全地形轮式移动机器人运动学建模与分析

提出全地形轮式移动机器人的正逆运动学问题。将机器人看成一个混合串-并联多刚体系统,从每个轮-地接触点到机器人车体分别构成一个串联子系统,抛弃车轮纯滚动假设,在轮-地接触点处建立瞬时坐标系,考虑车轮的平面滑移,从而对每个串联子系统形成一个封闭的速度链。对于每个速度闭链,可直接在驱动轮轮心处写出从机器人各驱动轮到机器人本体之间的运动方程,将每个速度闭链的运动方程合并即可得到机器人的整体运动学模型。以一个具有被动柔顺机构的六轮全地形移动机器人为对象进行推导,该方法既考虑了地形不平的影响,又考虑了车轮的前向、侧向及转向滑移,已知机构参数后就可以直接写出机器人的速度方程,且便于运动学求解。该方法对于轮式移动机器人的运动学建模具有一般性,且具有物理意义明确、推导过程简洁等特点。

A general method of kinematical modeling for all-terrain mobile robots is proposed.The robot is treated as a series-parallel multi-rigid body system.A series sub-system is formed from each wheel-terrain contact point to the robot body through compliant joints.Planar slips including forward slip,side slip and steering slip are considered by building instantaneous coordinate frame at each wheel-terrain contact point,and a closed velocity chain is developed for each series sub-system.In each closed velocity chain,the velocity relationship between the rigid body motion of the robot and the steering,and driving rates of the wheels can be directly written out at the axle center of each driving wheel.The whole kinemat ics equation of the robot body can be achieved by combining the velocity equation of each closed velocity chain.By using this kinematic s modeling method which considers both planar slips of each driving wheel and the effects of terrain profile,velocity equations can be easily developed for an all-terrain mobile robot.As long as the structure parameters of the robot are known,the kinematical equations of the robot body will be easily achieved,and also the forward and inverse kinematics are convenient to solve by using this method.The example of applying this method to a six-wheeled all-terrain mobile robot shows its merits of generality,definite physical meaning and concise derivation process.

国家自然科学基金重点资助项目(60535010)