Safety requirements for industrial robots

Ensuring the overall safety of a robotic solution is an extensive exercise as robot technology draws on several technical disciplines. The increased need for adequate protection of people from the safety risks associated with industrial robot systems led to the development of EN ISO 10218:2011 - “Robots and robotic devices - Safety requirements for industrial robots”. This is an international and European standard which covers the safety requirements for industrial robots.

ISO 8373 – “Robots and robotic devices — Vocabulary” - defines an industrial robot as: “An automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications.”

An ever-increasing number of manufacturing and logistics processes are now fully automated, and often assisted by industrial robots and automated guided vehicles (AGVs/AMRs). With their enhanced capabilities, robots can be the key to innovative processes and new services. Depending on the task and the selected solution, a robot can work in collaboration with the user, or work completely autonomously.

Safety is of the highest priority when humans and robots are working side by side. Consequently, robot manufacturers are faced with a broad set of safety requirements, as reflected in numerous technical guidelines and standards. To ensure reliable performance and safety, manufacturers, suppliers, integrators and operators must assess and validate robot compliance against a range of different standards, as well as considering application-specific requirements. For example, combinations of AGVs or AMRs with collaborative robots (cobots) necessitate particularly stringent safety requirements.

Collaborative applications

Cobot systems can combine manual and automated assembly operations to form a hybrid system, thereby uniting the strengths of humans and robots. If wisely deployed, cobots can increase process efficiencies and product quality, as well as relieve humans from physically exhausting and repetitive work. In its 2020 report summary, the International Federation of Robotics stated that: “There are still many “4d” (dull, dirty, dangerous and/or delicate) tasks that could be done by robots, improving worker health, safety and job satisfaction."

While EN ISO 10218contains some guidance on the use of collaborative robots, with the rapid pace of technological development, it was widely acknowledged that this needed to be enhanced. Consequently, ISO/TS 15066 – “Robots and robotics – Collaborative robots” was published in 2016. A barrier-free environment where the safety of the employee is always guaranteed is a basic requirement for a collaborative application and the technical specification should be followed.

The methods of collaborative working ‘speed and separation monitoring’ and ‘power and force limiting’ are particularly elaborated on in ISO/TS 15066. This includes recommendations for ‘biomechanical limits’ of pain thresholds for specific parts of the human body. Risk assessment according to EN ISO 12100 can also be used to define the safety requirements for collaborative industrial robot applications and their working environment.

An essential component of a cobot application is the robot end effector. Obviously, it is not possible to process and handle any items without it, but it does represent a possible risk. The force required for gripping and the specific handling of the work piece are crucial safety factors. ISO TR 20218-1 outlines the interface and safety requirements for gripper systems.

Industrial robots

Successful certification of industrial robots, robotic systems, and control systems demands compliance to all applicable technical guidelines and standards, and testing should cover the following aspects:

• Heavy loads and high speeds
• Unexpected start-up or behaviour
• Collision with work pieces or the surroundings
• Ejecting work piece items
• Presence of humans in the critical area

Service robots

Service robots and personal assistant robots differ profoundly from industrial robots, as this robot category typically performs high-value, individual and often (semi-)autonomous actions. This means it is usually characterised by great flexibility and a high level of autonomy. To perform their tasks - which often includes replacing or supplementing human activity – personal assistant and service robots must utilise learning and re-programming features to determine and analyse their environment.

Requirements for humans and robots to work together safely include:

• Uniform standards for hardware and software components
• Industrial security and aligned communication protocols
• Efficient determination of the environment
• Short reaction times
• High intelligence of the service robot systems
• Easy and intuitive operations (such as speech and gesture control)

Mobile robots

Mobile robots help to automate and optimise logistics processes. As they provide continuous service around the clock and can be flexibly assigned for a variety of applications, their contribution to increased efficiency and productivity is significant.

AGVs form a floor-based conveyor network which follow fixed routes, usually along wires or magnets embedded in the ground, helping to automate and optimise logistics processes. They therefore play a major role in process automation and materials transportation across a range of sectors, including manufacturing, logistics and hospitals. In smart factories and the Industry 4.0 environment, AGVs are particularly critical for sustainably enhancing efficiency in intralogistics. However, their extremely diverse applications pose distinct challenges to manufacturers and system integrators.

Autonomous Mobile Robots (AMR) are more sophisticated and packed with sensors and powerful on-board computers that allow them to navigate dynamically using a map. They are smart enough to recognise and react to obstacles to safely perform their function in a busy environment

As AGVs and AMRs provide continuous service around the clock and can be flexibly assigned for a variety of applications, their contribution to increased efficiency and productivity is significant. While their application within industry can be varied, AGVs and AMRs all have essential subsystems in common.

An Industrial Mobile Robot (IMR) is a combination of an AGV and AMR with an ‘Industrial Manipulator’ (robot). Market specific requirements that must be taken into consideration include U.S. standard ANSI/RIA R15.08– “Safety Standard for Autonomous Mobile Robots”, and international standards ISO 10218 parts 1 and 2.

In the European Economic Area (EEA) IMRs are required to comply with the Machinery Directive, which for the UK market aligns with the Supply of Machinery (Safety) Regulations 2008. This requires a task-based risk assessment, for which the guidance in the international standard ISO 12100 – “Safety of machinery - General principles for design - Risk assessment and risk reduction” can be used, although it does not explicitly mention collaborative applications.

Safety is a prerequisite for the use of robotics, as a system failure can have severe consequences for people, equipment and operations. Although the landscape of robotic safety requirements is fragmented, a combined application of established standards and industry best-practices will ensure the safety of your robotic solutions.