Patent ID: 8831755

Claim:
A system for controlling a linear time invariant, minimum phase, and strictly proper plant described by a plant transfer function P(s) using an input control signal u, the plant outputting a plant output signal y, the system comprising: a subtractor for calculating an error signal e comprising the difference between said system input signal u and said plant output signal y; a feedback loop for feeding the plant output signal y to said subtractor; a set of sensitivity requirements smaller than any positive number ε on a limited frequency range ω≦ω 1 and smaller than any number M>1 on a whole frequency range; and a stabilizing controller/compensator described by a transfer function C(s) for receiving said error signal e and providing a compensated control signal to said plant, said controller/compensator comprising a high gain filter having a fast time response and satisfying said set of sensitivity requirements on said limited frequency range described by a transfer function of a high gain filter J 1 (s); and a low pass filter J 2 (s) for ensuring that said set of sensitivity requirements are met on said whole frequency range; wherein said controller transfer function C(s) described by: C ( s )= P −1 ( s ) J 1 ( s ) J 2 ( s ) and wherein the parameters of J(s)=J 1 (s)J 2 (s) are adjusted to satisfy  J ⁡ ( ω )  > [ 1 + 1 ɛ ] over said limited frequency range and  J ⁡ ( ω )  > [ 1 + 1 M ] over said whole frequency range.