Input/output characterization of highly nonlinear multivariable systems

Graphical user interface for input output characterization of single variable and multivariable highly nonlinear systems

“…To put in layman's words, the input signals are more often towards minimum and maximum values than in the middle [1]. Thus, need for control design techniques, where robustness as the primary design criterion is imposed.…”

“…Furthermore, it has to be noted that the separate effects of each input on each output cannot be determined if any of the input frequencies are same. Keeping these points in mind, the input/output behavior of a multivariable system can be formulated by assuming the input to the system is of following general form [1].…”

“…Here, ‫ܯ‬ , is the log magnitude and ߶ , is the phase of ‫ܩ‬ , [1]. In order to obtain the sinusoidal input describing function models and thus the corresponding pseudo bode plots and time data plots, the user needs to input all the required parameters as discussed above in the case of single-input single-output system.…”

“…In real life systems, mathematical models are quite sophisticated and most of the times it could be represented only by using computer codes [1]. With the fact that all practical real life systems contain nonlinearities, describing function approach has attracted considerable interest when conventional controller design techniques were not able to satiate the designers.…”

Application of describing function technique to idle speed control

“…The listing of the software for generation of pseudo multivariable frequency response data is given in [23].…”