Measurement of bulk density of the payload in a dragline bucket

• US 8,930,091 B2
• Filed: 10/25/2011
• Issued: 01/06/2015
• Est. Priority Date: 10/26/2010
• Status: Active Grant

• Current Assignee: CMTE Development Limited
• Original Assignee: CMTE Development Limited
• Inventors: Upcroft, Benjamin, Shekhar, Rajiv Chandra, Bewley, Alex Joseph, Lever, Paul J. A.
• Primary Examiner(s): Nguyen, Cuong H
• Application Number:
  US13/281,328
• Publication Number:
  US 20120136542A1
• Time in Patent Office: 1,169 Days
• Field of Search: 37347-348, 373/98, 374/01, 37/32.R, 702173-174, 701/50, 701/99
• US Class Current: 701/50
• CPC Class Codes: E02F 3/48 Drag-lines
• CPC Class Codes: E02F 9/26 Indicating devices E02F5/145 takes precedence

Abstract

In particular embodiments of the technology, the bulk density of the payload in the bucket of a large electric dragline is measured during the carry phase of dragline operation by scanning the loaded bucket using a boom mounted scanner to provide data relating to the volume of the loaded bucket. Suitable methods can further include calculating the volume enclosed by the surface of the payload and the known base and sides of the bucket to give payload volume, and dividing the payload volume into payload weight data derived from rope length and motor current data to give the payload bulk density. Methods of screening data points originating from surfaces other than the bucket and payload, and methods of dealing with bucket ope and sway are also described and claimed.

Claims

1. A method of measuring, with a scanning device, bulk density of a payload having a weight, a volume, and a surface in a dragline bucket having a base and sides, during dragline operation, comprising:

scanning, by the scanning device, a loaded dragline bucket during an operating cycle of the dragline wherein the bucket is moving, to provide mathematical data relating to the surface of the payload in the loaded bucket, wherein the scanning comprises collecting scan line data from multiple scans;

calculating the volume enclosed by the surface of the payload and the base and sides of the dragline bucket from the mathematical data, wherein the calculating comprises;

analyzing the collected scan line data;

identifying a shift between scan line data from a first scan and scan line data from a second scan attributable to bucket motion between scans; and

using the shift to compensate for bucket motion;

receiving a weight of the payload; and

determining a bulk density of the payload by dividing the calculated volume into the weight.

2. The method of claim 1 wherein the operating cycle of the dragline comprises a lifting phase, a carry phase, and a dumping phase, and wherein scanning the loaded dragline bucket occurs during the carry phase of the operating cycle, between the lifting phase and the dumping phase.

3. The method of claim 1 wherein scanning the loaded dragline bucket comprises moving at least one of the loaded dragline bucket and a beam of the scanning device relative to the other.

4. The method of claim 3 wherein the scanning device comprises a laser scanner.

5. The method of claim 3 wherein the scanning device comprises a radar scanner.

6. The method of claim 1, further comprising analyzing, by a computing device, the mathematical data from the scanning device to screen out data that relates to surfaces other than the surface of the payload and the base and sides of the dragline bucket.

7. A computer-readable storage medium having contents configured to cause a computer to perform a method for measuring, with a scanning device, a volume of a payload having a surface in a moving dragline bucket, during dragline operation, the method comprising:

obtaining data points by scanning, with the scanning device, a loaded, moving dragline bucket during an operating cycle of the dragline;

identifying, from the obtained data points, data points associated with the bucket or the payload;

translating the data points associated with the bucket or the payload to compensate for the motion of the bucket;

determining a pose of the bucket;

filtering out, from the data points associated with the bucket or the payload, data points not associated with the payload;

estimating the payload surface using the filtered data points;

calculating, from the estimated payload surface and the determined pose, the volume of the payload.

13. The computer-readable storage medium of claim 7 wherein:

obtaining data points comprises collecting, from a laser scanner or radar scanner, data from multiple scan lines that are substantially orthogonal to the payload surface;

identifying data points associated with the bucket or the payload comprises;

classifying data points as terrain, bucket or noise; and

using point clustering to identify similar points within the scan;

translating data points associated with the bucket or the payload to compensate for motion of the bucket comprises;

determining a velocity of the loaded dragline bucket;

using the determined velocity to scale the data points to compensate for bucket travel;

translating data points by their mean x coordinate to compensate for bucket sway; and

smoothing data points by applying a polynomial or sine wave fit;

determining the pose of the bucket comprises identifying data points corresponding to reflectors attached to the bucket or using an iterative closest point algorithm;

filtering data points not associated with the payload comprises;

filtering data points associated with a dragline bucket arch, a spreader bar, a rope, or noise; and

filtering data points within a defined geometric shape representing a bucket feature; and

estimating the payload surface using the filtered data points comprises;

using a height grid representation of the surface;

identifying irregular portions of the surface including material extending above or gaps below an overall shape of the surface; and

interpolating data points to form a continuous surface.

14. The computer-readable storage medium of claim 7 wherein identifying data points associated with the bucket or the payload comprises classifying data points as terrain, bucket or noise.

15. The computer-readable storage medium of claim 7 wherein identifying data points associated with the bucket or the payload comprises using point clustering to identify similar points within the scan.

16. The computer-readable storage medium of claim 7 wherein translating data points associated with the bucket or the payload to compensate for motion of the bucket comprises translating data points by their mean x coordinate to compensate for bucket sway or rescaling data points to compensate for bucket travel.

17. The computer-readable storage medium of claim 7 wherein translating data points associated with the bucket or the payload to compensate for motion of the bucket comprises smoothing data points by applying a polynomial or sine wave fit.

18. The computer-readable storage medium of claim 7 wherein determining the pose of the bucket comprises identifying data points corresponding to reflectors attached to the bucket or using an iterative closest point algorithm.

19. The computer-readable storage medium of claim 7 wherein filtering data points not associated with the payload comprises filtering data points associated with a dragline bucket arch, a spreader bar, a rope, or noise.

20. The computer-readable storage medium of claim 19 wherein filtering data points not associated with the payload comprises filtering data points within a defined geometric shape representing a bucket feature.

21. The computer-readable storage medium of claim 7 wherein estimating the payload surface using the filtered data points comprises interpolating data points to form a continuous surface.

8. A method of measuring, with a scanning device, bulk density of a payload having a weight, a volume, and a surface in a dragline bucket having a base and sides, during dragline operation, wherein the dragline bucket is connected to at least one of a hoist rope and a drag rope, comprising:

scanning, by the scanning device, a loaded dragline bucket during an operating cycle of the dragline wherein the bucket is moving, to provide mathematical data relating to the surface of the payload in the loaded bucket, wherein the scanning comprises collecting scan line data from multiple scans;

calculating the volume enclosed by the surface of the payload and the base and sides of the dragline bucket from the mathematical data, wherein the calculating comprises;

collecting hoist rope and drag rope length data for a first scan and for a second scan; and

using the collected hoist rope and drag rope length data to determine a change in position of the loaded dragline bucket between the first scan and the second scan;

receiving a weight of the payload; and

determining a bulk density of the payload by dividing the calculated volume into the weight.

9. A method of measuring, with a scanning device, bulk density of a payload having a weight, a volume, and a surface in a dragline bucket having a base and sides, during dragline operation, comprising:

scanning, by the scanning device, a loaded dragline bucket during an operating cycle of the dragline wherein the bucket is moving, to provide mathematical data relating to the surface of the payload in the loaded bucket, wherein the scanning comprises collecting scan line data from multiple scans;

calculating the volume enclosed by the surface of the payload and the base and sides of the dragline bucket from the mathematical data, wherein the calculating comprises;

determining a velocity of the loaded dragline bucket;

measuring a displacement of position of the loaded dragline bucket between a first scan and a second scan as a function of the determined velocity of the loaded dragline bucket; and

using the measured displacement to scale the mathematical data relating to the scanned surface of the payload;

receiving a weight of the payload; and

determining a bulk density of the payload by dividing the calculated volume into the weight.

10. The method of claim 9 wherein the loaded dragline bucket has a pose, and wherein features of the dragline bucket are known, and wherein calculating the volume enclosed by the surface of the payload and the base and sides of the bucket comprises:

determining the pose of the loaded bucket; and

filtering out known features of the bucket from the volume calculation.

11. The method of claim 9 wherein calculating the volume enclosed by the surface of the payload and the base and sides of the dragline bucket comprises using a height grid representation.

12. The method of claim 9 wherein the surface of the payload is irregular, such that scanning the loaded dragline bucket comprises identifying portions of the surface extending above or below an average height of the surface.