The trajectory tracking control problem for wheeled mobile robot (WMR) subject to generalized torque constraints is studied in this paper. First, a more general model is obtained by taking the displacement between the centre of mass of the WMR and the midpoint of the driving wheels into consideration. Then, a virtual velocity controller and a generalized torque controller are designed based on a new Lyapunov function. Due to the advantages of the new Lyapunov function, the stability of the trajectory tracking error system can be derived directly and the constraint of the initial tracking errors is removed. Less conservative conditions for tuning the controller parameters to satisfy the saturation constraints are also derived. Finally, some numerical examples are given to show the effectiveness of the proposed controllers.