Development and Impedance Control of Lightweight Shape Memory Alloy Actuated Robotic Arms

Abstract

Shape memory alloys (SMAs) have been proposed as a lightweight actuator for robotic applications. Their low mass makes them an excellent candidate for aerial manipulation, where reducing the mass of a manipulator can increase usable payload and save energy. Existing SMA-actuated robotic arms are restricted in their size, strength, and degrees of freedom (DOFs). This thesis develops two 3-DOF, SMA-actuated robotic arms suitable for aerial manipulation. The developed arms are significantly more capable than existing SMA-actuated arms and can manipulate masses of up to 300 g. A novel compliant joint design is introduced that allows for simultaneous control of antagonistic SMA actuators. The joint provides direct measurements of the torque applied by each actuator, allowing for the development of a multi-level impedance controller. Finally, an extended Kalman filter formulation is introduced and integrated into the multi-DOF robotic arm.