An Arch-Shaped Electrostatic Actuator for Multi-Legged Locomotion

A simple actuator to create non-reciprocal leg motion is imperative in realizing a multi-legged micro-locomotion mechanism. This work focuses on an arch-shaped electrostatic actuator as a candidate actuator, and it proposes the operation protocol to realize a non-reciprocal trajectory. The actuator consists of two hard and flexible sheets and a leg attached to the flexible sheet. The flexible sheet is deformed through an electrostatic zipping motion that changes the height and/or angle of the attached leg. The fabricated prototype weighed 0.1 g and swung about 15 degrees with the applied voltage of 1000 V. The swinging force exceeded 5 mN, five times the gravitational force on the actuator’s weight. Large performance deviations among prototypes were found, which were due to the manual fabrication process and the varying conditions of the silicone oil injected into the gap. The trajectory measurement showed that the leg tip moved along a non-reciprocal trajectory with a vertical shift of about 0.3 mm between the forward and backward swings. The prototype locomotion mechanism using four actuators successfully demonstrated forward and backward motions with the non-reciprocal swing motion of the four legs. The observed locomotion speed was about 0.3 mm/s. Although the speed was limited, the results showed the potential of the actuator for use in multi-legged micro-locomotion systems.