Design and Control of a Shape Memory Alloy Wire Bundle Actuator

In this paper, the design and control of a novel shape memory alloy (SMA) actuator that possesses impressive payload lifting capabilities are presented. The actuator consists of 48 nickel-titanium SMA wires mechanically bundled in parallel forming one powerful artificial muscle. This new linear actuator can apply up to 100 lbf (445 N), which is approximately 300 times its weight, over a maximum distance of 0.5 in. (1.27 cm). The actuator was tested in two different loading configurations − linear displacement and operation of a revolute joint. A PID based controller with the addition of an input shaping function was developed for each loading configuration with excellent results, maintaining steady state error within ± 0.004 in. (0.1 mm) for linear motion and ± 1o for revolute joint rotation. This powerful, compact, and lightweight actuator shows promise for use in space, medical, and other macro-robotic applications.