CN116899067A - Motion electric stimulation feedback sensing system and method for proprioceptive artificial limb - Google Patents
Motion electric stimulation feedback sensing system and method for proprioceptive artificial limb Download PDFInfo
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- A61M2021/0072—Other devices or methods to cause a change in the state of consciousness; Devices for producing or ending sleep by mechanical, optical, or acoustical means, e.g. for hypnosis by the use of a particular sense, or stimulus with application of electrical currents
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Abstract
The invention provides a motion electric stimulation feedback sensing system and a motion electric stimulation feedback sensing method for a body sense artificial limb, which relate to the technical field of artificial limbs, wherein the system comprises a power supply module, a control circuit, a surface electrode and an artificial limb structure, wherein the control circuit comprises an inertial measurement unit, a main control chip and an electric stimulation chip; the method of the invention measures the motion of the artificial limb through the inertial measurement unit, and transmits the motion information of the artificial limb to the main control chip, and the main control chip reads the motion information of the artificial limb for analysis and processing; the electric stimulation feedback is transmitted to nerve endings of the stump, and can simulate the motor sensory function of the natural limb, so that an amputee can more accurately sense and control the motion of the artificial limb.
Description
Technical Field
The invention relates to the technical field of artificial limbs, in particular to a motion electric stimulation feedback sensing system and method for a proprioceptive artificial limb.
Background
Upper arm amputees face many living difficulties and it may become more difficult to accomplish some simple tasks. Prostheses are an important aid to them, helping them to perform daily functions and improve quality of life. To establish a stronger physical connection between the amputee and the prosthesis, sufficient feedback information is required to simulate the natural limb's perceptibility and motion control. By sensing the motion and state of the prosthesis, and gradually restoring confidence in its own capacity.
The current means of generating feedback for prostheses are mainly vibration, pressure feedback and electrical stimulation feedback. Conventional prostheses generally use mechanical motion to generate vibration and pressure feedback, which is generally effective and costly to maintain. The artificial limb based on the electric stimulation feedback mode has the advantages that the feeling and intensity of the electric stimulation are modulated by the amplitude, the frequency, the width and the like of the current pulse, one or a combination of the parameters is regulated, the current flows through the subcutaneous region between the anode and the cathode, and the nerve endings (namely the skin receptor) and the muscle receptors are stimulated, so that compared with vibration feedback, the artificial limb can present finer and richer feeling, and has quiet stimulation and better privacy. Compared with other mechanical devices, the electric stimulation device has the advantages of smaller size of a driver, portability and wearability, and has better application prospect.
The Chinese patent publication number is CN114177472A, and the patent name is: an implantable electric stimulation sensing feedback system applied to a lower limb artificial limb has the application date of 2022, 3 and 15. The invention provides an implantable electric stimulation sensing feedback system applied to a lower limb prosthesis, which can solve the problem that a patient cannot sense the motion state of the prosthesis truly in the prior lower limb prosthesis wearing process, realize the contraction of muscle groups at the residual limb of the lower limb, and strengthen the realism and the natural sense of the prosthesis used by the patient. However, the artificial limb needs to be implanted into a human body, is inconvenient to use, and has great discomfort caused by electrically stimulating muscles, so that the artificial limb needs a long time to adapt.
The Chinese patent publication number is CN111449813A, and the patent name is: a wearable electric stimulation system for the motion gesture and feel feedback of a prosthetic hand is provided, and the application date is 7 months and 28 days in 2020. The invention provides a wearable electric stimulation arm ring for motion posture sensory feedback of a prosthetic hand. The motion gesture information of the finger of the prosthetic hand, including the angle of the metacarpophalangeal joint and the finger motion angular speed, can be used for adjusting the channel, amplitude and frequency of the electric stimulation in real time, and the electric stimulation signals are output to be fed back to the user. However, the system lacks the theoretical basis of human perception, only can output a plurality of fixed electric stimulation parameters selected by experiments to correspond to the movement of the fingers, has obvious fault feeling when the stimulation parameters are converted, is only simple one-to-one correspondence to the original perception of the electric stimulation and the movement, does not have the feeling of the movement of the real fingers, and can be used barely after the user is required to learn and train.
In general, the prior electric stimulation wearable equipment has great harm to human body in a mode of implantable muscle stimulation, and the stimulation mode lacks theoretical basis of human body perception, and electric stimulation parameters are selected by experimental sensation, and the single grading stimulation mode is mostly adopted, so that the perception capability of natural limbs cannot be simulated. Therefore, it is necessary to design a motion electric stimulation feedback sensing system and method for a body-sensing artificial limb, which combines the human body sensing mechanism to meet the functional requirements of sensing the motion and state of the artificial limb.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a motion electric stimulation feedback sensing system and a motion electric stimulation feedback sensing method for a proprioceptive artificial limb, which are used for processing electric stimulation pulses with real-time frequency adjustment to stimulate the skin of a stump according to a muscle shuttle model and a human body nerve sensing mechanism by reading motion information of the artificial limb so as to solve the problem that the current electric touch stimulation equipment proposed by the background art can not simulate the sensing capability of a natural limb.
In one aspect, a motion electrical stimulation feedback perception system for a proprioceptive prosthesis comprises: the artificial limb comprises a power supply module, a control circuit, a surface electrode and an artificial limb structure;
the inside of the artificial limb structure is a hollow structure, the surface electrode is embedded in the inner wall of the artificial limb structure, and the control circuit and the power supply module are arranged on the outer surface of the artificial limb structure;
the control circuit comprises an inertial measurement unit, a main control chip and an electric stimulation chip;
the inertial measurement unit is a motion processing sensor, and the output end of the inertial measurement unit is connected with the input end of the main control chip. Preferably, the inertial measurement unit module is an MPU6050;
the output end of the main control chip is connected with the input end of the electric stimulation chip; preferably, the main control chip is a 32-bit microcontroller STM32 developed by ST company based on ARM Cortex-M kernel;
preferably, the electrical stimulation chip is an ENS001-A full-function nerve electrical stimulation chip of a heating core gamma company;
the surface electrode is a 3 x 3cm surface electrode with hydrogel, is embedded in the inner wall of the artificial limb structure and is connected with the current output interface of the electric stimulation chip;
the power module comprises a charging module, a lithium battery and a lifting pressure module; the output end of the charging module is connected with the lithium battery, the output end of the lithium battery is connected with the input end of the voltage increasing and decreasing module, and the output end of the voltage increasing and decreasing module is connected with the control circuit.
On the other hand, the motion electric stimulation feedback sensing method facing the body sense artificial limb is realized based on the motion electric stimulation feedback sensing system facing the body sense artificial limb, and comprises the following steps of:
step 1: the inertial measurement unit is used for measuring the motion of the artificial limb and transmitting motion information of the artificial limb to the main control chip;
step 2: the main control chip reads the motion information of the artificial limb;
step 2.1: the main control chip acquires motion information, and converts the motion information into frequency parameters for primarily controlling and regulating the electric stimulation chip to output electric stimulation pulses through a response algorithm; preferably, the response algorithm is a response algorithm based on a muscle shuttle model;
the muscle shuttle model is equivalent to a circuit model, and the formula of the muscle shuttle model is expressed as follows:
wherein Ka, kb and Kc are elastic coefficients of an elastic element, the elastic element can be equivalently used as a resistor in a circuit model, db and Dc are damping coefficients of a damping element, a damping component can be equivalently used as a capacitor in the circuit model, A (t), B (t) and C (t) are changes of corresponding position lengths along with time, after Laplace transformation, A(s), B(s) and C(s) are voltage changes of corresponding positions of the corresponding circuit model, after Laplace transformation, voltage changes at two ends of the resistor are changed into KaA(s), KBB(s) and KcC(s), and voltage changes at two ends of the capacitor are changed into sDb (A(s) -B (s)) and sDcC(s), wherein s is a Laplace operator;
the response algorithm is realized by adopting a second-order IIR filter, and the formula is as follows:
y(n)＝b0*x(n)+b1*x(n-1)+b2*x(n-2)-a1*y(n-1)-a2*y(n-2)
wherein b0, b1, b2, a1 and a2 are coefficients of the filter, corresponding to each coefficient of H (z), x [ n ] is a current sample of the input signal, y [ n ] is a current sample of the output signal;
step 2.2: converting the frequency parameters of the electric stimulation pulses output by the preliminary control and regulation electric stimulation chip into the frequency parameters of the electric stimulation pulses output by the control and regulation electric stimulation chip through an activation function; preferably, the activation function is an activation function based on a human body nerve sensing mechanism, in particular a Tanh function;
step 2.3: according to an electric stimulation parameter regulation strategy, the electric stimulation pulse output by the control regulation electric stimulation chip is perceived and regulated to electric stimulation parameters according to the electric stimulation of arm muscles and skin; preferably, the electrical stimulation parameter adjustment strategy is to adjust the frequency of electrical stimulation based on the muscle contraction activity signal and the human percutaneous electrical stimulation response characteristic;
preferably, the electric stimulation pulse output by the control and regulation electric stimulation chip is bidirectional constant current electric stimulation, the frequency parameter of the electric stimulation pulse output by the control and regulation is regulated after the response algorithm and the activation function, other parameters such as positive and negative pulse width, positive and negative current amplitude and dead time between positive and negative pulses of the electric stimulation are regulated, and the electric stimulation threshold is regulated in a self-adaptive way according to different users;
step 3: the main control chip transmits the motion information of the artificial limb to the electric stimulation chip in real time after the electric stimulation pulse parameters are adaptively regulated through the response algorithm and the activation function, the electric stimulation chip regulates electric stimulation output according to the parameters, the output finally passes through the surface electrode which is positioned on the inner wall of the artificial limb and is attached to the skin surface of the amputee, the electric stimulation pulse stimulates subcutaneous tissue and muscle, and the amputee can feel the motion of the artificial limb.
The beneficial effects of adopting above-mentioned technical scheme to produce lie in:
the invention provides a motion electric stimulation feedback sensing system and a motion electric stimulation feedback sensing method for a proprioceptive artificial limb. The electrical stimulation feedback provides real-time sensory feedback that enables the amputee to more accurately control the motion of the prosthesis. By sensing the electrical stimulation changes, the patient can adjust the posture and movement of the limb, thereby improving the accuracy and fluency of movement control. By stimulating the stump nerves, the nervous system can be promoted to reestablish the nerve path connected with the limbs, the nerve remodeling and re-adaptation of the amputee can be promoted, and the perception and control capability of the amputee on the artificial limb can be improved. Will greatly improve the quality of life and mental health of amputees. With frequency-tuned electrical stimulation feedback, intensity, pattern and area can be adjusted according to the patient's perceptive and control capabilities, and personalized customization can be achieved according to the individual needs of the patient, achieving optimal adaptability and effect.
Drawings
FIG. 1 is a block diagram of a system in an embodiment of the invention;
FIG. 2 is a flow chart of a method in an embodiment of the invention;
FIG. 3 is a block diagram of a prosthesis according to the present invention;
FIG. 4 is a graph of a muscle shuttle model and corresponding Maxwell viscoelastic model of the present invention;
wherein figure (a) -muscle shuttle model, figure (b) -maxwell viscoelastic model;
FIG. 5 is a graph of the motion angle and electrical stimulation frequency response of the prosthesis of the present invention;
FIG. 6 is a schematic diagram of an electrical stimulation waveform of the present invention;
in the figure: 1. a prosthesis body; 2. an inertial measurement unit module; 3. a control circuit and a power module; 4. a pair of electrodes; 5. a pair of electrode expanded views; 6. static motor neurons; 7. dynamic motor neurons; 8. primary afferent activity of type Ia myofascial; 9. muscle spindle type II secondary afferent activity; 10. myobag 1 nuclear bag fiber; 11. myobag 2 nuclear bag fiber; 12. myonuclear chain fibers.
Detailed Description
The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
In one aspect, a motion electrical stimulation feedback perception system for a proprioceptive prosthesis comprises: the artificial limb comprises a power supply module, a control circuit, a surface electrode and an artificial limb structure; as shown in fig. 1, the frame diagram of the motion electric stimulation feedback sensing system and method for the body-sensing artificial limb comprises an artificial limb structure, a pair of electrodes on the inner wall of the artificial limb, a control circuit and a power supply module on the outer side of the artificial limb, wherein the control circuit comprises an inertial measurement unit, a main control chip and an electric stimulation chip. The pair of electrode surfaces can be properly coated with hydrogel to enhance the contact between the electrode and the skin;
the inside of the artificial limb structure is a hollow structure, the surface electrode is embedded in the inner wall of the artificial limb structure, and the control circuit and the power supply module are arranged on the outer surface of the artificial limb structure;
the control circuit comprises an inertial measurement unit, a main control chip and an electric stimulation chip;
the inertial measurement unit is a motion processing sensor, and the output end of the inertial measurement unit is connected with the input end of the main control chip and can record arm position and motion information; preferably, the inertial measurement unit module is an MPU6050;
the output end of the main control chip is connected with the input end of the electric stimulation chip; and the inertial measurement unit module data can be read, and the output of the electric stimulation chip can be controlled. Preferably, the main control chip is a 32-bit microcontroller STM32 developed by ST company based on ARM Cortex-M kernel;
the electric stimulation chip outputs electric stimulation pulses under the control of the main control chip; preferably, the electrical stimulation chip is an ENS001-A full-function nerve electrical stimulation chip of a heating core gamma company;
the surface electrode is a 3 x 3cm surface electrode with hydrogel, is embedded into the inner wall of the artificial limb structure and is connected with the current output interface of the electric stimulation chip. The electrode stimulation positions are any positions from the elbow to the upper arm of the arm, and the number of the electrodes can be increased according to actual needs;
the power module comprises a charging module, a lithium battery and a lifting pressure module; the output end of the charging module is connected with the lithium battery, the output end of the lithium battery is connected with the input end of the voltage boosting and reducing module, and the output end of the voltage boosting and reducing module is connected with the control circuit;
as shown in fig. 2, the control flow of the motion electric stimulation feedback sensing system and method for the proprioceptive artificial limb sequentially comprises the steps of artificial limb motion, measurement by an inertial measurement unit, motion information reading by a main control chip, response algorithm and activation function of the read motion information by a muscle shuttle model, and finally regulation and distribution of percutaneous electric stimulation.
As shown in fig. 3, the artificial limb structure diagram of the motion electric stimulation feedback sensing system and method facing to the body sense artificial limb comprises a pair of electrodes on the inner wall of the artificial limb, an electrode unfolding schematic diagram and a control circuit and a power supply module on the outer side of the artificial limb.
Fig. 4 is a diagram showing a muscle shuttle model and maxwell viscoelastic model of the motion electric stimulation feedback sensing system and method for the proprioceptive artificial limb according to the present invention.
Among these, the muscle spindle organ is a special type of mechanoreceptors, which aims to sense the position and velocity of the muscle. Muscle spindles consist of three types of intraspindle fibers: longer bag1 and bag2 cores and shorter core chain fibers. These types of fibers react differently to the activation of two different types of fusion motion, static and dynamic, and their activities combine to produce primary and secondary afferent activities. As biological and anatomical knowledge it is known that Ia afferent terminals transmit information about muscle length and rate of stretching to the central nervous system, while II afferent terminals provide mainly information about muscle length. By processing the length and speed information, the central processing system can accurately determine the position of the limb.
From the muscle shuttle model principle, it can be inferred that there is a viscoelastic unit that is subject to continuous creep and relaxation. When creeping, the elastic member will respond quickly to stretching, but when reaching an equilibrium position will exhibit a relaxation behavior, the damping member will stretch, and the elastic member will contract. This behavior corresponds to maxwell viscoelastic model behavior. The linear description of the sensory codes requires a second order or higher order model, and in order to make the model simple and practical, a second order network model as shown in fig. 4 is constructed, and reasonable linear approximation is made for the system.
The left and right networks represent primary and secondary myofascial afferent activities of type Ia and type II, respectively. When a change in muscle length is applied across the system, the corresponding changes in length of the elastic elements Ka and Kc are believed to activate primary and secondary afferent activities. The damping member takes into account the viscoelastic behaviour of the endofusiform fibres. The system output may be superimposed by two part outputs. The formula is derived as follows:
for the convenience of calculation, the system can be equivalently a circuit model, wherein Ka, kb and Kc are elastic coefficients of elastic elements, the elastic elements can be equivalently resistors in the circuit model, db and Dc are damping coefficients of damping elements, a damping component can be equivalently capacitors in the circuit model, A (t), B (t) and C (t) are changes of corresponding position lengths along with time, after Laplace transformation, the capacitors are A(s), B(s) and C(s) are voltage changes of corresponding positions of the circuit model, after Laplace transformation, the voltage changes at two ends of the resistor are KaA(s), KBB(s) and KcC(s), and after Laplace transformation, the voltage changes at two ends of the capacitor are sDb (A(s) -B(s) and sDcC(s), wherein s is a Laplace operator.
The system branches represent:
K c C(s)+sD c C(s)＝K a A(s)+K b B(s)
K b B(s)＝sD b (A(s)-B(s))
total system length change:
X(s)＝A(s)+C(s)
transfer function of the system as a whole:
H(s)＝H a (s)+H b (s)
wherein:
the formulation of the muscle shuttle model is obtained by arrangement:
wherein, each element parameter is as follows:
| Ka(KΩ) | Kb(KΩ) | Kc(KΩ) | Db(uF) | Dc(uF) |
| 0.5 | 100 | 200 | 2 | 5 |
after bilinear variation (where T is 10 ms) and brings into parametric formulation:
the formula is realized by adopting a second-order IIR filter, namely a response algorithm, and the realization of the second-order IIR filter can be expressed by using a recursive differential equation:
y(n)＝b0*x(n)+b1*x(n-1)+b2*x(n-2)-a1*y(n-1)-a2*y(n-2)
where b0, b1, b2, a1 and a2 are coefficients of the filter, corresponding to each coefficient of H (z), i.e., 7.8,0.12676, -7.6445,0.112676, -0.831, x [ n ] is the current sample of the input signal and y [ n ] is the current sample of the output signal, respectively. By recursively calculating this difference equation, a digital filtering operation of the second-order IIR filter can be achieved.
The equation can be conveniently applied to a main controller, but the output of the filter cannot be directly used as electric stimulation acting on a human body, and according to a human body sensing mechanism, each receptor receives information of external stimulation or internal state in arm motion and converts the information into nerve signals to be transmitted to neurons, and the neurons feedback the contraction and relaxation of muscles through generating and transmitting electric signals, so that the arm motion is sensed. Neurons may saturate under extreme stimulation conditions, and when the stimulation is beyond the operating range of the neuron, the response capability of the neuron may be limited. Therefore, the invention selects the Tanh function as the activation function to simulate the human body perception effect. The function has a saturation character, which means that the slope of the function approaches 0 when the input becomes very large. The electric stimulation is expressed on the electric stimulation corresponding to the arm movement, namely, when the arm moves fast, the electric stimulation cannot be increased instantly and infinitely, and the electric stimulation tends to a maximum value, so that the stimulation feeling is ensured, and meanwhile, the human body cannot be damaged.
Fig. 5 is a graph showing the motion and response of the motion electro-stimulation feedback sensing system and method for a proprioceptive prosthesis of the present invention. The horizontal axis is time (in 10 ms), and the vertical axis is angle or electrical stimulation frequency division coefficient. The method comprises an original artificial limb movement angle curve graph, an electric stimulation prescaler graph after a response algorithm and an electric stimulation frequency division graph after an activation function.
Fig. 6 is an electrical stimulation waveform diagram of the motion electrical stimulation feedback sensing system and method for the proprioceptive prosthesis of the present invention. The electric stimulation waveform selects bidirectional constant current stimulation, and no charge residue is generated in the human body to harm the health. The electrical stimulation parameter regulation strategy of the invention is as follows: from the muscle electrical activity signal acquired based on the muscle conduction volume filtering characteristic, it is known that the frequency of the muscle electrical activity signal is more responsive to the contraction activity of the muscle in the signal component related to the muscle activity, and the frequency range is usually between several tens of hertz and several kilohertz, and the specific range depends on the characteristic of the muscle activity, so the present invention mainly adjusts the frequency of the electrical stimulation.
According to the foregoing and according to the response characteristics of human percutaneous electrical stimulation, that is, the interface impedance of the electrode and the skin decreases with the increase of frequency, the invention selects the initial frequency to be 5Khz with high frequency, at this time, the impedance is larger, the human body feel weak to the electrical stimulation, the frequency is reduced with the increase of angle, the human body can feel obvious electrical stimulation, and the human body can feel the sense of body sense of the artificial limb by combining the response algorithm and the activation function. The positive and negative pulse width of the electric stimulation is selected to be 70us, the current intensity is constant to be 1mA, and the whole parameter adjustment strategy meets the requirements of safety, comfort and wide perception range of the electric stimulation. In addition, the intensity and the area can be adjusted according to the perception and control capability of the patient, and can be customized individually according to individual requirements. The overall waveform can be divided into three phases, fast response, dynamic peak and static response. The first stage is a quick response stage, provides quick response when the arm starts to move so as to better sense the start of the arm movement, the second stage is a dynamic peak stage, can provide good speed sensing and direction sensing, the faster the movement speed is, the higher the dynamic peak is, and the third stage is a static response stage, and can provide good position information when the arm is static.
The motion electric stimulation feedback sensing system and method for the proprioception prosthesis disclosed by the embodiment of the invention can be applied to the occasions including:
1. natural feel and physical awareness of the prosthesis. Providing the prosthetic user with an experience that more closely approximates natural feel and physical awareness. By simulating the actual motion perception, the user can better feel the existence and action of the artificial limb, and the consciousness and the connection sense of the physical state of the user are enhanced. The accurate motion perception feedback is provided, and a user can better control the artificial limb to perform fine motion and accurate motion.
2. Disability assistance techniques. The electrical stimulation feedback technique can be applied to other disability assistance techniques. For example, in vision impairment aiding techniques, electrical stimulus feedback may simulate visual signals, helping the blind perceive and navigate the environment. In hearing impairment aiding techniques, electrical stimulation feedback may simulate auditory signals, providing sound localization and environmental awareness functions, among other functions.
3. And (5) remote monitoring and adjustment. The design of the electrostimulation feedback prosthesis can be used in combination with remote monitoring and adjustment techniques. By connecting the Internet and sensor technology, medical professionals can remotely monitor the state and performance of the prosthetic user, adjust and optimize, and provide more personalized and real-time support.
4. Intelligent assistant and robot. The electrical stimulus feedback technique can be applied in control and sensing systems of intelligent assistants and robots. By equipping the robots with electrical stimulation feedback prostheses, they can more accurately sense and manipulate objects, improving the quality and effect of physical interactions. The method has wide application prospect in the fields of medical treatment, nursing and service robots.
5. Virtual reality and augmented reality: the electrostimulation feedback prosthesis may be used in conjunction with virtual reality and augmented reality techniques. By combining the electrical stimulation feedback with visual and audible information of the virtual environment, the user may obtain a more immersive experience. This has potential in the fields of games, training, and simulated training.
The foregoing description is only of the preferred embodiments of the present disclosure and description of the principles of the technology being employed. It will be appreciated by those skilled in the art that the scope of the invention in the embodiments of the present disclosure is not limited to the specific combination of the above technical features, but encompasses other technical features formed by any combination of the above technical features or their equivalents without departing from the spirit of the invention. Such as the above-described features, are mutually substituted with (but not limited to) the features having similar functions disclosed in the embodiments of the present disclosure.
Claims (9)
1. A motion electro-stimulation feedback sensing system for a proprioceptive prosthesis, comprising: the artificial limb comprises a power supply module, a control circuit, a surface electrode and an artificial limb structure;
the inside of the artificial limb structure is a hollow structure, the surface electrode is embedded in the inner wall of the artificial limb structure, and the control circuit and the power supply module are arranged on the outer surface of the artificial limb structure;
the control circuit comprises an inertial measurement unit, a main control chip and an electric stimulation chip;
the inertial measurement unit is a motion processing sensor, and the output end of the inertial measurement unit is connected with the input end of the main control chip; the output end of the main control chip is connected with the input end of the electric stimulation chip;
the surface electrode is embedded in the inner wall of the artificial limb structure and is connected with the current output interface of the electric stimulation chip;
the power module comprises a charging module, a lithium battery and a lifting pressure module; the output end of the charging module is connected with the lithium battery, the output end of the lithium battery is connected with the input end of the voltage increasing and decreasing module, and the output end of the voltage increasing and decreasing module is connected with the control circuit.
2. The motor-driven electrical stimulation feedback sensory system for a proprioceptive prosthesis of claim 1, wherein said inertial measurement unit module is MPU6050.
3. The motor electrostimulation feedback sensing system of claim 1 where the surface electrode is a hydrogel 3 x 3cm surface electrode.
4. The motion electric stimulation feedback sensing method for the body-sense artificial limb is realized based on the motion electric stimulation feedback sensing system for the body-sense artificial limb according to claim 1 and is characterized by comprising the following steps:
step 1: the inertial measurement unit is used for measuring the motion of the artificial limb and transmitting motion information of the artificial limb to the main control chip;
step 2: the main control chip reads the motion information of the artificial limb;
step 3: the main control chip transmits the motion information of the artificial limb to the electric stimulation chip in real time after the electric stimulation pulse parameters are adaptively regulated through the response algorithm and the activation function, the electric stimulation chip regulates electric stimulation output according to the parameters, the output finally passes through the surface electrode which is positioned on the inner wall of the artificial limb and is attached to the skin surface of the amputee, the electric stimulation pulse stimulates subcutaneous tissue and muscle, and the amputee can feel the motion of the artificial limb.
5. The method for motion electro-stimulation feedback sensing for a proprioceptive prosthesis according to claim 4, wherein the step 2 comprises the steps of:
step 2.1: the main control chip acquires motion information, and converts the motion information into frequency parameters for primarily controlling and regulating the electric stimulation chip to output electric stimulation pulses through a response algorithm;
step 2.2: converting the frequency parameters of the electric stimulation pulses output by the preliminary control and regulation electric stimulation chip into the frequency parameters of the electric stimulation pulses output by the control and regulation electric stimulation chip through an activation function;
step 2.3: and according to an electric stimulation parameter regulation strategy, the electric stimulation chip is controlled to output electric stimulation pulses, and electric stimulation parameters are regulated according to the electric stimulation sensing of arm muscles and skin.
6. The method for motion electro-stimulation feedback perception of a proprioceptive prosthesis according to claim 5, wherein the response algorithm in step 2.1 is a response algorithm based on a muscle shuttle model;
the muscle shuttle model is equivalent to a circuit model, and the formula of the muscle shuttle model is expressed as follows:
wherein Ka, kb and Kc are elastic coefficients of an elastic element, the elastic element can be equivalently used as a resistor in a circuit model, db and Dc are damping coefficients of a damping element, a damping component can be equivalently used as a capacitor in the circuit model, A (t), B (t) and C (t) are changes of corresponding position lengths along with time, the changes of the corresponding positions of the circuit model are obtained after Laplace transformation, the changes of the voltages at two ends of the resistor are obtained after the Laplace transformation, and are obtained after KaA(s), KBB(s) and KcC(s), and the changes of the voltages at two ends of the capacitor are obtained after the Laplace transformation, and are obtained after sDb (A(s) -B (s)) and sDcC(s), wherein s is a Laplace operator;
the response algorithm is realized by adopting a second-order IIR filter, and the formula is as follows:
y(n)＝b0*x(n)+b1*x(n-1)+b2*x(n-2)-a1*y(n-1)-a2*y(n-2)
where b0, b1, b2, a1 and a2 are coefficients of the filter, corresponding to each coefficient of H (z), x [ n ] is the current sample of the input signal, and y [ n ] is the current sample of the output signal.
7. The method according to claim 5, wherein the activation function in step 2.2 is an activation function based on a human body neural sensing mechanism, in particular a Tanh function.
8. The method according to claim 5, wherein the electrical stimulation parameter adjustment strategy in step 2.3 is to adjust the frequency of the electrical stimulation based on the muscle contraction activity signal and the human percutaneous electrical stimulation response characteristic.
9. The method according to claim 5, wherein in step 2.3, the control and adjustment electric stimulation chip outputs electric stimulation pulses as bidirectional constant current electric stimulation, and frequency parameters of the control and adjustment output electric stimulation pulses are adjusted after the response algorithm and the activation function, other parameters such as positive and negative pulse width, positive and negative current amplitude, dead time between positive and negative pulses of electric stimulation, and electric stimulation threshold values are adjusted in a self-adaptive manner according to different users.
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