Methods for spatial calibration of vehicle ADAS service system

Patent metadata

Field	Value
Publication number	US-11538188-B1
Application number	US-202016894162-A
Country	US
Kind code	B1
Filing date	Jun 5, 2020
Priority date	Jun 5, 2019
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

A method and apparatus for calibrating a projection axis orientation for an optical projector associated with a vehicle inspection or service system so as to enable projection of indicia onto selected spatial locations within a vehicle service area. Projector axis orientations required for the projection of visible indicia onto reference targets disposed at determinable locations within a common coordinate system of the vehicle service area are utilized to establish a relationship utilized to mathematically transform between selected spatial coordinate locations for projected indicia and corresponding orientations of the projection axis, facilitating projection of the visible indicia to additional spatial coordinate locations within the common coordinate system.

First claim

The invention claimed is:

1. A method for orienting a projection axis of an optical projector associated with a vehicle inspection system, comprising:
determining a spatial relationship between said optical projector and each of a plurality of reference targets disposed in a common frame of reference;
for each reference target, determining an associated orientation for a projection axis of the optical projection required to align indicia projected along said projection axis with said associated reference target;
using said determined orientations to establish a transform between the projection axis orientations and the spatial locations of each reference target in said common frame of reference;
selecting a spatial location within said common frame of reference for illumination by said optical projector;
calculating, with said transform, an orientation of said projection axis required to direct projected indicia to said selected spatial location; and
aligning said projection axis of said optical projector to said calculated orientation.

2. The method of claim 1 wherein said optical projector and said plurality of reference targets are disposed at predetermined locations within said common frame of reference.

3. The method of claim 1 wherein said transform is a six-degree of freedom transformation between rotational orientations for said optical projector about three orthogonal axes and three-dimensional coordinates of spatial locations within said common frame of reference.

4. The method of claim 1 wherein said optical projector is mounted on a set of gimbals for independent rotational movement about at least two rotational axes.

5. The method of claim 1 wherein establishing said transform includes comparing an observed range from said optical projector to at least one reference target with a known or calculated range from said optical projector to said at least one reference target.

6. The method of claim 1 wherein determining said spatial relationship between said optical projector and each of said plurality of reference targets disposed in said common frame of reference includes acquiring at least one image of an optical target associated with said plurality of reference targets, said at least one image acquired by an optical camera in a determinable relationship with said optical projector.

7. A method for calibrating an optical projector to align projected indicia with a selected spatial location within an operative field of view of the optical projector, comprising:
determining a spatial relationship between a projection axis of the optical projector and a plurality of reference targets located within a first portion of said operative field of view of the optical projector;
for each of said plurality of reference targets, determining an associated orientation of said projection axis which aligns said projected indicia with said reference target; and
using said determined orientations of said projection axis to establish a transform between said projection axis orientations and a spatial location of each reference target within a common frame of reference.

8. The method of claim 7 further including calculating, with said transform, an orientation for said projection axis to direct projected indicia to a selected spatial location defined within said common frame of reference, and which is within said first portion of said operative field of view.

9. The method of claim 7 wherein determining said orientations of said projection axis to align said projected indicia with each reference target location further includes
actuating a multi-axis gimbal supporting said optical projector to orient said projection axis at an orientation calculated to align said projected indicia with a selected reference target location;
projecting said indicia towards said selected reference target location;
observing said projected indicia to identify misalignment between said projected indicia and said selected reference target location;
responsive to said identified misalignment, either
(a) operating said multi-axis gimbal to adjust an orientation of said projection axis to align said projected indicia with said selected reference target location to within an acceptable tolerance, or
(b) altering said location of said selected reference target to align said projected indicia with said selected reference target to within an acceptable tolerance; and

storing said projector axis orientation in association with said selected reference target location.

10. The method of claim 7 wherein determining said spatial relationship between said projection axis and said plurality of reference targets located within a first portion of said operative field of view includes evaluating images of a calibration fixture supporting at least one of said reference targets, said images acquired by an optical camera disposed in a known spatial relationship with said projection axis.

11. The method of claim 10 wherein said calibration fixture includes a set of optical targets; and
wherein evaluation of said images of said calibration fixture further includes determining relative positions and/or orientations of each of said optical targets from said acquired images.

12. The method of claim 7 further including
determining a spatial relationship between said projection axis and a second plurality of reference targets located within a second portion of said operative field of view of the optical projector;
for each of said second plurality of reference targets, determining an orientation of said projection axis required to align said projected indicia with each reference target location within said second portion of said operative field of view; and
wherein said determined orientations of said projection axis associated with each reference target location in the first and second portions of said operative field of view are utilized to establish said transform between said projection axis orientations and the spatial locations of each reference target in said common frame of reference.

13. The method of claim 12 further including altering a spatial position of said optical projector such that said second portion of said operative field of view encompasses said first plurality of reference targets;
wherein determining said at least one orientation of said projection axis to align said projected indicia with each reference target location within said second operative field of view further includes
actuating a multi-axis gimbal to alter an orientation of the optical projector to an orientation calculated to align said projected indicia with a selected reference target location;
projecting indicia towards said selected reference target location;
identifying misalignment between said projected indicia and said selected reference target location;
responsive to said identified misalignment, either
(a) operating said multi-axis gimbal to adjust an orientation of said projection axis to align said projected indicia with said selected reference target location to within an acceptable tolerance, or
(b) altering said location of said selected reference target to align said projected indicia with said selected reference target to within an acceptable tolerance; and

storing said projection axis orientation in association with said selected reference target location present within said second portion of said operative field of view.

14. The method of claim 12 wherein said first portion of said operative field of view is a forward-looking portion relative to said optical projector; and
wherein said second portion of said operative field of view is a rearward-

Assignees

• Hunter Eng Co

Inventors

• Cejka Brian M
• Dorrance Daniel R
• Haggard Asher L

Classifications

• G06T7/80 Primary

  Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration · CPC title

• G06T2207/10028

  Range image; Depth image; 3D point clouds · CPC title

• G06T2207/30252

  Vehicle exterior; Vicinity of vehicle · CPC title

• G01M17/00

  Testing of vehicles (testing fluid tightness G01M3/00; testing elastic properties of bodies or chassis, e.g. torsion-testing, G01M5/00; testing alignment of vehicle headlight devices G01M11/06; testing of engines G01M15/00) · CPC title

• G06T2207/30204

  Marker · CPC title