Contact Angle and Slippage Estimation of an Articulated Mobile Robot with Five Wheels

A general approach to kinematics modeling and analysis of articulated mobile robots traversing uneven terrain is described. Taking caster and camber into consideration, a full 6 DOF (degree of freedom) motion model is derived for a wheeled robot, and differential kinematics is derived for individual wheels in contact with ground. Then, forward and inverse kinematics models are given. During this process, slipping and wheel-terrain contact angle are considered. Based on the characteristics of rigid body movement, the contact angle is estimated according to the relationship of velocity of components. A passive fifth wheel is installed on the robot, and a slippage estimation method is given based on its kinematics model. Experiments on uneven terrain and sandlot are carried out to verify the effectiveness of the proposed contact angle and slippage estimation method.