A comparison of a classical PID and sliding mode: traction control for fast wheeled mobile robot

The controlling of mechanical systems subjected to rolling contact is studied. This paper presents a methodology using a classical PID, and sliding mode control to ensure robustness in wheeled mobile robot (WMR) control systems. The control laws consist of PI control, and an equivalent control, associated with a robust control. The equivalent control is designed such that the nominal systems exhibit the desirable dynamics; the robust control is then developed to guarantee the reaching condition in the presence of parameter and disturbance uncertainties. The two methods are applied to enhance the stability and to estimate a wheel slip at a reasonable value. The optimal slip ratio control is achieved by maintaining the slip ratio to the value to give the maximum road friction, this means that the driving force of the WMRs is fixed at its maximum level.