Robust Controller Design and PID Tuning for Multivariable Processes

In this paper, a robust controller design method is first formulated to deal with both performance and robust stability specifications for multivariable processes. The optimum problem is then dealt with using a loop-shaping H∞ approach, which gives a sub-optimal solution. Then a PID approximation method is proposed to reduce a high-order controller. The whole procedure involves selecting several parameters and the computation is simple, so it serves as a PID tuning method for multivariable processes. Examples show that the method is easy to use and the resulting PID settings have good time-domain performance and robustness.