Design and evaluation of a stick-slip piezoelectric actuator with flexure hinge mechanism inspired by the earthworm

In this work, a new bionic piezoelectric actuator inspired by the earthworm is proposed, fabricated, and tested. The operating principle of the actuator imitates the crawling motion of the earthworm. The piezoelectric stack is embedded in the stator with a flexure hinge mechanism. One side of the stator is inspired by the earthworm body. Then the elongation of the piezoelectric stack is transmitted to the driving tip to produce oblique displacement under such a stator. The vertical and horizontal components are used to press and drive the slider, respectively. The principle of the proposed actuator is described in detail. The static deformation is investigated by the FEM method. A dynamic model of the actuator is developed to further reveal the motion characteristics of the slider via theoretical analysis. Finally, the output characteristics of the proposed BPA are tested. The experimental results show that the actuator achieves a maximum output speed of 12.72 mm/s at a voltage of 100 V and a frequency of 710 Hz. The maximum output force is 3 N under a locking force of 2 N. Besides, the displacement resolution is tested at 87 nm at a frequency of 710 Hz, which indicates that the developed actuator can be applied in the field of precision actuation.