A Composite COG Trajectory Planning Method for the Quadruped Robot Walking on Rough Terrain

The COG trajectory planning method is the primary concern in the gait planning for quadruped robot, especially when the quadruped robot travelling on rough terrain. In this paper, we focus on the scenario where the quadruped robot walking on the rough terrain with the static walking gait. We present a smooth COG trajectory generator that the COG smooth trajectory characterized by continuous velocity and acceleration profiles can be generated automatically according to the current foot placement of the robot. A composite COG trajectory composed of quintic curves and straight lines is proposed in this paper. When the robot swings a leg forward, the COG trajectory is desired to be a straight line to eliminate the influence of acceleration of the body on the stability of the robot. However, the COG trajectory is desired to be a quintic curve when the robot is in the four legs support stage to guarantee the continuity of the COG trajectory. Moreover, the walk efficiency and the ability to keep the stability of robot are considered in this paper. Base on the COG trajectory generate method and the gait planning provided in this paper, the robot can walk through the rough terrain as soon as possible in the condition that the stability margin of the robot no less than the minimum stability margin. Via simulation the performance of the proposed COG trajectory is verified.