A free gait generation method for quadruped robots over rough terrains containing forbidden areas

Abstract

Planning a robust gait is one of the most basic aspects to enable a quadruped robot to walk stably on rough terrains. In this paper, we focus on the scenario where a quadruped robot travelling on the rough terrains containing forbidden areas, and a free gait generation method for quadruped robot is proposed. Under the assumption that a set of the positions which can be selected as the foothold is given, the quadruped robot can select the swing foot sequence and choose the best foothold for the swing foot automatically. A body sway motion is included into the motion planning of the free gait to enlarge the stability margin of the robot. With the aid of the sway motion, the stability margin of the robot is no less than the minimum stability margin during the whole walking process. In order to guarantee the locomotion continuity of the quadruped robot, a COG trajectory which has continuous velocity and acceleration profiles is automatically generated. Moreover, the locomotion speed of the robot is improved by ensuring the kinematic margin of the selected swing foot to be zero just before this foot lift-off the ground. With the free gait generation method proposed in this paper, the robot can autonomously navigate through rough terrains as soon as possible on the condition that the robot has enough stability margin. The simulation results show the correctness and effectiveness of the proposed method.