Development Of Electrotactile Feedback System For Prosthetics

Bionic prostheses help amputees to repair their appearance defects and replace the movement of lost limbs.Open-loop control is widely used in the design of upper limb prostheses.Patients can only manipulate the prostheses through their own visual perception to interact with the external environment.Due to the lack of effective tactile feedback,the operation experience is poor,especially in poor light conditions and dark environment,which seriously affects the daily life of disabled patients.Above-mentioned,this paper introduces electrotactile technology and develops a set of artificial limb feedback system based on electrotactile technology.By setting up mapping area corresponding to bionic artificial limb finger and claw on upper limb of patients,the mapping relationship between force and electric stimulation intensity of bionic manipulator is established.According to the data of tactile sensor from each finger and claw during the interactive process,the corresponding electric intensity is applied to the corresponding part of mapping area.Tactile stimulation is used to realize tactile feedback in the process of artificial hand environment interaction.The paper work is of positive significance for remolding the exterior image of amputees,enhancing their life confidence and encouraging them integrate into the group society.In addition,the paper work is of great value to helping the elderly and disabled in this aged society,as well as to the physical reconstruction of disabled soldiers.The paper mainly includes:1.Overall design.According to the design objective of the electrotactile feedback system for prosthetic limbs,the system requirements are analyzed,the overall architecture is defined,the electrotactile stimulation scheme,the rope-driven bionic prosthetic limb scheme are proposed,and the key hardware such as the tactile sensor is determined.The mapping scheme was designed,and the tactile information mapping between the stimulus array with 14 stimulus points and the prosthesis was established to realize the tactile reproduction of the grasping state.2.Electric tactile theory modeling.According to the physiological structure of human skin and the mechanism of tactile perception,a skin electrical stimulation model was established.The conduction process of skin surface electrical stimulation and the sensory characteristics of different tactile sensory corpuscles under different stimulation modes were discussed,the design of electrical stimulation process was assisted.3.Electric stimulator design.Based on Boost boost principle and voltage controlled constant current source circuit,a multi-channel electrotactile stimulator is designed,which can realize the parameter control of output stimulus waveform amplitude,frequency and duty cycle.4.Force tactile perception system design.FSR pressure sensor array is used to detect the stress state of each finger joint in the process of prosthetic limb and environment interaction.Discrete wavelet transform algorithm is introduced to analyze the data of tactile sensor in order to collect and evaluate tactile interaction force and sliding condition,so as to provide basis for electric tactile intensity stimulation.5.Experiments and tests.Classification of sensory output and intensity grade of the designed electrical stimulator were completed through experiments.Design experiments to verify the grasping information of the participants in the grasping process of the manipulator,and verify the control performance and practical value of the electric tactile feedback system of the prosthesis designed by this subject.In this paper,electric tactile stimulation is applied to the tactile feedback of prosthetic limbs,which realizes the closed-loop manipulation in the process of prosthetic environment interaction.It can meet the application needs of the prosthetic limbs of the disabled and achieve the objectives of the project.