Latency wasn't mentioned in the example; does it affect robustness?
Latency, or time delays, in a system not only affects the robustness of the system (for example, in the case of uncertain or unknown time delays), but it can also affect the stability of the system. For a rough example, imagine a cruise control system in a car that receives velocity information several seconds late. In addition to having terrible performance, this system could be unstable. If the car was going up a hill (and slowing down) several seconds ago, the control system will want to increase the speed of the car. Now, imagine that the car is presently going downhill and accelerating; the control input to increase the speed of the car would be inappropriate at this time, and actually, will make the system unstable.
--Julia Braman 17:06, 1 October 2007 (PDT)