This paper presents a design approach of robust active vibration control schemes for vehicle suspension systems using differential flatness, sliding modes and Generalized Proportional-Integral control techniques to attenuate undesirable vibrations induced by irregular road disturbances. Two control schemes are proposed: one employing position and velocity measurements and other requiring only position measurements. Integral reconstruction of the time derivatives of the flat output up to third order is proposed to avoid the use of velocity and acceleration sensors, as well as information of unknown road disturbances.