DIGITAL TERRAIN MAPPING WITH GPS AND LASER SYSTEM

• US 20100034421A1
• Filed: 10/04/2007
• Published: 02/11/2010
• Est. Priority Date: 11/16/2006
• Status: Active Grant

• Current Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Original Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Inventors: Roberts, Jonathan Michael, Winstanley, Graeme John
• Granted Patent: US 8,358,810 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry

Abstract

This invention concerns digital terrain mapping, and in particular a method for producing digital terrain maps of the vicinity around large rotating machinery, such as draglines, shovels, excavators, wheel loaders or cranes. The method involves the following steps: Mounting a 2-Dimensions laser scanner and a high-accuracy RTK GPS system to an item of large rotating machinery, at a radial extremity of the machinery. Arranging the laser scanner to record radial lines of data representing the terrain below the extremity of the machinery. Rotating the machinery completely about its axis of rotation and generating data from both the laser scanner and GPS system that represents the terrain around the machinery. Wherein, a calibration is conducted by recording data from markers at known locations in the terrain below the extremity of the machinery to determine the relative positions of the laser scanner centre and the GPS antenna, the orientation of the laser scanner and the time lag between the data generated from both the laser scanner and the GPS system. In a further aspect the invention concerns equipment for use in the method and software.

Claims

1. A method for producing digital terrain maps of the vicinity around large rotating machinery, the method comprising the following steps:

mounting a 2-Dimensions laser scanner and a high-accuracy RTK GPS system to an item of large rotating machinery, at a radial extremity of the machinery;

arranging the laser scanner to record radial lines of data representing the terrain below the extremity of the machinery;

rotating the machinery completely about its axis of rotation and generating data from both the laser scanner and GPS system that represents the terrain around the machinery;

wherein, a calibration is conducted by recording data from markers at known locations in the terrain below the extremity of the machinery to determine the relative positions of the laser scanner centre and the GPS antenna, the orientation of the laser scanner and the time lag between the data generated from both the laser scanner and the GPS system.

2. The method according to claim 1, wherein seven offsets are determined by the calibration step, namely:

the distance from the GPS antenna to laser scanner centre, that is x, y and z offsets, in total three values;

the installed roll, pitch and yaw angles of the laser scanner assembly with respect to the dragline, another three values; and

,

the time lag between the GPS and laser scanning sensors.

3. The method according to claim 1, wherein a number of calibrations are made to check system stability over time.

4. The method according to claim 3, wherein a plurality of markers are used for calibration, and the method includes the following steps:

placing a GPS antenna on top of each marker and recording the Easting, Northing and Altitude.

5. The method according to claim 4, including the step of aligning the 2D position of the marker as surveyed with the corresponding data estimated by the digital terrain mapping system using an Iterative Closest Point (ICP) algorithm.

6. The method according to claim 5, wherein the offsets determined by the calibration step are optimised.

7. The method according to claim 6, wherein optimisation uses a Genetic Algorithm.

8. The method according to claim 6, wherein optimisation uses a bundle adjustment.

9. The method according to claim 1, wherein data generated by both the laser scanner and GPS system while the machinery is rotated is time stamped.

10. The method according to claim 9, wherein the position of the GPS antenna is calculated at the time reported by the laser scanner.

17. Software for operating the equipment claimed in claim 11 to perform the method of claim 1.

18. Software according to claim 17, further providing a visualisation tool for the operator of the large rotating machinery, so that they may view the terrain around the machinery from any angle.

19. An Automatic Control System of the large rotating machinery including software according to claim 17.

11. Equipment associated with large rotating machinery for use in the method, the equipment comprising:

a 2D laser scanner and a high-accuracy RTK GPS system mounted together in a fixed relationship to each other and together with mounting means to mount the equipment on an extremity of an item of large rotating machinery.

12. Equipment according to claim 11, further including an embedded PC to interface with both the laser and GPS systems and to store data and generate terrain maps.

13. Equipment according to claim 11, wherein the laser has a 60 degree field-of-view.

14. Equipment according to claim 11 wherein the mounting means is designed to orient the laser downward with a slight tilt to avoid sighting any cables that hang down from adjacent the mounting point.

15. Equipment according to claim 11, wherein the GPS system returns its position in 3D space with at least 2 cm precision.

16. Equipment according to claim 11, when used to construct digital terrain maps while the large rotating machinery rotates in use.