A Quadruped Piezoelectric Ultrasonic Actuating Robot with Foot‐Leg‐Trunk‐Integrated Structure

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Legged piezoelectric robots have been extensively investigated due to their advantages in agile and stable locomotion. However, the existing designs predominantly adopt split‐type configurations, suffering from problems of complex structure, large size, and difficulty in characteristic consistency among multiple legs. This study proposes a quadruped piezoelectric robot with foot‐leg‐trunk‐integrated structure. It adopts a hybrid mode combining the first‐order out‐of‐plane bending vibration of the trunk and the first‐order horizontal bending vibration of driving legs to generate elliptical trajectories at foot tips. Actuating forces are achieved through frictional coupling among the feet and operating plane. Furthermore, a vibration decoupling strategy based on structural stiffness heterogeneity between the trunk and legs is proposed, effectively alleviating synchronization issues in multi‐leg vibration trajectories caused by assembly errors and vibrational coupling, enabling planar 3‐degree‐of‐freedom motion via multi‐leg coordination. The prototype has size of 51 × 51 × 8.5 mm and weight of 14.8 g, and it achieves maximum linear velocity of 51 mm/s, resolution of 0.46 µm, and maximum rotational velocity of 158°/s. The proposed robot features a compact structure, small size, lightweight, flexible motions, and high displacement resolution, exhibiting good application prospects in the field requiring small size and high accuracy.