Comparison of Methods for Solving the Singular Configuration of a Wheel-Legged Mobile Robot

Abstract

In this paper, the singular configuration problem of a wheel-legged mobile robot due to the rank deficiency in inverse kinematics is discussed. Rank deficiency occurs when multiple kinematic constraints conflict with each other or when the steering joint becomes perpendicular to the ground surface. A method was proposed for avoiding a singular configuration while simultaneously solving the constraints that uses inverse kinematics that considers priority and solves the singular configuration of the steering joint using kinematic constraints on acceleration. Consequently, a new singular configuration occurs in low-speed wheeled locomotion. The Levenberg-Marquardt method is used for the singular configuration in low-speed wheeled locomotion. This method is necessary for determining a suitable damping factor, because it affects the solution of the inverse kinematics. Therefore, a comparison of different damping factor determination methods and a proposed method that considers the steering motion of each leg are highlighted.