Projecting Safety onto Robot-Filled Work Zones
MAGDEBURG, Germany, July 12, 2011 — Human employees working next to industrial robots — rather than in separate areas — could become common because of a new imaging system that keeps an eye on both.
At present, automated helpers are usually enclosed by protective barriers. Industrial safety regulations permit contact between people and robots only under certain conditions because the risk of injury to humans is too great. In order to allow human-robot collaboration after all, new technologies must define workplaces and safe zones, which humans may not enter. A robot will stop or slow down whenever a human enters a designated safe zone. As part of the ViERforES project supported by Germany’s Federal Ministry of Education and Research, researchers at the Fraunhofer Institute for Factory Operation and Automation (Fraunhofer IFF) have developed a system that monitors workplaces highly flexibly.
Visible lines denote the safe zone. Should a person enter the zone, a robot will stop its work, and a warning may be signaled. (Photo: Fraunhofer IFF)
The Fraunhofer IFF system employs conventional projectors and cameras, which typically are mounted on the ceiling above a work space. One distinctive feature of the system is its projection of monitored safe zones directly onto a floor or wall. Projected beams produce visible lines in the work area. Thus, humans recognize the safe zone right away and know how close they may get to a robot. The camera immediately detects any intrusion in the safe zone by an individual when the projected lines are disrupted. When the system is triggered, the robot decelerates at once, and optical and acoustic warning signals can be generated.
Another distinctive feature is the variability of marked areas' position and size as well as shape — for instance, a circle, a rectangle or any free-form contour.
"Since we employ common standard components, our system can be installed cost-effectively. The projector and camera are calibrated and synchronized to one another," said Norbert Elkmann of Fraunhofer IFF. When a larger area must be monitored, the system can be extended by additional projectors and cameras.
The monitoring system operates with modulated light. "The advantage of this is its reliability even under the effects of external light, from sunlight to shadow. Present purely camera-based space-monitoring systems operate independently of external light only to a limited extent," Elkmann said. In addition, the experts can combine this system with robot controls and thus dynamically modify danger and safe zones. If, for example, a robot works only to the left of its work space at times, the maximum robot work space would not have to be monitored.
The potential applications of the projection and camera-based system are not limited to safe human-robot interactions. Other spaces in which safety is relevant, such as public buildings, can be monitored. The system also can be used wherever safe zones ought not to be perceptible — by projecting invisible light.
For more information, visit: www.iff.fraunhofer.de
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