Safety System: Robots, workers can unite

Robots interact with humans every day in the manufacturing arena, but safety between the two remains an issue. However, a new projection and camera-based system is designed to prevent collisions between robots and humans working together.

09/09/2011


Picture this scenario: A robot lifts and positions a heavy component while a worker welds lightweight aluminum components to a machine right next to it. Humans and robots will be able to team, especially on assembly jobs, and collaboratively play off their strengths: Steel assistants could bring their power, durability and speed to bear and humans their dexterity and motor skills.

At present, automated robots usually stay enclosed within protective barriers. Industrial safety regulations permit contact between people and robots only under certain conditions since the risk of injury to humans is too great. In order to allow their collaboration, new technologies have to define workplaces and safe zones, which humans may not enter.

That is where the ViERforES project comes in. Supported by the German Federal Ministry of Education and Research, researchers at the Fraunhofer Institute for Factory Operation and Automation IFF developed a solution that monitors workplaces.

This safety system employs conventional projectors and cameras, which are normally mounted on the ceiling.

One 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. The robot decelerates at once. In addition, the system could generate optical and acoustic warning signals. Another distinctive feature is the variability of marked areas’ position and size and the capability to give them any shape – for instance, a circle, a rectangle or any freeform.

“Since we employ common standard components, our system can be installed cost effectively,” said Dr. Norbert Elkmann, Robotic Systems Business Unit Manager at the Fraunhofer IFF. “The projector and camera are calibrated and synchronized to one another.”

When a larger area needs monitoring, you could extend the system as desired 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, e.g. sunlight and shadow,” Elkmann said. “Present purely camera-based space monitoring systems operate independently of external light only to a limited extent.”

In addition, the experts can combine this system with robot controls and thus dynamically modify danger and safe zones. If, for example, a robot only works to the left of its workspace at times, the system would not have to monitor the maximum robot workspace.

Elkmann and his team have filed a patent for their system. A prototype already exists. The potential applications of the projection and camera-based system are not merely limited to safe human-robot interaction. It can monitor other spaces in which safety is relevant. The system can also see use wherever safe zones might not be perceptible – by projecting invisible light.

- Edited by Chris Vavra, Plant Engineering, www.plantengineering.com 



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