Emergency Stop

A safety function that stops a machine with a single action in an emergency — typically a red mushroom button on yellow.

An emergency stop is a mandatory safety feature on any machine; the international standard ISO 13850 requires that anyone present be able to stop the machine with a single action, without having to think about it. The typical E-stop button is a red mushroom-shaped head on a yellow background; pressing it mechanically latches in place, and someone has to manually reset it before the machine can restart. IEC 60204-1 classifies stopping into three categories: category 0 cuts power to the drives immediately; category 1 brings the machine to a controlled stop first, then cuts power; category 2 brings it to a controlled stop while keeping power on. Only categories 0 or 1 are allowed for an emergency stop. Which one to use depends on whether cutting power immediately would actually be more dangerous: legged and humanoid robots collapse the instant power is cut, so they're often tested on a safety harness, and beyond the E-stop, a softer stop such as a damping mode is also provided. An E-stop is the last line of defense — it can't substitute for other safety measures like collision detection or speed limiting.

ExampleA collaborative arm's teach pendant usually has a built-in E-stop button; during real-robot VLA experiments, the operator typically also keeps a separate, standalone E-stop within reach, ready to hit it the moment the policy does something abnormal.

Also called

E-Stop, Stop Category 0/1/2

Related

Protective Stop · Functional Safety · Safe Torque Off (STO) · Damping Mode · Watchdog · Collision Detection (Robot Safety)

Sources

Wikipedia (de): Not-Halt（停止类别 0/1/2、ISO 13850、急停按钮形态） (Chinese)
Wikipedia: Kill switch（emergency stop, ISO 13850）