Control of hybrid FES system for restoration of paraplegic locomotion

Functional electrical stimulation (FES) technology for restoration of upper limb function is today in a process of transfer from the research laboratory to the clinical environment. However, the restoration of locomotion in paraplegics is still difficult even in the research level. The main reason of the difficulty comes from the fact that the stabilizing torques generated by lower limb muscles are strongly dependent upon the posture of the upper half of the body. In this paper,a new-technique, which is called as Hybrid FES system (HFES), is proposed. The hardware of HFES system consists of a conventional FES system and an active orthosis. A pair of actuator and sensor is attached at each joint in the orthosis, which can generate a required torque and obtain values of angle and angular velocity at the joint. Based on the dynamics of the orthosis, the posture of the upper body can be estimated using the measurements from the sensors. Moreover, the stabilizing torques for the actuators can be dynamically calculated from the estimated posture. Some preliminary results are obtained in a simulation study and discussion on the performance and realizability of proposed HFES systems has been given in this paper