Analysis and experiment of thrust-propelled closed-chain legged platform with passive locomotion ability

Abstract Current research concerning passive locomotion ability primarily focuses on open-chain legged platforms to enhance energy efficiency and walking stability. However, closed-chain legged platform with single degree of freedom (DOF) mechanism has the advantages of rotational driving property, control simplicity and payload capability. To further reduce dependence on ground friction and improve walking efficiency, a closed-chain passive-locomotion legged platform (CPLP) is proposed. First, the leg mechanism is analysed based on kinematic analysis, and three different types of leg groups are proposed as mathematical examples, after which the dimensional parameters are optimized. Then, walking period, walking critical conditions on horizontal ground are analysed based on zero moment point (ZMP) principle to quantitatively analyze the optimal leg group layout. Moreover, the critical conditions of passive locomotion ability are analysed and then verified by dynamic simulations. Finally, a series of experiments are conducted to verify the performance of the CPLP. This study of passive locomotion ability contributes to a high-efficiency thrust-propelled method of closed-chain legged platform.