Dynamic model and performance analysis of rigid-flexible coupling four-bar leg mechanism for small scale bio-inspired jumping robot

Abstract

Bio-inspired jumping robot can imitate the jumping process of creatures, and can move in environment with large obstacles. This type of robot can be applied to complex situations such as earthquakes and landslides, and has a broad application prospect. Aiming at the problems of the existing micro bionic jumping robots, such as the simple dynamic model and the unclear rigid-flexible coupling characteristics, the dynamic modeling and performance analysis of rigid-flexible coupling jumping leg is conducted in this paper. Based on the analysis of the jumping mechanism of stick insect, a design method of four-bar jumping leg mechanism under multiple constraint conditions is put forward. Then the dynamic model of the rigid-flexible coupling four-bar jumping leg with flexible equivalent tibia and elastic joint is established combining with Lagrange and Newton–Euler dynamic modeling methods, which can describe the dynamic characteristics of the robot quantitatively during jumping. The relationship between the stiffness of flexible tibia and jumping performance is analyzed, which includes energy storage capacity, take-off velocity/acceleration and jumping stability. The analysis results show that proper reduction of stiffness of flexible tibia can improve the dynamic performance of small scale bio-inspired jumping robot. This study offers primary theories for design and analysis of rigid-flexible coupling four-bar jumping leg with flexible equivalent tibia and elastic joint, and it establishes a theoretical basis for studies and engineering applications.