Development of a 3-DOF Planar Monopod Piezoelectric Robot Actuated by Multidirectional Spatial Elliptical Trajectories

A three degrees of freedom (3-DOF) planar monopod piezoelectric robot (MPR) is proposed in this work, in which five longitudinal vibration ultrasonic transducers are orthogonally set and gathered at a single driving foot. A prominent feature of the MPR is that the single foot can generate multidirectional spatial elliptical trajectories by the cooperation of the first-order longitudinal vibrations in three orthogonal directions to achieve flexible motions. The proposed MPR addresses the problems of complex structures, intricate control strategies, and motion inconsistency in existing multi-DOF piezoelectric robots employing multiple driving feet. By optimizing the distribution of the multidirectional spatial elliptical trajectories, the MPR realizes linear motions along X-Axis and Y-Axis, and rotary motion around Z-Axis. In addition, it holds the capability of generating planar omnidirectional motions. The working principle is illustrated and validated via simulations and experiments. The experimental results demonstrate that the MPR is capable of achieving 3-DOF fast motions at speeds of up to 700 mm/s, 712 mm/s, and 919 °/s. The linear motion resolution reaches 0.49 μm. Furthermore, the MPR can carry a maximum load of 3 kg. The proposed MPR successfully achieves outstanding performances including agile motion, fast speed, high resolution, and strong load capacity.