Robust MIMO PID tuning method

The paper describes a new criterion for tuning of decentralized PID control for MIMO plants. The tuning procedure consists of two stages. In the first stage, the desired critical point (DCP), which consists of the critical gains of M loops and a critical frequency, is identified. In the second stage, the data of the desired critical point is used to tune the PID controller by the Ziegler-Nichols rule or its modifications. In the proposed method, the process gains at crossover frequency, which are required for the appropriate choice of the desired critical point, are determined. The robustness and performance of proposed method are compared with the Palmor method.