Human-Robot Collaboration: a key driver for manufacturing sustainability in Europe
Today, Europe is experiencing the re-shoring of production facilities previously off-shored to emerging countries. Comparing Europe to emerging countries, the higher cost of labour means that automation is a key element in the growth of manufacturing (Bortolini, 2017). In this context, the adoption of a large use of robotics in production and assembly are key factors in making manufacturing within Europe economically viable. For these reasons, the European market for manufacturing robots is strongly expected to grow through diversification into industries with lower volumes, and into areas of manufacturing where manual assembly has previously moved away from Europe. For a manufacturing company which requires low installation and running costs and a high degree of flexibility, which cannot typically be provided by traditional large-scale manufacturing robotics, reshoring is also likely to be driven by the availability of highly flexible and easy to use manufacturing robots.
Recently introduced sensors and robot technologies enable different degrees of HRC on the factory floor, ranging from fenceless coexistence to close collaboration. According to the world's first specifications of safety requirements for collaborative robot applications (ISO/TS 15066:2016), collaborative operations between humans and robots may include one or more of the safeguarding methods depicted here
Representation of HRC safeguarding methods as per ISO/TS 15066:2016 (PILZ GMBH & CO. KG)
Safety-related stop (STO)
The robot motion ceases before an operator enters the collaborative workspace to interact with the robot system and complete a task (e.g. loading a part onto the end- effector). Robot system motion can resume without any additional intervention only after the operator has exited the collaborative workspace.
The operator uses a hand-operated device to transmit motion commands to the robot system. Before the operator is permitted to enter the collaborative workspace and conduct the hand-guiding task, the robot achieves a safety-rated monitored stop. The task is carried out by manually actuating guiding devices located at or near the robot end-effector.
Speed and distance monitoring
The robot system and operator may move concurrently in the collaborative workspace. Risk reduction is achieved by maintaining at least the protective separation distance between operator and robot at all times during robot motion. When the robot system reduces its speed, the protective separation distance decreases correspondingly.
Power and force limiting
A physical contact between the robot system (including the workpiece) and an operator can occur either intentionally or unintentionally. Power and force limited collaborative operation requires robot systems specifically designed for this particular type of operation. Risk reduction is achieved, either through inherently safe means in the robot or through a safety-related control system.
In modern factories, human and robots can share workspace in different ways, and in the robotic community the terms coexistence, cooperation and collaboration are widely-used in the robotic community to refer to a case in which a human and a robot are working together in a fenceless environment, giving rise to misunderstandings and unclear wording. Behrens, Saenz, Vogel, & Elkmann, (2015) propose a taxonomy based on three essential characteristics of collaborative workcells that may build on each other to determine different forms of co-work:
The human co-worker is intended to carry out a certain task in at least a limited part of the robot workspace.
The human co-worker is intended to carry out a certain task within the shared workspace while the robot is moving to complete its task
The human co-worker is intended to work hand in hand with the moving robot.
It is the closest form of cooperation and refers to joint actions to complete a common task at the same time, with physical contact needed and therefore included.
The Rossini answer
The involvement of the Robotic Systems Unit at the Fraunhofer Institute for Factory Operation and Automation IFF allowed to include, in the ROSSINI platform, also a set of tools and guidelines to speed up and increase the efficiency of risk assessment and validation procedures for HRC, particularly when measuring collision. Finally, in order to ensure an adequate feedback from end users and demonstration of the platform’s functionalities, the consortium added MACHINEBOUW, an experienced robot integrator, and three manufacturing companies, which will provide three use-cases related to Domestic Appliances Assembly (WHIRLPOOL), Electronic Components Production (SCHINDLER) and Food Products Packaging (IMA).
Through ROSSINI, the limits to HRC spread expressed above will be systematically addressed:
1) Safety requirements limiting applications in terms of speed and payload:
the ROSSINI platform will allow for higher working speeds and reduced separation distance in HRC thanks to specific technological improvement at the level of sensing, control and actuation technology
2) Need to assess the safety of HRC at the level of application
the ROSSINI holistic approach will carry out an effective harmonisation of different technologies through an integrated platform, thus ensuring the inherent safety of the developed applications
3) Lack of workforce acceptance in HRC
The ROSSINI human-robot mutual understanding will improve the quality of the human job, and will provide an early assessment of the job quality impact on HRC already in the design phase