Performance monitoring and tuning controllers

摘要

Tuning controllers by the step response method (CE, February 2007 "Academic Viewpoint") is a tried-and-true method, but not all take the trouble to do it. In 2000, Honeywell engineers surveyed various industries and found the following performance assessment numbers for installed controllers: 16% excellent, 16% acceptable, 22% fair, 10% poor, and 36% open loop. Tuning poorly performing loops on-line is an attractive option because of time efficiency, but widespread application of self-tuning controllers is still not trusted by many control practitioners and plant managers. With thousands of loops in some plants, the goal often is to have closed-loop performance that is more or less satisfactory all of the time, rather than controllers that work optimally some of the time and need attention some of the time.