Design of wearable system for closed-loop control of gait restoration system by Functional Electrical Stimulation

Abstract

This paper describes design and test of a wearable FES system for the purpose of improving the performance of gait in patients with post-stroke. The prototype system that was developed includes electrical stimulator and sensor systems. Electrical stimulator was designed to generate pulse train that was realized using non-isolated boost converter. Sensor system was designed to measure gait phases that was realized using FSR sensors and to measure lower limb joint angles that was realized using a fusion of gyroscope and accelerometer-based tilt angle sensor. In order to remove measurement error due to bias error of the gyroscope and fluctuation of tilt sensor, Kalman filter was used to estimate true lower limb joint angles. Each system was tested separately. Testing was done by measuring the stimulator's output on the tibialis anterior muscle stimulation in normal subjects. The characteristics of pulse train in accordance with the desired specifications and capable of producing contractions in the tibialis anterior muscle. Sensor system was tested to measure gait parameters in subjects who walk normally. Comparison of the measured data with existing research data, showed the same pattern of the signal, the magnitude value is still in the standard deviation value of comparative data.