Design and experimental evaluation of a compact inchworm piezoelectric actuator with bridge-type displacement amplification mechanism

Miniaturization is an important direction in piezoelectric actuator research, with related efforts focusing on reducing structural complexity and simplifying guiding mechanisms. However, some actuators experience backward movement after miniaturization design. There remains significant room for improvement in mechanism configuration and the design of flexible amplification mechanisms to further reduce actuator size. In this paper, a compact inchworm actuator with bridge-type displacement amplification mechanism (BTDAM) is proposed, which does not require an additional guiding mechanism and adopts a three-dimensional packaging approach with high space utilization and a compact amplification mechanism. Because the output capacity of the BTDAM significantly impacts the operating performance of the actuator, mathematical modeling and simulation analysis are conducted. Compared with the experimental results of the amplification ratio of the BTDAM, the error of the theoretical model was 5.05%, and that of the finite element method analysis was 9.1%. The dimensions of the prototype are 23 × 23 × 19 mm, and it weighs 23 g. The test results indicate that the proposed actuator can achieve stable stepping motion without backward movement. Under a voltage of 75 V, the proposed actuator achieves a maximum motion speed of 384 μm s⁻¹ and a maximum output force of 1.7 N. With its compact structure and light weight, the proposed actuator shows promising application prospects in the aerospace and bioengineering fields.