Closed-loop sensitivity reduction of linear optimal control systems

Inequalities are derived which demonstrate the reduction of sensitivity to plant-parameter variations of closed-loop linear optimal systems (as compared to nominally equivalent open-loop systems) according to a particular measure of sensitivity. The shortcomings of some other measures of sensitivity are discussed and illustrated in numerical examples. Numerical results for the sensitivity comparison of a first-order system and a third-order pitch-axis control system are given.