Abstract: In order to solve the leg dragging, sliding and impingement against the ground of a quadruped walking robot, a low contact impact gait planning method with particular attention on foot motion trajectory is proposed. After analyzing the leg phases of a four-legged mammal in walking, the foot trajectory generation method is used for a single leg. By applying it to four legs of the hydraulically actuated bionic quadruped robot that has been designed according typical gaits of mammals, a walking pattern generator is constructed. Joint angle functions are solved by inverse kinematics employing legs phases in typical gaits and the displacement for rods of hydraulic cylinders by mechanism. Thereby, gaits of prototype robot could be driven by there lengths. Simulation experiments show that the robot walks stably at the speed up to 0.8 m/s on the even surface, the foot trajectories are smooth and the undulation of body has small amplitude.

Key words: Contact impact, Foot trajectory, Gait planning, Locomotion control, Quadruped robot