A big thing that was emphasized in my computer engineering courses at Purdue in the early 90s with regards to machine interfaces was hysteresis. A machine has a

A big thing that was emphasized in my computer engineering courses at Purdue in the early 90s with regards to machine interfaces was hysteresis. A machine has a RANGE of behaviors throughout it's operating area that might not be accounted fro in your programing and you must take that into consideration (i.e. a robotic arm or electric motor doesn't just 'stop' instantly). Analog systems do not behave like computers.