Method for selecting an attack pose for a working machine having a bucket

• US 9,133,600 B2
• Filed: 09/23/2011
• Issued: 09/15/2015
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Volvo Construction Equipment AB (Volvo AB)
• Original Assignee: Volvo Construction Equipment AB (Volvo AB)
• Inventors: Martinsson, Torbjrn, Magnusson, Martin
• Primary Examiner(s): Badii, Behrang
• Application Number:
  US14/346,076
• Publication Number:
  US 20150046044A1
• Time in Patent Office: 1,453 Days
• US Class Current: 1/1
• CPC Class Codes: B25J 9/1607 Calculation of inertia, jacobian matrixes and inverses
• CPC Class Codes: E02F 3/304 with the dipper-arm slidably mounted on the boom E02F3/305 takes precedence
• CPC Class Codes: E02F 3/431 for bucket-arms, front-end loaders, dumpers or the like
• CPC Class Codes: E02F 3/434 providing automatic sequences of movements, e.g. automatic dumping or loading, automatic return-to-dig
• CPC Class Codes: E02F 3/437 providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant
• CPC Class Codes: E02F 3/439 Automatic repositioning of the implement, e.g. automatic dumping, auto-return E02F3/438 takes precedence
• CPC Class Codes: E02F 9/2029 Controlling the position of implements in function of its load, e.g. modifying the attitude of implements in accordance to vehicle speed control for hydraulic or pneumatic drives E02F9/2203, E02F9/2221 and E02F9/2253 take precedence
• CPC Class Codes: E02F 9/262 with follow-up actions to control the work tool, e.g. controller
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

A method for selecting an attack pose, when loading piled materials, for a working machine having a bucket includes acquiring three dimensional pile data, generating a set of attack poses, generating a bucket trajectory through the pile for each attack pose, for each attack pose in the set of attack poses, calculating a measure of a convexity of the pile surface for an area of the pile surface delimited by a bucket width and a vertical projection of the bucket trajectory, and selecting an attack pose based on the measure of convexity.

Claims

1. Method for selecting an attack pose, when loading piled materials, for a working machine having a bucket, the method comprising:

acquiring three dimensional pile data (P);

generating a set of attack poses;

generating a bucket trajectory through the pile for each attack pose;

for each attack pose in the set of attack poses, calculating a measure of a convexity (CC) of the pile surface for an area of the pile surface delimited by a bucket width and a vertical projection of the bucket trajectory; and

selecting an attack pose based on the measure of convexity (CC).

2. Method according to claim 1, further comprising

determining sweep volumes (VL, VC, VR) of segments of the bucket, a sweep volume being a volume of the pile within a sweep area defined by a width of a segment and length extension of the trajectory;

and

calculating the measure of convexity (CC) based on the sweep volumes (VL, VC, VR) of segments of the bucket.

3. Method according to claim 1, further comprising additionally determining a side load measure (CL) for each attack pose, and selecting an attack pose based on the side load measure (CS) and the measure of convexity (CC).

4. Method according to claim 1, wherein the segments including a central segment, a right wing segment and a left wing segment, further comprising

calculating the measure of convexity (CC) based on a comparison between the sweep volumes of the left wing segment (VL), the right wing segment (VR) and the central segment (VC).

5. Method according to claim 3, further comprising calculating the measure of convexity (CC) based on a comparison between the sweep volumes of the left wing segment (VL), the right wine segment (VR) and the central segment (VC), the side load measure (CS) is based on a comparison between the volumes of the left and right wing segments (VL, VR).

6. Method according to claim 1, wherein the width of the bucket is separated into three segments of equal width and the measure of convexity (CC) is calculated as CC=(Vc/max(Vr, Vl))−

1 and the side load measure is calculated as CS=(abs(Vr−

Vl))/(Vr+Vl).

7. Method according to claim 1, further comprising retrieving 3D point cloud from a sensor and separating the 3D point cloud into ground data and the three dimensional pile data.

8. Method according to claim 7, further comprising

fitting a ground plane to the ground data.

9. Method according to claim 1, further comprising selecting potential attack poses among scan points in the vicinity of and preferably at the border of the pile, wherein orientations of the attack pose is selected within a range of less than 20°

deviation from a border normal.

10. Method according to claim 1, further comprising that the sweep volumes are calculated from a ground plane to a pile surface and from the bucket trajectory to a pile surface.

11. Method according to claim 1, further comprising

fitting a surface to three dimensional pile data within an area at the surface of the pile defined by a width of the bucket and the bucket trajectory, and

calculating the measure of a convexity (CC) from the surface.

12. Method according to claim 11, wherein the method includes the following steps:

fitting a quadratic polynomial;

zr=axr2+bxryr+cyr2+dxr+eyr

to the three dimensional pile data within the area defined by a width of the bucket and the bucket trajectory; and

determining the measure of convexity (CC) from the factor a in the quadratic polynomial.

13. Method according to claim 12, further including the following steps:

fitting a plane to the three dimensional pile data within an area defined by a width of the bucket and the bucket trajectory,

constructing a rotated principal frame from a ground frame being rotated around the surface normal of the plane; and

mapping the three dimensional pile data into the rotated principal frame.

14. Method according to claim 13, further comprising

determining a measure of side load from the factor d.

15. Method for loading a bucket by use of a working machine having a bucket, a sensor system for detecting three dimensional pile data, and an automated steering system (45) for enabling propagation of the bucket along a bucket trajectory in a pile, the method including selection of an attack pose and a corresponding bucket trajectory by use of a method according to claim 1, control of the working machine to position the bucket at the selected attack pose and to run the bucket along the selected bucket trajectory in order to optimize the filling of the bucket.