Adaptive internal model control using inverses of signals

In this paper, we propose a new adaptive IMC scheme based on adaptive finite impulse response filters using inverses of signals, which can be designed for both minimum and non-minimum phase systems in the same fashion. The internal model of the plant is estimated by the normalized least mean squares algorithm as a finite impulse response system and the inverse of the system is designed using the inverses of signals concept. The closed-loop is designed such that the system from the reference input to plant output can be approximately represented by a pure delay. The use of inverses of signals simplifies the real time implementation of the controller and cancellation of non-cancellable zeros of the plant can be avoided. Ultimately, the plant output is forced to track the reference input with a delay. The stability of the closed-loop for both minimum and non-minimum phase systems is guaranteed. The results of computer simulation and laboratory scale experiments are included in the paper to show the effectiveness of the proposed method.