System for detecting the position of a moving body

• US 5,258,822 A
• Filed: 04/06/1992
• Issued: 11/02/1993
• Est. Priority Date: 04/11/1991
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Kamimura, Kenji, Nakamura, Toshikazu, Tsuzuki, Sadachika, Noda, Kazunori
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US07/864,468
• Time in Patent Office: 575 Days
• Field of Search: 356/1, 356/152, 356/141, 356/140
• US Class Current: 356/141.4
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G02B 26/10 Scanning systems

Abstract

A position detection system for a moving body comprising means for rotatively scanning the light beam projected from a light beam generator mounted on the moving body in a substantially horizontal plane, and vibrating to vertically vibrate the rotatively scanned light beam in a cycle two times or more longer than the cycle of the rotative scan. The light beam projected from the moving body and reflected by the retroreflector means provided at at least three positions spaced apart from the moving body is received by a light beam receiver on the moving body, and the position of the moving body is detected on the basis of the directions of the light reception and the known positional information on the retroreflector means.

Claims

1. In a system for detecting the position of a moving body comprising light beam scanner means for rotatively scanning a light beam in a circular direction around the moving body, light beam receiver means mounted on said moving body for receiving said light beam reflected by optical retroreflector means disposed at at least three reference points spaced apart from said moving body, and means for detecting the azimuth of said optical retroreflector means, wherein the position of said moving body is detected on the basis of said detected azimuth and position information of the reference points, the system comprising

vibrating means for continuously vibrating said light beam vertically in periodic cycles, said light beam being rotatively scanned around said body a plurality of times during each vibration cycle of said light beam.

5. A system for detecting the position of a moving body as set forth in claim 1 including means responsive to the azimuths of optical signals detected during each cycle of the vertical vibration of said light beam for specifying that when substantially the same azimuth has been detected a plurality of times during a given cycle, that azimuth is the azimuth of a predetermined retroreflector means.

2. In a system for detecting the position of a moving body comprising light beam scanner means for rotatively scanning a light beam in a circular direction around the moving body, light beam receiver means mounted on said moving body for receiving said light beam reflected by optical retroreflector means disposed at at least three reference points spaced apart from said moving body, and means for detecting the azimuth of said optical retroreflector means, wherein the position of said moving body is detected on the basis of said detected azimuth and position information of the reference points, the system comprising vibrating means for vertically vibrating said light beam, the rotative scanning of said light beam being performed several times during one cycle of the vertical vibration of said light beam, said vibrating means being operative to rotate a central axis of rotation of said light beam scanner means while keeping it inclined by a predetermined angle so that the inclination direction varies continuously and periodically.

3. A system for detecting the position of a moving body as set forth in claim 2 wherein said central axis of rotation is rotated so that the locus drawn by said central axis is conical.

4. A system for detecting the positions of a moving body as set forth in claim 2 wherein said central axis of rotation is rotated so that the locus drawn by said central axis of rotation is circular conical.

6. In a system for detecting the position of a moving body comprising light beam scanner means for rotatively scanning a light beam in a circular direction around the moving body, light beam receiver means mounted on said moving body for receiving said light beam reflected by optical retroreflector means disposed at at least three reference points spaced apart from said moving body, and means for detecting the azimuth of said optical retroreflector means, wherein the position of said moving body is detected on the basis of said detected azimuth and position information of the reference points, the system comprising

vibrating means for vertically vibrating said light beam, the rotative scanning of said light beam being performed several times during one cycle of the vertical vibration of said light beam,

means for storing azimuths on a detection block basis, said storing means storing the azimuths of optical signals detected during one cycle of the vertical vibration of said light beam in such manner that a plurality of optical signals received from substantially the same azimuth are treated as the optical signals of a single detection block whose azimuths are represented by a single value, and

means for storing the number of light reception times on a detection block basis, wherein

a plurality of detection blocks equal in number to the number of disposed retroreflector means are picked out in descending order of the number of light reception times in each block, and the stored azimuth representative of the particular detection block is determined to be the azimuth of said retroreflective means.

7. A system for detecting the position of a moving body comprising light beam generator means mounted on the moving body, means for rotatively scanning a light beam from said beam generator in a circular direction around said moving body, light beam receiver means mounted on said moving body for receiving said light beam after it has been reflected by optical retroreflector means disposed at positions spaced apart from said moving body, and means for detecting the position of said moving body on the basis of position information of said retroreflector means and information derived from reception of said reflected light beam, the system including means for increasing the probability that said rotatively scanned light beam will be incident on said retroreflector means during movement of said moving body, comprising:

precession means for precessing the central axis of rotation of said means for rotatively scanning a light beam so as to draw a substantially conical locus,

said light beam generator means and receiver means being precessed by said precession means continuously during operation of said rotative scanning means, whereby said light beam is vertically vibrated in a periodic cyclical fashion during the rotative scanning of said light beam.

8. A system for detecting the position of a moving body as set forth in claim 7 wherein said means for rotatively scanning a light beam comprises a reflecting mirror for bending the optical axis of the light beam from said light beam generator means, a driving motor for rotating said reflecting mirror around the optical axis of the light beam between said light beam generator means and said reflecting mirror, and a precession body which is precessed by said precession means, said means for rotatively scanning a light beam, said light beam generator means and said light receiver means each being attached to said precession body, the precession body being so driven that the rotating axis of said reflecting mirror draws a conical locus.

9. A system for detecting the position of a moving body as set forth in claim 8 wherein said precession body has said light beam generator means and said light receiver means provided at one side thereof and has said means for rotatively scanning a light beam provided at a different side thereof.

10. A system for detecting the position of a moving body as set forth in claim 7 wherein said light beam is rotatively scanned several times during one vertical oscillation cycle of said light beam.

11. A system for detecting the position of a moving body comprising light beam scanning means operative to rotatively scan the light beam substantially in a horizontal plane around the moving body, light beam receiver means mounted on said moving body for receiving said light beam reflected by optical retroreflector means disposed at positions spaced apart from said moving body, and means for detecting a positional relationship between said moving body and said retroreflector means on the basis of a light reception signal, wherein the position of said moving body is detected on the basis of said detection result, the system comprising:

light beam vibration means for vertically vibrating said light beam,

means for performing a plurality of rotative scannings of said light beam during one vertical vibration cycle of said light beam,

memory means for storing the azimuths of the light reception signal during one cycle of vertical vibration of said light beam,

predicted azimuth deciding means for predicting an azimuth in which the light beam reflected by said retroreflector means is to be detected in the next vibration scan, on the basis of the azimuth or azimuths detected up to the present, and

means for collating each said stored azimuth with said predicted azimuth for each said vibration scan cycle to determine the actual light reception azimuth, and the position of the moving body being detected on the basis of the collation result.

12. A system for detecting the position of a moving body as set forth in claim 11 wherein when a plurality of optical signals are received in substantially the same azimuth during one virtical vibration cycle of said light beam, only the azimuth of the latest light reception signal is stored.

13. A system for detecting the position of a moving body as set forth in claim 11 wherein said light beam vibration means rotates the central axis of rotation of said light beam scanning means around one point thereof, with the central axis of rotation of said light beam scanning means being inclined with predetermined angle to draw a conical surface.