Kinematic Control of Nonholonomic Wheeled Mobile Manipulator: A Differential Flatness Approach

This paper presents an integrated motion planning and control framework for a nonholonomic wheeled mobile manipulator (WMM) system taking advantage of the (differential) flatness property. We first develop the kinematic model of the system and analyze its flatness properties. Subsequently, a statically feedback linearizable system description is developed by appropriately choosing the flat outputs. Motion-planning can now be achieved by polynomial curve fitting to satisfying the terminal conditions in the flat output space while control design reduces to a pole-placement problem for a linear system. A case study of point-to-point motion is considered to study the effectiveness of pose stabilization in the WMM. The simulation and experimental results highlight the ease-of-implementation of proposed method for online real-time integrated motion-planning/control within a hardware-in-the-loop (HIL) electro-mechanical testing.