2012 年 6 巻 2 号 p. 131-144
The Proportional-Integral-Derivative (PID) controller structure is very widely used in industrial applications. Its structural simplicity and ability to solve many practical control problems have contributed to this wide acceptance. Recently, the parameterization of all stabilizing PID controllers has been considered. This method obtains admissible sets of PID parameters to guarantee the stability of a closed-loop system. However, several difficulties remain with this method. One is that admissible sets of P-parameters, I-parameters and D-parameters are related to each other. Another is that there are plants that cannot be stabilized by a PID controller. To overcome these problems, Yamada and Hagiwara proposed a design method for modified PID controllers that stabilize the closed-loop system for unstable plants, while allowing admissible sets of P-parameters, I-parameters and D-parameters to be independent of each other. However, no method has been published that can guarantee the stability of PID control systems for multiple-input/multiple-output plants, or find admissible sets of P-parameters, I-parameters and D-parameters that both are independent of each other and guarantee the stability of a PID control system. We propose a design method for modified PID controllers that achieves these goals.
