Displacement Linearity Improving Method of Stepping Piezoelectric Platform Based on Leg Wagging Mechanism

It is difficult to obtain linear output displacements for stepping piezoelectric platform due to their discontinuous outputs. Inspired by the theory that the maximum static friction force is greater than the sliding friction force, this letter proposed a bipedal alternating inertial actuation mode (BAIAM) to improve the displacement linearity of stepping platform. The output displacements are measured, the linear fitting is carried out by the least square method, the correlation coefficient and linear fitting function are used to evaluate the displacement linearity, the correlation coefficients of the forward and backward motions are calculated as 0.9998 and 0.9999 in BAIAM, respectively, which verifies the effectiveness of the proposed method. Closed-loop experiments in BAIAM are also carried out, the steady state errors for target position of 40 m within 0.2 m in the point-to-point positioning control experiments are achieved. The experiment results confirm that the developed platform can be applied in precision fields requiring large travel range, planar two-DOF motion and linear outputs.