METHOD FOR SELECTING AN ATTACK POSE FOR A WORKING MACHINE HAVING A BUCKET

• US 20150046044A1
• Filed: 09/23/2011
• Published: 02/12/2015
• 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
• Granted Patent: US 9,133,600 B2
• Time in Patent Office: Days
• US Class Current: 701/50
• 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 (9,α

), when loading piled materials, for a working machine (31) having a bucket (33), said method including the steps of;

acquiring three dimensional pile data (P) (S10);

generating a set of attack poses (9,α

) (S20);

generating a bucket trajectory (13) through said pile (1) for each attack pose (9,α

) (S30);

characterized by

for each attack pose (9,α

) in said set of attack poses (9,α

), calculating a measure of a convexity (C_C) of the pile surface for an area (15) of the pile surface (17) delimited by a bucket width (19) and a vertical projection (21) of the bucket trajectory (13) (S40); and

selecting an attack pose (9,α

) based on said measure of convexity (C_C).

2. Method according to claim 1, characterized by:

determining sweep volumes (V_L, V_C, V_R) of segments of said bucket (33), a sweep volume being a volume of the pile (1) within a sweep area defined by a width of a segment and length extension (21) of the trajectory (13); and

calculating said measure of convexity (C_C) based on said sweep volumes (V_L, V_C, V_R) of segments of said bucket (33).

3. Method according to claims 1 or 2, characterized by additionally determining a side load measure (C_L) for each attack pose (9,α

), and selecting an attack pose (9,α

) based on the side load measure (C_S) and the measure of convexity (C_C).

4. Method according to any of claims 1-3, wherein said segments including a central segment, a right wing segment and a left wing segment, characterized by:

calculating said measure of convexity (C_C) based on a comparison between the sweep volumes of the left wing segment (V_L), the right wing segment (V_R) and the central segment (V_C).

5. Method according to claims 3 and 4, characterized by said side load measure (C_S) is based on a comparison between the volumes of the left and right wing segments (V_L,V_R).

6. Method according to any of the preceding claims, wherein the width of the bucket (19) is separated into three segments of equal width and the measure of convexity (C_C) is calculated as C_C=(V_c/max(V_r, V_l))−

1 and the side load measure is calculated as C_S=(abs(V_r−

V_l))/(V_r+V_l).

7. Method according to any of the preceding claims, characterized by retrieving 3D point cloud from a sensor (43) and separating said 3D point cloud into ground data and said three dimensional pile data.

8. Method according to claim 7, characterized by:

fitting a ground plane to said ground data.

9. Method according to any of the preceding claims, characterized by selecting potential attack poses (9,α

) among scan points in the vicinity of and preferably at the border (5) of the pile (1), wherein orientations of the attack pose (9,α

) is selected within a range of less than 20°

deviation from a border normal.

10. Method according to any of the preceding claims, characterized by that said sweep volumes are calculated from a ground plane to a pile surface.

11. Method according to any of the preceding claims, characterized by that said sweep volumes are calculated from the bucket trajectory (13) to a pile surface.

12. Method according to any of claims 1 or 7-11, characterized by:

fitting a surface to three dimensional pile data within an area at the surface of the pile defined by a width of the bucket (19) and said bucket trajectory (13), and

calculating said measure of a convexity (C_C) from said surface.

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

fitting a quadratic polynomial;

z_r=ax_r²+bx_ry_r+cy_r²+dx_r+ey_r

to said three dimensional pile data within the area defined by a width of the bucket (19) and said bucket trajectory (13); and

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

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

fitting a plane to the three dimensional pile data within an area defined by a width of the bucket (19) and said bucket trajectory (13);

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

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

15. Method according to claim 13 or 14, characterized by:

determining a measure of side load from said factor d.

16. Method for loading a bucket (33) by use of a working machine (31) having a bucket (33), a sensor system (43) for detecting three dimensional pile data, and an automated steering system (45) for enabling propagation of the bucket (33) along a bucket trajectory (13) in a pile, said method including selection of an attack pose (9,α

) and a corresponding bucket trajectory (13) by use of a method according to any of claims 1-14, control of the working machine (31) to position the bucket (33) at said selected attack pose (9,α

) and to run said bucket (33) along said selected bucket trajectory (13) in order to optimize the filling of the bucket (33).