Trajectory Tracking Control Based On Improved Nonlinear Disturbance Observer For Mobile Robots Considering Unknown Skidding And Slipping of Wheels

The trajectory tracking problem of a type (2,0) wheeled mobile robots (WMR) with unknown longitudinal and lateral slippage is studied in this paper. The influence of slippage is considered by establishing more accurate kinematic and dynamic models. The total disturbances (slippage parameters, model uncertainties) of the dynamic model are estimated online through an improved disturbance observer and the slippage parameters can be derived using a low-pass filter. Meanwhile, auxiliary velocity input is tracked by a sliding mode controller in dynamic surface. Then, an error feedback controller is designed using backstepping method to achieve the position tracking. The index convergence of improved disturbance observer with LMI and the stability of all the signals of the considered systems is guaranteed using Lyapunov stability theory. Finally, simulation examples demonstrate the better effectiveness of the control methodology.