A FREQUENCY-RESPONSE APPROACH TO AUTOTUNING OF MULTIVARIABLE CONTROLLERS

The relay auto-tuning technique for PID controllers is here extended t o tune multivariable controllers. In the case of significant interacti on, a fully cross-coupled multivariable controller rather than a decen tralized controller should be employed. In this paper, an autotuning m ethod for multivariable controllers from sequential relay feedback is proposed. The frequency response a mxm multivariable process is identi fied from limit cycles using a FFT-based method, and a multivariable c ontroller is computed with linear least squares frequency response fit ting. Various typical examples are included for illustration of the ef fectiveness of the method.