Originally Posted by
clearedtocross
This is only true for a system that is basically stable and where a linear input produces a proportional linear output. Controllers for systems which have less or no inherent stability are highly complex and their design needs to incorporate more factors and functions and limitations than a "simple" proportional controller. It took years for instance to develop the stability controller of a Harrier jump-jet in the hover state. In an aircraft, a crossfeed of the other axes and/or configurations may also be required (e.g up-stick when the plane rolls into a turn). An autopilot that needs less up-stick in a standard turn than in a tight one might not be easy to implement.
Sure. But you can redesign machines around stability issues, you can’t redesign people.