A Controllable Biomimetic SMA-actuated Robotic Arm

In this paper, we present a biomimetic 2-DOF SMA-actuated robotic arm that can be controlled by a wearable sleeve in real-time. The designed lightweight robotic arm is intended to be an alternative to the existing heavy and bulky systems, used in different areas such as rehabilitation, haptics and, surgical robotics, etc. which are actuated by the regular hydraulic/pneumatic pistons and brushed/brushless motors. The robotic arm weighs 59g with a wide controllable range of motion (119° and 123° for the 1st and the 2nd joints, respectively). To enable closed-loop control of the joint angular positions, a PID controller was implemented, and its performance was evaluated. Then, the robot payload was evaluated by finding the maximum torque for each joint. The comparison between the existing commercial DC motors and the designed SMA-actuated rotary joints shows that the performance of the designed SMA-actuated rotary joints are acceptable as they outperform well-known commercial motor-based rotary joints in terms of power consumption, nominal voltage, nominal torque, and mass. Next, an End Effector displacement analysis was conducted to assess the robot positioning. Finally, the entire designed teleoperation system comprising the robotic arm and the wearable measurement sleeve was assessed by performing 20 flexion-extension trials. An average RMSE of 13.1mm was achieved for EE displacement.