AGV safety in practice: standards, zones and working alongside people

An automated guided vehicle that shares the shop floor with people cannot be safe "by feel". AGV safety is based on standards that describe precisely how the vehicle is to detect obstacles, stop and respond to the presence of a person. This article presents AGV safety as a coherent system made up of three layers: the robot's certified equipment, a well-organised shop-floor environment, and clear rules for cooperation between the machine and the workforce.

Three layers of one system

The safety of a deployment is not determined by a single scanner or a single button. It is determined by the interaction of three layers. The first is the robot itself — its sensors, safety functions and compliance with standards. The second is the environment, meaning the way the routes, marking and physical boundaries on the shop floor have been designed. The third is people and procedures — the rules of mixed operation, training and habits.

Omitting any of these layers weakens the whole. The best scanner will not help if pedestrians walk straight in front of the vehicle at an unmarked intersection. Perfectly laid-out routes will not replace a certified emergency stop. That is why AGV and AMR robots are treated as part of a larger system rather than as a stand-alone device.

AGV safety and standards — the foundation of certification

The technical layer is governed by several standards, compliance with which must be documented. The basis for driverless vehicles is ISO 3691-4 — it specifies safety requirements and the means of their verification for driverless industrial trucks and their systems, including braking systems, speed control and personnel detection. It is the overarching standard which, among other things, stipulates that the emergency stop function must comply with ISO 13850.

Control systems are covered by PN-EN ISO 13849-1. It defines the Performance Level (PL) and the categories of system architecture (Cat. 1–4). In practice, functions such as emergency stop, speed limitation and personnel detection within the protective field are designed to PL d or PL e — the highest levels used in machines of this type. The emergency stop is covered separately by ISO 13850: the E-Stop button must be actuated with a single movement, take priority over all other functions and remain latched until it is deliberately reset by a person. All of this sits within the framework of the general machinery safety standard ISO 12100.

Compliance is not a manufacturer's declaration to be taken "on trust". Mature suppliers have their vehicles assessed by an independent certification body, such as TÜV Rheinland, which confirms that the safety functions comply with ISO 13849-1. When buying an AGV, it is worth asking for a list of safety functions and the PL assigned to each; this is the quickest way to verify that the robot genuinely meets the requirements rather than merely listing them in the catalogue.

On-board safety equipment

At the heart of protection is a set of sensors that define zones around the vehicle. The standard solution is laser scanners mounted at the front and rear which, when properly configured, provide 360° protection. A scanner does not work in a simple on/off way — it defines several fields of increasing stringency:

• Warning zone — the outermost; detecting an obstacle causes the vehicle to reduce speed and emit a warning signal.
• Stop zone — closer in; entering it stops the vehicle before any contact occurs.
• Minimum zone — directly around the vehicle's footprint; the last line of detection at short range.

The fields are matched to the speed and braking distance so that the vehicle can stop within the limit at which a person is detected. On top of this come supplementary layers: emergency stop buttons on the vehicle (plus a socket for an external E-Stop integrated with the plant's safety system), proximity sensors that detect objects at short range, mechanical bumpers, and visual and audible signals informing the surroundings of the robot's movement and intentions. Modern platforms have a dozen or more such safety functions — each compliant with ISO 13849-1, and a violation of any one of them stops the vehicle.

The environment layer: routes, visual boundaries and barriers

A robot is only as safe as its surroundings are predictable. That is why the second layer is built on the shop floor, before the fleet is even commissioned. The starting point is designated travel routes — fixed AGV traffic corridors, laid out away from areas with heavy pedestrian traffic and tight corners.

The routes must be clear to people. Boundaries are marked with floor marking — tapes and floor markers — supplemented by vertical "Caution, robot" signs, warning lights at intersections and mirrors in places with limited visibility. Where the risk is greatest — at intersections with pedestrian traffic, set-down stations or zones with heavy equipment — marking alone is sometimes not enough. At such points, physical barriers are used: bumper guards, fencing and flexible protective barriers, which physically separate the vehicle's path from the space used by people and protect the infrastructure from the consequences of any contact. The principle is simple: the higher the risk at a given location, the harder the boundary.

The trust zone: collaboration between people and robots

The third layer concerns people. The key is predictability: a robot that always travels along the same routes, signals its movement and stops in a repeatable way builds what could be called a trust zone among the workforce. Predictable machine behaviour reduces employee stress and means that people stop seeing the vehicle as a threat and start seeing it as a permanent part of the shop floor.

This predictability has to be translated into clear rules for mixed operation. Occupational health and safety regulations should clearly define right of way at crossings, designate safe places to cross the routes and provide refuges for pedestrians — zones where a person can stop outside the vehicle's path. On top of this come firm rules: never step in front of the vehicle or into its operating zone while it is moving, never move an AGV on your own, and keep routes free of materials. Well-organised pedestrian protection is not a restriction on freedom but a condition for people and robots to coexist smoothly in the same space.

Pre-launch safety tests and drills

Before the fleet goes into production, the whole system has to be checked in operation. Once the shop floor has been prepared, it is worth carrying out an internal health and safety audit: is the new marking legible, have the scanners' protective fields been set correctly, and do employees know how to behave? A detection test involves introducing a controlled obstacle onto the route and checking whether the vehicle reduces speed and stops at the right moment, and whether the E-Stop buttons actually interrupt movement.

Equally important are safety drills — exercises in emergency scenarios involving the workforce. Simulating a situation in which the robot performs an emergency stop teaches who can release it and how, and who should be notified. Exercises like these in a real environment familiarise people with the machines and reduce fear of the unknown more effectively than any presentation. Emergency procedures should be agreed with the health and safety department and set down in instructions that employees can refer back to.

Summary: safety as a system, not a single element

A safe AGV deployment is the result of combining three layers. The checklist below helps you check that none of them has been overlooked:

• The robot has documented compliance with ISO 3691-4, ISO 13849-1 and ISO 13850, ideally confirmed by an assessment from an independent body.
• The list of safety functions and their assigned Performance Levels is known (PL d / PL e for critical functions).
• Laser scanners provide 360° protection with correctly configured warning, stop and minimum zones.
• The vehicle is equipped with E-Stop buttons, proximity sensors, bumpers, and visual and audible signals.
• AGV routes are designated and marked both on the floor and vertically, with signs, lights and mirrors where needed.
• At the highest-risk locations, physical barriers separate the vehicle's path from the space used by people.
• The mixed-operation rules define right of way, crossings and pedestrian refuges.
• Before launch, a detection and stopping test and an emergency scenario drill with the workforce have been carried out.

Is an AGV safer than a forklift with an operator?

An AGV does not suffer from fatigue, distraction or time pressure, and it travels only along designated routes with continuous obstacle detection. With the three safety layers correctly designed, it separates heavy transport traffic from pedestrians in a repeatable way — and improved safety is often one of the main reasons for a deployment.

Who is responsible for configuring the safety zones?

The scanners' protective fields are configured by the supplier or integrator during commissioning, matching the fields to the speeds and braking distances on individual sections. The scope and correctness of this configuration are verified together with the health and safety department during testing before production start-up.

Sources

• ISO 3691-4:2023, Industrial trucks — Safety requirements and verification — Part 4: Driverless industrial trucks and their systems: overview of the standard (ANSI)
• ISO 13849-1, Safety of machinery — Safety-related parts of control systems — Part 1: ISO catalogue
• ISO 13850:2015, Safety of machinery — Emergency stop function — Principles for design: ISO catalogue