On this page we discuss in irregular intervals topics related to Advanced Control - with emphasis on its economical aspects. Ziegler-Nichols Performance Measurement 1. First, a reduction of the range within the controlled variable can be kept and secondly smoother action on the process.
Consequences can be economic loss - or safety or environmental hazards.
The smaller the deviation from the setpoint the better. Two other methods, the ITSE and the ITAE do the same PLUS multiply the error always with the time elapsed since the setpoint change. Thus they penalise especially slow responses. In all cases, a smaller number gives better performance. These methods are well suited to judge and compare controller performance in response to setpoint changes, as it is done during controller tuning.