面向复杂地形的四足机器人步态生成方法

Method of Gait Generating for Quadruped Robot Walking on Rough Terrain

摘要:

为实现四足机器人在凹凸地形上稳定运动并能选择最大步长的目的,提出了基于稳定裕度的步态规划方法;基于研究对象,建立四足机器人的运动学方程及逆运动学方程,将机器人足端的位置映射为各关节的关节变量；提出工作空间矩阵的概念,将所需克服的地形高度反映到工作空间矩阵中,并选择最优步态区域；依据四足机器人的立足点在质心坐标系下的空间坐标,以纵向稳定裕度为约束条件,在工作空间矩阵中计算机器人摆动腿的最大步长并规划机械腿的运动轨迹；针对所提出的方法,分别利用MATLAB和ADAMS进行仿真验证;在MATLAB环境中计算并验证质心的水平投影是否在立足点形成支撑多变形内,而ADAMS平台分析机器人在复杂地形上的位移变化及姿态变化。仿真结果表明机器人的质心始终在支撑多边形内,机器人的躯干姿态基本保持不变且运动速度匀速,所提出的方法能够保证机器人稳定行走,为四足机器人的稳定运动提出依据。

Abstract:

In order to realize the stable motion on rough terrain for quadruped robot, a new gait generating method based on stable margin was presented in this paper, which focus on implement of motion at a steady speed without fluctuation on body for the quadruped robot moving on the concave and convex terrain. Based on the structure of robot, kinematics equation and inverse kinematics equation of quadruped robot had been established, mapping the location of foot into the joint variables of each joint. A new concept-- working space matrix, had been proposed, which can reflect shape of leg’s work space and terrain parameters that robot should overcome. Taking longitudinal stability margin as the constraint condition,calculated effective footholds of the swinging leg in the working space matrix based on footholds of supporting legs in centroid coordinates. Then, selected the biggest step and planed trajectory of swinging leg in working space matrix, guaranteeing foot of swinging leg working in its workspace. It verified the proposed method by MATLAB and ADAMS. It was observed whether COG moved in the supporting polygon formed by the foothold in the MATLAB while the posture and displacement of body in the coordinated system were analyzed in the AdAMS. The simulation results showed that the robot's COG was always within the support polygon, while the robot's posture and movement speed were similar to the expectations. Therefore, the proposed method could guarantee the stability of the robot to walking on rough terrain and put forward basis theory for the stability movement of the quadruped robot