EP1234159A1 - An optical position detector - Google Patents
An optical position detectorInfo
- Publication number
- EP1234159A1 EP1234159A1 EP00977736A EP00977736A EP1234159A1 EP 1234159 A1 EP1234159 A1 EP 1234159A1 EP 00977736 A EP00977736 A EP 00977736A EP 00977736 A EP00977736 A EP 00977736A EP 1234159 A1 EP1234159 A1 EP 1234159A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- target
- scale
- pattern
- optical axis
- image processing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
- G01B11/27—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
- G01B11/272—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes using photoelectric detection means
Definitions
- the present invention relates to an optical position detector, in particular for measuring the
- Optical position detectors are typically used to enable the displacement of an object to be
- Figure 1 shows an example of a conventional optical position detector.
- the system includes a
- target 2 target 2
- target holder 4 target holder 4
- alignment telescope 6 An operator 8 views the target 2 through
- the telescope defines an image line of sight 13 and an object line of
- the target holder 4 holds the target 2 in a precise spatial relationship to the object (not
- the displacement D of the target and hence the object is proportional to the angle ⁇
- Alignment telescopes have been in use for many years and have proven to be a reliable means of
- magnification of the alignment telescopes varies significantly with focus over the
- an optical position detector comprising:
- the target has a pattern of lines defining a
- processing system is arranged to receive an image of the target and determine therefrom the location of the object relative to said optical axis.
- the present invention provides a position detector using a target with a scale whose criticality
- the image processing system can thus compute
- the scaling factor between the measured image size (which may be in units of number of pixels of
- the image sensor and known, real world, image size and use this scaling factor to determine the
- the target is positioned in a known relationship relative to the object.
- the pattern may be a plurality of concentric shapes, and any adjacent pair of shapes can then
- the shapes can be identified uniquely, and the real dimensions can then be known
- the image processing system if the target is on a far away object, the image processing system
- Each shape also defines the fixed point on the target, for example the centre of the concentric
- the shapes preferably comprise circles and the image processing system is arranged to image at
- the image processing system preferably measures an offset between the optical axis and an
- the invention also provides a method of measuring the offset of an object from an optical axis
- magnification is required because the system is self calibrating. Furthermore, the system can
- Figure 1 shows an example of a conventional optical position detector
- Figure 2 shows an example of a control system used in the optical position detector
- Figure 3 shows an optical position detector according to the present invention
- Figure 4 shows a scaled pattern used on a target used in an optical position detector
- Figure 5 shows a table of values used in the optical position detector of the present
- Figure 3 shows an example of an optical position detector for measuring the displacement of an
- the system has a target 18 and an image processing system 20 having an optical axis 16.
- the target 18 and an image processing system 20 having an optical axis 16.
- the image processing system is arranged to
- the target may reflect
- ambient light or it may be transmissive and a light source may then be provided behind the
- the target 18 has a scaled pattern arranged on its surface which faces the optical processing
- Figure 4 shows an example of a scaled pattern used on the target used in the optical position
- the pattern has a number of concentric rings 22
- the diameter of the circular edge of one ring (either a light to
- the image processing system measures the diameters of the
- the ratio of the diameters of the two rings enables the system to detect which of the concentric
- Centroiding software enables the centre of the pattern to be obtained with high accuracy.
- the image of the target is obtained by the image processing system 20, and a measurement
- consecutive circles in the pattern may be detected (e.g. black to white boundary and white to
- pixels from the centre of the camera optical axis (or some other useful datum in the field of view)
- the distance of the target from the imaging system does not matter.
- the distance of the target from the imaging system does not matter.
- pattern for the target could be employed, including for example,
- This system can be used in the alignment of a number of objects where it is required that they are
- the system could be used to arrange a series of elements such as
- the optical axis may for example be defined by aligning the optical system with the first and the
- the target image is projected onto a reflective surface through a
- the reflected image is collected by the telescope and viewed through a beam splitter.
- the displacement of the reflected image which is dependant upon the rotation of the
- reflective surface to the instrument line of sight can then be measured using an appropriate target and processing system.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9928124 | 1999-11-26 | ||
GBGB9928124.8A GB9928124D0 (en) | 1999-11-26 | 1999-11-26 | An optical position detector |
PCT/GB2000/004496 WO2001038823A1 (en) | 1999-11-26 | 2000-11-24 | An optical position detector |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1234159A1 true EP1234159A1 (en) | 2002-08-28 |
Family
ID=10865311
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00977736A Withdrawn EP1234159A1 (en) | 1999-11-26 | 2000-11-24 | An optical position detector |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1234159A1 (en) |
AU (1) | AU1537101A (en) |
GB (1) | GB9928124D0 (en) |
WO (1) | WO2001038823A1 (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6704102B2 (en) | 2001-02-06 | 2004-03-09 | Metronics, Inc. | Calibration artifact and method of using the same |
GB2376533A (en) * | 2001-06-14 | 2002-12-18 | Instro Prec Ltd | Multi position alignment system |
GB0622451D0 (en) | 2006-11-10 | 2006-12-20 | Intelligent Earth Ltd | Object position and orientation detection device |
FR2946738B1 (en) | 2009-06-10 | 2011-08-19 | Electricite De France | AID FOR SPORTS COMPETITIONS OF PERSONS WITH POOR OR NON-INDICATOR. |
GB201317205D0 (en) * | 2013-09-27 | 2013-11-13 | Omarco Network Solutions Ltd | Product verification method |
US10475203B2 (en) | 2018-02-06 | 2019-11-12 | Saudi Arabian Oil Company | Computer vision system and method for tank calibration using optical reference line method |
GB2574064B (en) | 2018-05-25 | 2020-05-27 | Imetrum Ltd | Motion encoder |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4155648A (en) * | 1978-04-07 | 1979-05-22 | United States Steel Corporation | Optical pipe end-squareness gauge |
SE411686B (en) * | 1978-05-31 | 1980-01-28 | Bergkvist Lars A | DEVICE FOR INDICATING AN ANGLE OR DIRECTION OF PIPELINE OR CORRESPONDING |
US5724743A (en) * | 1992-09-04 | 1998-03-10 | Snap-On Technologies, Inc. | Method and apparatus for determining the alignment of motor vehicle wheels |
US5974365A (en) * | 1997-10-23 | 1999-10-26 | The United States Of America As Represented By The Secretary Of The Army | System for measuring the location and orientation of an object |
-
1999
- 1999-11-26 GB GBGB9928124.8A patent/GB9928124D0/en not_active Ceased
-
2000
- 2000-11-24 WO PCT/GB2000/004496 patent/WO2001038823A1/en not_active Application Discontinuation
- 2000-11-24 AU AU15371/01A patent/AU1537101A/en not_active Abandoned
- 2000-11-24 EP EP00977736A patent/EP1234159A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO0138823A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2001038823A1 (en) | 2001-05-31 |
AU1537101A (en) | 2001-06-04 |
GB9928124D0 (en) | 2000-01-26 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20020613 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: MORCOM, CHRISTOPHER JOHN,INSTRO PRECISION LIMITED Inventor name: APPERLEY, RALPH,INSTRO PRECISION LIMITED |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20061208 |