Tracking control of a robotic orthosis for gait rehabilitation: A feedforward-feedback control approach

Abstract

In this study, the trajectory tracking control problem of a 2 degrees of freedom robotic orthosis for the lower limb rehabilitation is discussed. The robotic orthosis is actuated by a pair of self-made pneumatic artificial muscles (PAMs) in an antagonistic configuration. A second order plus dead time (SOPDT) linear model is chosen for describing the antagonistic actuator behavior. In order to enhance the trajectory tracking performance, a modified feedforward-feedback control scheme which utilizes the known future information of the desired trajectory is employed. The effectiveness of the proposed strategy is verified by experiments in different gait cycles.