Biomimetic multi-segment worm robot based on shape memory alloy wire

Abstract

Shape memory alloy (SMA) has been used in robotic actuators due to its advantages, such as shape memory effect, high damping capacity, and temperature sensitivity. However, its practical application has been limited by the low frequency of heating-cooling cycles and small deformation caused by heat dissipation. To address this issue, this paper presents an insect-scale multi-segment worm robot actuated by a biomimetic soft compound muscle composed of Shape Memory Alloy Wire (SMAW), Polydimethylsiloxane (PDMS), and Acrylonitrile Butadiene Styrene (ABS). The robot’s design includes multiple SMAWs in parallel and an ABS fiber rib with a scaffold structure embedded into the PDMS matrix, allowing for the conversion of the linear small deformations of the SMAW into large bending-expanding motions of the biomimetic muscle. The robot consists of two independently and alternately excited segments that form worm gaits. The soft muscle with multiple thin SMAWs and the multi-segment design enable better heat dissipation, which improves the actuation frequency and the robotic locomotion ability. Experimental results show that the bimimetic robot actuated by SMAWs can reach a speed of 24.33mm/s for a 5Hz PWM signal and 7.33mm/s with a load of three times its weight, outperforming robots of the same scale size and SMA actuation. These results demonstrate that the multi-segment structure with multiple thin SMAWs of the biomimetic robot provides a feasible solution for applying SMA to robotic higher frequency actuation.