Describing Function Recording with Simulink and MATLAB
Krunoslav Horvat, Ognjen Kuljača, Tomislav Šijak · InTech eBooks · 2012
Describing function is an equivalent gain of nonlinear element, defined by the harmonic linearization method of nonlinear static characteristic (Novogranov, 1986, Slotine and Li, 1991, Schwarz and Gran, 2001, Vukic et al. 2003 and many others). It is a known method of analysis and synthesis when nonlinear system can be decoupled into linear and nonlinear parts (Fig. 1). If the linear part of the system has the characteristics of low-pass filter and if we apply periodical signal to the system, output signal will have the same base frequency as input signal with damped higher frequencies.