Collaborative robots are on the rise. These machines are being built to aid humans at home and at work. But they're not entirely safe yet. Earlier this year, a Volkswagen factory worker died at the hands of an assembly line robot in Kassel, Germany. A mechanical arm that pieces the cars together reportedly gripped the 22-year-old man as he was crushed against a metal plate. According to the report, over the last decade, there were 158 incidences of injuries that involved robots and humans in Germany alone.

These horrific accidents have raised pertinent questions about safety and liability that will need to be addressed for man-machine environments. For now, Behrens hopes to find a way for robots to be built with a better understanding of the human threshold for pain. "The best way is to avoid contact in the first place," he told Bloomberg. "If contact occurs, the consequences must be so low that the person can come into work the next day, at most with a bruise but not with an injury or open wound."

[Image credit: Martin Leissl/Bloomberg]