Design of a Flexure-Jointed Linkage in a Quadruped Walking Robot

Flexure-jointed linkages (FJLs) have distinct advantages, such as ease of manufacturing and assembly, no backlash, and light weight designs, over their rigid counterparts. However, the synthesis and analysis of FJLs are more complicated, especially when the compliant flexures have large deflections. This article addresses the optimal design of a large-deflection FJL, which is used as the leg of a compliant quadruped robot. The proposed FJL originates from a rigid six-bar linkage to mimic the foot path of walking mammals by replacing the passive revolute joints with two-segment combined flexible beams. Its kinematic and strain energy models are derived and verified by numerical simulations. Subjecting to material failures and geometrical constraints, the optimization of the FJL is carried out by minimizing the path deviation and strain energy to reduce needed input power, leading to the development of a quadruped walking robot. Experimental tests on the output path of the FJL and the motion capability of the robot are implemented. The results demonstrate the effectiveness of the derived models in predicting the deflections of the FJL and the feasibility of applying compliant linkages for legged robots.