Coordinate measuring instrument with feeler element and optic sensor for measuring the position of the feeler

• US 6,651,351 B1
• Filed: 03/08/2000
• Issued: 11/25/2003
• Est. Priority Date: 06/12/1997
• Status: Expired due to Term

• Current Assignee: Werth Messtechnik GmbH
• Original Assignee: Werth Messtechnik GmbH
• Inventors: Schwenke, Heinrich, Christoph, Ralf, Trapet, Eugen
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Gonzalez, Madeline
• Application Number:
  US09/445,430
• Time in Patent Office: 1,357 Days
• Field of Search: 335/56, 335/57, 335/58, 335/59, 335/60, 335/61, 335/03
• US Class Current: 33/503
• CPC Class Codes: G01B 11/007 feeler heads therefor

Abstract

A method for measuring structures of an object using a feeler element associated with a coordinate measuring instrument and extending from an elastic bendable feeler extension is disclosed, and wherein the feeler element is brought into contact with an object having structures to be measured and the position of the feeler is then determined by comparing the position of the feeler as determined by the coordinate measuring instrument with the position determined by the optical sensor.

Claims

1. A method for measuring the structure of an object by means of a flexible feeler means that is operatively connected to a coordinate measuring instrument, wherein the feeler means is brought into contact with the object and the position of the feeler means is then determined, the feeler means comprising a mechanically flexible and deflectable feeler extension, wherein said feeler extension is deflectable due to its inherent flexibility, the position of the feeler extension, or of a target extending from the feeler extension and operatively connected to the feeler extension is directly determined with an optical sensor, and wherein certain coordinates of the feeler extension or of the target are linked with those of the coordinate measuring instrument for measuring the structure of the object, using the optical sensor.

2.Method according to claim 1, wherein the feeler extension or the target is moved towards the object from its side facing towards the sensor.

2. Method according to claim 1, wherein the feeler extension is adjusted with the sensor as a unit.

3. Method according to claim 1, wherein a deflection of the feeler extension resulting from the contact with the object is optically determined.

9. Method according to claim 1, wherein the spatial position of the feeler extension is determined using a two-dimensional measurement system by means of at least three targets assigned thereto.

10. Method according to claim 1, wherein the feeler extension or a section thereof is used as a spatially extended target whose position is measured relative to the feeler body in freely selectable cross-sections.

11. Method according to claim 1, wherein targets arranged on the feeler extension for determining the position of the feeler means are measured by photogrammetry (at least two cameras).

12. Method according to claim 1, wherein the position of the feeler extension is measured by photogrammetry (at least two cameras).

4. Method according to claim 4, wherein the deflection of the feeler extension is measured by displacement of its image or of an image of a target on a sensor field.

5. Method according to claim 4, wherein the deflection of the feeler extension is determined by evaluating the contrast of the feeler sensed by the optical sensor.

6. Method according to claim 4, wherein the deflection of the feeler extension is determined from a size change of an image of a target resulting from the geometrical-optical correlation between object distance and enlargement.

7. Method according to claim 4, wherein the deflection of the feeler extension is determined from apparent size change of a target resulting from loss of contrast due to defocusing.

8. Method according to claim 4, wherein the deflection vertical to an optical axis of an electronic image-processing system is determined.

13. A coordinate measuring machine for measuring the structure of an object, the machine comprising a support table arranged on the X-Y axes of the measuring machine for supporting the object, a holding device adjustable in the X-Y-Z axes of the measuring machine, feeler means including a mechanically flexible and deflectable feeler extension, wherein said feeler extension is deflectable due to its inherent flexibility, said feeler extension having a contact tip at its end and being operatively connected to said holding device, an optical sensor for determining the location of said contact tip or a target directly associated with said contact tip, and a measurement computer for calculating the structure of the object based on the position of the contact tip or the target.

14. Coordinate measuring instrument according to claim 14 wherein the contact tip (14) or the target (46, 48, 50) is designed as a reflector.

15. Coordinate measuring instrument according to claim 14, wherein the contact tip (14) or the target (46, 48, 50) is designed self-emitting.

16. Coordinate measuring instrument according to claim 14, wherein the contact tip (14) or the target (46, 48, 50) is a ball or cylinder spatially emitting or reflecting a beam.

17. Coordinate measuring instrument according to claim 14, wherein the contact tip extension (38) is designed at least in some sections elastic to bending or as a light guide or comprising a light guide.

18. Coordinate measuring instrument according to claim 14, wherein the feeler extension (38, 40) or at least a section thereof is the feeler element (14) or the target (46, 48).

19. Coordinate measuring instrument according to claim 14, wherein several targets (46, 48) are assigned to the contact tip (14) and extend preferably from the feeler extension (30) or form sections thereof.

20. Coordinate measuring instrument according to claim 14, wherein the feeler extension (30) is designed L-shaped for alignment with an optical axis (24).

21. Coordinate measuring instrument according to claim 14, wherein the feeler extension (30) is designed at the end as a feeler element (14).

22. Coordinate measuring instrument according to claim 14, wherein the contact tip (14) or the target (46, 48, 50) are interchangeably connected to the feeler extension (30).

23. Coordinate measuring instrument according to claim 14, wherein the contact tip (14) or the target (46, 48, 50) are connected to the feeler extension (30) by gluing or welding.

24. Coordinate measuring instrument according to claim 14, wherein the feeler extension (18) extends from a holder (20) that is adjustable by at least three degrees of freedom, preferably five, and preferably interchangeable.

25. Coordinate measuring instrument according to claim 14, wherein the feeler extension (18) extends from a holder (20) that forms a unit with the sensor or is connected to the sensor.

26. Coordinate measuring instrument according to claim 14, wherein the feeler extension (18) is moved towards the object from its side facing towards the sensor.

27. Coordinate measuring instrument according to claim 14, wherein the contract tip (14) or the target (46, 48, 50) has or is a self-lighting electronic element.

28. Coordinate measuring instrument according to claim 14, wherein the sensor is an image-processing sensor.

29. Coordinate measuring instrument according to claim 14, wherein the sensor is a position-sensitive surface sensor.

30. Coordinate measuring instrument according to claim 14, wherein the diameter of the contact tip (14) is about 1 to 3 times greater than that of the feeler extension (38).

31. Coordinate measuring instrument according to claim 14, wherein the feeler extension (30) has at its end a cylindrical form and is designed as a feeler element (14).

32. Coordinate measuring instrument according to claim 14, wherein the feeler extension (30) is spherically rounded for formation of the feeler element.