Auto tuning sequence of thermal MIMO system

A multi-input multi-output (MIMO) temperature controlled system sets up several single-input single-output (SISO) controllers. Generally, the SISO controllers are operated as a decentralized control system. The problem for the MIMO system is PID tuning sequence of the SISO controllers (e.g., which loop is tuned first). A controlled performance and tact time for PID tuning of the MIMO system depend on the sequence. The tuning sequence is decided by the experience and the perception of user. This paper presents an evaluation function for decision of the best PID tuning sequence by using rate of temperature rise and thermal difference of each channel. The proposed method is verified by comparing the sequences based on the evaluation function, Relative Gain Array (RGA) and Dynamic Relative Gain Array (DRGA). The best sequence based on proposed method considers a dynamics of process. Experimental results show that tact time for tuning can be reduced and the best PID parameters for uniform temperature control can be tuned by the proposed method.