“What if it could monitor itself?”
Feedback: Measure the result of a process to adjust the process.
Examples
The classic example is a thermostat, that will turn on a furnace when the temperature is too low and turn it off again when the temperature is too high, regulating the temperature within a small range.
Most robot arms rely on position sensors and force feedback sensors to ensure their actions are accurate.
A gas (petrol) nozzle will automatically shut off when the task of filling the tank of the vehicle it is complete.
Navigation systems react to diversions from the original route with new instructions on how to reach the destination.
Project management is in part a process of reassessing the work to be done so that the original target is reached.
Internal combustion engines (car engines) rely on oxygen sensors in the exhaust to determine if they are running too rich or too lean a fuel-air mixture, or if there is a fault in the engine.
Another car system that relies on feedback is the ABS anti-lock braking system, which uses wheel sensors to detect a wheel slowing too fast indicating impending lockup and reducing brake pressure.
More examples
As I stumble across real world examples of this Inventive Principle in action I add them here.
Your turn
What problems do you face that this inventive principle could help solve? Have you used this principle before?