An approach to the problem of stabilizing systems with delay (Q1371064)

Servo systems describable by linear ODE's with constant delay are considered. The problem consists of designing a linear feedback network with delay (the controller) to render the system stable. Stability corresponds to the real parts of all eigenvalues being negative. The type of feedback network and the ``free parameters'' are chosen accordingly. The Wiener-Paley theorem on non-quasianalytic functions and its implications on the frequency response are used to exclude networks which are non-realizable (within the framework of linear theory). The publication is of interest mainly to `system engineers'.