Absolute Stability of Nonlinear Systems of Automatic Control

The problem of absolute stability of an ?indirect control? system with a single nonlineartiy ia investlgated by using a method which differs from the second method of Lyapunov. The main condition of the obtained criterion of absolute stability is expressed in terms of the transfer function of the system linear part. It is also shown that by fonning the standard Lyapunov function -?a quadratic form plus the integral of the nonlinearity? It is not possible In the case considered here to obtain a wider stability domain than the one obtained from the presented criterion. Graphical criteria of absolute continuinty are also given by means of the phase-amplitude characteristic or by what is known as ?the modified phase-amplitude characteristic? of the system linear part.