Design and experiments of a small resonant inchworm piezoelectric robot

A small resonant inchworm piezoelectric robot with six driving feet which are set evenly along the circumference is proposed and tested. A bonded-type structure is adopted to realize a small size. The radial bending vibration mode and longitudinal vibration mode are excited at the same frequency. The superposition of these two vibration modes makes the driving feet produce elliptical motions. And the driving force can be generated by friction coupling between the driving foot and the operating plane The structure of the robot is designed by finite element simulation. The geometric parameters are adjusted to make the resonant frequencies of the vibration modes as close as possible. The elliptical trajectories generated at the driving feet are discussed in detail. The vibration and motion characteristics of the prototype are tested, and the resonant frequencies of the radial bending mode and the longitudinal vibration mode are degenerated successfully. The optimal working frequency of the prototype is 21.5 kHz. The maximum speed of the prototype is 200 mm/s, and the displacement resolution is 0.71 µm. The measured results show that the resonant inchworm piezoelectric robot can be used for fast and high-precision transportation in narrow space.