Evaluation of ZigBee (IEEE 802.15.4) Time-of-Flight-Based Distance Measurement for Application in Emergency Underground Navigation

Low-cost ZigBee (IEEE 802.15.4) modules were evaluated as an underground radio frequency (RF) positioning technology. The work, which was carried out in two tunnels considered representative of the variety of mining conditions, forms part of a study of location technologies for use in a navigation device in mines and tunnels following an emergency incident. Accurate positioning within tunnels was successfully demonstrated over a significant operating range using time-of-flight measurements on multiple channels and combining the results using a filtered averaging algorithm. It was further shown that the technology would continue to provide accurate positioning information in the presence of RF interference from the types of microwave networks commonly used in mines and in the presence of metallic obstructions such as machinery or vehicles that are frequently encountered.