DE102010053418B4 - Coordinate measuring device with non-contact position detection device and calibration method - Google Patents

Coordinate measuring device with non-contact position detection device and calibration method

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Publication number
DE102010053418B4
DE102010053418B4 DE201010053418 DE102010053418A DE102010053418B4 DE 102010053418 B4 DE102010053418 B4 DE 102010053418B4 DE 201010053418 DE201010053418 DE 201010053418 DE 102010053418 A DE102010053418 A DE 102010053418A DE 102010053418 B4 DE102010053418 B4 DE 102010053418B4
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Germany
Prior art keywords
reference object
sensor head
coordinate measuring
position
characterized
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DE201010053418
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German (de)
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DE102010053418A1 (en
Inventor
Zeno Schmal
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Carl Zeiss Industrielle Messtechnik GmbH
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Carl Zeiss Industrielle Messtechnik GmbH
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Publication of DE102010053418A1 publication Critical patent/DE102010053418A1/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00Measuring arrangements or details thereof in so far as they are not adapted to particular types of measuring means of the preceding groups
    • G01B21/02Measuring arrangements or details thereof in so far as they are not adapted to particular types of measuring means of the preceding groups for measuring length, width, or thickness
    • G01B21/04Measuring arrangements or details thereof in so far as they are not adapted to particular types of measuring means of the preceding groups for measuring length, width, or thickness by measuring coordinates of points
    • G01B21/047Accessories, e.g. for positioning, for tool-setting, for measuring probes
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06Systems determining position data of a target
    • G01S17/42Simultaneous measurement of distance and other co-ordinates
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497Means for monitoring or calibrating
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06Systems determining position data of a target
    • G01S13/46Indirect determination of position data
    • G01S2013/466Indirect determination of position data by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined

Abstract

Coordinate measuring machine (10) with a sensor (14) for three-dimensionally measuring a workpiece (12), wherein the sensor (14) is arranged relative to a sensor head (16), and with a three-dimensional non-contact position detection device (22) for detecting a position of an the marking head (16) arranged relative to at least one reference object (26), characterized in that the sensor head (16) and the at least one reference object (26) each have coupling means (44, 51) for unambiguous mechanical coupling of the sensor head ( 16) with the reference object (26), and wherein at least the coupling means (51) on the sensor head (16) are formed such that the sensor head (16) in three different layers clearly mechanically coupled to the reference object (26), wherein the marker element (24) occupies a different known position relative to the reference object (26) in each layer.

Description

  • The present invention relates to a coordinate measuring machine with a sensor for three-dimensional measurement of a workpiece, wherein the sensor is arranged relative to a sensor head, and with a three-dimensional non-contact position detection device for detecting a position of a sensor element arranged on the marking element relative to at least one reference object.
  • Furthermore, the present invention relates to a method for calibrating a three-dimensional non-contact position detection device for detecting a position of a marking element relative to at least one reference object, wherein a zero point defined and the marking element is arranged relative to the zero point in at least one known position.
  • Such a coordinate measuring machine and such a method are from the document GB 2 285 550 A known.
  • In the control and regulation of coordinate measuring machines, it is of particular importance to know exactly the position of a sensor head of the coordinate measuring machine. Of course, the position of a sensor or of a sensor head is detected by means of further sensors, which, for example, detect the deflection of a robot arm carrying the sensor head of the coordinate measuring machine. However, it may be required that a further sensor device is provided, which detects the position of the sensor head or the sensor independently of the coordinate measuring machine own sensors. In this way, an adjustment of the acquired data on the position of the sensor head or the sensor can be carried out and a control of the coordinate measuring machine can be monitored or calibrated.
  • the sensor head be made portable. For example, with tactile measuring systems, the possibility arises that an operator in a measuring room manually moves the tactile sensor along the workpiece to be measured in order to measure it. Here, the position of the tactile sensor is known relative to the sensor head. However, it requires a further, non-contact coordinate measuring system to detect the position of the sensor head in the measuring space.
  • One possibility for such redundant position detection in coordinate measuring machines is, for example, in the European patent EP 1 322 905 B1 explained. There, a so-called "laser coherence μ global positioning system" is described, see also the magazine "Innovation, the magazine of Carl Zeiss, special research and technology No. 1", published in April 1999 by the company Carl Zeiss, Page 5.
  • Such a "laser coherence μ global positioning system" has a transmitting device, which also acts as a receiver and emits laser signals, which are reflected by a plurality of reflectors with exactly known position, so stationary reference stations. The position of the transmitter can be determined via a high-precision optical transit time measurement. The position detection thus takes place by means of a trilateration method relative to a number of reference objects. This procedure corresponds essentially to that of the generally known "Global Positioning System" (GPS), so that the term choice is explained therefrom.
  • Alternatively, photogrammetry systems are also known, for example, in which a marking element is recorded from reference objects via several cameras and the position of the marking element in the measuring space is calculated from the recorded images via the trigonometric relationships between the marking element and the cameras. A further alternative is a so-called "3-D localizer" in which a plurality of light emitting diodes distributed over an area in the region of the marking element to be detected emitting radiation having different wavelengths are observed by a plurality of video cameras on the reference object and also from the video images trigonometric relationship calculates the position of the marker element.
  • Of course, the components can also be arranged reversed. For example, in the "Local Coherence μ-Global Positioning System", the light emitter and receiver can also be arranged on the reference object and the reflectors on the marking element.
  • The knowledge about the exact position of the reference objects is decisive for the accuracy of the position detection. Furthermore, it is important that the position of the reference objects does not change during operation, for example due to mechanical or thermal influences.
  • It is often provided that the reference objects are firmly connected to the hall structure, for example, in a workshop. Depending on the arrangement of the reference objects in the factory hall, a certain measuring room is spanned there, in which, for example, a portable coordinate measuring machine can be used to measure workpieces located in the measuring room. In this way, quality control can be performed even on very large workpieces, due to their Size can not be traversed by a single robot arm.
  • Due to weather conditions, in particular due to temperature differences in the summer and winter months and the consequent expansion of the entire building in which the reference objects are mounted, an optical position detection device described above is subjected to calibration regularly, with deviations of the reference objects from the known Determine standard positions and provide appropriate correction factors during operation of the position detection device.
  • Such a calibration should be as quick and inexpensive as possible to make the work with the coordinate measuring machine as simple as possible for an operator. In particular, it is desired that an operator can carry out a calibration in a simple manner before each commissioning of the coordinate measuring machine without appreciable loss of time in order to obtain the most accurate measurement results possible.
  • The aforementioned document GB 2 285 550 A describes one way in which a portable tactile coordinate measuring machine can be calibrated.
  • It is proposed to use a known object having four accurately measured points whose relative position to each other is known. One of these points is defined as zero, and the position of the remaining three points is measured by means of the position detection device. From the measurement results, a correction factor can then be calculated for each reference object.
  • Such a method is particularly suitable for the initialization of a position detection device, since this allows the positions of the reference objects to be determined. However, the method is relatively expensive, especially since a known object must be arranged and measured in the measuring room. For operation during operation, this process is usually too time-consuming.
  • The publication GB 2 180 117 A also shows a tactile coordinate measuring machine, which is moved by means of a robot arm. In addition to the movement by means of the robot arm, the position of the tactile sensor is determined by means of a non-contact position detection device. However, the position of corresponding reference objects is assumed to be known.
  • A similar system shows the document WO 2004/033991 A1 , However, this document does not deal with the calibration of the non-contact position detection device.
  • In addition, the pamphlets show WO 2009/102266 A1 and WO 2007/015677 A1 tactile coordinate measuring machines, which are designed portable and are monitored by means of a so-called "indoor GPS" with respect to the position of the probe in the measuring room. As measuring system, it is merely proposed in these documents to provide accelerometers in the case of a movement of the probe by means of a robot arm in order to detect the position of the probe redundantly to the non-contact position detection device and to be able to calibrate them.
  • Furthermore, the document shows DE 101 43 539 A1 a method and an arrangement for determining the position and orientation of an image recording device in the optical measurement of objects by means of a coupling to a reference station.
  • The publication DE 103 49 361 A1 shows a method and an apparatus for positioning a handling device, wherein a position of a part to be positioned is determined by means of an inertial measuring system.
  • The publication US Pat. No. 5,921,992 A shows a method and apparatus for determining the position of a surgical instrument by means of a guide element.
  • It is therefore an object of the present invention to provide a coordinate measuring machine and a method for calibrating a coordinate measuring machine, in which an operator can perform a calibration in a simple and time-saving manner before the commissioning of the coordinate measuring machine.
  • According to a first aspect of the invention, it is therefore proposed to further develop the coordinate measuring device mentioned above in that the sensor head and the at least one reference object each have coupling means for unambiguously mechanically coupling the sensor head to the reference object, wherein at least the coupling means are formed on the sensor head such that the sensor head in three different layers is clearly coupled mechanically to the reference object, wherein the marking element assumes a different known position relative to the reference object in each layer.
  • In this way it becomes possible to arrange the marking element arranged on the sensor head in a known position relative to the sensor head. Set the position of the Reference object as the zero point of a coordinate system to be calibrated, the position of the marking element in the sensor head within this coordinate system is known. In this way, a calibration of the three-dimensional non-contact position detection device can thus be carried out by detecting position deviations of the at least one reference object.
  • In this way, it is possible for an operator to easily determine a calibration value, for example in the form of an equivalent length, for each reference object. In this case, by simply arranging the sensor head by means of the coupling means on the reference object, the marking element is set in the known position and the calibration process is started. There is no need to spend a known dimensions calibration object in the measuring room, so that the calibration process can be performed easier and faster. Of course, this advantage does not only result for portable coordinate measuring machines, but also in the case that the sensor head is carried by a robot arm. In this case, the sensor head is then moved by means of the robot arm to the reference object and coupled by means of the coupling means to the reference object.
  • Thus, the coupling means are formed on the sensor head so that three possibilities for unambiguous mechanical coupling of the sensor head with the at least one reference object are provided. The coupling means are, for example, to be arranged asymmetrically on different side surfaces of the sensor head such that the marking elements occupy three different known positions. In this case, identification means may be provided by means of which it can be recognized in which known position the marking element is arranged. This can be done, for example, by closing a corresponding circuit when coupling the sensor head to the reference object in the coupling means.
  • The sensor head can be coupled in several arrangements with the reference object. However, each of these arrangements must be done in a clearly mechanical way. This means that in the coupling the known position of the marking element in each order must necessarily result. The unique mechanical coupling must be designed in such a way that it is precluded that the operator couples the sensor head with the reference object in a wrong orientation, for example. The term "unique mechanical coupling" thus refers to the coupling of the sensor head to the reference object in each of the provided layers or assemblies. In principle, however, several different layers or arrangements may be possible, but these are each only clearly mechanically coupled.
  • By being clearly mechanically coupled to the reference object in three different layers, the marker element can occupy three known positions relative to the reference object, which are then used for calibration. In this way, three equations (one in each known position of the marker element) result for the calibration for each other reference object, so that the position of each reference object in the coordinate system to be calibrated can be determined exactly. In this way, the position of each reference object relative to the reference object, with which the sensor head is coupled, detectable. Thus, a calibration process can be carried out in a particularly simple manner even if the position of the other reference objects relative to the reference object, with which the sensor head is coupled, was not previously known.
  • Of course, in principle it can also be provided that the coupling means are designed such that the sensor head in more than three different layers, for example in four different layers, is clearly coupled mechanically with the reference object.
  • According to a second aspect of the invention, it is proposed to further develop the method mentioned above such that a position of the at least one reference object is defined as the zero point and the marking element is arranged by means of a unique mechanical coupling relative to the at least one reference object in the at least one known position, wherein the marking element is arranged by means of the unique mechanical coupling relative to the at least one reference object in three known positions.
  • This development of the method makes it possible to determine the distance of the marking element to each reference object three times in the calibration. In this way one obtains a system of equations in which the three unknowns, the spatial coordinates of the respective reference object, can be determined. By means of this development of the method, it is therefore possible to determine the position of each reference object relative to the reference object with which the sensor head was coupled, even if this position was previously unknown.
  • The inventive method according to the second aspect therefore has the same Advantages as the coordinate measuring machine according to the first aspect of the invention.
  • The object initially posed is thus completely solved.
  • In a further preferred embodiment it can be provided that the marking element is an optical transmitting / receiving device.
  • This has the advantage that only the marking element is to be designed as a transmitting / receiving device. Otherwise, each reference object would be designed as a transmitting / receiving device. This would lead to a multiplication of the costs for the transceiver.
  • Accordingly, it can be provided in a further preferred embodiment that the at least one reference object is a retroreflector.
  • In this way it is particularly easy to ensure that the rays of the optical transmitting / receiving device in the angle in which they are hit on the retroreflector, also reflected again. In this way, a particularly strong received signal for the transmitting / receiving device, so that the measurement result can be improved overall.
  • In a preferred embodiment, the position detection device may be a laser coherence μ-global positioning system, wherein at least three reference objects are provided.
  • By using this system described above results in a particularly high accuracy of the position detection device and thus both in the calibration and in the use of the coordinate measuring a correspondingly high accuracy.
  • In a preferred development of the invention, it is provided that the coupling means have an adapter device for arranging the sensor head at a specific distance and a specific direction relative to the at least one reference object and an orientation device for unambiguously aligning the sensor head.
  • It is thus provided that the coupling means on the one hand comprise an adapter device, with which the sensor head is coupled to the reference object, whereby it is determined in which direction and distance the marking element is arranged relative to the reference object. Preferably, it is provided that the adapter device is designed self-centering. In this way it is particularly effectively ensured that an operator can couple the sensor head only in the specific distance and in the specific direction. If it is provided that the sensor head can be arranged in three or more positions relative to the reference object, the coupling means are correspondingly designed such that the sensor head only exactly at these three or more layers with the respective determined distances and certain directions relative to the at least one Reference object can be arranged.
  • The at least one orientation device prevents the sensor head from being coupled to the reference object in any orientation in the specific distance and in the specific direction, which are both predetermined by the at least one adapter device. The orientation is predetermined by the at least one orientation device for each position of the sensor head relative to the reference object. In this way, an operator can not commit errors in the coupling of the sensor head with the reference object and thereby cause an incorrect calibration of the coordinate measuring machine. Furthermore, a robot arm possibly carrying the sensor head can arrange the sensor head only in the orientation, distance and direction predetermined by the adapter device and the orientation device relative to the reference object.
  • In a preferred embodiment of the invention it can be provided that the at least one adapter device by three either to the sensor head or to the at least one reference object offset by 120 ° to each other arranged cylindrical roller pairs and by three corresponding to the other of the sensor head and the at least one reference object each offset by approximately 120 ° arranged balls is formed.
  • In this way, a self-centering adapter device is provided in a mechanically simple and cost-effective manner, which specifies the direction and distance in which the sensor head is arranged relative to the reference object. For an operator, it is easy to see that the balls are to be pressed into the corresponding pairs of cylinder rollers. Due to the arrangement of three offset by about 120 ° to each other cylinder roller pairs, the adapter device is also self-centering.
  • All that remains open is the orientation of the sensor head on the reference object, since the adapter device designed in this way basically allows three orientations.
  • For this purpose, in a preferred embodiment of the invention, it is provided that the at least one orientation device is formed in each case by a pin arranged either on the sensor head or on the at least one reference object and by a recess arranged correspondingly on the other of the sensor head and the at least one reference object.
  • In this way, it is particularly easy to ensure that the sensor head is coupled to the reference object only in a specific orientation.
  • In a further embodiment of the invention it can be provided that the adapter device is formed from at least two rod elements of known length, which are made of a material with a low coefficient of thermal expansion.
  • In this way, the adapter device can also be provided. The bar elements should be made of a material with a low coefficient of thermal expansion so that their length does not vary due to temperature influences. For example, the bar elements could be made of Invar or Thermofit CFRP. These materials are stable in length under the influence of temperature and thus suitable for the adapter device. For example, the rod elements can be correspondingly inserted in the sensor head and in the recesses provided in the at least one reference object.
  • It can be provided that the orientation device is formed by different cross-sectional shapes of the rod elements.
  • In this way, it is simply ensured that the rod elements can be inserted only into certain of the recesses, resulting in a mechanically uniquely predetermined position of the sensor head relative to the at least one reference object and errors in the calibration can be avoided.
  • In a preferred embodiment of the method, it is provided that the marking element is designed as an optical transmitting / receiving device, wherein for calibration by means of the optical transmitting / receiving device in each case a distance of at least one known position to each in a field of view of the optical transmitting / receiving device arranged reference object is determined.
  • In this way, the process is implemented particularly cost-effectively. Alternatively, of course, it can also be provided that the at least one reference object is configured in each case as a transmitting / receiving device. However, this would require a large number of transceiver objects, thereby multiplying the associated costs. In the embodiment of the marking element as a transmitting / receiving device, only a transmitting / receiving device is provided. The reference objects can be configured, for example, as retroreflectors. In this way, you get a cost-effective and easy to maintain overall structure.
  • In a development of the method, it is provided that the method is repeated on a further reference object if not enough reference objects are arranged in the viewing area.
  • Under certain circumstances, it may be due to obstructions that during calibration insufficient reference objects are in the field of view of the transmitting / receiving device, so that no calibration of the CMM can be done. As a rule, at least two further reference objects should be in the field of view, so that a calibration for a total of three reference objects (the first reference object was defined as zero point) can be performed and based on these three reference objects, the position detection device can then determine the position of the sensor head by means of a corresponding trilateration method. Of course, any other number of reference objects may be determined as a minimum number. Accordingly, the accuracy of the position detection increases. It may further be provided that a warning sign is issued to an operator if the calibration could not be completed successfully, so that it can then proceed to another reference object and perform the calibration.
  • Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:
  • 1 an embodiment of a coordinate measuring machine according to a first aspect of the invention,
  • 2 a schematic representation of a reference object,
  • 3 a schematic representation of a first embodiment of a sensor head,
  • 4 a schematic representation of a second embodiment of a sensor head,
  • 5 a schematic representation of a third embodiment of a sensor head, and
  • 6 a schematic flow diagram of a method according to a second aspect of the invention.
  • 1 shows a schematic view of a coordinate measuring machine 10 according to a first aspect of the invention.
  • The coordinate measuring machine 10 serves to a workpiece 12 to measure. There is a sensor for this 14 provided, which is formed in the illustrated embodiment as a tactile sensor, ie by means of the sensor 14 are made by probing a variety of points of the workpiece 12 the dimensions of the workpiece 12 certainly. Such tactile measuring systems for coordinate measuring machines are known to the person skilled in the art. The sensor 14 is in a sensor head 16 stored. The sensor head 16 has, as known to those skilled in a measuring system that a deflection of the tactile sensor 14 opposite the sensor head 16 detected. In this way, the location of the sensor 14 relative to the sensor head 16 continuously recorded.
  • Furthermore, a data processing device 18 provided by means of the tactile sensor 14 processed data processed. A transmission of the means of the sensor 14 collected data is sent to the data processing unit 18 by means of a connection 20 , The connection 20 is preferably carried out wirelessly. In this way it is possible to use the sensor head 16 with the sensor 14 portable design. The connection 20 However, it can also be wired, especially if the sensor head 16 is carried and controlled by a robot arm (not shown).
  • It is further a position detection device 22 provided, which is intended to contact the position of the sensor head without contact 16 capture. This is in the sensor head 16 a marking element 24 intended. The position detection device 22 determines the position of the marking element 24 relative to a plurality of reference objects 26 , In particular, it is provided that it is in the position detection device 22 is an initially described laser coherence μ-global positioning system, which is then of the marking element 24 and the reference objects 26 is formed.
  • The reference objects 26 are spaced from each other and thus clamp between them a measuring space 28 on. In particular, it can be provided that the reference objects 26 are fixed, for example, on the structures of a workshop or the like. But it can also be provided that the reference objects 26 are held by a suitable support structure.
  • The measuring room 28 essentially results from imaginary connecting lines 30 between the reference objects 26 are curious. To a position of the sensor head 16 using a trilateration method, a line of sight should be at least three reference objects.
  • During a calibration of the coordinate measuring machine 10 is provided that the sensor head 16 clearly mechanical with one of the reference objects 26 is coupled, as it is in the 1 is shown. The position of this reference object 26 is then used as the zero point 32 Are defined. Due to the clear mechanical coupling of the sensor head 16 with the reference object 26 is a position 34 of the marking element 24 relative to the zero point 32 known. The in the 1 shown ratios are to be understood as exemplary only and may differ from the actual conditions.
  • By activating the position detection device 22 can now with existing line of sight between the marking element 24 and one of the reference objects 26 a measuring beam 36 between the marking element 24 and each of the reference objects 26 every now and then be sent back, leaving a distance from each of the reference objects 26 to the marking element 24 is determined. Based on the respective distance thus determined, the coordinate measuring machine can determine each of the reference objects by determining the actual position 26 be calibrated. As will be described in more detail below, the sensor head 16 still in other positions relative to a reference object 26 be arranged so that there are several known positions 34 of the marking element 24 can yield and in this way for different known points 34 one distance to each of the reference objects 26 can be determined. When using at least three known positions 34 ie with clear mechanical coupling of the sensor head 16 in three different positions with the reference object 26 , so can also be the position of each reference object 26 to the zero point 32 determine even if the arrangement of the reference objects 26 was not known in advance.
  • Under certain circumstances, it may happen that a reference object 26 ' not in a viewing area of the sensor head 16 lies, so no measuring beam 36 between the reference object 26 ' and the marking element 24 can run. To use a trilateration method for position detection, the coordinate measuring machine should 10 with three reference objects 26 be calibrated. However, it may be set for greater accuracy and a higher number. Should be the number of reference objects 26 Therefore, an indication to an operator that the sensor head 16 with another of the reference objects 26 . 26 ' is to couple.
  • 2 shows a schematic bottom and side view of an embodiment of a reference object 26 , The reference object 26 is designed as a retro reflector. This is indicated by the reference object 26 a reflector housing 38 in which a mount 40 for a retro reflector 42 is trained. Furthermore, the reference object 26 coupling agent 44 on, with which a clear mechanical coupling of the sensor head 16 to the reference object 26 is ensured. The coupling agents 44 have three pairs of cylindrical rollers 46 on, which offset each other at an angle 48 are arranged. In the illustrated embodiment, there are three pairs of cylindrical rollers 46 provided so that the angle 48 between the cylinder roller pairs 46 to 120 ° each. The three cylinder roller pairs 46 In the illustrated embodiment, form part of an adapter device which is provided to the sensor head 16 such by means of the coupling agent 44 with the reference object 26 to couple that marking element 24 in a known direction and with a known distance to the reference object 26 or a zero point defined there 32 is arranged. To ensure a clear orientation is an orientation device 49 intended. In the illustrated embodiment, this is a recess 50 provided in the one described below element of the sensor head 16 intervenes. In this way, by the coupling means 44 allows the sensor head 16 with the reference object 26 clearly to couple mechanically.
  • 3 shows an embodiment of the sensor head 16 , Also the sensor head 16 has coupling agent 51 on that with the coupling agents 44 at the reference object 26 cooperate to provide the unique mechanical coupling between the two elements.
  • In addition, the sensor head points 16 a transmitting / receiving device 52 of the laser coherence μ-global positioning system, which serves as a position detection device 22 is used. The transmitting / receiving device 52 is shown only schematically in the view shown and is located within the sensor head 16 , Accordingly, in the sensor head 16 one or more openings 54 be provided, via which the transmitting / receiving device 52 Transmitting laser beams and receiving reflected laser beams.
  • On one side of the sensor head 16 are three balls 56 provided, which each other if necessary, an angle 48 of about 120 °. These balls 56 form part of the coupling agent 51 out, and act with the cylinder roller pairs 46 of the reference object 26 together. On this a self-centering coupling is provided. There is also a pen 58 provided in the recess 50 of the reference object 26 intervenes. In this way is also the intended orientation of the sensor head 16 relative to the reference object 26 clearly. The through the coupling agent 44 . 51 provided coupling is therefore mechanically unique. An operator may choose the appropriate side of the sensor head 16 and the reference object 26 only to those through the coupling agent 44 . 51 couple the given way together. This ensures that the marking element 24 in the illustrated embodiment, the transmitting / receiving device 52 , actually the known position 34 relative to the zero point 32 occupies. Alternatively, for example, a Hirth toothing could be used to reproducibly couple the two elements together in a defined position. Other realizations that allow a well-defined position can be used, such as conical and conical pan, among others
  • Furthermore, the sensor head has a recess 60 on, so that the retro-reflector 42 not with the sensor head 16 collides with the coupling process.
  • 4 shows a further preferred embodiment of the sensor head 16 , Identical elements are designated by the same reference numerals and act in the same way. In the following, only the differences are discussed.
  • The sensor head in 4 indicates next to the coupling means 51 also other coupling agents 51 ' on another side of the sensor head 16 on. Also on the in the 4 remote side of the sensor head 16 Further coupling means (not shown) may be arranged. Also the other coupling agents 51 ' have three balls 56 ' on, which are arranged at an angle of 120 ° to each other. Also another pen 58 ' and a corresponding recess 62 ' are provided. In this way, the sensor head 16 in several different positions relative to the reference object 26 be clearly coupled mechanically. Thus arise for the marking element 24 several known positions 34 , Care must be taken to ensure that coupling agents, which are not shown on the coupling agents 51 ' opposite side of the sensor head 16 arranged are arranged asymmetrically to these, so that actually three different layers of the marking element 24 relative to the zero point 32 result. In this way it is possible to use the sensor head 16 in three different layers clearly mechanically with the reference object 26 to couple, with the openings 54 always pointing in the same direction, so that always a line of sight to the other reference objects 26 for the transceiver 52 consists. This allows calibration measurements for three known positions 34 the transmitting / receiving device 52 be made and the location of each reference object 26 to the zero point 32 be determined.
  • 5 shows a further embodiment of the sensor head 16 , The same elements are identified by the same reference numerals, in the following, only the differences will be discussed.
  • The coupling agents 51 are executed in the illustrated embodiment in other ways. These are two bar elements 62 provided to the sensor head 16 with the reference object 26 clearly to couple mechanically. Such coupling agents 51 may be provided in particular when the reference object 26 manually difficult to reach. In the present case are two bar elements 62 provided, which, as can be seen in the cross-sectional view, have different cross-sectional shapes. In this way it is ensured that the sensor head 16 only in a certain direction, distance, orientation by means of coupling 51 relative to the reference object 26 can be arranged. Of course, it can also be provided that further coupling agent 51 to the sensor head 16 , For example, on the other pages, are provided so that the transmitting / receiving device 52 in other known positions 34 relative to a zero point 32 can be arranged.
  • 6 shows a schematic flow diagram of a method 70 according to a second aspect of the invention.
  • The procedure 70 starts in a starting step 72 , After that connects in one step 74 an operator or a robot arm the sensor head 16 with one of the reference objects 26 , In one step 76 then this reference object is defined as zero point. Subsequently, in one step 78 the known position 34 the transmitting / receiving device in the sensor head 16 certainly. Due to the clear mechanical coupling of the sensor head 16 with the reference object 26 via the coupling agents 44 . 51 is the known position 34 known. Indicates the sensor head 16 several coupling agents 51 . 51 ' on, which is a clear mechanical coupling of the sensor head 16 in different positions with the reference object 26 may be provided that each of the coupling means 51 . 51 ' an identification unit, so that it can be determined which of the coupling means 51 . 51 ' with the coupling agents 44 of the reference object 26 was coupled.
  • Subsequently, by means of the transmitting / receiving device, a distance or a distance in one step 80 to each of the other reference objects 26 determined in a field of view of the transceiver 52 lie.
  • In one step 82 Now takes place a calibration of the coordinate measuring machine, in which the position of the other reference objects 26 checked and corrected if necessary. An embodiment of the method can now be provided that the sensor head 16 by means of further coupling agents 51 . 51 ' with the reference object 26 is coupled in a different position, so that the transmitting / receiving device 52 another known position 34 occupies. This can be repeated at least twice, so that in a total of three known positions 34 the distance to the other reference objects 26 was determined and so the position of the other reference objects 26 calculate, even if it was not known before.
  • Subsequently, in one step 84 be checked whether sufficient reference objects in the field of view of the transmitting / receiving device 52 and have sufficient calibration of the coordinate measuring machine 10 could take place. If this is not the case, the sensor head can be provided 16 with another reference object 26 in one step 86 to connect and the procedure in step 76 to start afresh. If there are enough reference objects in the field of view and sufficient calibration could take place, then the coordinate measuring machine will be available 10 ready for use and the process ends in one step 88 ,

Claims (13)

  1. Coordinate measuring machine ( 10 ) with a sensor ( 14 ) for the three-dimensional measurement of a workpiece ( 12 ), whereby the sensor ( 14 ) relative to a sensor head ( 16 ), and with a three-dimensional non-contact position detection device ( 22 ) for detecting a position of a on the sensor head ( 16 ) arranged marking element ( 24 ) relative to at least one reference object ( 26 ), characterized in that the sensor head ( 16 ) and the at least one reference object ( 26 ) each coupling agent ( 44 . 51 ) for unambiguous mechanical coupling of the sensor head ( 16 ) with the reference object ( 26 ), and wherein at least the coupling means ( 51 ) on the sensor head ( 16 ) are formed such that the sensor head ( 16 ) in three different layers clearly mechanically with the reference object ( 26 ), whereby the marking element ( 24 ) in each position a different known position relative to the reference object ( 26 ) occupies.
  2. Coordinate measuring machine according to claim 1, characterized in that the marking element ( 24 ) an optical transmitting / receiving device ( 52 ).
  3. Coordinate measuring machine according to claim 1 or 2, characterized in that the at least one reference object ( 26 ) a retroreflector ( 42 ).
  4. Coordinate measuring machine according to one of claims 1 to 3, characterized in that the position detection device ( 22 ) is a laser coherence μ global positioning system, wherein at least three reference objects ( 26 ) available.
  5. Coordinate measuring machine according to one of claims 1 to 4, characterized in that the coupling means ( 44 . 51 ) at least one adapter device for arranging the sensor head ( 16 ) at a certain distance and a certain direction relative to the at least one reference object ( 26 ) and at least one orientation device for unambiguously aligning the sensor head ( 16 ) exhibit.
  6. Coordinate measuring device according to claim 5, characterized in that the adapter device is designed self-centering.
  7. Coordinate measuring machine according to claim 5 or 6, characterized in that the at least one adapter device in each case by three either on the sensor head ( 16 ) or at least one reference object ( 26 ) each offset by about 120 ° cylindrical cylinder pairs ( 46 ) and by three corresponding to the other of the sensor head ( 16 ) and the at least one reference object ( 26 ) each offset by approximately 120 ° arranged balls ( 56 ) is trained.
  8. Coordinate measuring device according to one of claims 5 to 7, characterized in that the at least one orientation device in each case by one on either the sensor head ( 16 ) or at least one reference object ( 26 ) arranged pin ( 58 ) and by a corresponding to the other of the sensor head ( 16 ) and the at least one reference object ( 26 ) arranged recess ( 50 ) is trained.
  9. Coordinate measuring machine according to claim 5 or 6, characterized in that the adapter device consists of at least two rod elements ( 62 ) of known length, which are made of a material having a low coefficient of thermal expansion.
  10. Coordinate measuring device according to claim 9, characterized in that the orientation device by different cross-sectional shapes of the rod elements ( 62 ) is formed.
  11. Procedure ( 70 ) for calibrating a three-dimensional non-contact position detection device ( 22 ) for detecting a position of a marking element ( 24 ) relative to at least one reference object ( 26 ), where a zero point ( 32 ) and the marking element ( 24 ) relative to the zero point ( 32 ) in at least one known position ( 34 ), wherein a position of the at least one reference object ( 26 ) as zero point ( 32 ) and the marking element ( 24 ) by means of a unique mechanical coupling ( 44 . 51 ) relative to the at least one reference object ( 26 ) in the at least one known position ( 34 ), characterized in that the marking element ( 24 ) by means of the unique mechanical coupling ( 44 . 51 ) relative to the at least one reference object ( 26 ) in three known positions ( 34 ) is arranged.
  12. Method according to claim 11, characterized in that the marking element ( 24 ) as an optical transmitting / receiving device ( 52 ), wherein for calibration by means of the optical transmitting / receiving device ( 52 ) a distance of the at least one known position ( 34 ) to each in a field of view of the optical transceiver ( 52 ) arranged reference object ( 26 ) is determined.
  13. A method according to claim 12, characterized in that the method at a further reference object ( 26 ) is repeated, if not at least two reference objects ( 26 ) are arranged in the field of view.
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GB2180117A (en) * 1985-09-05 1987-03-18 Ferranti Plc Three-dimensional position measuring apparatus
GB2285550A (en) * 1994-01-05 1995-07-12 Creo Products Inc Optical coordinate measuring system for large objects
US5921992A (en) * 1997-04-11 1999-07-13 Radionics, Inc. Method and system for frameless tool calibration
DE10143539A1 (en) * 2001-09-06 2003-04-03 Daimler Chrysler Ag Method and arrangement for determining the position and orientation of an image recording device in the optical measurement of objects
WO2004033991A1 (en) * 2002-10-08 2004-04-22 Stotz Feinmesstechnik Gmbh Method and device for the three-dimensional measurement of objects
EP1322905B1 (en) * 2000-09-28 2005-03-30 Carl Zeiss Industrielle Messtechnik GmbH Device for measuring co-ordinates
DE10349361A1 (en) * 2003-10-23 2005-05-25 Kuka Roboter Gmbh Method and device for positioning a handling device
WO2007015677A1 (en) * 2005-08-04 2007-02-08 Hexagon Metrology Ab Measurement method and measuring device for use in measurement systems
WO2009102266A1 (en) * 2008-02-14 2009-08-20 Hexagon Metrology Ab Measurement arrangement with a measurement head in order to carry out inspection measurement

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2180117A (en) * 1985-09-05 1987-03-18 Ferranti Plc Three-dimensional position measuring apparatus
GB2285550A (en) * 1994-01-05 1995-07-12 Creo Products Inc Optical coordinate measuring system for large objects
US5921992A (en) * 1997-04-11 1999-07-13 Radionics, Inc. Method and system for frameless tool calibration
EP1322905B1 (en) * 2000-09-28 2005-03-30 Carl Zeiss Industrielle Messtechnik GmbH Device for measuring co-ordinates
DE10143539A1 (en) * 2001-09-06 2003-04-03 Daimler Chrysler Ag Method and arrangement for determining the position and orientation of an image recording device in the optical measurement of objects
WO2004033991A1 (en) * 2002-10-08 2004-04-22 Stotz Feinmesstechnik Gmbh Method and device for the three-dimensional measurement of objects
DE10349361A1 (en) * 2003-10-23 2005-05-25 Kuka Roboter Gmbh Method and device for positioning a handling device
WO2007015677A1 (en) * 2005-08-04 2007-02-08 Hexagon Metrology Ab Measurement method and measuring device for use in measurement systems
WO2009102266A1 (en) * 2008-02-14 2009-08-20 Hexagon Metrology Ab Measurement arrangement with a measurement head in order to carry out inspection measurement

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