Crawling–jumping synergic bioinspired robots harnessing electroactive bistable actuators by adjusting mechanical responses and forces

Abstract

Mechanical responses and forces are two urgently concerning factors in actuators. Actuation mechanisms inspired by natural systems are increasingly common, especially the snap-through mechanism in cascading power-induced bioinspired systems. Here, we propose an electroactive bistable actuator that can synergize the fast mechanical response and high mechanical forces. It is constructed by combining a single pretension spring (i.e., p-spring) bistable linkages as a “skeletal spine” and twinned SMA-springs (i.e., s-springs) as “skeletal muscle.” The p-spring connected to linkages plays a role in determining elastic instabilities threshold, while the coupled s-springs serve as actuation generators. The system shows a rapid and switchable snap-through between two stable states as each s-spring is individually actuated. The p-spring and the voltage exerted on s-springs are the two key parameters influencing response time (0.05 s) and mechanical forces (3.4 N). Additionally, synergic movements between crawling and jumping are enabled, which benefit from the ease of control of the exerted voltage and manual convenience in customized pretension. Our prototype can achieve a linear locomotion speed of 0.56 mm/s, a jump height of 95 mm, and a horizontal distance of 150 mm. We look forward to providing a new design paradigm in mechanical systems requiring fast dynamic properties and brilliant static capabilities.