Hisao Katoh

Robust-tracking deadbeat control

We derive the parametrization of all controllers that achieve both the robust-tracking and the deadbeat control. We also give the parametrization of all reference functions for which the robust tracking and designed deadbeat property is guaranteed by all robust-tracking deadbeat controllers for one reference. The solution to the robust-tracking deadbeat problem for more than two reference functions is also given. We use the H ∞-norm of the sensitivity function as the robustness index of the system. By using two-degree-of-freedom control systems, we can achieve both minimal-time deadbeat control and optimal robustness with only one controller.

Input/output deadbeat control

In this paper, we consider the deadbeat control for both the output and input of step-like references and single-input single-output processes. The controllers are selected from among two-degree-of-freedom robust-tracking controllers, and we derive the parametrization of all input/output deadbeat controllers. This parametrization is given by solving two polynomial Diophantine equations. We also derive the parametrization of all references for which input/output deadbeat response is maintained. In addition, we investigate the conditions for the processes under which the output deadbeat always implies the input deadbeat.

New Sampling Theorem Concerning the Ripple Phenomena

Abstract In this paper, we propose a new approach to the ripple phenomena, by using open-loop analysis, Fourier analysis and new sampling theorem. Our result can explain explain the emergence of ripple phenomena and reduce them.