Adaptive Control for a Lightweight Robotic Arm Actuated by a Shape Memory Alloy Wire

This paper presents the design, model and closed-loop control of a single degree-of-freedom (DOF) lightweight robotic arm actuated by a biased Shape Memory Alloy (SMA) wire. The highly non-linear dynamics of SMAs represent a challenge for control tasks, due to phenomena as hysteresis or parameters uncertainty. With this in mind, we propose a control capable to adapt itself to the hysteretic behavior and update its behavior to deal with the changing parameters of the material over time. An adaptive control for position regulation is presented. This control includes a set of techniques, providing a systematic way to adjust the control parameters in real time, so maintaining the stability of the system and a desired performance, while dealing with parameter and model uncertainties. The closed-loop approach is tested in experimentally showing its effectiveness to deal with the highly non-linear dynamics of the SMA wire.