A XY Transporting and Nanopositioning Piezoelectric Robot Operated by Leg Rowing Mechanism

A piezoelectric robot with four parallel legs operating in rowing mechanism was presented and tested. The driving feet of the legs moved in a triangular trajectory, and a pair of legs on the same axis operated like rowing to move the robot step-by-step through the static friction forces between the driving feet and platform. A kinematic model with respect to the motion of the piezoelectric legs was established based on the Timoshenko beam theory and Galerkin procedure, which was used to design and optimize the structure of the robot. A prototype was fabricated and its experimental system was established. The motion trajectory of one driving foot was measured, which agreed well with the calculated results using the kinematic model in terms of both magnitudes and trajectory. A nanopositioning ability was achieved with a resolution of 16 nm. The experiment results showed that the output speed was linearly related to the voltages of the excitation signals, and motions along any directions could be achieved by changing the applied voltages. The prototype achieved maximum output speeds of 584 and 614 μm/s along the X and Y axes, respectively, under voltage of 400 Vp-p and frequency of 100 Hz. Furthermore, a carrying capacity of 25 kg was achieved. The proposed piezoelectric robot could be used to transport heavy devices with nanopositioning accuracy.