Collaborative robots

Max Erick Busse-Grawitz (maxon motor ag)

Robots that work together with humans and take over unpleasant or dull tasks, thus making the production process more cost-efficient: collaborative robots, in short cobots, can satisfy this need. But the technology is still lagging behind the need, which is why collaborative robots are still a technological hopeful and not yet a star technology.

The situation today

The term “collaborative robot” is precisely defined in ISO norms 10218 and 15066 and includes the sporadic or constant collaboration between humans and robots. These collaborations require direct and contextual interaction: either the robot slows down when moving into the human working area, or the robot application is so safe that cobot and human work hand in hand. The major challenge lies in making robot applications safe and economically feasible at the same time: large quantities are best performed by dedicated machines, while for small volumes it is significantly cheaper to instruct a worker than to programme a robot. What remains are medium sized lots where both robot automation and manual work by themselves would be too expensive. As of today, there are few of those applications for cobots. Most often they  would be too expensive and too slow due to safety requirements and to the lack of technological maturity. The general safety requirements are defined in ISO 13849 or IEC 62061 and in ISO 10218-1 and -2, and are specified for collaborative robots in DIN ISO/TS 15066:2017-04. The latter norm is based on methods that are known in academic research, but that have barely made it to the industry. The technological gaps concern the fast force control with low inertia, impedance control strategies and their implementation in easily programmable industrial products. There has been some progress in three areas, however: intelligent grippers and intelligent robot skins combine sensors and actors. In software, there has been progress in terms of user interfaces and easier programming. And there are now several manufacturers offering integrated solutions with cobots on mobile platforms.

In Switzerland, the situation remains unchanged: there are many SMEs featuring small lot sizes, a high variance and high unit labour costs, making the use of collaborative robots attractive. Still, the integration of collaborative robots into production is slow, both in Switzerland and internationally. In Switzerland, cobot sales figures are decreasing and there is some disillusionment. A cobot is not just an intuitively programmable work colleague surrogate. That is why today we still find cobots in low-frequency tasks, like loading and unloading of machined parts. These and other tasks for cobots commonly fall under the “4D”: dull, dirty, dangerous, disallowed.

Future prospects

Using cobots will become attractive once there is a change in thinking and products and production infrastructure  are “designed for automation”, for example by creating suitable shapes or by using fiducials. As a matter of fact, the key technologies required for a productive use of cobots are advancing steadily, but very slowly. Progress is expected in the following realms: grippers with integrated compliance and rapid force measurement, cheaper and more robust object recognition, and intuitive programmability. For these areas, it would be wise for large and small enterprises to consult with possible research partners prior to purchase, in particular with universities of applied science working in collaborative robotics. Such institutions can suggest effective approaches to reduce costs while increasing the robustness of the production process, or the possibility of providing an unbiased assessment of robots. Long-term research focuses on intuitive, task-based programming and on human-robot collaboration with intent detection and dynamic path adjustments.