Metrology system

Patent metadata

Field	Value
Publication number	US-12289526-B2
Application number	US-202218078514-A
Country	US
Kind code	B2
Filing date	Dec 9, 2022
Priority date	Dec 14, 2021
Publication date	Apr 29, 2025
Grant date	Apr 29, 2025

Abstract

A metrology system comprising a target object, a metrology instrument and a control unit configured for controlling an alignment of the targeting unit and for deriving an orientation of the target object. The metrology instrument comprises a zoom objective, an illumination unit and a time-of-flight sensor comprising an array of pixels and capable of providing range data for each pixel of the array as point cloud data, the time-of-flight sensor provides the distance measuring device. The control unit comprises an object determination functionality which provides receiving the point cloud data provided by the time-of-flight sensor, deriving a digital representation of the target object by processing the point cloud data, comparing the digital representation of the target object with a reference pattern of the target object, and determining the orientation of the target object based on the comparison of the digital representation of the target object with the reference pattern.

First claim

The invention claimed is:

1. A metrology system comprising:
a target object,
metrology instrument for tracking the target object and/or for determining at least an orientation of the target object, the metrology instrument comprises:
a base unit,
a support unit mounted on the base unit and configured for being rotatable relative to the base unit around a yaw axis,
a targeting unit mounted on the support unit and configured for being rotatable relative to the support unit around a pitch axis,
an angle determining unit configured to provide angle determination data for determining an alignment of the targeting unit and
a distance measuring device configured to provide distance data with respect to the target object, and

a control unit configured for controlling an alignment of the targeting unit and for deriving at least an orientation of the target object,

wherein the metrology instrument comprises:
a zoom objective, an illumination unit and a time-of-flight sensor comprising an array of pixels and capable of providing range data for each pixel of the array as point cloud data, the time-of-flight sensor provides the distance measuring device,
wherein the zoom objective, the illumination unit and the time-of-flight sensor are arranged so that an optical axis of the zoom optics, an optical axis of the illumination unit and an optical axis of the time-of-flight sensor are coaxial and an orientation of the coaxial axes is alignable by means of the targeting unit,
the target object provides particular characteristics at the target object,
the control unit comprises an object determination functionality which, when executed, provides:
receiving the point cloud data provided by the time-of-flight sensor,
deriving a digital representation of the target object by processing the point cloud data,
comparing the digital representation of the target object with a reference pattern of the target object, the reference pattern is related to the characteristics of the target object, and
determining the orientation of the target object based on the comparison of the digital representation of the target object with the reference pattern.

2. The metrology system according to claim 1 , wherein the characteristics of the target object are provided by:
a shape and/or a dimension of the target object, and/or
an asymmetrical shape of the target object, and/or
particular orientation elements arranged at the target object.

3. The metrology system according to claim 1 , at least one orientation element,
comprises an ellipsoidal, parabolic, spherical or curved shape and/or
is embodied as a spherical or half-spherical body which defines a spherical or half-spherical elevations and/or depressions at the target.

4. The metrology system according to claim 1 , wherein when executed, the object determination functionality provides computing a digital model of at least a part of the target object based on the point cloud data, the computed digital model is the digital representation of the target object.

5. The metrology system according to claim 4 , wherein when executed, the object determination functionality provides fitting of the computed digital model to the reference pattern with respect to an orientation of the computed digital model, in particular also with respect to a scaling of the computed digital model.

6. The metrology system according to claim 5 , wherein when executed, the object determination functionality:
provides information about an orientation and/or position of the target object based on the fitting of the computed digital model, in particular an orientation with reference to the metrology instrument, and/or
provides determining a transformation matrix based on the fitting, the transformation matrix provides information about an orientation of the target object, in particular an orientation and/or position with reference to the metrology instrument.

7. The metrology system according to claim 5 , wherein the fitting of the computed digital model comprises:
based on the point cloud data or based on the computed digital model, identifying and extracting particular characteristics of the target object,
deriving a number of fitting points related to the identified and extracted particular characteristics, in particular deriving focal points and/or centre points of ellipsoidal, parabolic and/or spherical shaped characteristics representing the fitting points,
fitting the fitting points to respective pattern reference points provided by the reference pattern.

8. The metrology system according to claim 1 , wherein a digital reference model of at least a part of the target object is provided as the reference pattern, wherein the digital reference model provides information about dimension and shape of the target object, in particular about dimensions and shapes of the characteristics and their positions at the target object.

9. The metrology system according to claim 8 , wherein the digital reference model provides the pattern reference points and fitting of the computed digital model is performed with respect to the digital reference model, in particular wherein the pattern reference points provide positions of focal points and/or centre points of ellipsoidal, parabolic and/or spherical shaped characteristics with respect to the target object.

10. The metrology system according to claim 1 , wherein the target object comprises a high-reflectivity coating, the high-reflectivity coating is designed to reflect light emitted by the illumination unit, in particular wherein the high-reflectivity coating comprises retro-reflecting glass powder, in particular wherein at least one particular characteristic of the target object comprises the high-reflectivity coating.

11. The metrology system according to claim 1 , wherein when executed, the object determination functionality provides:
deriving a distance between the metrology instrument and the target object by processing of the point cloud data, and/or
deriving six degrees of freedom (6DOF) of the target object by processing of the point cloud data.

12. The metrology system according to claim 1 , wherein:
the target object comprises a set of 2D markers and
the metrology instrument comprises an image sensor, in particular wherein the image sensor is provided by the time-of-flight sensor,
wherein the control unit comprises a coarse orientation determination functionality which, when executed, provides:
capturing a marker image of at least a part of the set of 2D markers,
processing the marker image and determining marker image positions for the captured markers and
deriving an orientation of the target object based on the marker image positions.

13. A metrology instrument for tracking a target object and/or for determining at least an orientation of the target object, the metrology instrument comprises:
a base unit,
a support unit mounted on the base unit and configured for being rotatable relative to the base unit around a yaw axis,
a targeting unit mounted on the support unit and configured for being rotatable relative to the support unit around a pitch axis,
an angle determining unit configured to provide angle determination data for determining an alignment of the targeting unit,
a distance measuring device configured to provide distance data with respect to the target object and
a control unit configured for controlling an alignment of the targeting unit and for deriving at least an orientation of the target object,
wherein the metrology instrument comprises
a zoom objective,
an illumination unit and
a time-of-flight sensor comprising an array of pixels a

Assignees

• Hexagon Technology Ct Gmbh

Inventors

• Stigwall Johan
• Yang Zheng
• Jensen Thomas

Classifications

• G06T2207/30204

  Marker · CPC title

• G06T2207/10028

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

• G01S17/89

  for mapping or imaging · CPC title

• G01S17/66

  Tracking systems using electromagnetic waves other than radio waves · CPC title

• H04N25/705

  Pixels for depth measurement, e.g. RGBZ · CPC title