Multirate digital control system design using lifting technique

The conventional multirate pole-zero assignment method has the intersample ripple problem. In order to remedy the intersample ripple, a constraint on the controller parameters using the final value theorem was proposed. Recently a computationally efficient fixed order multirate digital control system design using discrete-time state matching was proposed. And it was shown that the multirate digital control system does not have ripples in control command. In this paper, we present that the compensator obtained by the discrete-time state matching method is in a special form of those designed using the conventional multirate pole-zero assignment method. We also show that the controller obtained can be formulated using feedforward and feedback compensators.