On stability of digital tracking systems with conversion of the error code into a sequence of width-modulated pulses

Stability of a set of equilibrium states of a digital tracking system with conversion of the error code into a sequence of width-modulated square pulses is studied by the second Lyapunov method. The Lyapunov function is chosen as a positive definite quadratic form. An example is given whereby the resultant sufficient conditions are compared with experimental necessary and sufficient ones.