis longus to induce a motor sensation of thumb flexion; the first finger area, the middle finger area, the ring finger area and the little finger area of the superficial flexor muscles of the fingers are stimulated to respectively induce the senses of flexion movement of the first finger, the middle finger, the ring finger and the little finger.

The surface electrode is used for providing stimulation current to cause contraction of muscle fibers of forearm muscles corresponding to fingers and functional regions thereof, muscle shuttle receptors form sensory nerve impulses, the target muscle position of an electric stimulation signal is determined by the artificial fingers (gesture action mode) participating in movement, and the output mode (start-end time, frequency, strength and the like of the electric stimulation signal) of the electric stimulation signal is controlled by the movement time phase and posture corresponding to the artificial fingers.

Further, the output waveform of the electric stimulator is a biphasic square wave; the output frequency range is 10-100Hz, and the precision is 1 Hz; the output amplitude range is 0-15mA, and the precision is 0.1 mA; the output pulse width is fixed at 100-; the number of channels for electrical stimulation output is 8, and parameters of each channel are independently adjusted.

Further, the microcontroller reads the real-time motion attitude information of the artificial hand finger according to the encoder of the motor in the artificial hand finger.

Further, the current motion posture information of the prosthetic finger comprises the motion direction, the motion speed and the current position of the prosthetic finger.

Further, the microcontroller selects a corresponding electrical stimulation mode according to the real-time motion posture information of the artificial finger and sends a corresponding control command to realize dynamic regulation and control of electrical stimulation output.

Further, the electrical stimulation pattern includes: selection of electrical stimulation frequency, selection of electrical stimulation intensity, selection of electrical stimulation channel.

Further, the dynamic regulation of the electrical stimulation output comprises:

the finger position is defined according to the angle of the metacarpophalangeal joints of the fingers and is divided into three areas, wherein 0-30 degrees is a1 area, 30-60 degrees is a2 area, and 60-90 degrees is a 3 area; the muscle contraction degree of the fingers at different positions is different, the high-frequency signal proportion in the myoelectricity is increased and the low-frequency signal proportion in the myoelectricity is reduced when the muscles contract, so that the positions of the fingers are represented by changing the frequency of the electrical stimulation output waveform, and the stronger the muscle contraction is, the higher the electrical stimulation frequency is; when the fingers do stretching movement, the extensors contract, so that the region 1 corresponds to a mode I with lower frequency, the region 2 corresponds to a mode II with medium frequency, and the region 3 corresponds to a mode III with higher frequency; when the fingers do flexion movement, the flexors contract, and the frequency corresponding to the region 1 is the mode three, the frequency corresponding to the region 2 is the mode two, and the frequency corresponding to the region 3 is the mode one;

dividing the finger motion angular speed into four grades, setting the angular speed as 0 grade when the angular speed is zero, setting the slower speed as 1 grade, setting the medium speed as 2 grade, and setting the faster speed as 3 grade; the increase of the motion speed of the finger can lead the nerve activity of the motor cortex to be enhanced, so that the angular speed of the motion of the finger is reflected by changing the amplitude of the electrical stimulation output, and the electrical stimulation amplitude is higher when the angular speed is higher; the 0-level corresponding amplitude is 0mA, the 1-level corresponding amplitude is a lower amplitude, the 2-level corresponding amplitude is a medium amplitude, and the 3-level corresponding amplitude is a higher amplitude;

selectively activating electrode channels of corresponding muscles according to the motion direction of the finger;

and reading the motion attitude information of the prosthetic hand every 10ms, and if the current motion attitude information is different from the last read motion attitude information, recoding the electrical stimulation mode.

Further, the H-bridge circuit controls the selection of the internal channel through a PWM signal output by the singlechip so as to realize the inversion of the polarity of the electrical stimulation waveform.

Further, the signal input end of the constant current source circuit is connected with the output end DAC out of the DAC module in the microcontroller, and constant current irrelevant to load is obtained according to the resistance value of the internal resistor of the circuit and the voltage value of the DAC out.

The invention has the beneficial effects that: the electrical stimulation system is safe and reliable, and works stably; the invention can feed back the motion posture information of the artificial limb fingers to the user in real time in an electrical stimulation mode; the invention is portable and easy to wear on the forearm in the form of an arm ring.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram of a wearable electrical stimulation system for sensory feedback of a hand's locomotor attitude according to the present invention;

FIG. 2 is a schematic diagram of an application of the wearable electrical stimulation system for the sensory feedback of the movement posture of the prosthetic hand according to the invention;

fig. 3 is a flow chart of the use of the wearable electrical stimulation system for the sensory feedback of the movement posture of the prosthetic hand.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

The invention provides a wearable electrical stimulation system for sensory feedback of the movement posture of an artificial hand, which comprises an arm ring body and an electrical stimulator arranged on the arm ring body; the arm ring is made of elastic materials, is worn on the forearm, is fixed on the forearm by adjusting the length of the arm ring according to the arm circumference, and is reserved with hole sites corresponding to each electro-stimulation site; the electric stimulator comprises a microcontroller, a power circuit, an H-bridge circuit, a constant current source circuit and an electrode; the microcontroller reads real-time motion attitude information of the artificial limb fingers and sends corresponding electrical stimulation control commands in real time according to the motion attitude information, a DAC (digital-to-analog converter) in the microcontroller outputs corresponding voltage signals according to the electrical stimulation control commands, constant current electrical stimulation signals which are not influenced by load resistance are obtained after passing through a voltage-controlled constant current source circuit, and a waveform is turned over through an H bridge to obtain a two-phase stimulation waveform with corresponding frequency and pulse width; the H-bridge circuit controls the selection of the internal channel through a PWM signal output by the singlechip so as to realize the reversal of the polarity of the electrical stimulation waveform. The signal input end of the constant current source circuit is connected with the output end DAC out of the DAC module, and constant current irrelevant to load is obtained according to the resistance value of the internal resistor of the circuit and the voltage value of the DAC out. The power supply circuit is used for converting the +9V direct-current input voltage into direct-current output voltages of +3.3V, +15V, -15V and 80V and supplying the direct-current output voltages to the microcontroller, the H-bridge circuit and the constant current source circuit to serve as working power supplies; all modules are connected through the internal routing of the PCB; the electrodes are self-adhesive electrode plates, the negative electrodes (stimulating electrodes) are respectively arranged on extensor hallucis brevis, extensor digitorum minimus, extensor digitorum digitalis, flexor hallucis longus and flexor digitorum superficialis of the forearm, the positive electrodes (reference electrodes) are arranged on the inner side of the arm ring along the circumference of the arm, and the electrode sites respectively correspond to the flexion and extension of the five fingers; corresponding muscles are stimulated by selecting corresponding electrode channels and stimulation parameters, so that the human body can generate corresponding finger motion feeling.

As shown in fig. 1, the nerve signals convert the human body active movement intention generated by the brain into specific muscle contraction to realize limb actions, the finger movement perception of a healthy person mainly comes from muscle contraction induced muscle shuttle receptor nerve afferents of finger movement, and the finger movement states (fast and slow, flexion and extension postures) directly influence the output mode of the muscle shuttle receptor. But the physically disabled person cannot perceive the movement state of the prosthetic hand. The surface electrode is used for providing stimulation current to cause contraction of muscle fibers of forearm muscles corresponding to fingers and functional regions thereof, muscle shuttle receptors form sensory nerve impulses, the target muscle position of an electrical stimulation signal is determined by artificial fingers (gesture action mode) participating in movement, and the output mode (start-end time, strength and weakness and the like) of the electrical stimulation signal is controlled by the movement time phase and posture of the corresponding artificial fingers, so that the perception feedback path of the nerve-muscle-artificial hand can be realized.

Stimulating different forearm muscle groups and functional partitions of multi-tendon muscles of the forearm muscle groups to ensure that the stimulation current induces corresponding muscle contraction, and corresponding bending and stretching motion feelings of fingers are formed due to muscle fiber contraction and muscle spindle receptor excitation; the stimulation of the extensor hallucis longus muscle can induce the motion feeling of the extension of the thumb; the extensor muscle of the index finger is stimulated to induce the motion feeling of the extension of the index finger; the stimulation of the extensor muscles of the little finger can induce the motion feeling of the extension of the little finger; the middle finger area and the ring finger area of the extensor muscles of the fingers are stimulated to respectively induce the feeling of stretching movement of the middle finger and the ring finger; stimulating the flexor hallucis longus can induce the motion sensation of the flexion of the thumb; the first finger area, the middle finger area, the ring finger area and the little finger area of the superficial flexor muscles of the fingers are stimulated to respectively induce the sense of the flexion motion of the first finger, the middle finger, the ring finger and the little finger.

The surface electrode is used for providing stimulation current to cause contraction of muscle fibers of forearm muscles corresponding to fingers and functional regions thereof, muscle shuttle receptors form sensory nerve impulses, the target muscle position of an electric stimulation signal is determined by the artificial fingers (gesture action mode) participating in movement, and the output mode (start-end time, frequency, strength and the like of the electric stimulation signal) of the electric stimulation signal is controlled by the movement time phase and posture corresponding to the artificial fingers.

As shown in the left side of fig. 2, a is the extensor digitorum, which starts from the external epicondyle of the lower humerus, descends to the posterior end of the forearm, and finally divides into four tendons, each of which points to one finger to control the extension of the metacarpophalangeal joints and interphalangeal joints of the 2 nd to 5 th fingers, respectively; b is extensor digitorum digiti, which originates from the external epicondyle of humerus and is attached to the dorsal-side enlargement of the first phalanx of the little finger for controlling the extension of the little finger; c is extensor hallucis brevis, starts from the back of radius and ulna and an interosseous membrane, stops at the bottom of the 1 st phalanx of the thumb and has the function of extending the thumb; d is flexor hallucis longus, starts from the anterior surface and the interosseous membrane at the upper ends of the radius and the ulna, stops at the bottom of the distal phalanx of the thumb, and has the function of bending the thumb; e is the superficial flexor of the finger, starting from the medial humeral epicondyle and anterior aspect of the superior radius, ending on both sides of the phalanx of the middle phalanx of the 2 nd to 5 th fingers, and used for controlling the metacarpophalangeal joints and proximal interphalangeal joints of the 2 nd to 5 th fingers to do flexion movement. Each marker site on the muscle is where the negative pole of the electrical stimulation (stimulation electrode) is placed.

The practical application of the system is shown on the right in fig. 2. The arm ring is worn on the forearm, the length of the arm ring is adjusted according to the arm circumference to enable the arm ring to be fixed on the forearm, hole positions are reserved on the arm ring, and the hole positions correspond to the electric stimulation sites. The rear A1 of the forearm corresponds to the forefinger area of the extensor muscle of the finger to control the extension of the forefinger; the middle finger and the ring finger area of the extensor muscles of the forearm corresponding to the position A2 behind the forearm are controlled to stretch; the part B behind the forearm corresponds to extensor muscles of the little finger to control the extension of the little finger; the position C behind the forearm corresponds to the extensor hallucis brevis to control the extension of the thumb; the front E1 of the forearm corresponds to the index finger area of the superficial flexor digitorum to control the flexion of the index finger; the anterior forearm E2 corresponds to the middle finger region of the superficial flexor digitorum and controls the middle finger to flex; the anterior E3 of the forearm corresponds to the ring and little finger areas of the superficial flexor digitorum and controls the flexion of the ring and little fingers; the anterior D of the forearm corresponds to the flexor hallucis longus and controls the flexion of the thumb. The G position is the positive electrode (reference electrode) of 8 channels, and the positive electrodes are distributed along the circumference of the arm. Electrodes are pasted according to positions. The electric stimulator is arranged on the arm ring at the position F.

The output waveform of the electric stimulator is a biphase square wave; the output frequency range is 10-100Hz, and the precision is 1 Hz; the output amplitude range is: 0-15mA, the precision is 0.1 mA; the output pulse width is fixed as follows: 100-; the number of channels of the electrical stimulation output is 8, and parameters of each channel can be independently adjusted.

The microcontroller reads real-time motion attitude information of the prosthetic finger according to an encoder of a motor inside the prosthetic finger, and the current motion attitude information of the prosthetic finger comprises the motion direction, the motion speed and the current position of the prosthetic finger.

The microcontroller selects a corresponding electrical stimulation mode according to the real-time motion posture information of the artificial finger and sends a corresponding control command to realize dynamic regulation and control of electrical stimulation output (including selection of electrical stimulation frequency, selection of electrical stimulation intensity and selection of electrical stimulation channels). Dynamic regulation of electrical stimulation output includes:

the finger position is defined according to the angle of the metacarpophalangeal joints of the fingers and is divided into three areas, wherein 0-30 degrees is a1 area, 30-60 degrees is a2 area, and 60-90 degrees is a 3 area; the muscle contraction degree of the fingers at different positions is different, the high-frequency signal proportion in the myoelectricity is increased and the low-frequency signal proportion in the myoelectricity is reduced when the muscles contract, so that the positions of the fingers are represented by changing the frequency of the electrical stimulation output waveform, and the stronger the muscle contraction is, the higher the electrical stimulation frequency is; when the fingers do stretching movement, the extensors contract, so that the region 1 corresponds to a mode I with lower frequency, the region 2 corresponds to a mode II with medium frequency, and the region 3 corresponds to a mode III with higher frequency; when the fingers do flexion movement, the flexors contract, and the frequency corresponding to the region 1 is the mode three, the frequency corresponding to the region 2 is the mode two, and the frequency corresponding to the region 3 is the mode one;

dividing the finger motion angular speed into four grades, setting the angular speed as 0 grade when the angular speed is zero, setting the slower speed as 1 grade, setting the medium speed as 2 grade, and setting the faster speed as 3 grade; the increase of the motion speed of the finger can lead the nerve activity of the motor cortex to be enhanced, so that the angular speed of the motion of the finger is reflected by changing the amplitude of the electrical stimulation output, and the electrical stimulation amplitude is higher when the angular speed is higher; the 0-level corresponding amplitude is 0mA, the 1-level corresponding amplitude is a lower amplitude, the 2-level corresponding amplitude is a medium amplitude, and the 3-level corresponding amplitude is a higher amplitude;

selectively activating electrode channels of corresponding muscles according to the motion direction of the finger;

and reading the motion attitude information of the prosthetic hand every 10ms, and if the current motion attitude information is different from the last read motion attitude information, recoding the electrical stimulation mode.

Fig. 3 is a flow chart of use of the wearable electrical stimulation system. Firstly, the myoelectric signal controls the movement of the prosthetic hand. The encoder wiring of the myoelectric prosthetic hand is connected with an IO port of a microcontroller, and the IO port is set to be in a counter mode to detect the rotation angle of a finger motor of the prosthetic hand, so that the current motion attitude information of the finger of the prosthetic hand, namely the motion direction, the motion speed and the current position of the finger of the prosthetic hand, is obtained. And the microcontroller encodes the electrical stimulation mode according to the motion attitude information. The finger position is defined according to the angle of the metacarpophalangeal joints of the fingers and is divided into three areas, wherein 0-30 degrees is a1 area, 30-60 degrees is a2 area, and 60-90 degrees is a 3 area; the finger is in different positions, the muscle contraction degree is different, the high-frequency signal proportion in myoelectricity is increased and the low-frequency signal proportion in myoelectricity is reduced when the muscle is contracted, the position of the finger is represented by changing the frequency of an electric stimulation output waveform, and the stronger the muscle is contracted, the higher the electric stimulation frequency is; when the fingers do stretching movement, the extensors contract, so that the region 1 corresponds to a mode I with lower frequency, the region 2 corresponds to a mode II with medium frequency, and the region 3 corresponds to a mode III with higher frequency; when the fingers do the flexion movement, the flexors contract, and the frequency corresponding to zone 1 is mode three, the frequency corresponding to zone 2 is mode two, and the frequency corresponding to zone 3 is mode one. Dividing the finger motion angular speed into four grades, setting the angular speed as 0 grade when the angular speed is zero, setting the slower speed as 1 grade, setting the medium speed as 2 grade, and setting the faster speed as 3 grade; the increase of the motion speed of the finger can lead to the enhancement of the nerve activity of the motor cortex, the angular speed of the motion of the finger is reflected by changing the amplitude of the electrical stimulation output, and the electrical stimulation amplitude is higher when the angular speed is higher; the 0-level corresponding amplitude is 0mA, the 1-level corresponding amplitude is a lower amplitude, the 2-level corresponding amplitude is a medium amplitude, and the 3-level corresponding amplitude is a higher amplitude. Electrode channels of the corresponding muscles are selectively activated according to the finger movement direction. The microcontroller outputs an electrical stimulation command in a corresponding mode, and the electrical stimulation command passes through the H-bridge circuit and the constant current source circuit to electrically stimulate the human body so as to realize the motion posture sensory feedback function of the artificial hand. And reading the motion attitude information of the prosthetic hand every 10ms, and if the current motion attitude information is different from the last read motion attitude information, recoding the electrical stimulation mode.

Stimulation mode to induce single-finger flexion/extension motor sensation: reading the bending/stretching movement of a single finger of the artificial hand by the microcontroller to obtain a corresponding electrical stimulation control command; adjusting the amplitude of the output of the electrical stimulation signal according to the movement speed of the finger; adjusting the frequency of the electrical stimulation signal output according to the current position of the finger; and selecting the electrode channel of the flexor/extensor corresponding to the finger to output an electrical stimulation signal.

Stimulation mode to induce fist-making motor sensation: reading the fist making movement of the fingers of the artificial limb hand by the microcontroller to obtain a corresponding electrical stimulation control command; adjusting the amplitude of the output of the electrical stimulation signal according to the movement speed of each finger; adjusting the frequency of the output of the electrical stimulation signals according to the current position of each finger; e1, E2, E3 and D electrode channels corresponding to the five-finger flexion motion are selected to output electrical stimulation signals.

The stimulation mode for inducing the three fingers to pinch the motor sensation is as follows: the microcontroller reads that the thumb, the index finger and the middle finger of the artificial hand do three-finger pinching motion to obtain a corresponding electrical stimulation control command; adjusting the amplitude of the output of the electrical stimulation signal according to the movement speed of each finger; adjusting the frequency of the output of the electrical stimulation signals according to the current position of each finger; e1, E2 and D electrode channels corresponding to the flexion of the thumb, the index finger and the middle finger are selected to output electrical stimulation signals.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.