Model-Based Hybrid Cooperative Control of Hip-Knee Exoskeleton and FES Induced Ankle Muscles for Gait Rehabilitation

Abstract

To regain mobility, stroke patients need to receive repetitive and intensive therapy. Robot-assisted rehabilitation is an active area of research. Cheap robotic leg rehabilitation devices should be developed to meet the demands and assist most patients. A low cost hip-knee exoskeleton prototype powered by pneumatic muscles was developed. On this basis, Functional Electrical Stimulation (FES) induced paralyzed muscles to realize ankle joint rehabilitation training. These three ankle muscles: the tibialis anterior, the soleus, and the gastrocnemius under electrical stimulation cooperated together to realize optimally coordinated control of dorsiflexion and plantar-flexion movement. As both of pneumatic muscle and FES induced muscle possess highly nonlinear characteristics, a sliding control algorithm called Chattering mitigation Robust Variable Control (CRVC) was applied to leg hybrid rehabilitation. The combination of exoskeleton and FES is a promising way to reduce the cost and the complexity of designing hip-knee-ankle exoskeleton. The proposed hybrid method was verified by treadmill-based gait training experiments.