High precision control of a walking piezoelectric motor in bending mode

This work presents functional description of a walking piezoelectric motor and its control in bending mode. For this purpose a dynamical model of the actuator is derived based on simple mass spring damper system. Identification experiments are conducted to verify the theoretical kinematics of the bimorph legs presented in previous works. These experiments demonstrate approximately linear relation between the legs displacement in x and y planes to the applied voltages. Based on these results a PI controller followed by Hadamard transformation is proposed as a controller scheme. Experimental results for staircase and sinusoidal tracking references reveal precise positioning down to few nano-meters.