Enabling Shape Memory Alloys as Actuators for Robotics

Abstract

Does any existing technology provide a viable actuator for the high degree-of-freedom robots that will soon be ubiquitous in society? If a technology exists that is in any way superior to the electric motor for robotics – why has it not come into common use? What are the technology’s benefits and flaws, and can these flaws be overcome? This thesis seeks to answer these questions. The author believes that, of all known devices which convert electrical energy to mechanical motion, shape memory alloy actuators provide the most convincing capabilities to fulfill the needs of complex robots over the next decades. The electro-magnetic motor has moved industry and automation for over a century, yet modern robotic machines are reaching the fundamental limits of its ability as mechanical systems increase in complexity while decreasing in size. Shape Memory Alloy (SMA) actuators have benefits of extraordinary high strength, high energy density, simplicity, and low cost. These benefits come along with obstacles of complex thermo-electro-mechanical behavior, difficult control, fatigue over time, and moderate speed – all of which can be overcome – as well as barriers of low energy efficiency and limited life-time which cannot be overcome. This thesis addresses all of the obstacles to enable more powerful and capable robots, answering the essential question: How can we enable SMA technology so that it becomes useful for robotics?