Tunnel-driving machinery is no place for sissies, or sensitive computers. Even in the weak glow of a mining light, one can see how the man in the cockpit shakes from machine vibrations. His eyes are glued on the 23 in. cutting head. It's mounted on a round surface about 11 feet in diameter, and moves along a wall of gravel and sand, carrying material away. A vibrating conveyor belt transports the displaced earth to the back of the machine. The operator looks at the computer touch screen again and again, because it's the only way he can acquire all the data pertinent to the position and movement of the machine, 72 feet below ground.
The touch screen belongs to a rugged industrial PC C12, made by noax Technologies, Sarasota, Fla. The noax touch-panel computer, together with a Siemens SPZAS S7 and software from VMT, is the control and switching center for a tunnel-driving machine used to dig in the Hofoldinger timberland in Germany. The Bilfinger Berger construction company recently built a new water pipeline from Mangfalltal, north of the Alps, to Munich, replacing drinking water pipelines that were more than 120 years old. The new 18.6 miles of pipeline now deliver about 80% of the total drinking water to the capital of Bavaria.
Construction began in 1993; starting August 2002, the tunnel-driving machine together with a noax industrial computer worked 20 hours a day, five days a week to complete the project. During machine operation, workers and equipment in the tunnel were subject to strong vibration, with occasional heavy blows that severely jolted the cockpit and its computer. None of these conditions had any adverse effect on the PC.
Industrialized computers, which have rugged enclosures but standard inner components, cannot withstand tunnel construction. That's why Bilfinger Berger requires industrial PCs (IPCs), designed specifically for such use, for its tunnel preparations. The computers are waterproof, rated to safety standard IP65, and an external enclosure protects the electronics against shock and vibration. The IPC's components are developed and produced by noax, so the computers can be outfitted with various all-in-one motherboards and upgraded and retrofitted for five years.
Hard drives are rigidly mounted, just as other components, so they function without disruption. In addition, there are no bundled cables or external fans, which can create problems for traditional, dust-sensitive PCs. Any excess heat generated by the energy-efficient touch screen is dissipated to the environment via the enclosure and specially designed cooling fans. The panel PC used in the tunnel-driving machine does not require a mouse or keyboard; data is entered on the easy-to-read touch screen.
To keep a tunneling machine as close to the desired axis as possible, the machine operator must receive direct feedback on how he is maneuvering the machine, because it moves forward at more than 3 feet per hour. The VMT Co., specializing in control and guidance systems, provides SLS-T APD software for operating the tunnel-driving machine and keeping the driver informed about the machine's exact location.
A universal surveying instrument (a theodolite) is rigidly attached to the wall and, by a laser beam, provides the control and guidance system with basic references; its measurements are then sent to the computer by a WLAN connection. This enables the driver to keep the unit on target within a relatively small tolerance. The software provides graphical and numerical data on machine position, and when there is a deviation from the target axis, the software calculates the correction, and returns the machine to position.
Visit noax Technologies Corp.for more information.