Abstract: This paper aims to establish a design framework for an innovative Closed-Chain-Based Compliant Robotic Leg (CCRL) that effectively reduces inter-joint interference while enhancing impact tolerance. The decoupling of leg extension-retraction motions from swing motions is achieved through a closed-chain-based mechanism, while the incorporation of elastic elements and passive prismatic joints contributes to its impact-mitigation capabilities. A comprehensive analysis of the closed-chain constraint Jacobian, which includes both actively actuated joints and passive joints, along with a stiffness model, is methodically conducted. The simulation analyses are performed to assess the benefits of the CCRL architecture, highlighting improvements in jump height, reductions in peak torque during jumping, and enhanced joint coordination that facilitates a dynamic and interference-free gait. An experimental prototype is also appropriately developed, and vertical jumping tests are conducted to validate the practicality of the proposed design and its theoretical analysis.

Key words: Legged robot')">Legged robot, Closed-chain-based leg mechanism, Closed-chain Jacobian, Compliant robotic leg, Robotic design