Modeling and controller design for non-minimum phase system with application to XY-table

In discrete-time control system, model obtained from small or reducing sampling-time would produce a non-minimum phase model. Feed-forward controller designed of this model using the inverse transfer function of the closed-loop system would have internal stability that usually not guaranteed. To overcome this stability problem, ZPETC that capable of cancelling all poles, cancellable-zeros, and phase error was proposed by Tomizuka. This paper presents model identification and controller design for non-minimum phase system using the zero phase error tracking control (ZPETC) method. The non-minimum phase system model was approximated using Matlab System Identification Toolbox from open-loop input-output experimental data using 80 ms sampling time. This approximated model was used in simulation and real-time studies. The effectiveness of ZPETC to overcome the non-minimum phase problem on XY-table shows that the proposed method gave acceptable performances.