A new motion mode of a parasitic motion principle (PMP) piezoelectric actuator by preloading the flexible hinge mechanism

[Display omitted] •A new motion mode of PMP actuators was proposed by preloading the flexible hinge mechanism.•The transition from the normal PMP to the new motion mode was experimentally confirmed and analyzed.•The new motion mode could improve the self-locking ability of PMP actuators.•Output performances of the actuator under the new motion mode were measured and discussed. For the purpose of increasing the self-locking ability of piezoelectric actuators designed by the parasitic motion principle (PMP), reducing the initial gap and applying a preloading force between the driving mechanism and the mover would be an effective method. By analyzing the contact and deformation status between the flexible hinge driving mechanism and the mover under an initial gap of zero, a new motion mode of PMP actuators was proposed, which would result in movement of the mover along an opposite direction to that under the normal PMP. To explore the transition from the normal PMP to the new motion mode, a piezoelectric actuator was designed by employing a flexible hinge mechanism with the lever-amplification structure. By measuring the output displacement of the mover under various initial gaps, the transition in motion mode was experimentally confirmed and analyzed. The new motion mode was readily activated when preloading the flexible hinge mechanism. The comparison in locking force proved that when the piezoelectric actuator worked under the new motion mode, its self-locking ability was greatly improved. Under the new motion mode, the effects of the initial gap, driving voltage, driving frequency, and vertical load on the output performances of the piezoelectric actuator were further studied. The results indicated that the new motion mode not only improved the self-locking ability of the PMP actuator, but also produced good output performances.