REHABILITATION ROBOT MANIPULATOR UPPER LIMB WITH IMPEDANCE CONTROL FOR FLEXION-EXTENTION PATH FOLLOWING MOTION

• Main Author: Hasan Sumarso, Ade
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/41398
• Institution: Institut Teknologi Bandung

This research studies about impedance control on rehabilitation robot for stroke rehabilitation. Rehabilitation robot base on 3 DOF (Degree of Freedom) is used together with absolute encoder as angle position censor, load cell as force censor, and BLDC (Brushless Direct Current) motor as an actuator. DH (Denavit Hartenberg) parameter is used to kinematic model on robot manipulator, and lagrange equations is used to dynamic model on robot manipulator. Rehabilitation robot for patients after stroke period is focused at upper limb body to move some flexion-extension movements on the shoulder. This research provides position and torque control with impedance scheme for a rehabilitation robot for post-stroke patients. Impedance schema consist of external force and impedance value. Force external is obtained by load cell at end effector robot that is produced by force from the subject/patient which is consists of 2(two) directions in cartesian axis x and y. Impedance value on the robot system is given constant value, and it would impact to the systems because impedance value is percentage value from robot inertia, so the systems would follow impedance characteristics. The robot system is simulated by giving external force variations at 10%, 100%, 150%, and 170% from the motor torque, and constant impedance value (50% from inertia robot). Next simulation the robot system is given impedance value variations at 100%, 200%, 300%, 500% from the robot inertia value and constant external force value (170% from motor torque). Results of this simulations obtained the relationships between external force from patients, impedance value is given to the system, and dynamic robot systems. While external force value from patients increasing, therefore the systems get oscillating. In order to keep the systems to be stable, then the impedance value needs to be enlarged. This characteristic could be used for stroke patients on stiff muscle characteristics. As per understand the characteristic above, robot could interact with patients on many conditions and different stiffness muscle condition. Implementation system control on the robot is applied after simulating process. Controlling robot uses 3 parameters PI controller ????1=0,8, ????2=0,8, ????3=3 and ????????1=200, ????????2=200, ????????3=350. Each parameter is function to error angle tracking, and error torque impedance tracking for each motor torque x, y, z directions. This robot has workspace/range of motion 332 ? ???? ? 1102, 0 ? ???? ? 90, ???????????? 45 ? ? ? 135 and performa value from controller gets 1 degree as error. Robot is moved by the patient based on following path in this rehabilitation. When robot moves, it follows to fixed moving pattern without affected by time. When the movements of the subject/patients could not follow path rehabilitation planning, it causing some force measured by force censor on end effector. This force value measured will give the feedback to the motor as a compliant (motor could move as directions and force value at end effector). If external force has stopped at end effector, robot would respose to assist the subject/patients to correcting path planning.