Development of a Planar Tripodal Piezoelectric Robot With a Compact Ring Structure

A novel miniature tripodal piezoelectric robot (MTPR) was designed with a compact ring structure. The prominent feature was that its three feet were driven by only one ring-shaped piezoelectric actuator instead of three actuators separately. The proposed MTPR could operate under two working modes, which were defined as the AR mode (the third-order axial and radial vibrations) and the FR mode (the fourth-order radial vibration) according to the employed vibration modes of the ring structure. The MTPR could achieve bidirectional motions in the former working mode, whereas it cannot reverse the motion in the later working mode, but it showed better performance. Both the two working modes were analyzed and verified by the finite-element method. Then, a prototype was fabricated, whose size was Φ67 × 27 mm
³
, and the performance was tested. Experimental results indicated that the working frequencies of the AR and FR modes were 19.85 and 36.75 kHz, respectively. The MTPR could run at speeds of up to 231.61 mm/s and achieve a resolution of 0.25
μ
m. In addition, the prototype robot could carry a load of 300 g (3.2 times its own weight) and perform good robustness due to its compact and solid structure.