制御技術／理論の歴史と現在とこれから 制御システムの高度化への多角的アプローチと今後の課題

Abstract

Effectiveness of the plant control systems depends on the level of the control technologies built in the systems. In the twenty first century, more advanced control technologies will be indispensable in areas of safe and flexible plant operations, energy and resources saving, and environment maintenance.This paper reviews the history of control technologies and theories, the development and interaction of them, and presents the author's view on the current results and the future issues. In the sixty years since the introduction of PID control, various other control technologies and theories were tried but none has replaced PID nor taken the the lead in control. In the present age of digital control, the PID control is still in dominant use with more than 90% of all controls, and no immediate change is anticipated.From these facts, in order to achieve more advanced operation of plants, it will be necessary to further refine the PID control and apply non-PID control in more effective and Practical ways. I have pointed out that in the PID control, which is the basis of the control system, there are still unknown areas and those portions that need further refinements, and as an example of advanced PID control, explained the two-degree of freedom PID control. Since the characteristics of control object often vary considerably in the process control, the refinement of control can be said to be a fight against the change of characteristics of the control object. With these facts in mind, I have explained that, to further advance the plant control, many sided approaches are required including the refinement of classical control and the wide and practical applications of modern control, knowledge control, and other new control theories. In developing them, realization of control technologies that are both effective and user-friendly is strongly desired.