EP2115695A1 - Method for determining the quality of a measuring point, in particular for determination of edge location, and optical precision measuring device - Google Patents
Method for determining the quality of a measuring point, in particular for determination of edge location, and optical precision measuring deviceInfo
- Publication number
- EP2115695A1 EP2115695A1 EP08701448A EP08701448A EP2115695A1 EP 2115695 A1 EP2115695 A1 EP 2115695A1 EP 08701448 A EP08701448 A EP 08701448A EP 08701448 A EP08701448 A EP 08701448A EP 2115695 A1 EP2115695 A1 EP 2115695A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- quality
- measuring
- measuring point
- edge
- image
- 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- Withdrawn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
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/0002—Inspection of images, e.g. flaw detection
- G06T7/0004—Industrial image inspection
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/10—Segmentation; Edge detection
- G06T7/13—Edge detection
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30108—Industrial image inspection
- G06T2207/30164—Workpiece; Machine component
Definitions
- the invention relates to a method for determining the quality of a measuring point in edge location determination (edge detection), in particular in optical length measuring technology. Furthermore, the invention relates to a precision measuring device, in particular a coordinate measuring machine for the dimensional detection of workpieces.
- Coordinate measuring devices are frequently used in optical length measuring technology.
- a coordinate measuring machine is understood to mean a device with a plurality of drives whose respective position can be determined by means of scales, wherein the measuring sensor system can be moved relative to the workpiece in the 3 coordinates x, y and z.
- the measuring sensor system can consist of one sensor or of several different sensors (multi-sensors).
- the present method can be used on all coordinate measuring machines in which at least one image sensor is present as part of the measuring sensor system.
- the present method can be used on all measuring devices that have at least one image sensor, but no movement axes (image sensor as a stand-alone solution), for example in automation technology.
- WO 02/084215 A1 discloses a method for optimizing the target variables during optical precision measurement.
- auxiliary parameters are first obtained from image information of a workpiece to be measured, from which subsequently control information for the influencing variables of these target variables be derived.
- the auxiliary parameters are determined such that they have a similar extreme of the functional dependence of the influencing variables.
- DE 196 54 067 A1 describes a method for measuring edges on workpieces. For this purpose, a scanning point is moved over an edge to be measured in such a way that the edge is cut in a plurality of adjacent points. From the measured distance values, the intersections of the trajectory and the measured edge are determined by interpolation.
- WO 2004/103181 A1 relates inter alia. a method for recording the movement of the internal organs of the body, wherein an image of the organ is generated and from this the movement parameters of the organ are determined.
- the edge location criterion is a mathematical calculation rule that determines the associated edge location from an intensity transition in the image. Depending on the nature of the intensity transition in the image, different edge location criteria are suitable for generating the measuring point. In edge detection in optical length metrology, however, measuring points are also generated which, for example, were recorded in image areas with a low contrast, and therefore have a higher probing uncertainty. Measuring points that were recorded with very good contrast, have a low Antastunsort. In known optical coordinate measuring devices, the quality of a measuring point is not recorded. Thus, all points in the subsequent calculation of the geometry elements are considered equivalent.
- WO 2005/050133 A1 relates to a method for calculating geometry elements and links between these measurement points measured on the basis of a coordinate measuring machine.
- the type of the geometric elements and the type of links should be found automatically by determining a match with mathematical models.
- measurement points with a high uncertainty with the same priority are taken into account in the geometry element calculation as measuring points with a low uncertainty. Consequently, not all the information available by the image sensor is used to solve the measurement task.
- the calculated geometric element may have positional and shape errors that would not occur or only to a limited extent if the different quality of the measuring points were taken into account.
- the object of the present invention is therefore to provide a method and a device for determining the quality of a measuring point, in particular for edge detection for optical length measuring technology.
- a subtask consists of using not only the measuring points but also their respective quality for the calculation of geometric elements within such a measuring method in order to be able to calculate the geometric elements with a lower uncertainty.
- the invention is characterized in particular by the fact that not only the per se known determination of the position of a measuring point P (x, y) in a sensor coordinate system by evaluating a measuring signal with image data I (x, y) is carried out to determine the quality of a measuring point.
- the determination of the quality of the measuring signal I and the determination of a quality index Q k which represents the quality of the measuring signal I at the measuring point P (x, y), take place according to the invention.
- the position data and the quality index are combined to form a "complete" quality-valued measuring point P (x, y, Q ⁇ ).
- FIG. 1 shows a basic structure of a known coordinate measuring machine, with which the inventive method can be performed
- FIG. 4 shows a flow chart of the method according to the invention for the determination of a measuring point and the evaluation of the quality of the measuring point.
- 1 shows by way of example the construction of a coordinate measuring apparatus (CMM) with which the method according to the invention can be carried out.
- the coordinate measuring machine comprises a plurality of drives with slides 5, 6 and 8, whose respective position can be determined by means of linear scales Ia, Ib and Ic.
- the carriages can be moved linearly along the coordinate axes x, y, z with the aid of the drives. In this case, the position of the respective carriages 5, 6 and 8 via the reading of an unillustrated reading heads, the associated
- the CMM may have an axis of rotation 4, the position of which is determined with respect to an angle coordinate ⁇ via an angular measuring standard Id.
- the drives and their carriages 5, 6, 8 are fastened to a base frame 2 or, in the case of the z-slide 8, to a z-pillar 3.
- a workpiece 9 to be measured is either clamped on the axis of rotation 4 or fixed on a measuring table 10.
- the measuring sensor system is an image sensor 7, which additionally has lighting devices and a corresponding imaging system.
- the measuring sensor system can be moved relative to the workpiece 9 in the four coordinates x, y, z and ⁇ .
- the measuring sensor can consist of a single sensor or several different sensors (multi-sensor).
- a computer 11 This can be used simultaneously for the evaluation of the image information supplied by the image sensor 7.
- the method according to the invention can be applied to all coordinate measuring machines in which at least one image sensor is present as part of the measuring sensor system. Instead of a CMM, simpler tasks such as acquiring the geometry of flattening In mass production, a much simpler gauge with only two or one axis of motion or without any relative movement between the image sensor and the workpiece can be used. The method according to the invention therefore does not depend on the use and special structure of the coordinate measuring device.
- quality of a measuring point includes the evaluation of the suitability of the optical intensity profile at an edge of the workpiece to be measured for the precise location of the edge
- An edge contains a change of the average intensity in the image stochastic errors. Systematic errors are not considered, as they can be detected and corrected by appropriate correction or calibration procedures.
- the analysis of the intensity profile at an edge in the image serves as the basis for the determination of the quality of the measurement point, which is determined from this intensity profile.
- the evaluation of the quality of the measuring point with the help of various quality indicators is shown in FIG.
- the formulas for determining the quality indices are shown in the appended FIG. 3 and will be explained in more detail below.
- the edge location is determined search-beam-based in the example explained in more detail below. Therefore, in all given formulas and equations (FIG. 3), the intensity I of the pixels always depends only on one spatial coordinate, namely the search beam coordinate x s . However, the edge location can not be determined search-beam-based.
- the type of edge location determination in the sense of search-beam-based (evaluation of I (x s )) or not search-beam-based (evaluation of I (x, y)) is irrelevant to the applicability of the present method.
- FIG. 4 shows the basic sequence of the method.
- the method initially starts in a manner known per se with the determination of the measurement scene and the acquisition of an image, wherein an optical image is generated on the image sensor.
- the image data I (x, y) of each individual pixel recorded by the image sensor are transmitted as measurement signal I to a processing unit, of which the following
- Image processing is carried out, performing the method according to the invention.
- the edge location determination initially takes place in a manner known per se, which need not be explained in more detail here.
- a measurement field (AOI) in the recorded image is expediently selected before executing the edge location determination.
- AOI a measurement field in the recorded image
- search beams which intersect the edge to be found (ideally orthogonal).
- the signal curve recorded by the image sensor, i. the measurement signal I corresponds to the intensity profile along a search beam (FIG. 2).
- An essential core idea of the invention is the completely independent evaluation of the signal curve I (x s ) on the one hand for the determination of the edge location and on the other hand for the determination of the quality information.
- the edge location determination (left branch in FIG. 4) yields as a result in each case a measuring point P (x, y) in the sensor coordinate system (SCS).
- the measuring point P (x, y) denotes a point on the search beam which has been detected as an edge location.
- Measurement signal along the search beam determines (right branch in Fig. 4).
- the quality of the signal curve is determined for each individual measuring point.
- Parallel processing is not necessarily to be understood as simultaneous, but in the sense of a determination of quality independent of the edge location determination. This corresponds to the separation of the measurement from the quality evaluation of the measurement signal.
- Q K provides information about the quality of the measuring signal representing it.
- the quality information on the suitability of the signal curve for precise edge location determination is combined with the coordinates of the measured edge location and yields the quality-evaluated measurement point P (x, y, Q ⁇ ) in the local sensor coordinate system (SCS) of the image sensor.
- Q K is the quality index which contains the quantitative information about the "quality of the measuring signal.” Since this value is assigned directly to the respective measuring point, as illustrated in Fig. 4, this value is also referred to as "quality of the measuring point" ,
- the value range of quality codes is between 0 and 100.
- the explained method of determining the quality of individual measuring points can be used in the evaluation of each individual search beam.
- the quality indicators obtained can be evaluated statistically, so that ultimately a statement about the quality of the found / measured edge can be made.
- the determination of the quality of the measurement points can also be limited to selected search beams, for example in order to reduce the computational effort.
- the methods for calculating the quality index Q K for the quality of a measuring point are based on the known signal-theoretical relationships in the image recording with areal image sensors. In the calculation of the quality index Q ⁇ for the quantitative determination of the quality of the measurement signal or of the intensity profile, no default values are used with regard to the variable to be measured.
- the quality index Q ⁇ for the quality of a measuring point can be composed of any number of individual quality indicators.
- five individual criteria (quality indicators) are used for the evaluation of the quality of a measuring point.
- the formulas for the calculation of the individual quality indices are shown in FIG. This quality score system does not contain redundancies, that is, one and the same feature of the intensity history is not scored twice.
- the quality index Q R is used to evaluate the noise of the intensity curve S 1 .
- the quality index Q R is used to evaluate the noise of the intensity curve S 1 .
- a possible extension of this quality index is to refer the noise not to the quantization levels Q n of the image sensor but to the contrast K along the search beam. This allows a much sharper evaluation of the intensity profile.
- this extension corresponds to an evaluation of the signal-to-noise ratio instead of the pure evaluation of the noise as indicated in FIG.
- the quality index for the edge increase Q A is in the simplest case from the two intensity measurements above and determined below the mean level I E. The larger the increase, the more accurate the edge location can be calculated.
- the quality index for the form Q F of the intensity transition provides information about the deviation from a jump signal. It is not redundant to Q A. For example, the quality index Q A can be excellent, but the quality index Q F is comparatively poor. This is true if the intensity transition is very steep in the middle intensity range but extremely flat in the upper or lower intensity range; for example, for measurements on height-extended measuring objects. Depending on the applied edge location criterion, this can lead to a shift of the detected edge location.
- the quality index edge width Q B evaluates the width of the intensity transition. Compared to Q B and Q A , only Q F provides the possibility to identify disturbed intensity transitions. These can occur, for example, in reflected light illumination and are frequently characterized by unwanted direct reflections on the surface of the measurement object.
- the quality index Q E is used for the assessment of uniqueness. This quality indicator is used to detect strong disturbances of the intensity profile. For measurements in incident light, the reflection pattern overlaps the surface of the measurement object with the diffraction effects at the edge. As a result, intensity traces can occur which intersect the mean level I E more than once. The precise edge location tuning on such a waveform is very difficult.
- a possible extension of the measure Q E is the consideration of the distance between the probable edge location in the interval [x S i..Xs2] and the location of the second or third pass. As a general rule, the overall quality index for the quality of a measuring point for intensity profiles recorded in reflected light is, on average, significantly worse than for intensity traces recorded in transmitted light.
- the signal course in the structure transition area is also evaluated with reference to an ideal signal course according to the five different criteria explained above (quality indicators).
- the ideal waveform corresponds to a jump input, which is imaged by the diffraction-limited optical imaging system on the image sensor and there depending on the
- Bit depth of the image sensor is detected. The more the actual waveform resembles that of the ideal waveform, the lower the probing uncertainty of the measuring point or the higher its quality.
- the overall quality of the measuring point is formed by weighted addition.
- the five individual criteria are e.g. Noise, edge width, edge slope, edge uniqueness and edge shape.
- the weighting of the individual criteria can be varied with each other or even criteria can be disregarded. This can be useful for computations that do not run on a PC, for computational reasons.
- the method according to the invention has a number of advantages, since it uses previously unused information that is always present in such optical measurements for the improved solution of the measuring task.
- the parameters of a measuring point in the I ++ DME specification include the parameter Q for the quality of the measuring point.
- this parameter can be filled with a value by means of the present inventive method (each measuring point is provided with an indication of its quality), so that a higher accuracy can be achieved in the calculation of the geometry elements.
- the detection and elimination of outliers for the high-precision geometry measurement is greatly simplified and the computational outlay of the outlier filters is reduced.
- Iint ⁇ mean intensity in the interval Int ⁇ (x s ) - Dirac momentum b k - measured edge width b k , ideal ⁇ ideal edge width
Landscapes
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Quality & Reliability (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102007003060A DE102007003060A1 (en) | 2007-01-15 | 2007-01-15 | Method for determining the quality of a measuring point in edge detection in optical length measuring technology |
PCT/EP2008/050314 WO2008087104A1 (en) | 2007-01-15 | 2008-01-12 | Method for determining the quality of a measuring point, in particular for determination of edge location, and optical precision measuring device |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2115695A1 true EP2115695A1 (en) | 2009-11-11 |
Family
ID=39267747
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP08701448A Withdrawn EP2115695A1 (en) | 2007-01-15 | 2008-01-12 | Method for determining the quality of a measuring point, in particular for determination of edge location, and optical precision measuring device |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP2115695A1 (en) |
DE (1) | DE102007003060A1 (en) |
WO (1) | WO2008087104A1 (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102008025896A1 (en) | 2008-05-23 | 2009-11-26 | Landesamt für Mess- und Eichwesen Thüringen | Method for determining the measurement uncertainty in geometry measurement |
DE102010037746B4 (en) | 2010-09-23 | 2013-01-24 | Carl Mahr Holding Gmbh | Method for optically sensing an edge in or on a surface area |
CN104165894B (en) * | 2014-06-23 | 2017-08-08 | 中国计量学院 | A kind of detection means for curve surface work pieces surface defect |
DE102017114811A1 (en) * | 2017-07-03 | 2019-01-03 | Volume Graphics Gmbh | Method for determining uncertainties in measured data from a measurement of an object |
DE102017212339A1 (en) | 2017-07-19 | 2019-01-24 | Robert Bosch Gmbh | Method and device for evaluating image sections for correspondence formation |
CN108107860A (en) * | 2017-12-26 | 2018-06-01 | 内蒙古蒙牛乳业(集团)股份有限公司 | Determine the method and system of characterization processes |
DE102018218095B4 (en) | 2018-09-28 | 2022-01-13 | Carl Zeiss Industrielle Messtechnik Gmbh | Procedure for edge determination of a measurement object in optical metrology and coordinate measuring machine |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19654067A1 (en) * | 1996-10-21 | 1998-04-23 | Zeiss Carl Fa | Method for measuring edges on workpieces |
US5969273A (en) * | 1998-02-12 | 1999-10-19 | International Business Machines Corporation | Method and apparatus for critical dimension and tool resolution determination using edge width |
DE10215135A1 (en) | 2001-04-18 | 2002-10-24 | Zeiss Carl | Automatic regulation of focus and lighting and optical sensing of edge position for precision optical measurement involves determining weighted sum of individual auxiliary parameters |
EP1631194A1 (en) * | 2003-05-21 | 2006-03-08 | Philips Intellectual Property & Standards GmbH | Apparatus and method for recording the movement of organs of the body |
WO2005050133A1 (en) | 2003-11-14 | 2005-06-02 | Werth Messtechnik Gmbh | Method for the automatic measurement using coordinate measuring instruments |
JP5069814B2 (en) * | 2004-11-19 | 2012-11-07 | 株式会社ホロン | Judgment method of measured value |
-
2007
- 2007-01-15 DE DE102007003060A patent/DE102007003060A1/en not_active Ceased
-
2008
- 2008-01-12 WO PCT/EP2008/050314 patent/WO2008087104A1/en active Application Filing
- 2008-01-12 EP EP08701448A patent/EP2115695A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2008087104A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2008087104A1 (en) | 2008-07-24 |
DE102007003060A1 (en) | 2008-07-17 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3278302B1 (en) | Motion-measuring system of a machine and method for operating the motion-measuring system | |
EP2040026B1 (en) | Method and system for calibrating an apparatus for measuring the shape of a reflective surface | |
DE3424806C2 (en) | ||
EP1711777B2 (en) | Method for determining the position and the relative motion of an object in a space | |
EP2108105B1 (en) | Method for determining an influencing variable on the eccentricity of an angle measuring device | |
EP1488191B1 (en) | Method for determining and correcting guiding errors in a coordinate measuring device | |
EP2115695A1 (en) | Method for determining the quality of a measuring point, in particular for determination of edge location, and optical precision measuring device | |
EP1910779B1 (en) | Method for correction of interpolation errors on a machine in particular a coordinate measuring device | |
EP1285224A1 (en) | Method and device for determining the 3d profile of an object | |
EP2133659A1 (en) | Method and device for determining the position of a sensor | |
EP2423639A1 (en) | Method for determining gap dimensions and/or flushness of bodywork sections of a motor vehicle and control program | |
DE10157174A1 (en) | Method and device for the spatial measurement of workpieces on a machine tool | |
DE102014106839A1 (en) | Drift compensation / restriction of the solution space | |
DE102019102927A1 (en) | Method and device for determining dimensional and / or geometric properties of a measurement object | |
EP2578988A1 (en) | Scanning white-light interferometer and method for spatially resolved optical measurement of the surface geometry of an object | |
DE19830646C2 (en) | Method for correcting geometric sequence errors of a coordinate measuring machine | |
DE102011001475A1 (en) | Method for determining e.g. position of robotic apparatus for controlling machines in aerospace industry, involves determining position of location relative to another location based on comparison of detected and simulated light patterns | |
DE10214489A1 (en) | Guidance error determination method, for use with metrology or coordinate measurement instruments, whereby guidance errors are related to a particular factor and determined as a function of the factor using finite element analysis | |
DE3909855A1 (en) | Method for determining the position of a positionable surface, and a position sensor (encoder) | |
DE102011000088A1 (en) | Method for determining structures and/or geometry of workpiece, involves defining path to be passed and/or sequence of executions for specified range and/or fixed amount of measuring points and/or measuring elements | |
DE102018208189B4 (en) | Method and device for determining the torsional errors of a machine axis | |
EP0479759B1 (en) | Procedure and device for length or angle measurement | |
DE112021000951T5 (en) | lidar detection arrays | |
DE4434233A1 (en) | Contactless three=dimensional measurement | |
DE10001800C2 (en) | Method and device for measuring, in particular, surface topologies in microscopic resolution |
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: 20090806 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: CARL MAHR HOLDING GMBH Owner name: TECHNISCHE UNIVERSITAET ILMENAU |
|
DAX | Request for extension of the european patent (deleted) | ||
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: TECHNISCHE UNIVERSITAET ILMENAU |
|
17Q | First examination report despatched |
Effective date: 20101022 |
|
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: 20160330 |