On-line auto tuning of PID controllers based on the cross-correlation technique

The development of an online version of an autotuning algorithm for proportional-integral-derivative (PID) controllers based on the cross-correlation technique is described. The autotuner causes only minor perturbation on the normal operation of the process, needs little prior information, and is robust to noise. The design rules for automatic selection of the length and bit interval of the pseudorandom binary-sequence (PRBS) probing signal used by this autotuner are also discussed. The accuracy and performance of this autotuning method have been substantiated by extensive simulations