Fuzzy logic control for ankle foot orthoses equipped with magnetorheological brake

Abstract

This study focused on the development of passive control ankle foot orthosis (PICAFO) for a specific purpose such as preventing foot drop in the post-stroke patient. The PICAFO utilized the magnetorheological (MR) brake as the actuator in which the braking torque was controlled by regulating direct current (DC) from current driver. The Fuzzy Logic Controller (FLC) was employed to control output voltage for current driver based on the inputs, i.e. Electromyography (EMG) bio signal and ankle position. Walking experiment to test the controller was carried out on a single subject where the input and output FLC was monitored and logged. The results showed that the output voltage of the FLC was 94.41% of the maximum output (high) on forward ankle position during swing phase and gradually increase from 9.667% to 77.34% of maximum output during stance phase. The FLC successfully controlled the output voltage according to the required needs. According to the experimental results, the FLC strategy was applicable for PICAFO realizing it contributes to prevention of foot drop.