Event-driven e-skin eases robots’ compute requirements
With this large scale skin, they proceeded to almost entirely cover the body of an H-1 humanoid robot, with skin cells spreading on its upper body, arms, legs and even the soles of its feet. In effect, the sensitive feet also enables the robot to respond to uneven floor surfaces and even balance on one leg.
combining artificial skin with new control algorithms.
Image: Astrid Eckert / TUM
In order to reduce the processing power requirements of such a large number of sensors operating simultaneously, the researchers developed new event-based control algorithms directly inspired from neurosciences. The event-driven approach avoids data overload, as all the sensors no longer need to be interrogated simultaneously at precise clock-cycles but will only send out their data individually upon value changes.
The researchers reported their results in a paper titled “Evaluation of a Large Scale Event Driven Robot Skin” published in the IEEE Robotics and Automation Letters. The 1260 skin cells were distributed in 47 skin patches, combining in total 7560 multi-modal tactile sensors. The authors evaluated the efficiency of the robot skin in both a clock-driven mode and an event-based mode, demonstrating the superior performance of the event-driven system.
In the clock-driven mode, they write, the robot skin system constantly produces 315 000 packets/s, while in event-driven mode the system at most produces 40 000 packets/s (13%). The CPU load reduces drastically, from constantly 270% to at most 100% (37%). Also, in a clock-driven mode, the authors noted that the PC dropped on average 80 000 packets/s (25% of all packets), while in the event-driven mode, package loss was practically negligible. This efficient large-scale robot skin enables the complete onboard integration into a humanoid robot without the need for additional external power or processing capabilities.
skin cells send out their data.
With its special skin, the H-1 could give a person a hug safely, without exerting excessive force, taking into account the various pressure points from its body parts in contact with a human. “This might not be as important in industrial applications, but in areas such as nursing care, robots must be designed for very close contact with people,” explains Gordon Cheng, Professor of cognitive systems at TUM who took part in the research and the original inventor of the hexagonally-tiled robot skin.
What’s more, because the skin consists of individual cells, it remains functional even if some cells stop working. “Our system is designed to work trouble-free and quickly with all kinds of robots,” added Gordon Cheng. The researchers are now working on shrinking the skin cells further and making them cost effective to manufacture in volume.
Technical University of Munich – www.tum.de
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