Bio-inspired miniature self-moving ultrasonic piezoelectric actuator: combinatorial design, analysis, and...

Fast movement, multi-degree-of-freedom motions (multi-DOF), and strong payload capacity are key performance indicators for miniature self-moving piezoelectric actuators, yet balancing these in structural design is challenging. Inspired by the walking gait of crab spiders, this work presents a miniature ultrasonic piezoelectric actuator (UAHPA) that addresses this trade-off through a distinctive structural strategy. Based on beam topology, a ring-shaped combined elastic structure for the actuator is developed. The actuator endows its driving foot with multidirectional, large-amplitude oscillations resembling those of crab spiders, enabling rapid 3-DOF motions. Meanwhile, its sturdy structure supports a substantial payload. This design strategy also significantly reduces the structural stiffness, thereby avoiding excessive power loss caused by high-frequency excitation. The fabricated prototype measures 31 × 31 × 7.8 mm³ and weighs 5.73 g. The actuator achieves an ultrafast linear speed of up to 1.02 m/s, equivalent to 32.9 body lengths per second, and a rotational speed of 25.84 rad/s. The maximum payload of the prototype reaches 402.06 g, approximately 70 times its own mass. Taken together, these metrics outperform those of comparable miniature piezoelectric actuators. Additionally, the proposed actuator exhibits multitasking capabilities, including slope climbing, obstacle avoidance, and trajectory execution, while achieving high-accuracy localization at submicron and submilliradian levels. Leveraging these strengths, the UAHPA demonstrates broad application potential in wafer inspection. More importantly, this study presents a new idea for designing miniature self-moving piezoelectric actuators, with a focus on multi-performance integration.