화학공학소재연구정보센터
IEEE Transactions on Automatic Control, Vol.48, No.3, 427-439, 2003
Composite nonlinear feedback control for linear systems with input saturation: Theory and an application
We study in this paper the theory and applications of a nonlinear control technique, i.e., the so-called composite nonlinear feedback control, for a class of linear systems with actuator nonlinearities. It-consists of a linear feedback law and a nonlinear feedback law without any switching element. The linear feedback part is designed to yield a closed-loop system with a small damping ratio for a quick response, while at the same time not-exceeding the actuator limits, for the desired command input levels. The nonlinear feedback law is used to increase the damping ratio of the closed-loop system as the system output approaches the target reference to reduce the overshoot caused by the linear part. It is shown that the proposed technique is capable of beating the well-known time-optimal control in the asymptotic tracking situations. The application of such a new technique to an actual hard disk drive servo system shows that it outperforms,the conventional method by more than 30%. The technique can,be applied to design servo systems that deal with "point-and-shoot" fast targeting.