On the design of control systems that are robust in terms of performance index

A plant can typically operate in normal and emergency modes. A method of correcting the controller that is optimal in normal mode so as to make it operate satisfactorily in the emergency mode is described. The available approaches to the solution of this class of problems (see [1?C4]) are elabo-rated. In distinction from the solution of one such problem in [4], the requirement that the numbers of right poles of the transfer functions of the plant in the normal and emergency modes be identical is removed.