AN ALGEBRAIC CRITERION FOR ROBUST STABILITY OF LINEAR-CONTROL SYSTEMS

A new robust stability test for linear control systems is described. T he condition at which robust stability is violated is transformed into an equivalent problem in which the existence of a real root of a mult ivariable polynomial is investigated, This multivariable problem is re duced to that of the solvability of a set of univariable polynomial eq uations in real numbers, for which a number of efficient numerical met hods are available, The use of the method is illustrated in the design of feedback control for an open-loop unstable batch chemical reactor.