1. The Excitement of Control Engineering
A final point is that all interconnected systems, including control systems, are only as good as their weakest element. The implications of this in control-system design are that one should aim to have all components (plant, sensors, actuators, communications, computing, interfaces, algorithms, etc,) be of roughly comparable accuracy and performance. If this is not possible, then one should focus on the weakest component to get the best return for a given level of investment. For example, there is no point placing all one's attention on improving linear models (as has become fashionable in parts of modern control theory) if the performance-limiting factor is that one needs to replace a sticking valve or to develop a virtual sensor for a key missing measurement. Thus, a holistic viewpoint is required with an accurate assessment of error budgets associated with each subcomponent.