Design and Analysis of Double Closed Chain Walking Leg Mechanism

A 2-DOF double closed chain walking leg mechanism composed of parallel four-bar mechanism and crank slider mechanism was designed. The compound cycloid was used as the objective curve of foot end trajectory planning. Based on the analytic geometry method, the mathematical model of foot end trajectory of walking leg was established. The optimization model of walking leg bar size parameters was established with the minimum distance between foot end trajectory and compound cycloid trajectory theoretically calculated as the optimization objective. Genetic algorithm and fmincon function interior point method were used to obtain the optimal length of walking leg. In ADAMS software, the trajectory of the foot end of the walking leg was simulated and analyzed. and the walking leg prototype test was carried out. The results show that the simulation curve is consistent with the optimization curve, and the displacement, velocity and acceleration curves are continuous. The walking leg can achieve 322 mm stride length and 106 mm obstacle height, and the error between the experimental results and the simulation result is 7% and 6% respectively, which verifies the feasibility of the walking leg structure design and foot trajectory planning.