Sep 23, 2008West Virginia and Kentucky mines are using or testing wireless systems that employ telecommunications technology in conjunction with active RFID tags and readers to locate miners in underground tunnels. Although the mines in both states use Axcess International RFID Dot tags, they utilize different wireless platforms to relay RFID and telecommunications data.
An unnamed West Virginia mine, for instance, is using an RFID-based tracking system known as MineAx, provided by Tunnel Radio of America, in conjunction with Tunnel Radios' UltraComm wireless networking technology. Several other West Virginia mining companies will be installing the system later this year as well.
The MineAx system employs Axcess' active RFID tags and wireless readers to ensure real-time data regarding its miners' locations as they move around tunnels underground. The system will help West Virginia mines comply with the Mine Improvement and New Emergency Response Act of 2006, which requires improved communications and emergency plans in the event of an underground mine accident.
With MineAx, when miners enter a shaft, they first pass through an Axcess reader portal. The portal reads the miners' Axcess Micro-Wireless ID active RFID tags, which can be placed in a pocket or attached to a hard hat. The portal emits a 126 kHz signal that awakens a dormant tag, which begins transmitting a signal in the 315 to 433 MHz ultrahigh-frequency (UHF) band. Typically, the portal contains two readers, one located in front of a mine's entrance, the other behind that entrance. The read sequence is then interpreted by Tunnel Radio software and provides data as to whether a particular miner is entering or leaving the mine. Elsewhere throughout the mine, additional RFID readers are deployed.
At the West Virginia site, the readers transmit data to the mine company's back-end system via the UltraComm wireless network, which includes a leaky feeder—a cable deployed throughout the mine that has "gaps" enabling it to function as a radio antenna and thereby emit and receive RF signals along its entire length. The mine utilizes the same UltraComm wireless network to support its two-way telecommunication system, also provided by Tunnel Radio. According to Mark Rose, Tunnel Radio's president and CEO, the two-way wireless communication system enables the mining company to contact underground miners via a Motorola radio each worker carries on a belt.
On the back-end system, Tunnel Radio software interprets that data and displays the employees' locations on a mine map generated from a computer-aided design (CAD) drawing of the mine. On that map, Rose says, a small hat icon represents each individual in the mine, color-coded according to that person's job function or experience. By placing the cursor over a hat, a manager can read the employee's name, as well as any other necessary data about that individual. If a miner has a problem, he can use the Motorola radio to place a call, and the manager or dispatcher can then utilize the RFID system to locate that worker on the display and communicate with him accordingly.
The system does not always provide real-time data, Rose says, but instead pinpoints the location of the most recent RFID transmission—that is, when the miner last came within range of an RFID reader, and which reader it was. Based on the sequence of transmissions, he explains, as well as information regarding the miner's work assignment for that day, dispatchers can approximate that miner's location.
Tunnel Radio software also allows a user to pull up manifests listing who is in a particular tunnel at any given time, Rose says, and who has recently entered or exited. During an evacuation, for example, a manager can watch names leave the "in" manifest and appear in the "out" manifest.
Rose has been at mines when accidents have occurred, he says, noting, "The first thing managers ask is, 'Who's in?'" At any given time, a mining company may have employees, contractors, electricians, inspectors and various other visitors within its tunnels. "If everyone is electronically tracked, you have a really good idea of who is where," he says.
Tunnel Radio is providing the MineAx Bird Dog system to existing customers using the two-way radio system, and also has some new customers for the combined solution. "We're a one-stop shop, and people really like that," Rose states. Some mines span as much as 80 miles, he says, and the system can transmit data throughout their length. The system has received the requisite Mine Safety and Health Administration (MSHA) and State of West Virginia approvals for operating in that state's mines.
According to Griebenow, the active RFID tag is small enough that a person can easily carry it into the mine, but has a transmission range of 150 feet to 1,000 feet in optimal conditions. UHF-based transmissions are the best in this environment, he says, because they are robust and do not interfere with any existing Wi-Fi systems.
Axcess is currently working on further features for the DOT tags and readers, including panic buttons for miners in emergency conditions, as well as sensor capabilities that would transmit a person's temperature or indicate whether that individual is moving.
The state of Kentucky has also been looking into RFID tracking systems that work in tandem with communications backbones. Last week, Foundation Telecommunications Inc. (FTI) completed a pilot for the state using its own satellite communications and tracking system, combined with Axcess RFID tags and communications hardware and integration services from Architron XRF.
The 30-day trial was completed on Sept. 19. In this case, the research team utilized a system of tunnels closely resembling the coal mines of Kentucky. FTI placed 12 wireless nodes every 250 feet throughout the tunnels, which are located in Missouri. Each node, provided by Architron, contained an Axcess interrogator, a telephone handset, a video camera and a computer keyboard that enabled voice, data and video communications.
From there, explains Byron del Castillo, Architron's CEO, the data was made available on a Web server that authorized users in remote locations could then access via the Internet to gain information regarding the miners' location in the tunnels, or real-time audio or video images of what was happening in the mine. Because the nodes were placed 250 feet apart, and since the RFID readers proved able to receive transmissions at about 125 feet, FTI had real-time visibility the entire time a miner was in the tunnels.
The wireless mesh system, del Castillo says, enabled multiple transmissions, including voice, RF data and video, all to be directed to the Internet-based system. "At any time," he explains, "if there was a collapse, we would know what zone they are in."
Kentucky has approved the initial pilot's results, and the system must now receive MSHA approval before FTI can commence marketing it to Kentucky mines. FTI first began discussing such a system with the state approximately two years ago, according to FTI's president and CEO, George Livergood.
"We started looking at RFID companies, and we came across Axcess and liked the technology path they were taking," Livergood says. "That was when we hooked up with them [Axcess and Architron]. With this system, you could be in a conference room in Kentucky and see a miner down in a tunnel in Missouri."
The FTI software system displays a list of employee names, and when a name is selected, it also provides pictures and other details about that particular miner. While awaiting MSHA approval, Livergood says, researchers plan to spend several more weeks working out the mounting of the nodes on tunnel walls. The nodes must be installed within 3 inches of the ceiling, he says, noting. "We've proven without a doubt that wireless mesh works."