Implement angle determination using a laser distance meter

Patent metadata

Field	Value
Publication number	US-10794038-B2
Application number	US-201916435916-A
Country	US
Kind code	B2
Filing date	Jun 10, 2019
Priority date	Dec 21, 2016
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A calibration framework comprises an excavator, a laser distance meter (LDM), and a plurality of laser reflectors. The excavator comprises a chassis, linkage assembly (LA), implement, and control architecture. The control architecture comprises a controller programmed to execute an iterative process at n linkage assembly positions to determine a position of an nth calibration node of the a plurality of nodes of the LA to determine triangular angles and side lengths of an external triangle formed between the nth calibration node and two other nodes having identified positions. The iterative process is repeated n times until triangular angles and side lengths of three external triangles are determined that form an internal triangle. Angles of the internal triangle are determined to generate an implement angle.

First claim

What is claimed is:

1. A calibration framework comprising an earthmoving machine, a laser distance meter (LDM), and a plurality of laser reflectors, wherein:
the earthmoving machine comprises a machine chassis, a linkage assembly, an earthmoving implement, and control architecture;
the linkage assembly collectively defines a plurality of linkage assembly positions comprising a terminal pivot point B and a plurality of nodes;
the LDM is configured to generate at least (i) an LDM distance signal D LDM indicative of a distance between the LDM and a laser reflector of the plurality of laser reflectors and (ii) an angle of inclination signal θ INC indicative of an angle between the LDM and the laser reflector;
the plurality of laser reflectors are disposed at respective positions corresponding to the plurality of nodes;
the control architecture comprises one or more linkage assembly actuators and an architecture controller programmed to execute an iterative process at n linkage assembly positions, the iterative process comprising:
positioning the linkage assembly at a linkage assembly position n;
setting one of the plurality of nodes as an nth calibration node with the linkage assembly at the linkage assembly position n,
determining a height Ĥ and a distance {circumflex over (D)} between the nth calibration node and the LDM based on the LDM distance signal D LDM and angle of inclination signal θ INC ; and
determining a position of the nth calibration node at least partially based on the height Ĥ and the distance {circumflex over (D)};
identifying respective positions of two other nodes that, together with the nth calibration node, form an external triangle, the two other nodes comprising one of the plurality of nodes, and a node corresponding to a position of the terminal pivot point B;
determining side lengths for each of the legs of the external triangle formed between the nth calibration node and the two other nodes; and
determining triangular angles of the external triangle based on the side lengths of the external triangle; and

the architecture controller is further programmed to:
repeat the iterative process n times until triangular angles and side lengths of at least three external triangles are determined, wherein the external triangles form an internal triangle therebetween, the internal triangle shares two nodes and one side with each of the three external triangles and comprises a set of three internal triangle side lengths;
determine the angles of the internal triangle at least partially based on the set of three internal triangle side lengths;
generate an implement angle of the earthmoving implement at least partially based on a summation of a set of adjacent determined triangular angles, the set of adjacent determined triangular angles comprising an angle from the internal triangle and angles from at least two of the external triangles; and
operate the earthmoving machine using the implement angle.

2. The calibration framework as claimed in claim 1 , wherein linkages of the linkage assembly comprise an implement linkage, a rear side linkage, a dogbone linkage, and a front side linkage.

3. The calibration framework as claimed in claim 1 , wherein:
the machine chassis is mechanically coupled to a terminal pivot point A; and
in the iterative process, determining a position of the nth calibration node at least partially based on the height Ĥ and the distance {circumflex over (D)} comprises:
calculating a total height {hacek over (H)} and a total distance Ď between the nth calibration node and the terminal pivot point A based on a summation of the height Ĥ and the distance {circumflex over (D)} between the nth calibration node and the LDM and a height H 0 and a distance D 0 between the LDM and the terminal pivot point A.

4. The calibration framework as claimed in claim 1 , wherein the architecture controller is further programmed to execute machine readable instructions to
determine a first total height {hacek over (H)} and a first total distance Ď between a terminal point G and a terminal pivot point A based on a boom limb length L B , a stick limb length L S , a boom angle θ B , and a stick angle θ S ,
determine a second total height {hacek over (H)} and a second total distance Ď between the terminal pivot point B and the terminal pivot point A based on a boom limb length L B , and a boom angle θ B , and
identify a height H 0 and a distance D 0 between the LDM and the terminal pivot point A.

5. The calibration framework as claimed in claim 1 , wherein:
for n=1, the 1st calibration node is positioned at a node D;
for n=2, the 2nd calibration node is positioned at a node F; and
for n=3, the 3rd calibration node is positioned at a node H.

6. The calibration framework as claimed in claim 1 , wherein:
the machine chassis is mechanically coupled to a terminal pivot point A; and
when n=1:
the 1st calibration node is positioned at a first node D of the plurality of nodes, such that calculating a total height {hacek over (H)} and a total distance Ď between the 1st calibration node and the terminal pivot point A of the excavator boom, respectively comprising D y and D x , is based on a summation of the height Ĥ and the distance {circumflex over (D)} between the 1st calibration node and the LDM and a height H 0 and a distance D 0 between the LDM and the terminal pivot point A;

the two other nodes comprise the terminal pivot point B and a second node G;
the legs of the external triangle comprise GD, BD, BG; and
the triangular angles of the external triangle comprise angles BGD, GDB, DBG and are determined based on the side lengths determined for the legs GD, BD, and BG and the law of cosines.

7. The calibration framework as claimed in claim 6 , wherein determining the side lengths for the legs BG, GD, and BD comprises calculating the side length for the leg BG based on:
the total height {hacek over (H)} and the total distance Ď between the second node G and the terminal pivot point A, respectively comprising G y and G x ; and
the total height {hacek over (H)} and the total distance Ď between the terminal pivot point B and the terminal pivot point A, respectively comprising B y and B x .

8. The calibration framework as claimed in claim 7 , wherein when n=2:
the 2nd calibration node is positioned at a pin F, such that calculating a total height {hacek over (H)} and a total distance Ď between the 2nd calibration node and the terminal pivot point A of the excavator boom, respectively comprising F y and F x , is based on a summation of the height Ĥ and the distance {circumflex over (D)} between the 2nd calibration node and the LDM and the height H 0 and the distance D 0 between the LDM and the terminal pivot point A;
the two other nodes comprise the terminal pivot point B and the first node D;
the legs of the external triangle comprise DF, BF, and BD;
the triangular angles of the external triangle comprise angles BDF, DFB, FBD and are determined based on the side lengths determined for the legs DF, BF, and BD and the law of cosines; and
the angle BDF is representative of an actual dogbone angle BDF.

9. The calibration framework as claimed in claim 8 , wherein when n=3:
the 3rd calibration node is positioned at a pin H, such that calculating a total height {hacek over (H)} and a total distance Ď between the 3rd calibration node and the terminal pivot point A, respectively comprising H y and H x , based on a summation of the height Ĥ and the distance {circumflex over (D)} between the 3rd calibration node and the LDM and the height H 0 and the distance D 0 between the LDM and the terminal pivot point A;
the two other nodes comprise the pin F and the second node G;
the legs

Assignees

• Caterpillar Trimble Control Tech Llc

Inventors

• Howell Mark Nicholas
• Frei Samuel Joseph

Classifications

• E02F9/264

  Sensors and their calibration for indicating the position of the work tool · CPC title

• E02F3/32

  working downwardly and towards the machine, e.g. with backhoes · CPC title

• E02F9/265

  with follow-up actions (e.g. control signals sent to actuate the work tool) · CPC title

• G01S17/08

  for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) · CPC title

• G01S17/88

  Lidar systems specially adapted for specific applications · CPC title