Design and analysis of a multi-joint lower limbs rehabilitation robot

This paper presents a multi-joint lower limbs rehabilitation robot with three degrees of freedom. The robot includes seat, left mechanical leg, right mechanical leg and electric control box, and each mechanical leg includes the hip joint, knee joint and ankle joint which correspond to the hip joint, knee joint and ankle joint of human. The mechanical structure of the rehabilitation robot is described. By adjusting the seat angle, the patient can do the rehabilitation training in different postures. However, when the posture of human upper body changes with the elevation of the seat, the swing limit position of human thigh also changes. In order to guarantee the safety of patients, the mechanical limit of hip joint is designed to be variable. Therefore, the workspace of the robot is also variable. The inverse kinematics and variable workspace of the rehabilitation robot are analyzed. The trajectory planning for the variable workspaces is discussed and the flow chart of the trajectory planning is given.