WO2014044505A1 - Procédé pour orienter deux capteurs laser l'un par rapport a l'autre - Google Patents

Procédé pour orienter deux capteurs laser l'un par rapport a l'autre Download PDF

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Publication number
WO2014044505A1
WO2014044505A1 PCT/EP2013/067780 EP2013067780W WO2014044505A1 WO 2014044505 A1 WO2014044505 A1 WO 2014044505A1 EP 2013067780 W EP2013067780 W EP 2013067780W WO 2014044505 A1 WO2014044505 A1 WO 2014044505A1
Authority
WO
WIPO (PCT)
Prior art keywords
laser
distance sensors
laser distance
measurement
calibration body
Prior art date
Application number
PCT/EP2013/067780
Other languages
German (de)
English (en)
Inventor
Roland KEMPF
Ulrich Dörr
Norbert Möller
André Mecklenburg
Original Assignee
Evonik Litarion Gmbh
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Evonik Litarion Gmbh filed Critical Evonik Litarion Gmbh
Publication of WO2014044505A1 publication Critical patent/WO2014044505A1/fr

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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
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/026—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring distance between sensor and object
    • 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
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • 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 invention relates to a method for aligning at least two laser distance sensors to each other, wherein the laser distance sensors each having a laser and a sensor.
  • the invention also relates to a method for measuring the thickness of a body or a coating of a coated body in a measuring setup, which are used in the measurement of the two laser distance sensors. Finally, the invention also relates to a device for carrying out such a method.
  • Laser distance sensors are used, inter alia, when the thickness of a body or a coating is to be measured precisely. In this case, the light reflected from the object to be measured is measured and the thickness determined therefrom.
  • Such a method is known, for example, from EP 2 031 347 A1, in which the temperature of the object to be coated is also measured during the measurement in order to obtain a more accurate estimate of the thickness of a coating in the case of a thickness measurement.
  • a method for measuring the coating thickness by means of laser triangulation is known from EP 2 312 267 A1. The measurement is measured before and during or after coating and can be carried out selectively. A similar method is used in DE 103 13 888 A1. In the method, a distance is determined by a laser triangulation method and compared with a reference value in order to be able to estimate the thickness of a coating.
  • the data measured with the two lasers may be one compensate for possible uncertainty in the positioning of the object to be measured. For this it is important that these lasers are aligned with each other as accurately as possible in order to determine a reliable and accurate determination of the layer thickness of a coating can.
  • the object of the invention is therefore to provide a method for positioning two lasers to one another, which is as simple as possible to carry out and leads to the most accurate adjustment and positioning of the laser distance sensors to each other.
  • the present invention is accordingly realized by a method for aligning at least two laser distance sensors to one another, the laser distance sensors each having a laser and a sensor, comprising the following chronological steps A) to D):
  • the method is simple to implement and therefore inexpensive to implement.
  • a high accuracy of a subsequent measurement can be achieved.
  • Adjusting the position and orientation of at least two laser distance sensors to each other is the same when only the positions and the orientations of the laser of the laser distance sensors are adjusted when the lasers and the sensors of the laser distance sensors are not fixed to each other.
  • Laser triangulation methods are simple and inexpensive to implement and particularly suitable for the implementation of methods according to the invention.
  • the objects of the invention are also achieved by a method for measuring the thickness of a body or a coating of a coated body in a measurement setup, wherein the measurement of the thickness two laser distance sensors are used, previously in the measurement setup with a method according to any one of the preceding claims to each other were aligned.
  • Such methods may preferably also include the following chronological steps:
  • steps A) to D) of alignment methods according to the invention are carried out in chronological order and according to steps A) to D) of alignment methods according to the invention.
  • the calibration body is rotatably mounted in the device or can be stored and the calibration body by defined angle ( ⁇ ) about an axis of rotation is rotatable and / or with at least one defined angular velocity (co) is rotatable.
  • the calibration body is a disc which is inclined against the axis of rotation, preferably tilted by a Verkippungswinkel ( ⁇ ) between 5 ° and 60 °, more preferably by a Verkippungswinkel ( ⁇ ) between 15 ° and 30 ° is inclined, most preferably inclined by a tilt angle ( ⁇ ) between 20 ° to 25 °.
  • the aim of a measurement setup according to the invention and an evaluation procedure or a method according to the invention is to determine the position and tilt of a plurality of laser distance sensors relative to one another and relative to a rotation axis defined by the measurement setup.
  • the process is very robust because it does not necessarily use the absolute value of the laser distance sensor.
  • the test setup is characterized by a low height.
  • FIG. 5 a perspective diagram for clarifying the geometric relationships.
  • the lasers 4, 8 are oriented and positioned in a desired orientation relative to each other.
  • the laser distance sensors 1, 2 are arranged in the desired orientation and position such that the laser beams generated by the lasers 4, 8 could meet in opposite directions at a point if the calibration body 12 were not arranged between the laser distance sensors 1, 2. If the laser beams are understood as vectors in the same coordinate system, one laser beam is equal to the other laser beam with a negative sign.
  • the alignment and positioning of the laser distance sensors 1, 2 shown in FIG. 1 is to be achieved relative to one another.
  • the laser distance sensors 1, 2 are only roughly aligned in the measurement setup. This arrangement is shown in Figure 2 as a schematic side view.
  • the laser distance sensors 1, 2 are not exactly opposite arranged and also tilted against each other.
  • the aim of the method is to align the laser distance sensors 1, 2 against each other so that the arrangement comes as close as possible to the state shown in Figure 1.
  • the calibration body 12 is introduced into the measurement setup and rotatably mounted there. With the laser distance sensors 1, 2 a plurality of measuring points are recorded on the upper and the lower surface of the calibration body 12. For this purpose, the calibration body 12 is rotated in construction. Preferably not only discrete measuring points are recorded on the surface of the calibration body 12, but a continuous course of the distances between the two laser distance sensors 1, 2 is recorded by the two surfaces of the rotating calibration body 12.
  • information can be obtained from the periodic signal of the laser distance sensors 1, 2, which allow precise conclusions about the arrangement and alignment of the lasers 4, 8 and thereby the laser distance sensors 1, 2 to each other. The information thus obtained can be used to adjust the laser distance sensors 1, 2 in order to achieve the desired state in FIG. 1 or to come as close as possible to this.
  • a turntable 12 is rotatably mounted as a calibration body 12 in the measurement setup.
  • the turntable 12 is inclined from the rotation axis z by an angle.
  • the turntable 12 is placed in the laser beams of the laser distance sensors 1, 2 and the distance of the laser 4, 8 measured to the point of impact of the laser beams on the turntable 12 during its rotation.
  • the absolute angle (or at least its zero crossing) of the rotary disk 12 is measured on the rotation axis z.
  • FIG. 3 shows a schematic perspective illustration for clarifying the angular relationships in a structure for implementing a method according to the invention in an initial situation with coarsely adjusted lasers 24, 28 of two laser distance sensors.
  • the laser beams of the lasers 24, 28 must of course hit the turntable 32.
  • the displacement of the lasers 24, 28 in the xy plane is used here only for a clearer representation of the angular relationships.
  • the position and orientation of the laser sensor are by the Richtun svektor c ⁇ des
  • FIG. 4 shows two schematic side views of the turntable 32 according to the illustration according to FIG. 3 in order to be able to vividly discuss the mathematical derivation of a solution according to the invention of the problem.
  • the normal vector is parameterized by n.
  • FIG. 5 shows a perspective diagram for clarifying the geometric relationships.
  • the vectors of a first laser beam of a first laser for example of the laser 28 according to FIG. 3
  • the vectors and angles used for the calculation are shown in relation to the coordinate system and the laser beam.
  • analogous diagrams result, which in the following lead to analogous considerations.
  • Unit vector 1 1 11 which points in the direction of the first laser beam and in
  • This equation can already be used according to the invention to calculate the position and orientation of the lasers with respect to one another by means of the distance measurements and the known ones.
  • the equation can be solved mathematically using parameter fits.
  • further mathematical simplifications lead to a preferred embodiment of the invention with much simpler calculation.
  • b yi B, -sin ( ⁇ J, which are required when using linear tables and tilting tables in the x and y directions.
  • the z-alignment of the lasers 24, 28 determines whether the turntable 32 is from above or below
  • the constant term of the Fourier series, ie 01 is not required for this calculation step and thus the measured value may also be offset.
  • Lasers (in the measuring range) unambiguously assign the measured value ⁇ by + h , ⁇ ) 'c ⁇ , in particular also determine the zero point P ⁇ ⁇ ⁇ ⁇ ' Cl in space.
  • the offset in the measured value can be determined as the difference between the current measured value and the desired measured value, and the offset can then be taken into account in the evaluation of the later measured values.
  • the tilt angle ⁇ is defined and known by the structure of the turntable 32.
  • the angle ⁇ scales the amplitude value of the normalized tilting C l and the derived values c xl , c yl , C l , c xl , c yl only. The same applies to B x and derived values b xl , b yl , if it has already been ensured that C l «1.
  • the parallel alignment of multiple lasers 24, 28 with each other one seeks zeros of such derived quantities, which are independent of the scaling effect of ⁇ .
  • the Fourier coefficients 01 , 1 1 , 2 1 and the phases ⁇ ⁇ , ⁇ ⁇ of ⁇ ⁇ ( ⁇ ) can be obtained in practice in various ways, as the following cases show:
  • the measurement signal is measured at predefined, discrete angular positions (spatial discrete on the turntable 32) and the parameters of ⁇ ⁇ ( ⁇ ), for example, determined by a discrete Fourier transform. According to the invention, continuous measurements are preferred for ease of handling.
  • the setting accuracy of the laser 4, 8, 24, 28 directly determines the uncertainty of a thickness measurement.
  • the second laser 4, 24 provides an analogous contribution.
  • the largest possible angle ⁇ should be selected and the full measuring range should be used as far as possible so that F can be as large as possible.
  • this is limited by the real dimensions of the measurement setup, such as the dimensions of the laser distance sensors 1, 2, optionally the thickness of the turntable and the axis of rotation or the diameter of the laser beam.
  • an angle ⁇ between 15 ° and 35 ° is particularly preferred since it can be easily implemented with these components.
  • the resolution of the laser distance sensors 1, 2 should be as high as possible so that AF and AF V are as small as possible.
  • 1, 2 may for example be limited by a measurement noise to 1 ⁇ .
  • this should be as little as possible tilted, that is, the angle ⁇ 'be as small as possible, and lie as quiet as possible in the direction of the z-axis, that is, h should be as low as possible.
  • An inclination of the object to be measured of 0 ° can preferably be provided.
  • the constructed measuring device is inserted into the beam path of the lasers 4, 8, 24, 28.
  • Rotational axis to be replaced by a ⁇ -dependent expression. Since only the Fourier components of the measurement signal are evaluated, it is sufficient to take into account the effect of the Taumein by the first terms of its Fourier evolution, ie by tan ( ⁇ 5) - (l + i cos ( ⁇ p - p)) ,
  • wobbling of the rotational axis causes each measurement errors in the values of the tilt of the laser 4, 8, 24, 28 with respect to the coordinate axis z, that is, ci ⁇ c xl, c y f l * c yl, ⁇ ⁇ 2 ⁇ ⁇ ⁇ 2 and c y f 2 ⁇ c y2 .
  • methods according to the invention have the advantage that a tumbling of the axis of rotation, as well as a not exactly known axis of rotation and geometry of the calibration body 12, 32 by determining the position and orientation of the laser 4, 8, 24, 28 to each other in good Approximation can be compensated.
  • T j arctan (C 1 ) Angle between first laser beam (8, 28) and parallel to

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

La présente invention concerne un procédé permettant d'orienter au moins deux capteurs de distance laser l'un par rapport à l'autre, chaque capteur de distance laser comportant un laser et un capteur, le procédé comportant les étapes chronologiques A) à D): A) orienter approximativement les deux capteurs de distance laser l'un par rapport à l'autre et mettre en place un élément d'étalonnage de géométrie définie dans une structure de mesure comprenant les capteurs de distance laser; B) mesurer les distances de plusieurs points de mesure ou d'une ligne continue sur la surface de l'élément d'étalonnage au moyen des capteurs de distance laser, l'élément d'étalonnage étant déplacé dans la structure de mesure relativement aux capteurs de distance laser pour permettre aux lasers des capteurs de distance laser d'irradier les différents points de mesure ou la ligne continue pour les mesures de distances; C) déterminer la position et l'orientation des deux capteurs de distance laser l'un par rapport à l'autre sur la base des mesures de distances et de la géométrie et de la position connues de l'élément d'étalonnage dans la structure de mesure; et D) aligner au moins un des capteurs de distance laser sur la base de la position ainsi déterminée et orienter les capteurs de distance laser l'un par rapport à l'autre de manière à obtenir une position voulue et une orientation voulue des capteurs de distance laser l'un par rapport à l'autre. L'invention concerne également un procédé permettant de mesurer l'épaisseur d'un corps ou le revêtement d'un corps enduit dans une structure de mesure, la mesure de l'épaisseur du revêtement étant réalisée au moyen de deux capteurs de distance laser préalablement orientés l'un par rapport à l'autre dans la structure de mesure selon un procédé de ce type. L'invention concerne enfin un dispositif permettant de réaliser ce procédé.
PCT/EP2013/067780 2012-09-24 2013-08-28 Procédé pour orienter deux capteurs laser l'un par rapport a l'autre WO2014044505A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102012217175.4 2012-09-24
DE102012217175.4A DE102012217175A1 (de) 2012-09-24 2012-09-24 Verfahren zur Ausrichtung zweier Lasersensoren zueinander

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WO2014044505A1 true WO2014044505A1 (fr) 2014-03-27

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PCT/EP2013/067780 WO2014044505A1 (fr) 2012-09-24 2013-08-28 Procédé pour orienter deux capteurs laser l'un par rapport a l'autre

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4375921A (en) * 1980-03-13 1983-03-08 Selective Electronic Co. Ab Dimension measuring apparatus
US5442573A (en) * 1992-04-28 1995-08-15 Taymer Industries Inc. Laser thickness gauge
US6281679B1 (en) * 1998-12-21 2001-08-28 Honeywell - Measurex Web thickness measurement system
US20030007161A1 (en) * 2001-03-05 2003-01-09 Bowles Dennis Lee Laser non-contact thickness measurement system
JP2007256091A (ja) * 2006-03-23 2007-10-04 Space Vision:Kk レンジファインダ校正方法及び装置
US20070236680A1 (en) * 2006-03-29 2007-10-11 Barker Lawrence D Calibration system for sawmill scanning systems
US20120229621A1 (en) * 2011-03-09 2012-09-13 Zygo Corporation Object thickness and surface profile measurements

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10313888A1 (de) 2003-03-27 2004-10-28 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren und Vorrichtung zur online Materialschichtdickenbestimmung
US7824730B2 (en) 2007-08-31 2010-11-02 United Technologies Corporation Method and apparatus for measuring coating thickness with a laser
EP2312267A1 (fr) 2009-10-19 2011-04-20 Siemens Aktiengesellschaft Procédé de mesure de l'épaisseur de couche par triangulation laser et dispositif

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4375921A (en) * 1980-03-13 1983-03-08 Selective Electronic Co. Ab Dimension measuring apparatus
US5442573A (en) * 1992-04-28 1995-08-15 Taymer Industries Inc. Laser thickness gauge
US6281679B1 (en) * 1998-12-21 2001-08-28 Honeywell - Measurex Web thickness measurement system
US20030007161A1 (en) * 2001-03-05 2003-01-09 Bowles Dennis Lee Laser non-contact thickness measurement system
JP2007256091A (ja) * 2006-03-23 2007-10-04 Space Vision:Kk レンジファインダ校正方法及び装置
US20070236680A1 (en) * 2006-03-29 2007-10-11 Barker Lawrence D Calibration system for sawmill scanning systems
US20120229621A1 (en) * 2011-03-09 2012-09-13 Zygo Corporation Object thickness and surface profile measurements

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Publication number Publication date
DE102012217175A1 (de) 2014-03-27

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