Simultaneous Design of 3D Lower Limb Rehabilitation Trajectory and External Force in Consideration of Biomechanical Stability

Abstract

Many physical medicine and rehabilitation strategies have been developed for physically disabled people. Most of them have been developed by the physical therapists who assess anatomical and physiological states of the patients. We can design a better rehabilitation method with application of robot technologies, since we can achieve complex motional trajectories in smooth and accurate manner, realize creatively active and passive guidance of patient's limb motion according to the patient's state, and even load and unload on specific muscles. We have developed a sequential design method of lower limb rehabilitation trajectory and external force acting on foot based on a 2D musculo-skeletal model of lower-limb. In this paper, we extend the previously developed method to a 3D musculo-skeletal model for 3D training trajectory and external force design. We introduce spline curves for both smooth position and force tracking trajectories. The structural parameters of the spline curves are explored by applying genetic algorithm. The usefulness of the proposed method is confirmed through simulation results and the comparison with a conventional training trajectory.