Muscle Modeling of Wrist Joint Using First-Order System

Abstract

Functional electrical stimulation (FES) is the method that causes joint movements by electrical stimulation to a muscle. Output reaction caused by erectrical stimulation is important information for FES system. The aim of this research was modeling and verification of the relationship between stimulation intensity and joint torque. Primary delay system was used for model. As input, voluntary pulse width was used for identification of parameters. Gain was found to depend on the stimulation intensity while the time constant was found to depend on the build-up time. After the identification of parameters, verification experiment for modeling was conducted by using disturbance observer (DOB). The result showed that the calculated torque was close to the estimated torque by DOB. This model is effective for the feed back control system for FES system.