Achieving a safe mobile robot installation

Autonomous mobile robots (AMRs) are increasingly used to automate the transportation of materials through industrial buildings, leaving companies with questions on how to ensure a safe robot installation.

According to the International Federation of Robotics (IFR), the market for AMRs in logistics automation is booming, with an expected increase from 110,000 in 2018 to more than 700,000 in 2022. This represents a CAGR of 45% in the manufacturing industry and 60% in non-manufacturing environments such as e-commerce and hospitals. While these mobile robots are designed to navigate safely around people, rapid changes in the market can leave companies with questions on how to ensure a safe mobile robot installation. With an increasing number of AMRs being installed, new AMRs on the market and new customers with limited experience with this new technology, the topic of mobile robot safety is more important than ever.

Which safety requirements should AMRs live up to today?

AMRs are designed to work safely in environments with people

AMRs complete their given missions using sensors and software algorithms to manoeuvre through dynamic environments, avoiding obstacles and for some AMRs recomputing their path on the fly. Extensive built-in safety mechanisms allow the robots to navigate collaboratively around human co-workers by slowing down, changing direction or stopping to avoid collision. These safety features are key to the success of mobile robots, but companies deploying AMRs need to go a step further to ensure workers’ ongoing safety. Safety standards are made to ensure machines and robots operate in a way that does not bring humans into dangerous situations when working with them.

It is important to distinguish between the AMR, which is the mobile robot itself, and the AMR system, which is the AMR (or fleet of AMRs), charging stations, load transfer stations, top modules that are mounted on the AMR to create a complete machine and other peripheral equipment within the environment where the AMR operates.

The AMR is defined as the out-of-the box mobile robot without top modules and without the customer environment taken into account.

Understanding applicable standards, laws and directives for mobile robots

Legal requirements must also be understood and properly applied in order to ensure that mobile robot applications remain as safe and reliable as they are intended to be. In response to the rapid adoption of AMRs, global standards organisations are updating and developing guidelines for the safe design, manufacture and commissioning of mobile robots. The development of this new technology has been faster than the development of relevant standards. But in the meantime, mobile robot manufacturers, purchasers and integrators must enforce safety requirements using a variety of existing standards that focus on similar applications of industrial vehicles, even though these were not written specifically for AMRs.

The most applicable standard for AMRs is currently EN 1525:1997 – Safety of industrial trucks – Driverless trucks and their systems. This standard applies to an automated guided vehicle (AGV) as well as its systems and also applies to the commissioning and preparation of the environment in which the robot will be used. EN 1525 is a European standard that establishes strict safety requirements for vehicles from AGVs to industrial trucks, which often are larger and heavier than AMRs and can have a completely different set-up. One key difference is that EN 1525 does not take autonomous navigation into account. However, EN 1525 fills the void for safe implementation of mobile robots until newer standards are adopted that also address potential hazards connected to AMRs. The ANSI/ITSDF standard B56.5-2012 is an American standard that was also written to address AGVs and has the same scope as EN 1525. An update of B56.5 was published in August 2019.

A well-designed AMR system should be able to work safely around people.

Like standards, laws related to worker safety and machinery can vary widely by geography. In the European Union, a user can assume that a mobile robot that has a CE mark is safe and meets relevant standards because it has been designed and manufactured according to the Machinery Directive (MD). This means that if the robot is used as promoted or described in the manual and an injury occurs, the manufacturer, rather than the customer, can be liable for the injury.

It is important to note that the CE mark only covers the robot itself, not the AMR system as a whole. When one or more mobile robots are deployed into a facility with top modules, loading stations and chargers, the full system also needs to be CE marked by the part that is responsible of commissioning the AMR system.

Upcoming standards

Standards organisations worldwide are working on new standards that address AMRs. The successor to EN 1525 as the most applicable standard for AMRs is ISO/FDIS 3691-4 – Driverless industrial trucks and their systems, which was scheduled for release in January 2020. ISO/FDIS 3691-4 addresses safety concerns for internal logistics and the hazards related to recompute paths on the fly, which are key aspects of AMRs. The new standard will provide detailed requirements for commissioning mobile robots as well as environment and work-cell design.

There are also other standards in progress that will likely have impacts on manufacturers, users and integrators of mobile robots in the future. These include ISO 10218, prRIA 15:08 and prUL 3100, each of which addresses different aspects of AMRs and their implementation.

Summary

Standards and laws that are amended for AMRs are under development and planned to be introduced in 2020:

• Safety standards are developed to ensure that robots do not bring humans into dangerous situations when working with them. Therefore, it is important that your AMR manufacturer follows the current standards that are developed for logistics applications to make sure you have a safe AMR and AMR system.
• Safety standards and laws are determined locally by country/region, so deployed AMRs must meet those local standards.
• The European standard EN 1525:1997 and the CE mark provide a good framework when it comes to safety for the AMR as well as the AMR system. While it is not a requirement to comply to EU laws and standards outside the EU, it makes sense to use these principles to ensure a safe AMR system across all regions.
• For global manufacturers that are making global use of AMRs, the European standards and laws provide a good framework that can be applied to all factories with an amendment to address local aspects.

Manufacturer, integrator and customer responsibilities

A safe workplace requires a joint effort from the AMR manufacturer, the integrator of the AMR system and the end user. It is essential that roles and responsibilities between the parties are clarified.

The guidelines provided by the European MD help customers and integrators ensure a safe workspace as the MD takes into account both the AMR and the full AMR system. By law, it is not required to follow the MD outside EU, but it is recommended to do so as it describes the current state of the art for safe AMR installations.

The manufacturer of the AMR must provide a vehicle that is designed to be commissioned in a safe AMR system and provide adequate information for integration and operation. This means that the manufacturer is responsible for specifying intended use and limitations of the AMR, which is typically to transport materials without a driver in industrial environments. The manufacturer must CE-mark the AMR according to intended use through compliance to safety standards for AGVs, comply with complementary standards to address all risks and provide integrated safety functions to address hazards expected in the intended use.

In addition to designing a safe robot, the manufacturer must also provide adequate documentation, including instructions regarding commissioning of the AMR into an AMR system, operating instructions for operation and maintenance of the AMR, and a list of identified residual risks for the AMR. Ultimately, the manufacturer is responsible for providing a safe AMR out of the box with all the required documentation.

At the time of installation, the responsibility moves to the integrator of the system. The integrator of the AMR system (which may be the end user if they are integrating the robot themselves) is responsible for providing an installation where all hazards are addressed or identified and providing adequate information for operation. Because AMRs can be programmed to move throughout a building, factory or warehouse, the integrator who commissions the AMR must anticipate potential safety hazards and program the robot to act appropriately in compliance with safety standards. Commissioning also extends to the top module. If the robot is commissioned outside of those limitations, the integrator (or user) must incorporate additional protections to ensure that safety standards are met for the full robot application. The integrator must therefore specify the intended use and limits of the AMR system and make a risk assessment of the AMR system in the light of the AMR manufacturer’s specifications, intended use and limitations. As the application changes from an AMR to an AMR system, the integrator must CE-mark the AMR system according to the new intended use, and provide documentation consisting of operating instructions for operation and maintenance of the AMR system and a list of identified residual risks from risk assessment for the AMR system.

Roles and responsibilities to ensure a safe AMR system workspace. For a larger image, click here.

Once the AMR system has been deployed, the end user is responsible for setting up and following procedures for operation and maintenance of the AMR system. The end user must ensure that the intended use and limitations are met, and set up procedures for inspections and maintenance for the AMR system, including warning and markings. The end user should define safe operating procedures for operators and define training for operators, other staff and visitors for safe operation.

Deploy a safe AMR installation in close cooperation with your AMR manufacturer

The state of the art in the design and implementation of mobile robots is changing rapidly, and standards organisations are challenged to keep up. Compliance with current standards developed for logistics systems is still relevant, however. Many factors must be taken into account when deploying not just an AMR but an AMR system, which is often working in many different locations of a facility and in different applications. Users and integrators should expect guidance from robot manufacturers in order to reap the benefits of AMRs while ensuring workers’ safety. At the same time, users must ensure that chosen AMR manufacturers are up to date with current and future safety standards and laws not limited to the AMR itself.