Identification and control—closed-loop issues
Automatica (Journal of IFAC) - Special issue on trends in system identification
Robust and optimal control
Identification of closed-loop systems with low-order controllers
Automatica (Journal of IFAC)
Relay Feedback: Analysis, Identification, and Control
Relay Feedback: Analysis, Identification, and Control
Identification of Continuous-time Models from Sampled Data
Identification of Continuous-time Models from Sampled Data
Special section system identification tutorial: Step response and frequency response methods
Automatica (Journal of IFAC)
Closed-loop identification revisited
Automatica (Journal of IFAC)
Robust identification of continuous systems with dead-time from step responses
Automatica (Journal of IFAC)
On the frequency domain accuracy of closed-loop estimates
Automatica (Journal of IFAC)
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A continuous-time model identification method is proposed based on a closed-loop step response test for obtaining a low-order process model to facilitate control design in industrial engineering practices. By introducing a damping factor to the closed-loop step response for realisation of the Laplace transform, a frequency response estimation algorithm is developed in terms of the closed-loop system configuration used for identification. Correspondingly, two model identification algorithms for obtaining the widely used low-order process models of first-order-plus-dead-time (FOPDT) and second-order-plus-dead-time (SOPDT) are derived analytically respectively. To improve model fitting accuracy over a specified frequency range interested to controller tuning, in particular for identification of a higher order process, another identification algorithm is given based on weighted least-squares fitting of the process frequency response points estimated in the specified frequency range. Using the identified low-order models, a model-based controller design and tuning method is proposed for improving load disturbance rejection. Illustrative examples from the recent literature are used to demonstrate the effectiveness and merits of the proposed identification algorithms and controller tuning method.