FEATURE ROBOTICS & MOTION CONTROL
A FUTURE WITH COLLABORATIVE ROBOTS
Collaborative robots, sometimes referred to as ‘cobots’, are expanding the possibilities of automation as they are often easier to deploy and use, offering more flexible manufacturing practices, but they do represent new safety concerns as Stewart Robinson, principal engineer and functional safety expert at TÜV SÜD Product Service explains...
D
ue to advances in sensor and robot controller technology, collaborative robots often operate in the human- occupied workspace without safety fencing. However, not all collaborative robots are guard-free, depending on their function and related safety requirements. For example, the tool the robot carries may mean guarding is still needed. While cobots offer more flexible
production automation, they do represent new safety concerns. There is currently an international and European standard relating to industrial robot systems, which has two parts: • EN ISO 10218-1:2011 Robots and
robotic devices — Safety requirements for industrial robots — Part 1: Robots. • EN ISO 10218-2:2011 Robots and
robotic devices — Safety requirements for industrial robots — Part 2: Robot systems and integration. The current standards describe four
measures for risk reduction, of which it is required that at least one is fulfilled, in addition to having visual indication that the robot is in collaborative operation. 1. Safety-rated monitored stop When a human has entered the
collaborative workspace, the robot should be stopped until the human leaves. 2. Hand guiding The human can guide the robot at the end effector by hand, that is the tool adapted on the robot arm with which the robot performs tasks. 3. Speed and separation monitoring The robot must maintain a specified separation distance from the human and operate at a predetermined speed. 4. Power and force limiting by
inherent design or control The power and force of the robot actuators is monitored by safety related control systems.
24 OCTOBER 2015 | AUTOMATION
Stewart Robinson, principal engineer and functional safety expert at TÜV SÜD Product Service, a global product testing and certification organisation
NEXT STEPS A Technical Specification (ISO/TS 15066 Robots and robotic devices — Safety requirements for industrial robots - Collaborative operation) was started in 2010, and is currently under preparation, to deal specifically with the rapid pace of robot technology enhancement. ISO/TS 15066 covers: • The design of the collaborative work space.
• The design of the collaborative
operation: - minimum separation distance and
maximum robot speed - static (worst case) or dynamic
(continuously computed) limit values - safety-rated sensing capabilities - ergonomics • Methods of collaborative working: - safety-rated monitored stop - hand-guiding - speed and separation monitoring - power and force limiting
(biomechanical criteria) • Changing between: - collaborative/non-collaborative - different methods of collaboration • Operator controls for different
applications. There are also working groups of the standards organisations reviewing various aspects of human-machine interactions, which will also inform the development of future standards. But for now, EN ISO 10218 Parts 1 and 2, and the ISO/TS 15066 specification defines the safety requirements for the sphere of collaborative robots, with the most relevant published guidance being contained in EN ISO 10218.
HSE GUIDANCE Published in 2012, a Health & Safety Executive (HSE) Research Report, (RR906) - Collision and injury criteria
when working with collaborative robots, also offers some useful guidance. The introduction to the HSE report states that “this study explored the safety, reliability and evidence for the force limits defined by the draft TS 15066, and of the methods for testing them. It also addressed whether the proposed approach in the draft TS 15066 is likely to adequately protect people from the risks. Risk assessment of potential collision scenarios, human reliability and behaviour issues, and equipment failure modes and rates are discussed, as is the adequacy of personal protective equipment against collision injuries”. The report identifies several areas that the HSE considers need more consideration within ISO/TS 15066. For example, it concludes that the psychological, behavioural and organisational aspects affecting the level of human-robot collision risk, along with the effects of human movement velocities, are not strongly represented in ISO/TS 15066. The HSE also points out that the frequency of injury is not included in the criteria for acceptable collision limits. While the cobot offers exciting
possibilities for industry, some end- effectors may create hazards, especially as contact between the collaborative robot and the operator can lead to the possibility of collision. It is therefore vital that a complete risk assessment is undertaken before a cobot is deployed, as you would with any machinery in the workplace. This must cover the intended industrial workplace, with the basis for this risk assessment being EN ISO 10218 Parts 1 and 2, alongside the Machinery Directive.
TÜV SÜD Product Service T: 01642 345637
www.tuv-sud.co.uk
/AUTOMATION
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72