Method for the automatic recognition of surface defects in body shells and device for carrying out said method

{
  "publication_number": "US6320654B1",
  "country": "US",
  "kind": "B1",
  "title": "Method for the automatic recognition of surface defects in body shells and device for carrying out said method",
  "abstract": "In a vehicle production process, a system for detecting selected surface defects of a vehicle body prior to painting generally consisting of a conveyor operative for advancing a plurality of such vehicle bodies along a line of travel; an array of devices disposed transversely of the line of travel, operative to irradiate at the selected angles, sequential transverse sections of each of such vehicle bodies with grid patterns of light; a plurality of devices, operative to optically detect reflective grid patterns of light from the transverse sections; a computer including a processor and a database provided with files of reference data representing relevant defect surfaces of selected vehicle bodies, operative to process data generated by the detecting devices, utilizing triangulation techniques and accounting for three-dimensional phase shifts, to generate composite detected data, comparing such composite detected data with selected reference data to generate identification data representing coordinates of relevant defect surfaces of such vehicle bodies; and a substance emitting device operative in response to said identification data for marking relevant defect surfaces of such bodies.",
  "claims": [
    "1. In a vehicle production process, a system for detecting selected surface defects of a vehicle body prior to painting, comprising: a conveyor operative for advancing a plurality of said vehicle bodies along a line of travel; an array of devices disposed transversely of said line of travel, operative to irradiate at selected angles, sequential transverse sections of each of said vehicle bodies with grid patterns of light; a plurality of devices, operative to optically detect reflective grid patterns of light from said transverse sections; a computer including a processor and a database provided with files of reference data representing relevant defect surfaces of selected vehicle bodies, operative to process data generated by said detecting devices, utilizing triangulation techniques and accounting for three dimensional phase shifts, to generate composite detected data, comparing said composite detected data with selected reference data to generate identification data representing coordinates of relevant defect surfaces of said vehicle bodies; and means operative in response to said identification data for marking relevant defect surfaces of said bodies.",
    "2. A system according to claim 1 including means for detecting the presents of a vehicle body at a selected point along said line of travel and transmitting data representing said position to said computer.",
    "3. A system according to claim 1 including means for identifying the configurations of said vehicle bodies and transmitting data representing said configurations to said computer.",
    "4. A system according to claim 1 wherein the nature of said relevant defects includes at least one of depth, extent, frequency in occurrence, positioning and frequency in time.",
    "5. A system according to claim 1 wherein said reference data comprises a compilation of defect surfaces visually determined by an operator.",
    "6. A system according to claim 1 including means for editing said reference data to alter the composition of said relevant defect surfaces.",
    "7. A system according to claim 1 wherein said marking means comprises at least one nozzle operative in response to command signals of said computer for training and ejecting a marker substance onto at least one relevant defect surface of a vehicle body as determined by said computer.",
    "8. A system according to claim 7 wherein said marker substance comprises a water soluble material.",
    "9. A method of detecting selected surface defects of a vehicle body comprising: conveying a plurality of said vehicle bodies along a line of travel; irradiating sequential transverse sections of said vehicle bodies at selected angles with grid patterns of light; optically detecting reflective grid patterns of light from said transverse sections; processing data representing said reflective grid patterns, utilizing triangulation techniques and accounting for three-dimensional phase shifts, to generate composite detected data, comparing said composite data with selected reference data representing relevant defect surfaces of selected vehicles bodies and generating identification data representing coordinates of relevant defect surfaces of said vehicles bodies; and marking relevant defect surfaces on said vehicle bodies responsive to said coordinates of said identification data.",
    "10. A method according to claim 9 including detecting the presents of a vehicle body at a selected point along said line of travel and transmitting data representing said position to means for processing said data.",
    "11. A method according to claim 9 including identifying the configurations of said vehicles bodies and transmitting data representing said configurations to means for processing said data.",
    "12. A method according to claim 9 including editing said reference data to alter the composition of said relevant defect surfaces.",
    "13. A method according to claim 9 including ejecting a substance on surface areas of said vehicle bodies corresponding to relevant defect surfaces as determined by said data processing."
  ],
  "description_excerpt": "The invention relates to a process for automatic recognition of surface defects in body shells and a device for application of the process.\n\nIn the manufacture of vehicles, body shells which are conveyed from a body shell construction line to an enameling line painting station generally have surface defects which are regarded by a customer as quality- lowering defects unless subjected to finishing operations. Consequently, such surface defects in body shells are to be detected and reworked.\n\nIn the past, relevant surface defects in series production have been recognized and evaluated subjectively by an inspector, especially by probing while wearing gloves, by display from different viewing directions and, if desired, by stripping with a whetstone if the inspector's experience has been that surface defects often occur at specific points on a body shell type.\n\nSurface defects such as this may be dents/bulges, collapses, injection point/solder voids, uneven areas/hairline cracks, etc. The geometric parameters in evaluation are depth, extent, gradients, surface curvature, local frequencies of undulations, and positions of surface defects. Determination of whether a surface defect is relevant for a reworking operation normally depends on evaluation of a combination of the parameters indicated. For example, a dent 20 μm deep and 50 mm long can easily be recognized and must be reworked, while a dent of the same depth and 200 mm long normally is not recognized as a surface defect impairing quality and accordingly no reworking is required.",
  "cpc": [
    "G01N 21/8806"
  ],
  "ipc": [
    "G01B 11/25",
    "G01N 21/88"
  ],
  "assignees": [
    "Audi AG"
  ],
  "inventors": [
    "Klaus Alders",
    "Martina Lehe",
    "Gang Wan"
  ],
  "filing_date": "1998-07-10",
  "publication_date": "2001-11-20",
  "grant_date": "2001-11-20",
  "priority_date": "1997-07-18",
  "application_number": "US-46278600-A",
  "family_id": "7836137",
  "cited_by_count": 84,
  "citations": [
    "DE3712513A1",
    "EP0286994A2",
    "US4792232A",
    "US4989981A",
    "DE3813239A1",
    "DE4041166A1",
    "US5331169A",
    "US5414518A",
    "DE4338223A1",
    "US5367378A",
    "US5546189A",
    "DE19534145A1",
    "GB2308656A"
  ]
}