An integrated performance and robust stability based multi-model control of nonlinear systems: A pH neutralization reactor

This paper presents a new multi-model control scheme which integrates the stability and performance requirements to determine the nominal local models. Gap metric and stability margin concepts are applied to measure the distance between the local models and to grid the operation range of nonlinear system, respectively. The minimization of the integral of time absolute error is included as performance criterion. Furthermore, the multi-model decomposition and local controllers design are integrated in an optimization problem which provides avoidance of the redundancy issue. A fixed PI structure is considered as the local controllers to simplify the global multi-model controller structure. Therefore, the advantages of the presented method are: to avoid the dependency on experience, to eliminate the redundancy problem, to guarantee the stability and performance, and to have a simple structure. A pH neutralization reactor is simulated to evaluate the efficiency of the proposed method. Results demonstrate that this approach is systematic and works better than the traditional multi-model controller in terms of set-point tracking and disturbance rejection.