A Small and Agile Ring-Shaped Tripodal Piezoelectric Robot Driven by Standing and Traveling Mechanical Waves

For miniature piezoelectric robots, it is difficult to realize multi-degree-of-freedom motion with a simple structure. In this article, a novel ring-shaped tripodal piezoelectric robot (RTPR) is proposed to solve the above difficulty. Multiple motion modes, based on the propagation of mechanical waves on the rigid ring-shaped structure, are designed to realize continuous/step linear and in-situ rotational motions. The prototype is fabricated with a weight of 2.2 g and a size of 20 mm × 20 mm × 4.6 mm, and the performance is tested. The test results show that RTPR can achieve a maximum linear speed of 39.3 mm/s (2 BL/s) and a maximum in-situ rotational speed of 16.5 rad/s. In addition, RTPR also shows strong load capacity (22 times of its weight) and submicrometer linear resolution (0.38 μm). In the experiment, RTPR also shows the capability of moving on narrow and curved roads with its multiple motion modes. RTPR has the characteristics of simple structure, agile motion, strong load capacity, and high resolution, which provides a new idea for achieving the multi-degree-of-freedom motion of miniature robots.