ISO 3691-4 is the international safety standard for driverless industrial trucks and their systems, such as AGVs and load-carrying autonomous mobile robots, covering safety functions, personnel detection and operating zones.
The standard sets requirements for the truck and for the system around it: speed control, braking, detection of people in the path of travel, protective field sizing, warning devices and verification of safety functions. It also defines the zones a driverless truck operates in, with different protection requirements depending on whether people can enter them. The current edition is ISO 3691-4:2023.
In the EU, manufacturers use the European adoption of ISO 3691-4 as a route to show conformity with machinery law for driverless trucks. In the US, the parallel consensus standard is ANSI/ITSDF B56.5, and sites with mixed fleets of manned forklifts, driverless trucks and pedestrians usually need to consider both. The standard covers the driverless truck and its system, not detection systems fitted to manned forklifts. See AGV forklift safety.