Research On Disturbance Suppression Of Lower Limb Rehabilitation Robot

As China has gradually entered the aging society, due to diseases, accidents and othercauses, the number of patients with lower limb extremity diseases who can not move normallyincreases every year. The latter rehabilitation is more important. For patients, a scientific,repeating, reliable rehabilitation training is the key to breaking away illness. This thesis wasbased on an omni-directional lower limb rehabilitation robot that arouse wide attention aroundthe world because of its high intelligence and safety. This thesis provides an effective methodto restrain disturbances of robot tracking control.The main characteristics of omni-directional lower limb rehabilitation robots is nonlinearand highly coupled, there are many uncertain or unknown parameters within it, and the systemmodel is not able to obtain accurately. The external disturbances also lead to the change of thetraveling direction and speed of the robot. Besides, there are mechanical errors, mechanicalshocks and frictions between components at runtime. These factors undoubtedly make therobot produce path deviation when it assists patients in training. Especially, the disturbancesfrom uncertainty load mass and the centre-of-gravity shift because of the load factors areimportant issues of rehabilitation robot to be solved.This thesis analyzed the kinematics and dynamics model of omni-directional lower limbrehabilitation robot and designed a robust controller to reduce to influence of load masschange toward robot movement. By contrast with the conventional PD controller in robottrajectory tracking, simulation results show that the new controller is feasible and effective.Then, the thesis was based on the dynamics model with centre-of-gravity shift, and designed acontroller to reduce the influence of centre-of-gravity shift vary on rehabilitation robottrajectory tracking. The stability of controller was proved by Lyapunov function. Movementperformances of the robot were improved under the centre-of-gravity shifting, and the newcontroller made robot control system have a better ability to restrain the disturbance. Finally acontroller designed was based on the above two methods. The different paths trackingsimulation verified the reliability of the control algorithm.In our country the research of omni-directional rehabilitation robot is still in a early stage.Reliability and effectiveness of the control algorithm are crucial for hardware and software combination. I hope the disturbance suppression control strategy contributes to the study of therehabilitation robot.