Motion-measuring system of a machine and method for operating the motion-measuring system

{
  "publication_number": "US10706562B2",
  "country": "US",
  "kind": "B2",
  "title": "Motion-measuring system of a machine and method for operating the motion-measuring system",
  "abstract": "A method for operating a motion-measuring system of a machine, such as a coordinate-measuring device or a machine tool. An image-recording device arranged on a first part of the machine records at least one recorded image of a second part of the machine. The first part and the second part can be moved in relation to each other. A capturing structure, which is formed by the second part and/or which is arranged on the second part, is captured by the at least one recorded image, and, by using information about an actual appearance of the capturing structure, a speed of the relative motion of the first part and the second part is determined from differences of the at least one recorded image from the actual appearance of the capturing structure.",
  "claims": [
    "1. A method for operating a motion-measuring system of a machine, in particular of a coordinate measuring machine or of a machine tool, wherein: an image recording device arranged on a first part of the machine captures a spatial radiation distribution on the basis of radiation emanating from a second part of the machine and records at least one corresponding recording image of the second part, wherein the first part and the second part are movable relative to one another, a capturing structure, which is formed by the second part and/or which is arranged on the second part, is captured by the at least one recording image, and using information about an actual appearance of the capturing structure in a motionless state, a speed of the relative movement of the first part and the second part is determined from differences between the at least one recording image and the actual appearance of the capturing structure, where the differences arise as a result of a temporal profile of the spatial radiation distribution within a recording time interval of a respective recording image during a relative movement of the first part and the second part, wherein the at least one recording image is captured by a digital camera that comprises a plurality of sensor elements, each sensor element producing one pixel of the respective recording image by integrating impinging radiation of the spatial radiation distribution over an exposure time interval of the respective recording image, wherein the differences arise because the radiation impinging on at least some of the sensor elements varies over the exposure time interval due to the relative movement and the pixels produced by each of the at least some of the sensor elements as well as image regions comprising a plurality of these pixels are therefore different from local areas of the capturing structure in the motionless state, wherein the information about the actual appearance of the capturing structure comprises a reference image of the capturing structure, wherein the speed of the relative movement is determined by evaluating differences between the reference image and the at least one recording image recorded by the image recording device, and wherein, by performing a mathematical convolution of the reference image with a region of the at least one recording image in which the capturing structure is imaged, a convolution kernel of the convolution is determined and the speed of the relative movement is determined from the convolution kernel.",
    "2. The method as claimed in claim 1, wherein: the convolution kernel is interpreted as a geometric structure whose external dimensions correspond to the external dimensions of the reference image and the external dimensions of the region of the at least one recording image in which the capturing structure is imaged, and the speed of the relative movement is determined from at least one geometric property of a partial structure of the convolution kernel.",
    "3. The method as claimed in claim 2, wherein: the at least one recording image and the reference image are two-dimensional images, and an absolute value and/or a direction of the speed of the relative movement are/is determined from a geometry of the partial structure of the convolution kernel.",
    "4. A method for operating a motion-measuring system of a machine, in particular of a coordinate measuring machine or of a machine tool, wherein: an image recording device arranged on a first part of the machine captures a spatial radiation distribution on the basis of radiation emanating from a second part of the machine and records at least one corresponding recording image of the second part, the first part and the second part are movable relative to one another, a capturing structure, which is formed by the second part and/or which is arranged on the second part, is captured by the at least one recording image, using information about an actual appearance of the capturing structure in a motionless state, a speed of the relative movement of the first part and the second part is determined from differences between the at least one recording image and the actual appearance of the capturing structure, the differences arise as a result of a temporal profile of the spatial radiation distribution within a recording time interval of a respective recording image during a relative movement of the first part and the second part, and the capturing structure is a structure whose position function transformed into the frequency domain has function values greater than zero within a frequency range that begins at a frequency greater than zero and that ends at a predefined maximum frequency.",
    "5. The method as claimed in claim 4, wherein the predefined maximum frequency is predefined such that it is not less than the Nyquist frequency of the image recording device.",
    "6. The method as claimed in claim 4, wherein the function values of the position function of the capturing structure transformed into the frequency domain are greater than a predefined minimum value in-throughout an entirety of the frequency range.",
    "7. The method as claimed in claim 6, wherein the predefined minimum value is greater than a statistical fluctuation amplitude of image values of the at least one recording image, the statistical fluctuation amplitude being brought about by the recording of the at least one recording image and by a determination of the speed.",
    "8. The method as claimed in claim 4, wherein the function values of the position function of the capturing structure transformed into the frequency domain are constant throughout an entirety of the frequency range.",
    "9. In a method for operating a motion-measuring system of a machine, in particular of a coordinate measuring machine or of a machine tool, wherein: an image recording device arranged on a first part of the machine captures a spatial radiation distribution on the basis of radiation emanating from a second part of the machine and records at least one corresponding recording image of the second part, the first part and the second part are movable relative to one another, a capturing structure, which is formed by the second part and/or which is arranged on the second part, is captured by the at least one recording image, using information about an actual appearance of the capturing structure in a motionless state, a speed of the relative movement of the first part and the second part is determined from differences between the at least one recording image and the actual appearance of the capturing structure, and the differences arise as a result of a temporal profile of the spatial radiation distribution within a recording time interval of a respective recording image during a relative movement of the first part and the second part; a method for producing the capturing structure which is usable or is used in the method for operating the motion-measuring system of the machine, wherein dimensions of structure elements of the capturing structure are chosen depending on a magnitude of an expected speed of the relative movement of the first part and of the second part of the machine."
  ],
  "description_excerpt": "The invention relates to a motion-measuring system of a machine, a machine comprising a motion-measuring system, a method for operating a motion-measuring system of a machine, and a method for operating a machine comprising a motion-measuring system.\n\nMachines, such as e.g. coordinate measuring machines or machine tools, usually have a movable part, which e.g. carries a sensor for capturing coordinates of a workpiece or carries a processing tool for processing a workpiece. The movable part is therefore a sensor carrier, in particular. The movable part is movable within a movement range relative to another part of the machine, e.g. relative to a base.\n\nBy way of example, the sensor of the coordinate measuring machine (for short: CMM) is a measuring head mounted on the movable part (for example a sleeve or an arm) of the CMM. On the measuring head it is possible to mount a probe (e.g. a probe pin), in particular, using which the CMM probes the surface of the workpiece in a tactile manner in order to generate the sensor signals of the measuring head. Therefore, in particular, a probe for the tactile probing of the workpiece to be measured is also an example of a sensor or of a part of the sensor.\n\nThe measuring head has a sensor system, in particular, which generates measurement signals whose evaluation enables the coordinates to be determined. However, other sensors also crop up in coordinate measuring technology. By way of example, the sensor may merely initiate the measurement of the coordinates.",
  "cpc": [
    "G06T 7/248",
    "B23Q 17/2409",
    "G01B 11/002",
    "G01B 21/042",
    "G01B 5/008",
    "G06T 2207/30164"
  ],
  "ipc": [
    "B23Q 17/24",
    "G01B 5/008",
    "G01B 11/00",
    "G01B 21/04",
    "G06T 7/246"
  ],
  "assignees": [
    "Carl Zeiss Industrielle Messtechnik GmbH"
  ],
  "inventors": [
    "Nils Haverkamp",
    "Dominik Seitz",
    "Tanja Teuber",
    "Lars Omlor"
  ],
  "filing_date": "2017-09-28",
  "publication_date": "2020-07-07",
  "grant_date": "2020-07-07",
  "priority_date": "2015-03-30",
  "application_number": "US-201715718156-A",
  "family_id": "55640744",
  "cited_by_count": 15,
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}