Characteristic polynomial assignment for delay-differential systems via 2-D polynomial equations

A new method of characteristic polynomial assignment for delay-differential systems both retarded and neutral, is presented. The method consists in solving a 2-D polynomial equation. Solvability conditions well suited for a practical testing are given and the class of all assignable polynomials is parametrized. The problems of minimality, causality, properness and stabilization are discussed. The method is used to stabilize even not formally stable plants. All the design procedures proposed are based on classical 1-D techniques.