Crawling Gait Planning Based on Foot Trajectory Optimization for Quadruped Robot

A simple and compact quadruped robot of 12 DoF is designed. In order to solve the leg dragging, impingement against the ground and obstacle climbing, a foot trajectory gait planning based on a compound cycloid is proposed. The method can improve the obstacle-overcoming ability of the quadruped robot. In consideration of the influence of positions of joints on the center of gravity, a gait planning method and a posture adjustment strategy are designed based on ZMP stability criterion. Finally, the simulation is completed on the different terrains including flat lands, slopes and steps. The result shows that the robot walks stably on even terrain, the foot trajectory is smooth and minimum values of stability margin on the flat land, slope and step are 41.4 mm, 37.4 mm and 36.6 mm respectively.

I. Introduction

Due to the strong adaptability to irregular and complex terrains, legged robotic platforms are particularly promising. Legged robots are common in biped, quadruped and hexapod robots. Biped robots have low requirement for walking environment and strong obstacle-overcoming ability, but the walking stability is not high. Besides, the control system is extremely complicated. Hexapod robots maintain high reliability and stability during the walking process, but the moving speed is low. In contrast, quadruped robots have the advantages in walking stability and speeds. Therefore, researches on gait planning and motion control of quadruped robots have attracted more and more scholars’ attention [1 – 3] .