Driverless transport systems, safety and ISO 3691-4
Driverless transport systems – AGVs and AMRs – are the classic form of autonomous driving in industrial environments. Their use is growing rapidly, especially in the automotive and supplier industry, but also in logistics centres and production plants with high material flow.
In all of these environments, vehicles move in areas where people are present: at hand-over stations, aisles, buffer zones or mixed zones with forklifts. These mobile hazards require different safety concepts than a stationary machine.
The key standard here is ISO 3691-4. It defines safety requirements and verification for driverless industrial trucks and their systems – from classic AGVs to modern AMRs.
What does ISO 3691-4 cover?
The standard addresses both manufacturers and operators of AGV/AMR systems and covers, among other things:
- safe operation in automatic areas
- requirements for person detection and monitoring of hazardous zones
- operating modes (automatic, manual, service) and their enabling conditions
- safety-related functions with PL/SIL verification (e.g. stop, speed monitoring, direction monitoring)
- validation of safety functions and documented testing
ISO 3691-4 has completely replaced the former EN 1525 and is today the key international reference in Europe for AGV/AMR safety.
In the US, ANSI/ITSDF B56.5 is the corresponding standard for automated guided industrial vehicles.
Typical hazards & protection concepts
Typical hazards in AGV/AMR applications include:
- hitting, crushing or running over people
- collisions with other vehicles or conveyor systems
- crushing and shearing points at transfer stations
- hazards caused by lifted or unstable loads
To address these, the standard requires concepts such as:
- Speed concepts: reduced speed in mixed-traffic areas, further speed reduction when approaching people or obstacles, and safe stop in case of danger
- Protective fields & zones: warning and protective fields in front of and beside the vehicle, monitored areas at curves, crossings and transfer stations
- Safe manual mode: defined reduced speeds, enabling devices and clear role allocation between operator and vehicle
- Signals: optical and acoustic warning signals indicating driving state, direction and faults
My contribution: test and verification concepts according to ISO 3691-4
In 2019 I developed a test concept for an AGV manufacturer based on ISO 3691-4 and have since tested more than 100 driverless transport systems at various automotive OEMs and suppliers.
Today I support manufacturers, integrators and operators with:
1. Concept and layout review
- Review of the safety concept for routes, transfer stations and mixed zones
- Comparison with the requirements of ISO 3691-4 (and, if needed, ANSI B56.5)
- Recommendations for suitable operating modes, speed levels and protective fields
2. Initial verification at the manufacturer
- Testing of safety functions (stopping, speed limitation, person detection, etc.)
- Review of documentation (risk assessment, safety concept, PL/SIL calculations)
3. Initial verification at the operator’s site
- Comparison of the real layout with the approved safety concept
- Measurement and verification of braking and stopping distances in the actual installation
- Checking interfaces to higher-level safety functions (e.g. emergency stop, blocked zones)
4. Periodic inspections
- annual or application-specific recurring tests
- documented results including a prioritised action list for remediation
All inspections are documented in a way that stands up to audits, with clear measures and responsibilities so that operators can demonstrate compliance to customers, notified bodies and authorities.