Two-degree-of-freedom Controller Design for Uncertain Processes Using Input/output Linearization Control Technique

Pisit Sukkarnkha (Center for Petroleum, Petrochemicals, and Advanced Materials, Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok, 10900, Thailand)
Chanin Panjapornpon (Center for Petroleum, Petrochemicals, and Advanced Materials, Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok, 10900, Thailand)

ASEAN Journal of Chemical Engineering
Vol 11, No 1 (2011)

In this work, a new control method for uncertain processes is developed based on two-degree-of-freedom control structure. The setpoint tracking controller designed by input/output linearization technique is used to regulate the disturbance-free output and the disturbance rejection controller designed is designed by high-gain technique. The advantage of two-degree-of-freedom control structure is that setpoint tracking and load disturbance rejection controllers can be designed separately. Open-loop observer is applied to provide disturbance-free response for setpoint tracking controller. The process/disturbance-free model mismatches are fed to the disturbance rejection controller for reducing effect of disturbance. To evaluate the control performance, the proposed control method is applied through the example of a continuous stirred tank reactor with unmeasured input disturbances and random noise kinetic parametric uncertainties. The simulation results show that both types of disturbances can be effectively compensated by the proposed control method.