Review of Micro and Miniature Piezoelectric-Driven Robots and Their Untethered Actuation Technologies

With the advancement of novel functional material-driven technologies and micro-nano manufacturing techniques, micro-miniature robots have demonstrated significant application potential due to their compact size and high efficiency. As a core foundational technology, actuation systems for micro-miniature robots have attracted considerable attention. In contrast to traditional motor-driven approaches limited by miniaturization constraints, actuators and drive systems based on novel functional materials have become the primary focus in micro-miniature robotics research. Piezoelectric materials, utilizing their efficient bidirectional energy conversion mechanism, offer distinct advantages in micro-miniature robotic applications, including low power consumption, rapid response, and high output force. However, they face challenges such as limited displacement and operating voltages that exceed those of conventional onboard power supplies. This review focuses on micro-miniature piezoelectric-driven robots, first introducing piezoelectric actuators and their associated transmission mechanisms, then summarizing research achievements in both mobile and stationary micro-miniature piezoelectric robots. It further analyzes untethered motion technologies for micro-miniature robots, examines characteristics of drive circuits tailored to different actuation methods, and specifically addresses untethered drive technologies for piezoelectric micro-miniature robots. The paper summarizes key developments in piezoelectric drive circuits and the current state of untethered micro-miniature piezoelectric-driven robots. This work provides a systematic review of recent progress in micro-miniature piezoelectric-driven robots, with particular emphasis on untethered piezoelectric actuation technologies, offering a reference for future practical robotics research.