Flexible topology: design and optimization of drive feet for piezoelectric robots

Abstract The leg unit, serving as the primary actuating component in piezoelectric robots, plays a critical role in motion generation. Conventional leg architectures in piezoelectric crawling robots often incorporate rigid elements or complex transmission systems, leading to constrained kinematic performance and energy losses during force transmission. In this study, we propose a kinematically optimized leg unit (KLU) based on topology optimization, designed to overcome these limitations by achieving an optimal balance between static stiffness and dynamic flexibility. A resonant legged piezoelectric robot (LPR) prototype integrating three KLUs in a centrosymmetric arrangement is developed. Through comprehensive simulation and experimental validation, the optimized KLU achieves a displacement amplification factor of 1.18 compared to the piezoelectric bimorph alone. Furthermore, the LPR demonstrates a maximum speed of 53.136 mm s −1 and a robust load capacity of 70 g (4.9 times its own weight). The proposed design and optimization framework offers a generalized and efficient methodology for the development of advanced piezoelectric crawling robots.