Simultaneous Proportional and Independent sEMG Based Hand Wrist Prosthesis Control

DESCRIPTION provided by applicant Surface electromyogram sEMG controlled powered hand wrist prostheses are used by upper limb amputees to return partial upper limb function Conventional transradial prostheses can use surface EMG amplitudes from the residual forearm flexors and extensors to control hand closing and opening respectively Additional degrees of freedom DoFs e g wrist rotation are not controlled simultaneously in conventional commercial systems Rather prostheses apply EMG based or mechanical mode switching so that the same EMG sites sequentially control the additional functions This limitation is problematic as many basic tasks e g drinking from a cup combing hair require the simultaneous activation and control of two or more joints It was reported that the ability to control andquot coordinated motions of two joints at the same timeandquot was the second highest priority improvement desired by these users The first priority was for a rotating wrist a necessary prerequisite for two DoF control and a device that is already commercially available A number of research studies have reported on the development of proportional simultaneous and independent DoF controllers initially using upwards of or more high density electrodes electrodes that were not intended for clinical use and recently using as few as commercial electrodes For practical clinical use however fewer electrodes are necessary and a method is needed to determine where to locate them within the socket The manual palpation and trial and error methods used to locate two myoelectrodes for existing DoF systems is inadequate for DoF electrode site selection In our Phase work we demonstrated the feasibility of a system for electrode site selection that controls two DoFs with only four commercial electrodes A calibration procedure using a channel EMG system without the prosthetic socket is used in the laboratory or in the prosthetistandapos s office in commercial implementation to select EMG sites and relate their electrical activity to DoFs In this Phase application we propose to transitin this method to a commercial product Aim will develop the necessary hardware software to prototype the embedded commercial controller as well as the clinical fitting training system Aim will refine the site selection and control algorithms Our Phase work will focus on utilizing only the affected limb for a more direct control relationship and on determining ways to rapidly calibrate a DoF controller in the laboratory and in the field Aim will evaluate the prototyp devices and algorithms developed in Aim and in a laboratory study and then in a pilot field study facilitating commercialization PUBLIC HEALTH RELEVANCE Upper limb amputees report that direct control of two joints simultaneously two degrees of freedom of proportional control is a greatly desired prosthesis improvement In our Phase project we demonstrated the feasibility of an EMG based prosthesis controller that applies four conventional electrodes on the forearm and provides two proportional simultaneous and independent degrees of freedom This number of electrodes is small enough for use in commercial prosthetic systems a prototype of which will be developed by the Phase work