Six degree of freedom sensor

• US 5,883,803 A
• Filed: 09/24/1996
• Issued: 03/16/1999
• Est. Priority Date: 09/24/1996
• Status: Expired due to Fees

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Vann, Charles S.
• Primary Examiner(s): Elmore, Reba I.
• Assistant Examiner(s): BROWN, THOMAS
• Application Number:
  US08/719,061
• Time in Patent Office: 903 Days
• Field of Search: 364/167.01, 356/138, 356/139.03, 356/139.04, 356/139.05, 356/139.06, 356/139.07, 356/141.1, 356/141.2, 356/141.4, 356/152.2, 356/152.1, 356/152.3 , 356/445-448
• US Class Current: 700/59
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates

Abstract

This small, non-contact optical sensor increases the capability and flexibility of computer controlled machines by detecting its relative position to a workpiece in all six degrees of freedom (DOF). At a fraction of the cost, it is over 200 times faster and up to 25 times more accurate than competing 3-DOF sensors. Applications range from flexible manufacturing to a 6-DOF mouse for computers. Until now, highly agile and accurate machines have been limited by their inability to adjust to changes in their tasks. By enabling them to sense all six degrees of position, these machines can now adapt to new and complicated tasks without human intervention or delay--simplifying production, reducing costs, and enhancing the value and capability of flexible manufacturing.

Claims

1. A six degree of freedom sensor, comprising:

a reflective bar;

a reflective dot, wherein said reflective bar is tilted with respect to said reflective dot;

wherein said reflective bar and reflective dot are attached to a workpiece;

means for producing a light beam for simultaneously illuminating said reflective bar and said reflective dot;

means for diverging said light beam;

a beamsplitter for splitting light reflected from said reflective dot to produce a first reflected beam and a second transmitted beam;

a first photodiode for detecting said first beam;

a second photodiode for detecting said second beam;

a lens to focus said second beam onto said first photodiode;

a third photodiode for detecting light reflected from said reflective bar;

a digitizer for digitizing the signals from said first, second and third photo diode; and

a computer comprising a computer program for multiplying the digitized signals by a calibration matrix to produce matrix data, wherein said computer program decouples said matrix data into discrete position information in all six degrees of freedom.

2. A six degree of freedom sensor, comprising:

a reflective bar;

a reflective dot, wherein said reflective bar is tilted with respect to said reflective dot;

wherein said reflective bar and reflective dot are adjacent and are attached to a workpiece;

a light source comprising a light beam for simultaneously illuminating said reflective bar and said reflective dot

means for diverging said light beam;

a beamsplitter for splitting light reflected from said reflective dot to produce a first reflected beam and a second transmitted beam;

a first photo diode for detecting said first beam;

a second photo diode for detecting said second beam;

a lens to focus said second beam onto said second photo diode;

a third photo diode for detecting light reflected from said reflective bar;

a laser emitting diode for providing background light on said first photo diode, said second photo diode and said third photo diode;

a signal processing unit to condition and amplify signals from the photo diodes;

a digitizer for digitizing the signals from said first, second and third photo diode; and

a computer comprising a computer program for multiplying the digitized signals by a calibration matrix to produce matrix data, wherein said computer program decouples said matrix data into discrete position information in all six degrees of freedom.

3. A six degree of freedom sensor, comprising:

means for reflecting laser light from a part to produce reflected light, wherein said part comprises six degrees of freedom, comprising Tz, Rz, Ty, Ry, Tx and Rx;

means for directing said reflected light onto three photodiodes, wherein a first photodiode of said three photodiodes is sensitive to translation between said part and said sensor (Tz) and rotation of said part (Rz), wherein a second photodiode of said three photodiodes is sensitive to tilt about Rx and Ry and wherein a third photodiode of said three photodiodes is sensitive to translation of said part in the Tx and Ty directions; and

means for determining the position of Tz, Rz, Ty, Ry, Tx and Rx of said part from light detected by said three photodiodes.

4. A sensor, comprising:

a reflective dot;

wherein said reflective dot is adhesively attached, made into, or painted onto to a part;

a light source to produce a light beam for illuminating said reflective dot, wherein said light source is selected from a group consisting of a light emitting diode (LED) and a laser light source;

means for diverging said light beam;

a beamsplitter for splitting light reflected from said reflective dot to produce a first reflected beam and a second transmitted beam;

a first photodiode for detecting said first beam;

a second photo diode for detecting said second beam;

a lens to focus said second beam onto said second photodiode;

a laser emitting diode for providing background light on said first photo diode and said second photo diode;

a signal processing unit to condition and amplify signals from the photo diodes;

a digitizer for digitizing the signals from said first and second photo diode; and

a computer comprising a computer program for multiplying the digitized signals by a calibration matrix to decouple the data into unambiguous position information in four degrees of freedom.

5. A six degree of freedom sensor, comprising:

a first light source fixedly attached to an object of interest, wherein said first light source provides a first beam of light for illuminating said sensor;

a beamsplitter for splitting said light from said light source to produce a first reflected beam and a second transmitted beam;

a first photodiode for detecting said first beam;

a second photo diode for detecting said second beam;

a lens to focus said second beam onto said second photodiode;

a second light source on said object of interest, wherein said second light source provides a second beam of light for illuminating said sensor;

a third photo diode for detecting said second beam of light from said second light source;

a laser emitting diode for providing background light on said first photo diode, said second photo diode and said third photo diode;

a signal processing unit to condition and amplify signals from the photo diodes;

a digitizer for digitizing the signals from said first, second and third photo diode; and

a computer comprising a computer program for multiplying the digitized signals by a calibration matrix to decouple the data into unambiguous position information in all six degrees of freedom.

6. A six degree of freedom sensor, comprising:

a reflective bar;

a reflective dot, wherein said reflective bar is tilted with respect to said reflective dot;

wherein said reflective bar and reflective dot are adjacent and are attached to a workpiece;

a light source comprising a light beam for simultaneously illuminating said reflective bar and said reflective dot;

a fiber optic to transport and diverge said light beam from said light source;

a lens to collimate the diverging beam reflected from said reflective dot;

a beamsplitter for splitting light reflected from said reflective dot to produce a first reflected beam and a second transmitted beam;

a first photo diode for detecting said first beam;

a second photo diode for detecting said second beam;

a lens to focus said second beam onto said second photo diode;

a third photo diode for detecting light reflected from said reflective bar;

a laser emitting diode for providing background light on said first photo diode, said second photo diode and said third photo diode;

a signal processing unit to condition and amplify signals from the photo diodes;

a digitizer for digitizing the signals from said first, second and third photo diode; and

a computer comprising a computer program for multiplying the digitized signals by a calibration matrix to produce matrix data, wherein said computer program decouples said matrix data into discrete position information in all six degrees of freedom.