Abstract In this paper, a new continual self-tuning control scheme based on unknown process response under load disturbance is proposed. It can re-estimate the possibly changed process frequency response using the benign process transients under an unknown step or impulse like load disturbance. According to disturbance response pattern, the unknown step/impulse like load disturbance is assumed to be generated by passing a step or an impulse through an unknown rational function dynamics. With process input and output frequency response computed by FFT, the best estimation of the process frequency response is obtained using least squares method. A PID controller is re-tuned based on the re-estimated process frequency response to adapt the possible changes in process. The effectiveness of the method is demonstrated through simulation examples and real-time tests.
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