[TFortunato]

Related fun fact - On many industrial robots that I've worked with, the teach pendant (the handheld controller you drive it around with), requires you to hold a 3 position spring-loaded switch in a middle position for the robot to operate, which requires you to hold with a rather precise amount of force. Squeeze it either too loosely or too tightly and the robot disables.

The idea being that not only will you dropping the pendant disable the robot, but it will also disable if you accidentally touch energized equipment and your hand clenches, or (more likely) you panic and squeeze the controller too tightly.

https://us.idec.com/idec-us/en/USD/Safety-Components/Enablin...