Design Of Electrical Stimulation Device For Proprioception Of Prosthetic Hand

Prostheses are artificial limbs used by amputees to compensate for the partial function of the limbs.For patients with upper limb disabilities,in addition to rehabilitation training,wearing prosthetic hands is also extremely important.Because wearing a prosthetic hand can make up for the appearance and function of the hand disabled.However,the current commercial prosthetic hands lack the function of perceptual feedback.Prosthetic hand users can only perceive the working status of the prosthetic hand through visual feedback,which increases the burden and pressure of the user when using the prosthetic hand.The establishment of a perception pathway between the user and the prosthetic hand can enhance the user’s "proprioception" of the prosthetic hand,thereby assisting the user to better use the prosthetic hand.In order to reconstruct the sensory feedback path of the prosthetic hand,so that the user of the prosthetic hand can grasp the motion state of the prosthetic hand without visual gaze,this paper proposes an electrical stimulation device that induces the proprioception of the prosthetic hand.Electrical stimulation of the corresponding muscles of the forearm causes muscle contraction and excitement of muscle spindle receptors,thereby generating a sense of movement.The device uses electrical stimulation signals to encode the motion state of the prosthetic hand,so that the user of the prosthetic hand can judge the motion direction,speed,and angle information of the prosthetic hand based on the proprioception induced by the electrical stimulation.The work of this paper is as follows:A multi-channel forearm muscle electrical stimulator is designed to induce the sensation of prosthetic hand movement.The hardware part of the electrical stimulator mainly includes a single-chip microcomputer module,a waveform synthesis module,a constant current source module,an H-bridge module,and a multiplexing module;the software part is used to control the single-chip microcomputer to output corresponding signals to drive peripheral circuits to generate target electrical stimulation waveforms.The output accuracy,linearity,constant current characteristics,and multiplexing function of the electric stimulator are tested.The test results show that the output characteristics of the electric stimulator meet the pre-designed parameter indexes.A coding method for sensory feedback electrical stimulation based on the motion posture of the prosthetic hand is designed.Based on the FSQ-1 prosthetic hand,the driving circuit and driver program of the prosthetic hand fingers are designed,and the control of the motion posture of the prosthetic hand is tested.Based on the MPU6050,the motion posture monitoring system of the prosthetic hand is designed,which can monitor the movement direction,speed and angle of the fingers of the prosthetic hand.The monitoring system has been tested statically and dynamically.The test results show that the monitoring system can effectively obtain the motion posture information of the prosthetic hand.Based on STM32F429,the electric stimulator and the prosthetic hand movement posture monitoring system are integrated design,which realizes the function of dynamically regulating the electric stimulation output of the prosthetic movement posture.The appearance of the device is designed based on the requirements of portability and easy to put on and take off.The experiment verified the function of the electric stimulation device to dynamically adjust the electric stimulation parameters according to the motion posture of the prosthetic hand,and the electrical safety performance of the device was tested.Designing a human body experiment initially verified the feasibility of the electrical stimulation coding method designed in this article.The device provides a clinical application scheme for reconstructing the prosthetic hand movement sensing pathway for patients with upper limb disability.