Self-tuning control in the presence of periodic disturbance

A pseudo-feedforward method is proposed for adapting an incremental self-tuning controller to reject periodic disturbances. The algorithm begins with an estimate of the disturbance frequency. The amplitude and phase of the disturbance are estimated by augmenting the parameter estimation vector. The estimated disturbance can then be used as a feedforward term with the self-tuning controller. A second stage allows for the estimate of the disturbance frequency to be improved using the estimated amplitude. The algorithm has been shown to be robust in simulation examples and on a pilot heat exchanger.