GPS stakeout (waypoint navigation)

Waypoint navigation, or stakeout as it is called by surveyors, provides guidance to a GPS user in reaching his or her destination in the best way (shortest time and/or distance). By feeding the GPS receiver (or the GPS receiver controller) with the coordinates of his or her destination, a GPS user receives on-screen guidance instantaneously (see Figure 10.13 for details). Surveyors use this principle to lay out points and lines.

The idea behind GPS waypoint navigation is simple. As a first step, the user must feed the GPS receiver (or the GPS controller) with the coordi- nates of his or her destination. Most GPS receivers are capable of storing a number of destination points (waypoints) in their internal memory. The second step is to let the GPS receiver compute its own position, that is, the user’s positions). Based on the receiver and the destination positions, the built-in receiver computer calculates the distance and the azimuth of

the line connecting the receiver’s position and the destination points.

The built-in computer uses the position information to calculate other parameters such as the expected arrival time to the user’s destination based on the user’s speed. In addition, the offset distance from the receiver posi- tion to the original line between the starting point and the destination can be calculated. All of this information and other data are displayed on a con- tinuous basis to guide the GPS user.

This guidance information can be displayed in different ways [25].

One of these displays is the bull’s-eye, where the destination point is located at the center of the displayed concentric circles while the user’s location is displayed as a moving cursor. The top point of the bull’s-eye is normally selected to represent the north. The user will reach his or her des- tination point when the moving cursor stays at the center of the concentric circles. In addition to this, a number of navigation parameters are dis- played to help the user as well.

References

[1] Laser Technology Inc., “Survey Laser for Forestry,” PowerPoint Presentation, accessed July 18, 2001, http://www.lasertech.com/

downloads.html.

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>>>> + <<<<

12 o’clock

“to destination”

1 o’clock

Origin Current position

Reference d = 1.321m Azimuth = 1 o’clock d

V = 15 km/hr DTT = 7.231 km d = 1.20m

COG = 23 13 mg° ′ CTT = 10 11 mg° ′ rms = 0.02m

+

N

V = 15 km/hr DTT = 7.23m d = 5.20m

COG = 123 13 mg° ′ CTT = 235 11 mg° ′ rms = 0.02m

+

Figure 10.13 GPS waypoint navigation.

[2] Phillips, B., “GPS Field Applications in Forestry Consulting,”Global Positioning System in Forestry Workshop, Kelowna, British Columbia, Canada, November 25–28, 1996.

[3] Bauer, W. D., and M. Schefcik, “Using Differential GPS to Improve Crop Yields,”GPS World, Vol. 5, No. 2, February 1994, pp. 38–41.

[4] Petersen, C., “Precision GPS Navigation for Improving Agriculture Productivity,”GPS World, Vol. 2, No. 1, January 1991, pp. 38–44.

[5] Smith, B. S., “GPS Grade Control for Construction,”Proc. ION GPS 2000, 13th Intl. Technical Meeting, Satellite Division, Institute of Navigation, Salt Lake City, UT, September 19–22, 2000, pp. 1034–1037.

[6] Elfick, M., et al.,Elementary Surveying, 8th ed., New York: HarperCollins, 1994.

[7] El-Rabbany, A., A. Chrzanowski, and M. Santos, “GPS Applications in Civil Engineering,”Ontario Land Surveyor Quarterly, Summer 2001, pp. 6–8.

[8] Flinn, J. A., C. Waddell, and M. A. Lowery, “Practical Aspects of GPS Implementation at the Morenci Copper Mine,”Proc. ION GPS-99,12th Intl. Technical Meeting, Satellite Division, Institute of Navigation, Nashville, TN, September 14–17, 1999, pp. 915–919.

[9] Flinn, J. A., and S. M. Shields, “Optimization of GPS on Track-Dozers at a Large Mining Operation,”Proc. ION GPS-99,12th Intl. Technical Meeting, Satellite Division, Institute of Navigation, Nashville, TN, September 14–17, 1999, pp. 927–931.

[10] Dai, L., et al., “GPS and Pseudolite Integration for Deformation Monitoring Applications,”Proc. ION GPS 2000,13th Intl. Technical Meeting, Satellite Division, Institute of Navigation, Salt Lake City, UT, September 19–22, 2000, pp. 1–8.

[11] Shields, S., J. Flinn, and A. Obregon, “GPS in the Pits: Differential GPS Application at the Morenci Copper Mine,”GPS World, Vol. 11, No. 10, October 2000, pp. 34–39.

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DGPS and Barometry for Seismic Surveys,”GPS World, Vol. 5, No. 2, February 1994, pp. 20–26.

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[16] Abwerzger, G., “Georeferencing of Laser Scanner Data Using GPS Attitude and Position Determination,”Proc. 3rd Intl. Symp. Mobile Mapping Technology,Cairo, Egypt, January 3–5, 2001, CD-ROM.

[17] Favey, E., et al., “3D-Laser Mapping and Its Application in Volume Change Detection of Glaciers,”Proc. 3rd Intl. Symp. Mobile Mapping Technology,Cairo, Egypt, January 3–5, 2001, CD-ROM.

[18] Bowditch, N.,American Practical Navigator, Bethesda, MD: Defense Mapping Agency Hydrographic/Topographic Center, 1995.

[19] Maxfield, H. E., “Recent Developments in Seafloor Mapping Capabilities,”

Hydro International, Vol. 2, No. 1, January/February 1998, pp. 45–47.

[20] Zhao, Y.,Vehicle Location and Navigation Systems, Norwood, MA: Artech House, 1997.

[21] Hada, H., et al., “The Internet, Cars, and DGPS: Bringing Mobile Sensors and Global Correction Services On Line,”GPS World, Vol. 11, No. 5, May 2000, pp. 38–43.

[22] El-Rabbany, A., A. Shalaby, and S. Zolfaghari, “Real-Time Bus Location, Passenger Information and Scheduling for Public Transportation,”

Presented at GPS meeting,GOEIDE 2000 Conference, Calgary, Alberta, Canada, May 24–26, 2000.

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[25] SOKKIA Corporation,GSR2300 Operation Manual, 1996.

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Communications,”GPS World, Vol. 4, No. 4, April 1993, pp. 42–46.

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