Foot Trajectory Planning and Prototype Experiment of Double Closed-Chain Walking Leg

A 2-DOF double closed-chain walking leg was proposed, which the first closed-chain adopted a crank rocker mechanism to realize the step and swing action of walking leg; the second closed-chain adopted a crank slider mechanism to adjust the step height of walking leg. Given the different rotational speed ratio and phase difference of the crank of the two mechanisms, different foot-end trajectories could be obtained. Considering the advantages and disadvantages of common foot-end trajectories, the waist type foot-end trajectory was selected as the research object. Firstly, the mathematical model of foot-end trajectory of walking leg was established. Then, taking the minimum distance between waist foot-end trajectory and compound cycloid foot-end trajectory as the optimization objective, the optimization model of walking leg bar size was established. The optimized walking leg bar size was obtained by using genetic algorithm. Finally, the walking leg simulation and prototype experiment were carried out, and the simulation and experiment results verified the feasibility of leg structure and foot-end trajectory planning.