Mining Contract: Design and Demonstration of a Location Tracking System for Underground Coal Mines (Award 1)
Extreme Endeavors partnered with the U.S. Army, Communications-Electronics Research, Development and Engineering Center (CERDEC) to develop a miner tracking system based on inertial navigation technology combined with a reverse RFID correction system. The inertial navigation unit developed by CERDEC has been shown to be accurate for location tracking and navigation in the first responder industry.
RFID has been in commercial use for more than 20 years and relies on storing and remotely retrieving data using devices called RFID tags or transponders. A reverse RFID system (RRFID) uses stationary tags (passive or active) encoded with an exact location and a mobile transceiver (reader) attached to the miner. The reader can keep track of its location relative to the tags that have come within its range. Including passive RFID devices with the inertial system will provide correction over the course of miles and increase accuracy with substantially fewer RFID stations throughout the mine.
Contract Status & Impact
The contract is complete. To receive a copy of the final report, send a request to OMSHR@cdc.gov.
The final prototype system used a micro-electro-mechanical (MEMS) inertial navigation unit (INU) that is worn by the miner. The INU tracks the velocity and heading of miners as they walk through the mine by using miniature accelerometers, gyroscopes, and magnetometers. Phase I (prototype feasibility testing) was completed and the results reported to NIOSH.
Tests at NIOSH's Experimental Coal Mine showed problems with the INU system. Larger-than-expected errors were seen as the miner walked through the mine workings. A consistent drift in the calculated position resulted in approximately 50 to 80 ft of error for every 200 ft of walking distance. This was corrected using the RFID system; however, several deficiencies were seen including:
- Large position errors over relatively short walking distances.
- Short read ranges of the RFID tags that required the miner to walk directly underneath these roof-mounted tags.
- The requirement of the INU to be mounted on the miner's boot.
- Inability of the INU to provide location information when the miner crawled or rode in a vehicle.
For these reasons, this contract was not selected to proceed to phases II and III. While inertial navigation technology may have future promise for miner tracking, this system was not sufficiently mature to provide a commercial tracking system within the funding and timeframe of the MINER Act.