Design on subsection based mix position controller for lower limb rehabilitation robot

Abstract

The technology of lower limb rehabilitation robot is a hot research topic in recent years, while the exoskeleton robot is a typical representative. Accurate trajectory tracking ability is the base of the exoskeleton mechanical leg to coordinately drive trainers to do rehabilitation training on the treadmill. In this paper, aiming at the existing exoskeleton body, taking into account the uncertain factors such as the modeling errors and the environment, the position controller is designed based on different gait events. During the swing phase, the kinetic model of the robot is basically determined, and the position controller is designed by using the sliding mode control (SMC) method, and the fuzzy compensation method is introduced to reduce disturbances; during the stand phase, as the introduction of treadmill contact force, the kinetic model cannot be determined, then, the cerebellar model articulation controller (CMAC) is used as feedforward control, and the PID control is introduced as feedback to ensure the stability of the control system; finally, the above methods are mixed by the position segmentation. The simulation results show that the proposed method has good trajectory tracking ability and stability in the presence of modeling errors and other disturbances when compared with the traditional computed torque control.