ROBUST STABILITY OF SYSTMS k'ITH INTEGW COKTROL

A necessary and sufficient condition is derived which nust be satisfied by the plant steady state gain matrix of a linear time invariant system in order for an integral controller to xis st for which the closed loo? system is unconditionally stable. Based on this theorem the robustness of intezral control systems is analyzed, i.e. the family of plants is defined which are stable when controlled wit3 the same integral controller, Conditions for actuator/sensor failure tolerance of systems with intezral control are also gi:Ten. Finally,. parallels are drawn between the results of this paper and the iifurcation theory of nonlinear systems.