Construction And Verification Of Tactile And Opening Information Feedback In Prosthetic Hand Based On Evoked Tactile And Substitution Sensation

Although modern prosthetic hands have rich functions,the lack of sensory feedback leads to a high rejection rate of amputees.In the paper,how to provide tactile and opening information feedback for prosthetic hands based on evoked tactile sensation(ETS)and non-somatotopic stimulation(NSS)was discussed and the feasibility was verified.Firstly,the electrical stimulation sensory feedback system in the laboratory was improved.The prosthetic hand was equipped with multiple pressure sensors and bending sensors.The electrical stimulation system was improved to collect pressure and opening signals from multiple channels and encode them into multiple electrical stimulus.Also,the control logic of length and hand opening was added in the host computer.Then,experiments of single-or multi-finger perception were designed to evaluate finger perception ability of ETS.Stimulation electrodes were placed at five most sensitive points of projected finger map on two transradial amputees.The electrical stimulation of each channel was modulated independently.The results showed that high accuracy of finger perception can be provided based on ETS,but the accuracy of multi-finger perception was reduced by 37.5% and 42.0%,respectively.Finally,three experiments of functional gripping with prosthetic hands were conducted,to verify the feasibility of length feedback,hand opening feedback and combination feedback.Results from two transradial amputees showed that the accuracy of length identification,in essence the number of digits in contact with objects,reached 98.3% and 73.3%,respectively.Hand opening can be well distinguished with NSS in the ipsilateral upper arm.Finally,combined information of object length and size can be conveyed to amputees through combined ETS and NSS in upper arm.