Design and tests of a wearable functional electrical stimulation (FES) system for knee joint movement using cycle-to-cycle control method

Paralysis has became more widespread nowadays. Mostly caused by stroke, spinal cord injury, and multiple sclerosis, the growing number of paralysis case also implied for a better treatment for its bearer. Some of the main problems for individual with paralysis is to improve health problems related to paralysis and to decrease the dependence to other people by regaining muscle function. In this study, a wearable functional electrical stimulation with cycle-to-cycle control system for knee joint movement restoration was developed. The system consists of sensor system, electrical stimulator, and fuzzy logic controllers. The controller was developed as Single Input Single Output (SISO) controller for knee flexion movement and Multi Input Single Output (MISO) controller for knee extension movement. Sensor system was used to measure angle of knee joint. A combination of two inertial sensors, accelerometer and gyroscope, made up the sensor system. The angle measured by sensor system was also used as feedback to realize closed-loop control. The data from the system could be monitored and saved as database using user interface program in a PC/laptop. Tests with neurologically intact subjects was done to test the performance of the system designed. It resulted in small number of RMSE and Settling Index for both maximum knee flexion and maximum knee extension control. The system designed was expected to be developed further to provide a full wearable FES system for lower limb motoric restoration.