Stable inverse control for nonminimum-phase nonlinear processes

Since most of the chemical processes happen to be nonlinear, nonlinear controllers with feedback linearization have been recently designed which can directly cancel the nonlinearities and establish a linear input/output map. However, this I/O linearization algorithm requires the control with stable inversion and state feedback. In the present study, a stable inversion technique for non- minimum-phase systems is developed under appropriate assumptions, which includes several steps such as ®nding the bounded control and bounded state trajectories for tracking the desired signal. In this design, the output tracking error as well as the e€ect of measurable disturbances can be asymptotically eliminated through generating a feedforward control. Finally, the proposed control methodology is applied to a chemical process, viz. a Van de Vusse reaction in an isothermal or adiabatic stirred-tank reactor, and its performance is evaluated.