Thermal MIMO controller for setpoint regulation and load disturbance rejection

The thermal interaction problem of a multi-input multi-output (MIMO) temperature process is caused by the temperature gradient through the plant. Generally, industrial controllers are used for the decentralized control and do not use a process mathematical model. In many cases, trial-and-error tuning is required for solving the problem. The present paper introduces a MIMO thermal model and the decoupling PID control strategy. The decoupling control and its shortcomings are described from the perspective of the user. An improved strategy based on a robust observer is developed. For industrial implementation, this observer is quite simple because only the first-order model given by the decoupling model is implemented. The program code is simple for the microprocessor of a low-cost commercialized controller. In addition, a hunting rejection method based on the observer is presented. The present paper applies the method to the twin screw extruder in order to verify the effectiveness of the proposed strategy. The proposed method has been successfully to solve the interaction problem for MIMO temperature process.