Article

Identification of frequency domain models for nonlinear systems

Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506-00456, USA
Advances in Engineering Software (1978) 01/1988; DOI: 10.1016/0141-1195(88)90038-1

ABSTRACT This paper presents a computer-aided engineering approach for identification of linear models from a set of frequency response data. The approach is based on a new system identification technique. The primary intention of the developed system identification technique and the associated software is to identify linear models for nonlinear systems whose input/output behaviour is characterized by their corresponding sinusoidal-input describing function models. However, the technique may also be applied to identification of linear models from experimental frequency response data. At present, the identification approach and the associated software is limited to single-output, linear, deterministic, and time-invariant systems. A computer-aided engineering environment based on the developed system identification technique has also been developed. The software is developed on a Harris-800 super-minicomputer and a Tektronix 4115B high resolution, raster, and color graphics terminal.

0 Bookmarks
 · 
43 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new single range controller design approach for use with nonlinear liquid propellant engines (LPE) is developed. The approach is based on a describing function model of the nonlinear LPE coupled with the application of the H∞ control theory. The approach is applicable to nonlinear LPEs of a general nature without any restrictions on nonlinearity type, number of nonlinear terms, nonlinearity arrangement, or system order. The approach is applied to an existing nonlinear LPE, and the results are compared with those obtained with an alternative method that was previously reported in the open literature.
    Acta Astronautica 01/2009; 64(2):206-211. · 0.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: New Matlab functions for inversion of describing function models are developed. These functions are based on a newly developed computer-aided procedure. The procedure starts by guessing the initial values for the independent variables of an assumed nonlinear function. Then, the describing function model of the nonlinearity is numerically generated. This is followed by minimizing an objective function that yields the desired parameters of the nonlinear function. Such software has applications in synthesizing nonlinear gains of a controller. The printout of the software is given, and three demonstration problems are presented.
    Advances in Engineering Software. 01/2009;
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new systematic single-range controller synthesis procedure for use with nonlinear, multivariable, and time-varying liquid propellant engines is developed. The developed procedure is based on one describing function model of the nonlinear plant coupled with two different linear algebraic controller design procedures; one of the algebraic procedures is to achieve decoupling, and the second one is to achieve command following. The developed procedure is demonstrated by solving an example problem comparing the results using a H∞ controller design procedure.
    Aerospace Science and Technology. 01/2006;