GPS in the Earthmoving Industry

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History of GPS in the Earthmoving Industry

GPS Technology was officially introduced as a guidance system for earthmoving machines in the late 1990s. Since this time, many manufacturers of earthmoving equipment now offer GPS and other guidance systems, as a factory option. Many companies exist that also sell GPS guidance systems for the earthmoving industry as a retrofit option. The two main companies for heavy equipment guidance systems are Trimble and Topcon. In April 2002, Trimble and Caterpillar Inc. began a joint venture known as Caterpillar Trimble Controls Technology LLC (CTCT). "The joint venture develops machine control products that use site design information combined with accurate positioning technology to automatically control dozer blades and other machine tools".[1] Though aftermarket kits were available from various companies to retrofit an existing machine for GPS guidance, Caterpillar Inc. was the first heavy equipment manufacturer to offer GPS guidance systems as a factory option from the dealer called an ARO (Attachment Ready Option).[2] John Deere soon followed with their own version of ARO called "Integrated Grade Control" in 2006 on many Track-Type Tractors (TTT) and Motorgraders (MG).[3]

Types of GPS Systems Used in the Heavy Equipment Industries

While there are various GPS systems currently used in the heavy equipment industry, they can typically be categorized as either "indicate only" or "fully automatic".[4] Both systems can utilize one or two GPS receivers. Using only one GPS receiver limits how the guidance system can orient the machine's position in respect to the site design. Using two GPS receivers gives the guidance system two points of position allowing it to calculate what angle the machine is on relative to the site plan. The following describes "indicate only" and "fully automatic" in more detail.

Indicate Only

Indicate only uses GPS positioning information as a guide to the operator. Depending on the system used, the machine position can be displayed over the specific design site that was created for the earthmoving project. Machines that typically use indicate only consist of Soil Compactors (SC), Track-Type Tractors (TTT), and Motor Graders (MG). The use of a base station really depends on the accuracy requirements of the project. Some projects such as clearing overburden at a mine site with a TTT, may not need two to three centimeter accuracy while as grading a road base with a MG does.


GPS Applications

The key to successfully using GPS in the earthmoving industry is having an accurate site design. The site design, typically created by an engineering firm, can be imported from the original design file into the machine's GPS display. Most GPS guidance systems also have the ability to allow the operator to define a specific grade elevation or grade angle without a specific design. The following describes common machine applications that utilize GPS guidance systems.

Track-Type Tractors TTT are an extremely popular machine platform for GPS guidance systems specifically in the smaller sized models that are used for fine grading. Caterpillar Inc. and John Deere both offer fully automatic integrated GPS as an option from the factory on some of these models. One example of GPS being used on a TTT would be on a road project.

Motorgraders

Motorgraders are another popular machine platform since they also perform fine grading activities that can benefit from the GPS accuracy. Caterpillar Inc. and John Deere also offer some models with integrated GPS.

Hydraulic Excavators

Hydraulic excavators are just beginning to be integrated using GPS technology and are typically indicate only. Excavators use GPS technology in conjunction with angle sensors integrated in the machine's boom, stick, and bucket. This allows the operator to see how deep they are digging by comparing the actual bucket location to the site design on the GPS display.

Scrapers

Scrapers use GPS technology and are typically indicate only. The GPS antenna is typically mounted on the bowl of the scraper and allows the operator to compare the depth of the cut versus the site plan. This takes a lot of the ambiguity out of moving large amounts of material.

Compactors

GPS technology is applied in both trash compactors and soil compactors. Typical systems record where the compactor has been in order to create a map of the area's compaction. Usually the display has various colors that indicate that the machine has compacted the area.

Financial Information

GPS systems typically have a high initial cost of around $100,000 per machine. When used properly GPS on average can increase productivity by as much as 30% over traditional methods. There is also cost reduction of material (since less is needed) because such high accuracy can be achieved. Some construction projects even require the use of GPS since it can bring down the overall cost of the project due to its efficiency advantages. Some GPS systems allow the user to switch systems to other machines making this tool very versatile. The contractor must plan for greater efficiency, since increasing one aspect of the job by 30% may not increase the overall efficiency, since another area may not be able to keep up. "If you do everything right and boost overall productivity say 30 percent, you’re going to have to line up 30 percent more work in the future or send crews home early".[4]

GPS Limitations

GPS is extremely versatile in the earthmoving industry but it does have its limitations. GPS satellite signals can only be received in a non obstructed view of the sky with the exception of clouds. If a contractor wanted to perform grade work in preparation for a concrete floor within a building for example, the roof would block the view to the GPS satellites preventing the system from working. Working too close to a structure can also obstruct the machine's view of the sky creating dead zones. High-voltage power-lines can also create dead zones when working underneath them. GPS satellite coverage can also be weaker during certain parts of the day lowering the amount of satellites the machine's system can use. This all depends on the geographical location and time of day. Improvements in GPS technology and the addition of GLONASS (Russian GNSS Satellites) satellites have reduced this issue. As mentioned earlier, in order to increase the overall accuracy of GPS you have to purchase and use a base station which adds additional cost.

Future use of GPS in the Earthmoving Industry

GPS continues to be integrated in the construction industry and soon will be an industry standard. Autonomous cars that utilize GPS are currently being developed and someday the earthmoving industry could incorporate such features. Already new machines are coming equipped with GPS integrated from the factory. The possibilities are endless and who knows what other practical uses for GPS in the earthmoving industries will be discovered.

Resources

2010 saw the advent of the first user-oriented web resource for prospective 3D machine control users. The Kellogg Report [5] publicized a detailed comparison of the major systems available on the market, evaluating more than 200 system features. The report continues to be updated as the technology evolves.

Notes

  1. ↑ Trimble. (2008). Trimble: The Construction Technology Authority. Article: Trimble.com Retrieved March 11, 2009 from http://www.trimble-productivity.com/articles/95?page=3
  2. ↑ Caterpillar Inc. (2003). AccuGrade GPS. Article: Cat.com. Retrieved March 14, 2009 from http://www.cat.com/cda/components/fullArticleNoNav?ids=113001&languageId=7
  3. ↑ John Deere (2008). Deere Supports Dozer Customers With Innovative Offerings. Article: John Deere.com. Retrieved March 11, 2009 from http://www.deere.com/en_US/cfd/construction/deere_const/newsroom/2008/080312_dozer_support.html
  4. ↑ 4.0 4.1 Jackson, T. (2008). Technology: GPS by the numbers. Article: Equipment World. Retrieved March 11, 2009 from http://www.equipmentworldmagazine.com/apps/news/articleeqw.asp?id=66334
  5. ↑ The Kellogg Report LLC (2010). Article: The Kellogg Report. Retrieved December 15, 2010 from http://www.kelloggreport.com/index.html