If you want to manually operate an industrial robot via its controller, you usually have to squeeze a "deadman" switch or else the robot will engage its brakes.

If you want to manually operate an industrial robot via its controller, you usually have to squeeze a "deadman" switch or else the robot will engage its brakes. What's neat is that the deadman switch is a 3-position switch: They discovered that when people panic they either let go or squeeze harder, so both actions stop the robot.