Measuring system for determining 3D coordinates of an object surface

• US 9,482,524 B2
• Filed: 04/13/2012
• Issued: 11/01/2016
• Est. Priority Date: 04/14/2011
• Status: Active Grant

• Current Assignee: Hexagon Technology Center GmbH (Hexagon AB)
• Original Assignee: Hexagon Technology Center GmbH (Hexagon AB)
• Inventors: Metzler, Bernhard, Siercks, Knut
• Primary Examiner(s): CASS, JEAN PAUL
• Application Number:
  US14/002,657
• Publication Number:
  US 20140046589A1
• Time in Patent Office: 1,663 Days
• US Class Current: 1/1
• CPC Class Codes: B64U 2101/30 for imaging, photography or videography
• CPC Class Codes: B64U 2201/10 autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS]
• CPC Class Codes: G01B 21/04 by measuring coordinates of points
• CPC Class Codes: G01C 15/004 Reference lines, planes or sectors
• CPC Class Codes: G05D 1/0094 involving pointing a payload, e.g. camera, weapon, sensor, towards a fixed or moving target

Abstract

A measuring system for determining 3D coordinates of measurement points on an object surface which has a scanning apparatus for measuring the measurement points on the object surface and for determining inner measurement point coordinates in an inner scanning coordinate system. Furthermore, a referencing arrangement for producing referencing information for referencing the inner measurement point coordinates in the outer object coordinate system and an evaluation unit for determining the 3D coordinates of the measurement points in the outer object coordinate system on the basis of the inner measurement point coordinates and the referencing information are provided such that the inner measurement point coordinates are in the form of 3D coordinates in the outer object coordinate system. The scanning apparatus is in this case carried in an unmanned, controllable, automotive air vehicle.

Claims

1. A measuring system for determining 3D coordinates of measurement points of an object surface in an outer object coordinate system, the measuring system comprising:

an optical scanning device based on a triangulation principle for point by point optical measurement of the measurement points of the object surface and for determining inner measurement point coordinates in an inner scanning coordinate system;

a referencing arrangement for generating referencing information for referencing the inner measurement point coordinates in the outer object coordinate system;

an evaluation unit for determining 3D coordinates of the measurement points in the outer object coordinate system depending on the inner measurement point coordinates and referencing information, so that the inner measurement point coordinates are present as 3D coordinates in the outer object coordinate system;

an unmanned, controllable, automotive air vehicle carrying the optical scanning device; and

a control unit configured such that the air vehicle is moved relative to the object surface under automatic control while maintaining a predefined range of measuring distances, wherein a measuring distance takes into account at least one of;

respective current inner measurement point coordinates determined with the optical scanning device; and

a digital model object surface predefined by a digital model along a flight path defined by the digital model;

wherein at least one of

the control unit is configured to move and orient the air vehicle while being automatically controlled relative to the object surface depending on the measuring distance to the object surface that is determined with the optical scanning device;

a position and a target profile of the object surface is pre-determinable by a digital CAD model and, based on a predefined object surface, respective target surface coordinates are comparable with the respective 3D coordinates and the referencing arrangement is referenced to the object surface by referencing predefined reference points; and

the optical scanning device comprises at least one of;

an optical scanning apparatus generating scanning strips during a movement of the air vehicle,

the measuring system configured to use image sequences for determining at least one of the inner measurement point coordinates in the inner scanning coordinate system and the inner measurement point coordinates in the outer scanning coordinate system,

a line scanner,

a strip projection scanner, and

a camera.

2. The measuring system as claimed in claim 1, wherein the 3D coordinates of the measurement points comprise a plurality of 3D coordinates of measurement points of the object surface and the object surface is a surface of an industrial product.

3. The measuring system as claimed in claim 1, wherein the inner measurement point coordinates comprise 3D coordinates in the outer object coordinate system as a scatter plot.

4. The measuring system as claimed in claim 1, wherein the unmanned, controllable, automotive air vehicle carrying the optical scanning device is configured to be oriented and moved while hovering.

5. The measuring system as claimed in claim 1, wherein at least one of:

the control unit is configured to move and orient the air vehicle while being automatically controlled relative to the object surface depending on at least one of

a measuring position and a measuring orientation of the optical scanning device are continuously being determined with the referencing arrangement;

the measuring distance to the object surface that is determined with the optical scanning device; and

at least one of the position, and the target profile of the object surface is defined and the scanning strips are generated during a movement of the air vehicle.

6. The measuring system as claimed in claim 1, wherein:

the flight path is automatically determined depending on a surface position, a target surface profile, and the flight path;

a flight speed is optimized with regard to at least one of a scanning travel, a scanning time, a scanning accuracy, a stability of motion of the air vehicle, determination of a position and orientation of the air vehicle, and collision avoidance; and

a distance to an obstruction is determined with a distance measurement sensor, the scanning strips being at least partly overlapped depending on the flight path, wherein at least one of;

the scanning accuracy, the scanning travel, and the scanning time is adjusted; and

a movement and the orientation of at least one of the air vehicle and the optical scanning device is determined with an analysis of an overlap area of the scanning strips by image processing.

7. The measuring system as claimed in claim 1, wherein the referencing arrangement comprises at least one of:

a position determining arrangement, which is designed such that an outer measuring position of the optical scanning device is determined in relation to the object coordinate system; and

an orientation determination arrangement, which is designed such that a measuring orientation of the optical scanning device is determined in relation to either or both the inner object coordinate system and the outer object coordinate system.

8. The measuring system as claimed in claim 1, wherein:

at least one of the optical scanning device and the air vehicle comprise a reflector;

the referencing arrangement comprises at least one of a geodetic measuring device, a total station, and a laser tracker, with at least;

a radiation source for generating an optical measurement beam for distance measurement;

a base defining a vertical axis;

a beam deflection unit for emitting the measurement beam and for receiving at least part of the measurement beam reflected at the reflector, wherein for orientation of an optical target axis the beam deflection unit is configured to pivot by a motor relative to the base about the vertical axis and an inclination axis essentially orthogonal to the vertical axis;

angle measuring functionality for high precision recording of an orientation of a target axis; and

evaluation means for data storage and controlling an orientation of the beam deflection unit, and

wherein the measurement beam is configured to orient to the reflector continuously so that a measuring position of at least one of the optical scanning device and an air vehicle position is determined.

9. The measuring system as claimed in claim 8, wherein at least one of:

the measuring system is configured to send a signal to at least one of the optical scanning device and to the air vehicle, the signal comprising at least one of;

position information, wherein the position information is convertible into control data for controlling the air vehicle in a first processing unit associated with the air vehicle; and

the control data for controlling the air vehicle, wherein the control data is determinable from the position information with a second processing unit associated with the referencing arrangement.

10. The measuring system as claimed in claim 9, wherein:

at least one of the optical scanning device and the air vehicle comprises a GNSS antenna, configured to receive GNSS signals and determine the measuring position of the optical scanning device from the GNSS signals;

the referencing arrangement comprises a pseudo satellite module for transmitting positioning signals; and

a receiver unit of at least one of the optical scanning device and of the air vehicle is designed to receive positioning signals and to determine at least one of the measuring position and a measuring orientation of the scanner from the received positioning signals.

11. The measuring system as claimed in claim 1, wherein the referencing arrangement comprises at least one of:

a sensor unit associated with at least one of the optical scanning device and the air vehicle for determining at least one of a measuring orientation and a measuring position of at least one of the line scanner, an inclination sensor, a magnetometer, an acceleration sensor, a turn rate sensor and a speed sensor;

the referencing arrangement comprises a distance image acquisition unit for recording an image of the air vehicle, wherein at least one of a contour and image point-dependent distance data to the air vehicle is derivable from at least one of the image and the measuring orientation and the measuring position is determinable therefrom; and

the air vehicle comprises an environment recording unit including the camera for recording a position marker disposed in at least one of a defined pattern and a pseudo-random pattern, wherein determining of at least one of the measuring orientation and the measuring position is carried out with a position and orientation of a marker recorded on a second image.

12. The measuring system as claimed in claim 1, wherein:

the optical scanning device or the air vehicle comprises a marker giving the measuring at least one of a defined pattern, a pseudo random pattern, a barcode, and a light emitting diode, and

the referencing arrangement comprises a recording unit including the camera for recording the marker and for determining a measuring orientation of the optical scanning device from a position and arrangement of the marker.

13. The measuring system as claimed in claim 1, wherein at least one of:

the referencing arrangement comprises a distance image acquisition unit for recording an image of the air vehicle, wherein a contour and/or image point-dependent distance data to the air vehicle is derived from the image and a measuring orientation and/or a measuring position is determinable therefrom; and

the air vehicle comprises an environment recording unit including the camera for recording a position marker disposed in a defined pattern or a pseudo-random pattern, wherein a determination of the measuring orientation or the measuring position are executable with a position and orientation of a marker recorded on the image.

14. The measuring system as claimed in claim 1, wherein the optical scanning device is pivotable in two or three axes.

15. The measuring system as claimed in claim 1, wherein the automotive, unmanned, controllable air vehicle is configured to:

receive control data for controlling the air vehicle relative to the outer object coordinate system; and

derive the control data with a processing unit for controlling the air vehicle from receivable referencing information for determining a flying orientation and a flying position of the air vehicle;

wherein;

the air vehicle carries the optical scanning device based on the triangulation principle for optical scanning of measurement points of the object surface and for determining inner measurement point coordinates in the inner scanning coordinate system;

the processing unit is configured to reference the inner measurement point coordinates in the outer object coordinate system;

the processing unit is configured to determine 3D coordinates of the measurement points in the outer object coordinate system from the inner measurement point coordinates and from referencing of the inner measurement point coordinates, so that the inner measurement point coordinates are present as 3D coordinates in the outer object coordinate system as a scatter plot; and

the air vehicle is moved while being automatically controlled relative to the object surface while maintaining the predefined range of measuring distances.

16. The measuring system as claimed in claim 15, wherein the air vehicle is moved while being automatically controlled relative to the object surface while maintaining the predefined range of measuring distances and the measuring distance taking into account at least one of:

respective current inner measurement point coordinates determined with the scanning device; and

the object surface predefined by the digital model along the flight path defined by the digital model.

17. The measuring system as claimed in claim 15, wherein at least one of:

the air vehicle is moved and/or oriented depending on at least one of a measuring position, a measuring orientation, and the measuring distance to the object surface as determined by the optical scanning device while being automatically controlled relative to the object surface;

the optical scanning device comprises the optical scanning apparatus, wherein the scanning strips are generated during movement of the air vehicle;

the measuring system with an image sequence for determining the measurement point coordinates;

an orientation determination unit that comprises a sensor unit or the air vehicle comprises a distance measurement sensor for distance measurement to an object;

the air vehicle for defined orientation of the optical scanning device comprises at least one of a gimbal suspension and orientation means for orientation of the optical scanning device, wherein the optical scanning device is pivotable in two or three axes;

the air vehicle comprises at least one of an input unit and an output unit wherein the input unit is configured for input of at least one of information and control commands and the output unit is configured to output information; and

the air vehicle comprises a remote controller for controlling an air vehicle plot.

18. The measuring system as claimed in claim 7, wherein at least one of:

the measuring position and the measuring orientation of the optical scanning device are determined with a known positional relationship and orientation relationship of the air vehicle to the optical scanning device; and

an air vehicle position and an air vehicle orientation is determined by the referencing arrangement.

19. The measuring system as claimed in claim 8, wherein:

the referencing arrangement comprises at least one GNSS satellite represented by GPS, GLONASS or Galileo, wherein the at least one GNSS satellite provides one or more GNSS signals, and

the optical scanning device or the air vehicle comprise a receiver unit to receive GNNS signals and the measuring position of the optical scanning device is determined from the one or more GNSS signals.