H∞ robust control of high order system based on adaptive low order model with dead-time

High-order systems are commonly encountered in production processes. Due to the uncertainty and load disturbances, the performance of the systems which are designed with reduced approximated model are often not satisfactory. In this paper, a reduced-order model plus dead time is used to approximate high-order systems and to compensate the inertial lag. Based on the Popov hyperstability theorem, an adaptive mechanism is designed to minimize the broad sense predictive output error. Simulation results show that the adaptive reduced-order model has good ability to auto-approximate high-order systems and to compensate the inertial lag. Based on the adaptive dead-time compensation, an H_∞ robust controller is designed for high-order systems. Control simulation results prove that the H_∞ robust control system, which is described by the adaptive low-order model with dead time, has good robust stability and dynamical performance.