System Architecture and Complexity

6The Problem of Control

6.1. An open world: the transition from analog to all-digital

As briefly mentioned in the recap of historical developments, the 1990s was marked by a profound era of disruption in systems engineering, which have been from then onwards described as “complex” without reference to what “complex” truly means. The polysemy of the word “complex”, at the time, was even more vague than the word system in the 1940s–1950s. In fact, as soon as there is feedback, meaning a non-linearity, there is a complexity, so we can say that all systems are complex; consequently, reference to a “complex system” is almost a pleonasm.

The control mechanisms whose importance we have stressed, in other words, the feedback loop, are initially purely electromechanical, hydraulic and/or pneumatic with motors and pumps. Analog devices (we call these analog “calculators”, but this is almost an incorrect use of language!) which provide the command have a latency in the form of a time period which is specific to electronic circuits and generally very small (propagation of signals at our scale is almost instantaneous), which means that synchronization between the magnitude to be controlled and the controller is excellent due to its construction.

There is only one disadvantage; these devices cost a lot to develop, the transfer function that they carry out is “hard cast”, as we say in common language, in the circuit itself. In short, they are not programmable, impossible to maintain without ...