Abstract: This paper presents the moving mechanism of a high-speed insect-scale microrobot via electromagnetically induced vibration of two simply supported beams. The microrobot, which has a body length of 12.3 mm and a total mass of 137 mg, can achieve reciprocating lift motion of forelegs without any intermediate linkage mechanisms due to the design of an obliquely upward body tilt angle. The gait study shows that the body tilt angle prevents the forelegs from swinging backward when the feet contact the ground, which results in a forward friction force applied on the feet. During forward movement, the microrobot utilizes the elastic deformation of the simply supported beams as driving force to slide forward and its forelegs and rear legs work as pivots alternatively in a way similar to the movement of soft worms. The gait analysis also indicates that the moving direction of the microrobot is determined by whether its body tilt angle is obliquely upward or downward, and its moving speed is also related to the body tilt angle and as well as the body height. Under an applied AC voltage of 4 V, the microrobot can achieve a moving speed at 23.2 cm·s?1 (18.9 body lengths per second), which is comparable to the fastest speed (20 cm·s?1 or 20 body lengths per second) among the published insect-scale microrobots. The high-speed locomotion performance of the microrobot validates the feasibility of the presented actuation scheme and moving mechanism.

Key words: Legged microrobot, electromagnetic actuation, moving mechanism, high-speed