Frequency domain approach to self-tuning PID control

Abstract

The design of an adaptive PID controller using the frequency domain approach is presented. The algorithm is robust. It is not affected by low-frequency disturbances or high-frequency noise. The identified process model can be validated. For most industrial processes, the phase and amplitude of the Nyquist curve are monotone functions of frequency. The identification results can thus be rejected if they do not satisfy this monotone condition. Supervision, which is very important in adaptive control is included in the design. An implementation on a heat exchanger is also presented.