# Third-order nonlinear discrete-time system #2

## Model description:

Image below shows the block diagram of a discrete-time system.

\begin{align*} H_1(z) &=\dfrac{0.2z^{-1}}{z^{-1}-0.21z^{-2}} \\ H_2(z) &=\dfrac{0.1z^{-1}}{1-1.1z^{-1}+0.3z^{-2}} \\ H_3(z) &=\dfrac{0.3z^{-1}}{1-0.4z^{-1}} \end{align*}

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## Publication details:

 Title Nonlinear system identification using genetic algorithms with application to feedforward control design Publication Type Conference Paper Year of Publication 1998 Authors Luh, Guan-Chun, and Rizzoni G. Conference Name Proceedings of the 1998 American Control Conference, 1998. Date Published 06/1998 Publisher IEEE Conference Location Philadelphia, PA ISBN Number 0-7803-4530-4 Accession Number 6076036 Keywords autoregressive processes, continuous time systems, discrete time systems, feedforward, genetic algorithms, identification, inverse problems, nonlinear systems Abstract A GAMAS-based system identification scheme is developed to construct NARX model of nonlinear systems. Several simulated examples demonstrate that it can be applied to identify both nonlinear continuous-time systems and discrete-time systems with acceptable accuracy. Inverting the identified NARX model, a feedforward controller may be derived to track desired time varying signal of nonlinear systems. Sufficient conditions of the invertibility of NARX model are proposed to investigate the existence of the inverse model. Simulation results depict the effectiveness of the feedforward controller with the aid of simple feedback controller designed for regulation purpose DOI 10.1109/ACC.1998.703056