Multiple Degrees of Freedom Control for Cascade Processes with Time Delay

A new cascade control of multiple degrees of freedom program based on modified internal model control is proposed for chemical and industrial cascade processes. Because the set-point tracking and disturbance rejection in the secondary control loop exercise influence on performance of primary loop simultaneously, they are decoupled completely and can be adjusted independently. A disturbance observer is added in the primary loop which realizes the decoupling control between set-point tracking and disturbance rejection, and there is no tradeoff any more. Simple and effective analytical method is adopted to devise the controllers. Finally, simulations example demonstrates the validity of the proposed control scheme.