The Control Subsystem

Abstract

In considering a natural or human made system that operates as expected, it is often difficult to differentiate between process and controller. Is the teacher in control of the class, or is the class in control of the teacher? Even simpler, when flushing the toilet there is the clear understanding that the action of starting the process, be it by a proximity sensor, or pressing a button, or pulling a chain achieves the desired effect: the toilet is cleaned, and ready for its next use. Nobody really cares about the internal workings of the toilet system. From this perspective, it is difficult to realize that a feedback loop is at work, let alone that certain references such as flushing time, and fill level have been set.