Development of a Closed Loop FES System Based on NARX Radial Based Network

Abstract

In this paper design of a closed loop FES system for torque control is presented. Snap power worker s used for measuring muscle torque. Using this system torque is proportional to angle of a flexion so by controlling angle of a flexion torque is controlled too. During functional electrical stimulation 3 parameters can be changed: pulse width, pulse amplitude and time between two impulses. In this paper pulse amplitude and frequency are constant and system is controlled by changing pulse width. PI regulator is used to minimize difference between desired trajectory and system output. Parameters of a PI controller are obtained by minimizing mean square error on simulated system. In this paper NARX Radial based neural network model of system is used for simulation. Result on a real system show that this type of control system can be used for torque control.