Journal ArticleDOI
System Identification Under Relay and PI Control
Saurabh Pandey,Somanath Majhi +1 more
TLDR
On-line identification scheme is proposed where the system characteristics is extracted with respect to proportional-integral (PI) controller dynamics in terms of sustained oscillatory responses broadly known as limit cycle at the system output.Abstract:
This brief presents a symmetrical relay-based identification scheme for a class of linear time-invariant systems with time delay. During off-line identification, the adverse effect of static load disturbance may lead to erroneous system model parameters. Therefore, on-line identification scheme is proposed where the system characteristics is extracted with respect to proportional-integral (PI) controller dynamics in terms of sustained oscillatory responses broadly known as limit cycle at the system output. Utilizing the relay settings (amplitude and hysteresis width), controller parameters and limit cycle information, an explicit set of mathematical expressions for on-line parameter estimation of system dynamics in terms of a stable first order plus time delay (FOPTD) model is deduced from frequency domain and state space analyses. As compared to recent relay-based identification methods, the proposed set of explicit expressions does not require any prior guess of initial values of the system model parameters for the simultaneous solution of a nonlinear set of mathematical equations. Simulation of a benchmark example from literature and experimental results from the coupled tanks system are included for validation of the proposed identification algorithms using the deduced set of mathematical expressions.read more
Citations
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Journal ArticleDOI
A Robust Decentralized PID Controller Based on Complementary Sensitivity Function for a Multivariable System
TL;DR: This brief presents design, development and real-time implementation of a robust decentralized PID controller based on complementary sensitivity function through a graphical tuning method for a multivariable system.
Journal ArticleDOI
Accelerated Gradient Descent Estimation for Rational Models by Using Volterra Series: Structure Identification and Parameter Estimation
TL;DR: In this article , a rational model identification problem using a novel gradient descent algorithm is studied, where the rational model is approximated by a second-order Volterra system, whose parameters and structure are estimated through an accelerated gradient descent method.
Proceedings ArticleDOI
Modeling of Integrating and Non-minimum Phase Dynamics using Limit Cycles
TL;DR: In this paper , an asymmetrical relay is fedback to bring sustained oscillatory responses from the unknown process dynamics broadly known as limit cycle, considering the relay settings and the limit cycle information, an explicit set of mathematical expressions for identification of non-minimum phase integrating first-order plus dead time, integrating first order plus dead-time and pure integrating-plus-dead-time processes is deduced which does not need an appropriate guess in the solution of nonlinear equations.
Journal ArticleDOI
Transfer function identification of a liquid flow-line pressure control system from simple relay auto-tuning
TL;DR: In this article, an accurate modeling of liquid flow systems is needed for the effective operation of the plant under different conditions. But the model may change with time, and due to this, the operation ma...
References
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Karl Johan Åström,Tore Hägglund +1 more
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Relay Control Systems
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Journal ArticleDOI
Derivation of transfer functions for highly nonlinear distillation columns
TL;DR: Mise en place d'une procedure de commande simple which utilise la methode "autotune" d'Astrom for obtenir les gains and les frequences critiques for chaque element diagonal de la matrice des fonctions de transfert as discussed by the authors.
Journal ArticleDOI
Autotuning and controller design for processes with small time delays
Somanath Majhi,Derek P. Atherton +1 more
TL;DR: In this paper, a set of general expressions derived from a single asymmetrical relay feedback test for online plant identification is derived, and conditions for the existence of limit cycles in unstable FOPDT and SOPDT processes are derived.
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