Industrial Robots with a Proximity Detection System for Safe Human-Robot Collaboration
The primary distinguishing features of industrial robots are high load carrying capacities, high ranges, precision and robustness. Manufacturing has great need of robots with high load carrying capacity for human-robot collaboration. Since the potential risk for humans in the event of a collision is naturally greater than when robots are smaller, the use of robots with high load carrying capacity in the direct vicinity of humans requires smart sensor systems such as capacitive sensors that detect proximity. The Fraunhofer IFF has demonstrated the use of such capacitive sensors on an ABB IRB4600, a medium duty industrial robot with a 60 kg payload.
Given the high forces and the robot’s stopping distances, collision detection solely with the aid of a tactile skin that detects contact is often not enough to eliminate injuries. That is why a hybrid sensor system was developed, which uses locally distributed capacitive sensors in addition to tactile sensors to detect proximity. This makes it possible to detect a person’s presence early and to stop or at least decelerate robot movement before a collision occurs. The detection range is 10 to 15 cm when a hand approaches and even larger for bigger body parts such as a head or torso. The use of several distributed sensors additionally allows localizing proximity, thus making smart evasive movements possible as well.
In the demo application, the hybrid sensor system was implemented on axes 3 to 6. An entire robot can be made safe because the hybrid sensor system can be modified for virtually any geometry.