Abstract: Micro-robots have the characteristics of small size, light weight and flexible movement. To design a micro three-legged crawling robot with multiple motion directions, a novel driving scheme based on the inverse piezoelectric effect of piezoelectric ceramics was proposed. The three legs of the robot were equipped with piezoelectric bimorphs as drivers, respectively. The motion principles were analyzed and the overall force analysis was carried out with the theoretical mechanics method. The natural frequency, mode shape and amplitude were analyzed with simulation software COMSOL Multiphysics, the optimal size was determined through parametric analysis, and then the micro three-legged crawling robot was manufactured. The effects of different driving voltages, different driving frequencies, different motion bases and different loads on the motion speed of the robot were tested. It is shown that the maximum speed of single-leg driving was 35.41 cm/s, the switching ability between different motion directions was measured, and the movements in six different directions were achieved. It is demonstrated the feasibility of multi-directional motion of the structure. The research may provide a reference for the design and development of miniature piezoelectric three-legged crawling robots.

Key words: Three-legged crawling robot , · Piezoelectric drive , · Mechanical property analysis , · Kinematic features analysis