AGVE » AGV School & Information » Safety

Safety

General

The safety level in an AGV is very high as it has several safety functions to protect the vehicle and people.

Compared with manually operated forklift trucks the AGVs are much safer because they are running at lower speeds and with a more predictable behavior.

The vehicle has bumpers that protect the AGV in the traveling direction. The bumper activates the bumper relay, which is hard-wired and will stop the AGV when activated. The bumpers will also generate a signal to the AGV control board, which stops the AGV through software.

Forklift AGV safety features

AGV Safety Features Overview

Safety regulations and standards

Europe

  • The AGV must comply with the Machinery Directive 98/37/EC.
  • The AGV must comply with the electro-magnetic radiation EMC Directive 89/336/EEC.
  • The AGV must comply with the low voltage LVD Directive 73/23/EEC if the DC voltage is above 75V, which is not normal for an AGV.
  • There is also a type C-standard that normally is used, EN1525 'Safety of industrial trucks - Driverless trucks and their systems'. This is a harmonized standard used to conform with the safety requirement of the Machinery Directive.

USA

  • The AGV must meet the requirements in the standard ANSI/ASME B56.5-1993

AGV safety features

The vehicle has bumpers that protect the AGV in the traveling direction. An AGV has also always E-stop buttons. Besides these are there several other safety functions to protect people and machinery.

Front bumper

The front bumper is a personnel protection device in the main travel direction. It protects the AGV from the front and sides. In some vehicles it also has a function from the rear direction. The standard front bumper is a shield made in polycarbonate plastic. It uses two photocells mounted on AGV detect reflectors on the bumper shield. Limit switches may also be used as sensors. The stroke of the bumper is always designed to stop the vehicle before the AGV frame or any rigid part of the AGV hits the object.

  • Protection in the main travel direction must be made according category 3 of standard EN954-1 in Europe.

Laser scanner

There are also laser scanners which may be used as a stand-alone safety protection device, or in conjunction with a mechanical bumper. The advantage is that it is programmable, which makes it possible to shape the protection zones after the AGV and application. The laser scanner protects only at the laser beam height. The laser scanner is also used to slow down the speed when objects are detected at longer range. The laser scanner is quite expensive.

Rear bumper

The rear bumpers are located in the rear end of each support leg, and are used when the AGV is reversing. Where it is suitable can the rear bumpers be added with optical sensors for side protection and protection of the load area of an AGV.

Fork tip bumper

A forklift AGV from AGV Electronics has always fork bumpers in each fork tip used to prevent hitting loads or stationary objects if loads or lift heights are misaligned. This is an added safety device that is not required by any regulation or standard but is very useful in automatic material handling.

Side protections

Side protections are used at longer vehicles as there will be a large area of the AGV that sweeps in curves and a side protection device can protect this area.

A side protection can be made of an optical beam that is broken by objects and will stop the AGV.

So called safety edges are often used as side protections. They are normally made of a profile of a rubber material. Inside this profile is the sensor located, which can be of a contact strip material or optical fiber

E-stop

Emergency stop pushbuttons located on each side of the control cabinet on a forklift AGV. On other vehicle types are the E-stops located in the four corners of the AGV. The E-stops are always located for easy accessibility in an emergency situation.

  • The E-stop device must comply with category 0 of EN418 and must be made according category 3 of standard EN954-1 in Europe.

Warning lights and beepers

Warning lights are normally always mounted on the AGV. They can shine with a steady light or flash with different frequency to indicate different modes of operation.

A beeper is mounted on the AGV for audible warning. It sounds when the AGV is in motion or can be programmed to sound when suitable.

Anti-collision sensors

Anti-collision sensors or slow down infrared sensors can also be added on the AGV and will reduce the travel speed when detecting an object. These sensors are used to make a more comfortable stop when the AGV is approaching a person.

Key switch

All AGV Electronics AGVs has a key switch, which is used for turning on the power to the AGV and switching between manual and automatic mode.

The key must be in the vehicle to enable manual mode and is a way of avoiding non-authorized personnel to handle the AGV in manual mode.

Stability

The stability of an AGV must be taken into consideration during the design. AGV Electronics uses standards for manual forklift when calculating the stability of an AGV. The stability is always a part of the type test, which must be done for every new vehicle type.

To control the stability is the speed is automatically reduced in sharp curves and at high lift heights with a forklift AGV.