Knee joint movement assistance through robust control of an actuated orthosis

In this paper, we present a robust controller of a new knee joint orthosis. This orthosis is intended to help or to restore lower limb movements of people with reduced mobility. Dynamic modeling and parametric identification of the knee joint-orthosis system are presented. Due its robustness, a High Order Sliding Mode Controller (HOSMC) is used to control the knee joint. Experiments were conducted on a person in sitting position with flexion/extension of the knee. Performances of the HOSMC are compared to those of a classical Proportional Integrator Derivative (PID) controller in terms of stability, tracking trajectory, convergence in a finite time and robustness against external perturbations.