Robust and ultrafast design of a control system based on optimal sensitivity and optimal complementary sensitivity

A new patented control algorithm achieves an optimized performance of the time response while preserving all the advantages that high gain feedback offers in terms of stability margins and robustness without having to worry about a risk of oscillations or instability. The algorithm is applied to stable invertible systems and is based on the quasi-linear principle i.e. the poles of the controller depend on the gain. It is applied to control a hard disk drive and simulation results show its superior performance. The design of optimal sensitivity is fine-tuned by the plot of the inverse of the plant on Nichols chart while the design of optimal complementary sensitivity is fine-tuned on the Nichols chart. This paper shows that the addition of phase networks in the intermediate frequency range further improves the time response of the system as predicted in [1].