SUNS: THE SUSSEX UNIVERSITY NONLINEAR CONTROL SYSTEMS SOFTWARE

Abstract The paper outlines the capabilities of the Sussex University Nonlinear Software. The programs based on two theoretical techniques, the describing function and Tsypkin's method, evaluate limit cycle solutions in both continuous and discrete feedback systems. The software allows the display of solution waveforms at the input to each nonlinearity and an exact orbital stability criterion, for continuous systems, is used for the limit cycles predicted by the Tsynkin method. Most of the software is for fixed structure canonical feedback systems although one of the DF based programs allows analysis of systems of a free structure. The software may also be used for frequency domain design where gain and phase margins of compensation schemes may be calculated by finding the minimum amount of additional gain or time delay required for a system to limit cycle.