A Modified Cascade Control Strategy for Tobacco Re-Drying Moisture Control Process With Large Delay-Time

A novel series structure is proposed based on cascade control for dominating a class of unstable processes with large delay-times. The modified structure consists mainly of one controller that exists in the inner loop, and the inner loop controller is devised on the basis of internal model control (IMC) principles. The outer loop setpoint tracking controller and the inner loop load disturbance rejection controller are designed according to the H2 optimal performance. At the same time, the tuning parameters are selected through the experience approach. Moreover, a suitable example and real value are recommended for the inner loop controller based on a wide-ranging simulation, and the results are implemented to certify the effectiveness of the proposed method. Simultaneously, the proposed method is applied to in a real-world tobacco production line, and the test results prove that the above method is significant in terms of rapidity, robustness and residual errors.