Wheel Slip Angle Estimation of a Planar Mobile Platform

Wheeled mobile robots and simplified motion of an automobile on a flat surface are common applications of a planar mobile platform. Improving the quality of state variable feedback under the lack of global positioning is imperative for enhancing the motion control performance. This paper proposes an alternative method of wheel slip angle estimation requiring only on-board measurement. The kinematics-based analytical solution is derived so that the slip angle of any free-rolling wheel can be estimated from the measured information of the wheel rolling speed and steering angle, along with the yaw rate and the linear accelerations of the mobile platform. The complete estimation of state variables: traveling speed, sideslip and radius of curvature is obtained from kinematic relationships. An experimental prototype of planar mobile platform is modified from a scaled RWD vehicle with free-rolling front wheel. During extremely sliding random motion, the estimated wheel slip angle and state variables are validated with the motion captured data. This proposed estimation technique can be applied for motion control applications of wheeled mobile robots and automobiles.