Penalty switch
A penalty switch is a device that ensures a human operator is alert and on the job and sooner or later take some action if the operator falls asleep or takes ill. This is an example of fail-safe practice. Because the action is usually to slow down or stop a vehicle, this is also sometimes known as a penalty brake.
The best known example is the railway locomotive's vigilance control.
One possible future application is automotive cruise control, to reduce road toll from highway hypnosis and pre-accident driver deaths.