In classical gasoline injection systems, the control of the throttle plate position is important for efficiency and emission of the engine. The angular position, depending on the current load of the engine, must track a desired trajectory which is performed by the accelerator. In Feedback linearization approach the state space must be available: measurable or observable. If the system is nonlinear, observers of the state in real time application are often difficult to be implemented. A technique to approximate derivatives is proposed in order to avoid velocity and acceleration measurements. The tracking problem is treated by using Kharitonov's approach. Thanks to an approximated PD regulator robustness in the proposed feedback linearization is achieved. Measured results on the real experimental set point are reported.