Method and apparatus for three-dimensional non-contact shape sensing

• US RE35,816 E
• Filed: 03/30/1995
• Issued: 06/02/1998
• Est. Priority Date: 10/15/1990
• Status: Expired due to Term

• Current Assignee: Northern Digital Inc. (Roper Technologies, Inc.)
• Original Assignee: Image Guided Technologies, Inc. (Stryker Corporation)
• Inventors: Schulz, Waldean A.
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/415,126
• Time in Patent Office: 1,160 Days
• Field of Search: 356/375, 356/376, 356/3.14, 356/141.4, 356/139.03, 356/141.5, 356/152.1, 128/653.1, 128/653.2, 606/130, 250/559.19, 250/559.22, 250/559.23, 250/559.29, 250/559.31
• US Class Current: 356/608
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2034/2068 using pointers, e.g. pointers having reference marks for determining coordinates of body points
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01S 17/023 Combination of lidar systems, with systems other than lidar, radar or sonar, e.g. with direction finder
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

This method and apparatus optically samples numerous points on the surface of an object to remotely sense its shape utilizing two stages. The first stage employs a moveable non-contact scanner, which in normal operation sweeps a narrow beam of light across the object, illuminating a single point of the object at any given instant in time. The location of that point relative to the scanner is sensed by multiple linear photodetector arrays behind lenses in the scanner. These sense the location by measuring the relative angular parallax of the point. The second stage employs multiple fixed but widely separated photoelectronic sensors, similar to those in the scanner, to detect the locations of several light sources affixed to the scanner, thereby defining the absolute spatial positions and orientations of the scanner. Individual light sources are distinguished by time-multiplexing their on-off states. A coordinate computer calculates the absolute spatial positions where the scanner light beam is incident on the object at a given instant and continuously on a real time basis to generate a computer model of the object.

Claims

1. Optical mensuration apparatus for mapping and recording the location.Iadd.s .Iaddend.of points on a surface of a three dimensional object comprising:

. .a mounting structure, and.!. .Iadd.an .Iaddend.object positioned in . .immovable relation to said mounting structure, and.!. a three dimensional coordinate system . .defined in fixed relation to said mounting structure.!.;

. .scanning means.!. .Iadd.a scanner .Iaddend.for projecting a scanning beam onto . .the.!. .Iadd.a .Iaddend.surface of . .the.!. .Iadd.an .Iaddend.object to illuminate a plurality of spots on the surface of the object;

said . .scanning means.!. .Iadd.scanner .Iaddend.being hand holdable and freely moveable by hand in relation to . .both said mounting structure and.!. said object and not connected mechanically or structurally to . .either said mounting structure and.!. said object;

.Iadd.a .Iaddend.spot detector . .means.!. mounted to said . .scanning means.!. .Iadd.scanner .Iaddend.for detecting the . .positions.!. .Iadd.locations .Iaddend.of the illuminated spots on the surface of the object in relation to said . .scanning means.!. .Iadd.scanner.Iaddend.;

.Iadd.a .Iaddend.position . .detecting means mounted on said mounting structure and.!. .Iadd.detector .Iaddend.remotely located from both said object and said . .scanning means for detecting the position of said scanning means.!. .Iadd.scanner .Iaddend.in .Iadd.known .Iaddend.relation to . .the.!. .Iadd.said .Iaddend.coordinate system.Iadd., which position detector is adapted to determine the position of said scanner in relation to said three dimensional coordinate system.Iaddend.;

. .and

computing means.!. .Iadd.a computer .Iaddend.connected to said . .scanning means.!. .Iadd.scanner .Iaddend.and to said position . .detecting means.!. .Iadd.detector .Iaddend.for determining . .and recording.!. the . .positions.!. .Iadd.locations .Iaddend.of said illuminated spots on the surface of the object in relation to the coordinate system by correlating the . .positions.!. .Iadd.locations .Iaddend.of said illuminated spots in relation to said . .scanning means.!. .Iadd.scanner .Iaddend.with . .the respective.!. positions of said . .scanning means.!. .Iadd.scanner .Iaddend.in relation to said coordinate system when . .each.!. .Iadd.a .Iaddend.respective spot is illuminated.

2. The optical mensuration apparatus of claim 1, wherein said spot detector . .means.!. comprises a plurality of one dimensional spot . .sensing means.!. .Iadd.sensors .Iaddend.in spaced apart relation for sensing the . .position.!. .Iadd.locations .Iaddend.of the illuminated spot.Iadd.s .Iaddend.on the surface of the object.

3. The optical mensuration apparatus of claim 2, wherein each of said one dimensional spot . .sensing means.!. .Iadd.sensors .Iaddend.comprises:

a linear photodetector; and

a lens positioned between said linear photodetector and said illuminated spot on the object for focusing light from said illuminated spot onto said linear photodetector.

4. The optical mensuration apparatus of claim 3, wherein said position . .detecting means.!. .Iadd.detector .Iaddend.comprises:

a plurality of pilot light . .source means.!. .Iadd.sources .Iaddend.mounted on said . .scanning means.!. .Iadd.scanner .Iaddend.for projecting a plurality of pilot light rays; and

a plurality of one-dimensional pilot light . .sensing means.!. .Iadd.sensors .Iaddend.in spaced apart relation remotely located from said . .scanning means.!. .Iadd.position detector .Iaddend.for sensing the . .positions.!. .Iadd.locations .Iaddend.of each of said plurality of pilot light . .source means.!. .Iadd.sources.Iaddend..

5. The optical mensuration apparatus of claim 4, wherein each said one-dimensional pilot light . .sensing means.!. .Iadd.sensors .Iaddend.comprises:

a linear photodetector; and

a lens positioned between said linear photodetector and said plurality of pilot light . .source means.!. .Iadd.sources .Iaddend.for focusing light from said plurality of pilot light . .source means.!. .Iadd.sources .Iaddend.onto said linear photodetector.

6. The optical mensuration apparatus of claim 5, wherein each of said plurality of light . .source means.!. .Iadd.sources .Iaddend.is strobed off and on in a predetermined manner.

7. The optical mensuration apparatus of claim 5, wherein said . .scanning means.!. .Iadd.scanner .Iaddend.comprises:

.Iadd.at least one .Iaddend.light source . .means.!. for producing said scanning beam; and

.Iadd.a corresponding number of .Iaddend.scanning beam . .direction means.!. .Iadd.directors .Iaddend.for directing said scanning beam over the surface of the object.

8. The optical mensuration apparatus of claim 7, wherein said light source . .means.!. for producing said scanning beam is a laser.

9. The optical mensuration apparatus of claim 7, wherein said scanning beam . .direction means.!. .Iadd.director .Iaddend.is a rotating mirror having at least three sides.

10. The optical mensuration apparatus of claim 9, wherein each said lens of each said one-dimensional spot . .sensing means.!. .Iadd.sensor .Iaddend.is a cylindrical lens.

11. The optical mensuration apparatus of claim 9, wherein each said lens of each said one-dimensional pilot light . .sensing means.!. .Iadd.sensor .Iaddend.is a cylindrical lens.

12. A method of determining and mapping the location.Iadd.s .Iaddend.of surface points on an object in relation to a . .mounting structure.!. .Iadd.three dimensional coordinate system.Iaddend., comprising the steps of:

defining a three dimensional coordinate system . .in fixed relation to said mounting structure.!.;

positioning said object in a fixed spatial relation to said . .mounting structure.!. .Iadd.coordinate system.Iaddend.;

projecting a . .scanning.!. .Iadd.scannable illuminating .Iaddend.beam from a beam projector.Iadd., .Iaddend.. .mounted on a hand holdable and freely moveable scanning device.!. that is not connected mechanically or structurally to . .either said mounting structure or.!. the object, . .and moving the scanning device by hand in relation to said object.!. in such manner as to illuminate a . .plurality of spots on the.!. .Iadd.a sufficient portion of a .Iaddend.surface of the object .Iadd.to map said surface.Iaddend.;

.Iadd.scanning said surface with a hand holdable and freely moveable scanner to detect a sufficient portion of said projected beam illuminations to map said illuminated surface portion.Iaddend.;

detecting the . .positions.!. .Iadd.locations .Iaddend.of the respectively illuminated . .spots on.!. .Iadd.portions of .Iaddend.the surface of the object in relation to the respective positions of the . .scanning device.!. .Iadd.scanner .Iaddend.when each respective . .spot.!. .Iadd.portion of the surface .Iaddend.is illuminated;

projecting a plurality of pilot light rays from a plurality of pilot light sources positioned in fixed spatial relation to each other on said . .scanning device.!. .Iadd.scanner substantially .Iaddend.simultaneously with the steps of projecting said . .scanning.!. .Iadd.illuminating .Iaddend.beam and detecting the . .positions.!. .Iadd.locations .Iaddend.of the illuminated . .spots.!. .Iadd.surface portions.Iaddend.;

detecting the plurality of pilot rays with a plurality of detectors mounted . .on said mounting structure in fixed.!. .Iadd.in known .Iaddend.relation to said coordinate system and in . .fixed.!. .Iadd.known.Iaddend., spaced apart relation to each other .Iadd.substantially .Iaddend.simultaneously with the step of detecting the . .positions.!. .Iadd.locations .Iaddend.of said illuminated . .spots.!. .Iadd.surface portions .Iaddend.on said object in relation to said . .scanning device.!. .Iadd.scanner .Iaddend.to determine the . .positions.!. .Iadd.locations .Iaddend.of the plurality of pilot light sources and said . .scanning device.!. .Iadd.scanner .Iaddend.in relation to the coordinate system; and

computing the . .positions.!. .Iadd.locations .Iaddend.of the illuminated . .spots on.!. .Iadd.portions of .Iaddend.the surface of the object in relation to the coordinate system by correlating the . .positions.!. .Iadd.locations .Iaddend.of said illuminated . .spots.!. .Iadd.surface portions .Iaddend.in relation to the . .scanning device.!. .Iadd.scanner .Iaddend.with the . .position.!. .Iadd.locations .Iaddend.of the . .scanning device.!. .Iadd.scanner .Iaddend.in relation to said coordinate system. .Iadd.13. Optical mensuration apparatus for mapping and recording the locations of points on a surface of a three dimensional object as claimed in claim 1 further comprising a mounting structure, fixedly positioned in said three dimensional coordinate system, to which said object is immovably related, and wherein said position detector is mounted on said mounting structure..Iaddend..Iadd.14. An optical system as claimed in claim 13 further comprising;

multiple energy emitters disposed on said spot detector;

emitted energy detectors disposed in known relationship to said three dimensional coordinate system sufficient to detect energy emitted by said energy emitters; and

a computer operatively associated with said energy detectors adapted to calculate the position and orientation of said light detector in said three dimensional coordinate system..Iaddend..Iadd.15. An optical system for determining locations of a plurality of points on a portion of a surface of a three dimensional object, in relation to a three dimensional coordinate system in which said object resides, wherein the number of points on said surface portion is sufficient to map said surface portion, said system comprising;

at least one three dimensional object having at least one surface positioned in a three dimensional coordinate system;

a beam projector unconnected mechanically or structurally to said object, and freely moveable in relation to said object;

at least one scannable beam adapted to be projected from said projector onto a surface of said object and to thereby illuminate said plurality of points on said surface portion;

a scanner comprising at least one light detector, unconnected mechanically or structurally to said object, and freely moveable in relation to said object, and adapted to detect locations of said illuminated points on said surface of said object in said three dimensional coordinate system in relation to said spot detector;

means to maintain said object in a substantially stationary condition during said illumination and detection of at least three of said plurality of spots sufficient in number to map said surface portion of said object;

at least one light detector locator disposed in known position in said three dimensional coordinate system, for optically detecting the position and orientation of said light detector in relation to said three dimensional coordinate system; and

a computer connected to said light detector and to said detector locator for correlating respectively the locations of said illuminated portions of said surface of said object in relation to said light detector and the location of said light detector in relation to said three dimensional coordinate system;

whereby indirectly determining the locations of each of said illuminated surface portions with respect to said three dimensional coordinate system, and therefore mapping said portion of said surface of said

15. said mounting structure..Iaddend..Iadd.22. A method of mapping at least a portion of a surface on an object, which object is in a known position and orientation in a three dimensional coordinate system, comprising:

disposing an object, comprising at least one surface, in a known position and orientation in a three dimensional coordinate system;

disposing a hand holdable scanner in said coordinate system, unconnected mechanically or structurally to said object and freely moveable within said three dimensional coordinate system, so positioned that it can scan said surface;

projecting a plurality of spots onto said surface portion;

detecting the locations on said surface portion, in relation to a spot detector, of a sufficient number of spots to map at least said portion of the surface;

at substantially the same time as the locations of the respective spots are being determined, determining the location of said spot detector in said coordinate system;

correlating the locations of said respective spots with the position and orientation of said spot detector;

thereby

indirectly determining the locations of said illuminated spots in said three dimensional coordinate system; and

mapping said surface..Iaddend.

13. object..Iaddend..Iadd.16. An optical system as claimed in claim 15 wherein said light detector is located together with said illuminating beam projector..Iaddend..Iadd.17. An optical system as claimed in claim 15 wherein said light detector locator is located together with said

14. object..Iaddend..Iadd.18. An optical system as claimed in claim 15 wherein said scanner is hand held and is moved by hand..Iaddend..Iadd.19. An optical system as claimed in claim 15 further comprising said locator being adapted to locate said light detector at substantially the same time as the locations of each of said illuminated surface portions are being detected by said light detector..Iaddend..Iadd.20. An optical system as claimed in claim 15 wherein said object is in a fixed position in said three dimensional coordinate system..Iaddend..Iadd.21. An optical system as claimed in claim 20 wherein said object is attached to a mounting structure which is in fixed spatial relationship to said three dimensional coordinate system, wherein said scanner has said light detector affixed thereto, and wherein said light detector locator in fixed relationship to