ABSTRACT

Stability analysis based on harmonic balance provides suf‘cient accuracy when applied to well-designed control feedback loops having low-pass ‘lter properties.

Describing function (DF) stability analysis is simple and convenient. In this chapter, DFs are derived for most common nonlinear links: saturation, dead zone, three-position relay, and hysteresis. Simple approximate formulas are derived and used in the design of nonlinear controllers.