Varying-sampling-time LPV control for rejecting harmonically related nonstationary multisine disturbances

In this paper, a novel approach to design linear parameter-varying (LPV) controllers with time-varying sampling time to reject nonstationary harmonically related multisine disturbances is presented. The sampling time is chosen as a fraction of the smallest period of the harmonically related disturbance component. The plant is discretized with this sampling time using zero-order hold (ZOH). As a result, the disturbance model is regarded as one with fixed state-space representation subject to a time-varying sampling time. A polytopic LPV (pLPV) controller which quadratically stabilizes the plant under the disturbance is obtained. The number of the scheduling parameters is determined by the precision of the Taylor approximation for the discretized plant, independently of the number of frequencies. Excellent disturbance rejection is achieved in simulation.