Analytical Design for Parallel Cascade Control of Multiple Degrees of Freedom

Abstract

A new parallel cascade control program of multiple degrees of freedom is proposed for chemical and industrial cascade processes. Firstly, the two degree of freedom IMC structure is adopted in the secondary control loop, and the set-point tracking and disturbance rejection are decoupled, therefore, the influence on performance of primary loop because of the coupling between the set-point tracking and disturbance rejection in the secondary loop is reduced. Then, based on a modified structure of the Smith predictor control, the primary loop realizes the decoupling control between set-point tracking and disturbance rejection, and simple and effective analytical method is adopted to devise the controllers. Finally, simulations example demonstrates the validity of the proposed control scheme.