Dynamics modeling and control of a wheeled mobile robot with omni-directional trailer

Trajectory tracking of wheeled mobile robots is one of the most important subjects of mobile robots. In addition, the control of underactuated systems possesses a particular complexity and is of major importance; so that it has been focused by many researchers during the past years. In this paper, these two important control subjects are discussed in a differential drive wheeled mobile robot towing an omni-dierectional trailer. Underactuation is due to the use of omni wheels in trailer instead of standard wheels to increase robots´ maneuverability and degrees of freedom. Standard wheels create nonholonomic constraint by means of pure rolling and nonslip conditions. Here, kinematic and kinetic models are obtained, and then by combining these equations, an appropriate state space model is introduced. Finally, a Lyapunov-based control algorithm is proposed.