Input/output characterization of highly nonlinear multivariable systems

This paper presents a software in the MATLAB environment for input/output characterization of highly nonlinear multivariable systems. The, software is based on obtaining the sinusoidal-input describing function (SIDF) models of the nonlinear multivariable plant. The mathematical development of the input/output characterization approach is outlined, and the printout of the nucleus of the characterization software is given. The method and the associated software have no restriction on nonlinearity type, configuration, and arrangement, system order as well as the number of inputs and outputs; the only requirement is that system output(s) for sinusoidal input(s) must be obtainable or available by either simulation or experiments. The software has a variety of applications in such industries as robotics, aerospace, automotive, and chemical processes. The method and the associated software are demonstrated by solving a problem of the sort encountered in aerospace. (C) 2002 Elsevier Science Ltd. All rights reserved.