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Model Approximation and Controller Synthesis for H∞ Robust Control of Multiple Time Delay Transfer Functions

Shyma Muhammed(1*), P. Venkata Mahesh(2), Abraham T. Mathew(3), T. K. Sunil Kumar(4)

(1) Department of Electrical Engineering, National Institute of Technology, Calicut, India
(2) Rajeev Gandhi Memorial College of Engineering, Nandyal, AP, India
(3) Electrical Engineering in the National Institute of Technology Calicut, India
(4) Electrical Engineering, National Institute of Technology, Calicut, India
(*) Corresponding author



It is well known that the modeling issues in Dynamical systems in chemical processes, networked control systems and automation systems are very complex and model may contain subsystems with different delays. Because of the mathematical complexity, the robust control of these types of multiple time delay system is a challenging one. The problem becomes more difficult and complex when the system is having time delays in both the denominator and the numerator. In this paper a new method is proposed for approximating general multiple time delay continuous-time transfer function system with multiple time delays in both the denominator and the numerator to a single input/output delay. Both Single Input Single Output(SISO) and Multi Input Multi Output(MIMO) cases have been considered. In this proposed methodology, the Approximated Generalized Time Moments (AGTM)/ Approximated Generalized Markov Parameter (AGMP) methods are used to transform the multiple time delay system into a single input/output delay system. A Linear Matrix Inequality (LMI) approach is developed for synthesizing robust H∞ control of the approximated time delay system. The efficacy of the proposed method is shown through illustrative examples. It is evident from the simulation results that the approximated system is stable with the proposed LMI H∞ controller.
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Approximated Generalized Time Moments/Approximated Generalized Markov Parameters; Model Approximation; Multiple Time Delay Transfer Function; Robust Control; Time Delay Systems

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