Optical scanning-based system for detecting position and/or orientation of objects

• US 8,553,932 B2
• Filed: 09/25/2009
• Issued: 10/08/2013
• Est. Priority Date: 09/26/2008
• Status: Expired due to Fees

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Barbier, Bruno, Rouzes, Siegfried
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): Valentin, II, Juan D
• Application Number:
  US12/566,958
• Publication Number:
  US 20100085581A1
• Time in Patent Office: 1,474 Days
• Field of Search: None
• US Class Current: 382/103
• CPC Class Codes: F41G 3/225 Helmet sighting systems
• CPC Class Codes: G01S 17/875 for determining attitude
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

The optical device for determining position and orientation of an object comprising a fixed part comprises a laser beam projector with sequential scan and a projection centre (O), defining the centre of a reference frame (R) in space. The projector emits, in a zone comprising at least four sensors fixed to the said object, the four sensors having a known disposition on the object. The instants at which each of the sensors provides an electrical pulse determine the angular directions of the said sensors in the reference frame, the four straight lines passing through the origin and through each of the sensors intercepting an image plane of the fixed part at four projected points. The positions in the image plane of the mappings of the four points determine a geometric shape making it possible to calculate the position and the orientation of the object in space.

Claims

1. Optical device for determining position and orientation of an object comprising a fixed part of known position comprising a laser beam projector with sequential scan defining a fixed center of a fixed three-dimensional reference frame in space containing three coordinate axis, the projector scanning at least a beam, each beam being scanned from the fixed center and passing through the fixed center, each scanning a zone comprising at least four point-like sensors fixed to the object, the orientation of the scan being known at each instant, the four point-like sensors forming a parallelogram, wherein the instants, at which each of the sensors is scanned by the beam, determine four directions of each of the sensors in the reference frame, the four straight lines passing through the origin and having the directions intercepting an image plane of the fixe part at four projected points, the positions in the image plane of the mappings of the four points determining a quadrilateral, the optical device having an electronic analyzer for calculating a rotation performed by the object about the three coordinate axis with respect to a reference position of the parallelogram in the fixed three-dimensional reference frame and a translation performed by the object with respect to a reference position of the parallelogram in the fixed three-dimensional reference frame.

2. Optical device for determining position and orientation of an object according to claim 1, wherein the determination of the position and of the orientation of the object in space comprises:

The calculation of the two intersections, in the image plane, of two pairs of straight lines, each of the straight lines comprising a side of the quadrilateral, the straight lines being chosen pairwise on opposite sides of the quadrilateral;

The determination of the components of a rotation of the parallelogram about the three coordinate axis with respect to the reference position of the parallelogram in the fixed three-dimensional reference frame as a function of the reference position of the parallelogram and of the positions of the two intersections;

The determination of a translation of the sensors forming a parallelogram with respect to the reference position of the parallelogram in the fixed three-dimensional reference frame as a function of the reference position of the parallelogram and of the positions of the two intersections.

3. Optical device for determining position and orientation of an object according to claim 1, wherein the projector is adapted to scan a single, point-like beam, during a determined period in a recurrent manner alternately horizontally and vertically.

4. Optical device for determining position and orientation of an object according to claim 1, wherein the scan of the zone comprises a first horizontal scan of a vertical linear beam intercepting the sensors at four first instants and a second vertical scan of a horizontal linear beam intercepting the sensors at four second instants, the direction of a sensor in space being determined by two angular positions, one being vertical and the other horizontal.

5. Optical device for determining position and orientation of an object according to claim 1, wherein the point-like sensors are photosensitive surfaces of a linear sensor, of strip type.

6. Optical device for determining position and orientation of an object according to claim 1, wherein the point-like sensors are photosensitive surfaces of a sensor of matrix type.

7. Optical device for determining position and orientation of an object according to claim 1, wherein the projector radiates at fixed power.

8. Optical device for determining position and orientation of an object according to claim 1, wherein the scan of the light beam in the zone is performed in less than 20 ms.

9. Optical method for determining position and orientation of an object, wherein it comprises:

a first initialization step comprising a first scan by the optical device of claim 1 of a first zone of space and;

a second tracking step comprising a second scan, following the first scan, of a second zone smaller than the first zone.

10. The optical device of claim 1, wherein the scan of the zone comprises a first scan of a first linear beam, in a first direction, intercepting the sensors at four first instants and a second scan of a second linear beam, in a second direction, intercepting the sensors at four second instants, an angle between the first and the second direction being different from zero.

11. The optical device of claim 10, wherein the angle between the first and the second direction is 90°

C.

12. The optical device of claim 1, wherein when in the reference position, the parallelogram is in a plane perpendicular to a projection axis of the projector and centered at the fixed center,

13. The optical device of claim 1, wherein the projector scans at most two beams.

14. The optical device of claim 1, wherein the projector scans a single point-like beam.