Mobile Robot Communication Without the Drawbacks of Wireless Networking

The default solution for mobile robot communication is RFnetworking, typically based on one of the IEEE 802.11 standards also known as WLAN technology. Radio communication frees the robots from umbilical cords. But it suffers from several significant drawbacks, especially limited bandwidth and range. The limitations of both aspects are in addition hard to predict as they are strongly dependent on environment conditions. An outdoor RF-link may easily cover 100m over a line-of-sight with full bandwidth. In an indoor environment, the range often drops to a few rooms. Walls made of hardened concrete even completely block the communication. Driven by a concrete application scenario where communication is vital, namely robot rescue, we developed a communication system based on glassfibre links. The system provides 100MBit ethernet connections over up to 100m in its default configuration. The glassfibres provide high bandwidth, they are very lightweight and thin, and they can take a lot of stress, much more than normal copper cable. The glassfiber links are deployed from the mobile robot via a cable drum. The system is based on media converters at both ends. One of them is integrated on the drum, thus allowing the usage of inexpensive wired sliprings. The glassfibre system turned out to be very performant and reliable, both in operation in the challenging environment of rescue robotics as well as in concrete experiments.