THE TRACKING PROBLEM OF WHEELED MOBILE ROBOTS (WMR) OR AUTOMATED GUIDED VEHICLES (AGV) IS ADDRESSED IN THIS PAPER. THE VEHICLE CONSIDERED IS A TRICYCLE MODEL WITH THE STEERING WHEEL IN THE FRONT. A LINEAR DYNAMIC MODEL IS DEVELOPED BY TAKING INTO ACCOUNT THE EFFECTS OF THE SIDE-SLIP FORCES AND ROLLING RESISTANCE OF EACH INDIVIDUAL TIRE. IT CAN BE SHOWN THAT THE LINEARIZED SYSTEM CAN BE DECOUPLED INTO TWO FAST AND SLOW MODE SUBSYSTEMS. BASED ON THAT, AN OPTIMAL CONTROL LAW IS DERIVED THAT MINIMIZES A QUADRATIC PERFORMANCE CRITERIA CONSISTING OF THE TWO MEASURABLE ERRORS, POSITION ERROR AND ORIENTATION ERROR. STEADY-STATE ERROR ANALYSIS SHOWS THAT A SIMPLE PROPORTIONAL CONTROL LAW CONSISTING OF THE TWO ERRORS CANNOT COMPENSATE FOR THE ERRORS DUE TO PATH CURVATURE AND, THEREFORE, BY AUGMENTING THE STATES TO PRODUCE AN INTEGRAL ACTION IN THE CONTROLLER AN OPTIMAL PI CONTROLLER IS DESIGNED.