Study of External Force and Impedance Scheme on Stroke Rehabilitation Robot Manipulator

This paper presents rehabilitation robot with torque control with impedance scheme for post-stroke patients in the upper limb of the shoulder. This impedance scheme consists of external force input and impedance value. The external force input comes from the load cell at the end of the robot (the end effector), which is generated by the patient's force. The input force consists of two Cartesian directions, which will affect the robot dynamic torque for the X-axis and Y-axis. Meanwhile, the value of the impedance in the robotic system is provided by the therapist who handles the stroke patients. The amount of impedance in the robotic system can be adjusted according to the patient's condition. In this paper, we used 3 DOF (Degree of Freedom) self-produced robots. The rehabilitation trajectory consists of two parameters, the position parameter, and the torque control parameter in the impedance system. The impedance scheme in the robotic system use impedance characteristics and Proportional Integral (PI) controller. Proportional Integral (PI) controller is used as a simulation control in tracking errors of position and the torque impedance of the robot. With a simple controller, the characteristics relationship between the changes in the magnitude of the external force produced by the patient and the change in impedance values given to the robot system are obtained. By knowing these characteristics, robots can interact with various types of stroke patients.