Bio-inspired shape memory alloy actuated hexapod robot

Abstract

This work presents the design and testing of a shape memory alloy and spring steel flexure actuator for use in a meso-scale, 18 degree of freedom hexapod. The paper discusses the general hexapod body design as well as a detailed design of the joints, actuators, and control methods of the individual hexapod legs. The performances of the control methods and of the hexapod legs are presented and discussed. Based on this measured performance, the expected rates of movement for different gaits are given. Other work on SMA actuated walking robots differs in scale or environment. In the field of walking robots the use of SMA as an actuator is mainly limited to micro-scale applications, in which we consider robots measuring less than 5 cm in any dimension micro-scale. This work seeks to demonstrate that actuation with SMA is also possible and worthwhile at the meso-scale of robotics, the proposed robot measuring roughly 45 centimeters. A notable meso-scale SMA actuated walking robot, the RoboLobster, differs from this work in intended environment. The RoboLobster, designed to operate in shallow ocean water, benefits from its environment through cooling for the SMA actuators which improves cycle time (Ayers [1]). This robot also differs in leg number, possessing eight legs over the six of a hexapod. A final group of meso-scale walking robots, hexapods and otherwise, are actuated by smart materials other than shape memory alloys, including piezoelectric actuators (Goldfarb [2], Yumayanto [3]).