Velocity

2013

NovAtel's Annual Journal of GNSS Technology Solutions and Innovation

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GNSS-Aided Mining GNSS antenna at mine's base station. Image credit: Flanders ProPak to provide the precise heading. Each receiver is connected to its own GPS-702GG antenna. Don Treadaway, a Flanders GIS project manager, said that Flanders likes the fact that the heading version is firmware-upgradable, which saves its customers money, and helped make the ProPakV3 the company's standard rover receiver. Flanders mounts two arms off of the left and right of the mast support onto which the GNSS antennas are installed. This is necessary as that portion of the drilling equipment is exposed to the movement of heavy components, such as the lowering and raising of the mast, and requires access for frequent maintenance. The ProPakV3s are mounted in a stainless steel enclosure, usually along a handrail on the side of the drill. To determine the combined position of the drill steel, Flanders applies basic geometry to the position and heading provided by the GNSS receivers. Once an ARDVARC kit is installed on a drill, Flanders captures the static offsets needed to calculate the geometry of the drill itself. The offsets are measured from each GNSS antenna to the center line of the drill; from that intersection point, along that center line, to the center of the drill steel; from the horizontal plane of the antennas down to the stops; and from the stops to the tip of the drill bit, when the steel is fully retracted. The position and heading from the two GNSS receivers are imported into the ARDVARC system. Flanders uses a custom application to continuously derive the current location of the drill bit using this geometry. Most mines use local coordinates, occasionally based upon historical surveys from the 19th or early 20th century, notes Treadaway, adding that mines usually retain the local coordinates to maintain their historical accounting processes. So, Flanders configures its system to incorporate these coordinates. Treadaway points out that mining offers unique satellite signal reception challenges that are addressed by the ProPak-V3's multi-constellation reception capability. Figure 4 ALIGN heading recorded during the drilling of a hole (2,000 seconds, approximately 33 minutes to drill the hole); real-time data recorded on a drill. Heading is approximately ±0.3 degrees, which would contribute about ±6 centimetres of error in bit location. 34 velocity 2013 For more Solutions visit http:/ /www.novatel.com

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