The electronic speed controllers we use in RC have a loop time of a few milliseconds and are fully programmable. Some of them are capable of sensing the current

The electronic speed controllers we use in RC have a loop time of a few milliseconds and are fully programmable. Some of them are capable of sensing the current going into the motor. You can also monitor the voltage instead of/in addition to the current. It's easy to cut the throttle when there is an unexpected power surge. I personally haven't seen this technology in DIY multirotor parts, but I know that the AR.Drone has what they call "cut-out detection". They use it to prevent damage to the craft rather than humans, but the technology could be tuned for this as well.