Art In Process Control Research Articles

State of the art of process control of molten droplet and pool in gas metal arc welding

State of the art of process control of molten droplet and pool in gas metal arc welding

How to avoid the ‘invisible gorilla’ in aluminum smelting process control: Visual guidelines

Over the last three decades, process control in aluminum smelters has improved significantly as it is the biggest leverage for cost and energy reduction in production and product quality improvement, as well as for meeting environmental compliance. The implementation of computerized automatic control systems two decades ago was a step change in improvement in the state of the art of process control. However, the complex and dynamic nature of the process requires human monitoring, diagnosis, and intervention from time to time. This study investigates the use of the supervisory screen of the control system of a smelter, as well as the effectiveness of visual guidelines to help the operators to identify process abnormalities. The results show that visual guidelines such as voltage patterns which are used as a reference improve the performance of the operators. Detection time and falsealarm rates were reduced in addition to increasing detection sensitivities. It is proposed that a higher level of human and system interaction would improve the overall performance process control.

ガスシールドアーク溶接における溶滴および溶融池の制御プロセスの最新動向

ガスシールドアーク溶接における溶滴および溶融池の制御プロセスの最新動向

The State of the Art in Advanced Chemical Process Control in Japan

In this age of globalization, the realization of production innovation and highly stable operation is the chief objective of the process industry in Japan. Obviously, modern advanced control plays an important role to achieve this target; but it is emphasized here that a key to success is the maximum utilization of PID control and conventional advanced control. This paper surveys how the three central pillars of process control – PID control, conventional advanced control, and linear/nonlinear model predictive control – have been used and how they have contributed toward increasing productivity. In addition to introducing eminently practical methods, emerging methods, and their applications, the authors point out challenging problems. In Japan, industry and academia are working in close cooperation to share their important problems and develop new technologies for solving them. Several methods introduced in this paper are results of such industry-academia collaboration among engineers and researchers in various companies and universities. Furthermore, soft-sensor or virtual sensor design is treated with emphasis on its maintenance, because soft-sensors must cope with changes in process characteristics for their continuous utilization. Maintenance is a key issue not only for soft-sensors but also for controllers. Finally, we will expand our scope and briefly introduce recent activities in tracking simulation and alarm management. A part of the results of our recent questionnaire survey of process control are also introduced; the results are extremely helpful in clarifying the state of the art in process control in Japan.