Method for contactlessly and dynamically detecting the profile of a solid body

• US 20060232787A1
• Filed: 10/06/2005
• Published: 10/19/2006
• Est. Priority Date: 03/25/2003
• Status: Active Grant

• Current Assignee: Gutehoffnungshütte Radsatz GmbH
• Original Assignee: Gutehoffnungshütte Radsatz GmbH
• Inventors: Hoffmann, Dleter, Brinkmann, Dinslaken, Hoffmann, Manfred, Walter, Michael J.
• Granted Patent: US 7,602,506 B2
• Time in Patent Office: Days
• US Class Current: 356/602
• CPC Class Codes: B61K 9/12 Measuring or surveying wheel-rims measuring techniques G01
• CPC Class Codes: G01B 11/2522 the position of the object changing and being recorded

Abstract

The invention relates to a method for contactlessly and dynamically detecting the profile of a solid body. At least one light beam is generated by a laser device and expanded to form a linear light band projected onto the moving surface of the solid body. Light reflected from the surface of the solid body is focused in an imaging device whose optical axis is at a fixed triangulation angle to the direction of projection of the laser device and which is arranged at a fixed based distance from the laser device. The reflected light is detected by a planar light receiving element at a frequency that is high by comparison with a speed of movement (v) of the solid body after which the measured values of the profile are obtained as a function of the triangulation angle and the base distance.

Claims

1. A method for contactlessly and dynamically detecting the profile (P) of a solid body, in particular for the purpose of determining wear occurring on the solid body, the method comprising the steps of:

generating at least one light beam by a laser device and expanding the light beam to form at least one linear light band, projecting the light band onto at least one area of the surface of the solid body, moving the solid body past the laser device, and focusing the reflected light from the area of the surface of the solid body in an imaging device, whose optical axis is at a fixed triangulation angle (φ

) to the direction of projection of the laser device and which is arranged at a fixed base distance (B) from the laser device, detecting the light reflected at a frequency (f) that is high by comparison with a speed of movement of the solid body by means of a planar light receiving element outputting signals from the light receiving element as a function of the triangulation angle (φ

) and the base distance (B) by means of trigonometric relations and in combination with correction values (Kv) determined in accordance with the speed of movement of the solid body, obtaining with a data processing device measured values (z_B) of the profile (P) using the signals from the light receiving element, and storing the measured values (z_B) in the data processing device as a profilogram (PG).

2. The method as claimed in claim 1, wherein the measured values (z_B) of the profile (P) are obtained in combination with correction values (Ko) determined in accordance with the area of the surface of the solid body.

7. The method as claimed in claim 2 wherein the correction values (Ko) determined in accordance with the area of the surface of the solid body are vectorial factors determined as a function of a radius (R) of the solid body being a rotationally symmetrical body.

8. The method as claimed in claim 1 wherein the correction values (Kv) determined in accordance with the speed of movement of the solid body are vectorial factors proportional to the speed of movement.

9. The method as claimed in claim 1 further comprising the steps of correlatively combining the speed of movement

17. The method as claimed in claim 15, further comprising the step of simultaneously performing the contactless and dynamic measurements on the moving solid body by means of at least three light beams respectively expanded to form a linear light band in conjunction with a prescribed distance (N1, N2) of the areas of the surface of the solid body onto which the light bands are projected.

18. The method as claimed in one of claim 14claim 14 wherein the base quantity is a radius (R) of a rolling rotationally symmetrical body, which is determined from the following system of equations:

R²=x₁²+z₁²  

 

(1)
R²=x₂²+z₂²  

 

(2)
R²=x₃²+x³²  

 

(3)
x₁−

x₂=k*(x₂−

x₃)  

 

(4),

z₁, z₂, z₃ being three measured values lying on a circular arc of radius (R), respectively determined in a unidirectional fashion and corresponding to the ordinate (z) of a Cartesian coordinate system, of the length of the linear light band and which respectively correspond to half the length of a chord (s1₁, s1₂, s1₃) through the circular arc, x₁, x₂, x₃ being the abscissa values (x) respectively associated with these measured values, and k being a factor corresponding to prescribed time intervals (Δ

t) or distances (N1, N2) of the areas of the surface of the solid body.

19. The method as claimed in claim 1 further comprising the step of visualizing the profilogram (PG), in an indicating device such as a display. with the frequency (f) of the detection of the reflected light to determine the correction values (Kv) determined in accordance with the speed of movement.

10. The method as claimed in claim 1 further comprising using a number of profilograms as component profilograms (PG_a, PG_b, PG_c) by using at least three laser devices, that project light bands onto areas lying on various sides of the surface of the solid body and imaging devices assigned to said laser devices, storing the component profilograms in the data processing system, and obtaining an overall profilogram therefrom.

11. The method as claimed in claim 10, wherein the solid body has a shape that is substantially cylindrical and has at least three areas onto which the light bands are projected that lie on the two end faces and on the lateral surface of the cylinder.

12. The method as claimed in claim 11, wherein the overall profilogram of a rolling solid body is obtained from three component profilograms (PG_a, PC_b, PG_c) and determined simultaneously at one detection instant (t_k) by the two end faces and on the lateral surface, the detection instant (t_k) of the individual component profilograms (PG_a, PG_b, PG_c) being selected in such a way that a measured value (z_k) determined at this detection instant (t_k) assumes a maximum from at least three measured values (z₁, z₂, z₃) that lie on a circular arc of radius in one of the end faces (D₁, D₂) and are respectively determined at successive instants (t₁, t₂, t₃) and in a unidirectional fashion from the respective length of the linear light band, and that respectively correspond to half the length of a chord (s1₁, s1₂, s1₃) through the circular arc.

13. The method as claimed in claim 12, further comprising the steps of comparing one of the profilogram, the component profilograms (PG_a, PG_b, PG_c) and overall profilogram with at least one reference profilogram, and ascertaining the respective deviations (Δ

PG) from the respective reference profilogram.

14. The method as claimed in to claim 13, further comprising the step of referring one of the profilogram, the component profilograms (PG_a, PG_b, PG_c), the overall profilogram the respective reference profilogram and the respective deviations (Δ

PG) to a fixed long-term invariant geometric base quantity.

15. The method as claimed in claim 14, wherein the base quantity is determined from at least three measured values that are determined by contactless and dynamic measurements on the moving solid body and are undertaker in the same way as the detection of the profilogram or the detection of the component profilograms (PG_a, PG_b, PG_c).

16. The method as claimed in claim 15, further comprising the step of performing the contactless and dynamic measurements on the moving solid body in prescribed time intervals (Δ

t) at at least three instants (t₁, t₂, t₃) by means of a single light beam expended to form a linear light band.

20. The method as claimed in claim 1 further comprising the step of using a device that supplies digitized signals as the light receiving element.

21. The method as claimed in claim 1 further comprising the step of using a position-sensitive detector as the light receiving element.

22. The method as claimed in claim 1 wherein the light of the light band has a wavelength in the range of 400 nm to 1000 nm.

23. The method as claimed in claim 1 wherein the light of the light band has a wavelength in the visible region, and the imiting value of the accessible radiation (GZS) of the laser device is less than 1 mW.

24. The method as claimed in one of claim 1 wherein the power of the laser device is in the range of 0.5 to 50 mW.

25. The method as claimed in claim 1 wherein the laser device includes a cw (continuous wave) solid state diode including a semiconductor material selected from the

26. The method as claimed in claim 1 wherein the light band has a width in the range of 0.3 mm to 6.5 mm.

27. The method as claimed in claim 1 wherein the light band has a length in the range of 50 mm to 750 mm.

28. The method as claimed in claim 1 wherein the triangulation angle (p) has values in the range of 15°

to 40°

.

29. The method as claimed in claim 1 wherein the frequency (f) with which the reflected light from the surface of the solid body is detected by means of the light receiving element is in the range of 25 Hz to 100 kHz.

30. The method as claimed in claim 1 wherein a speed of a translatory movement of the solid body is less than 3.5 m/s.

31. The method as claimed in claim 1 wherein a mean working distance (L) of the laser device of the imaging device from the area of the surface of the solid body onto which the light band is projected is in the range of 20 mm to 650 mm.

32. The method as claimed in claim 1 wherein the base distance (B) between the imaging device and the optical axis (O-O) of the laser device is in the range of 30 mm to 450 mm.

33. The method as claimed in claim 13 wherein at least one of the profilogram the component profilograms (PG_a, PG_b, PG_c), the overall profilogram, the respective reference profilogram and the respective deviations (Δ

PG) are based on a resolution (dz_A) of less than 2.0 mm.

36. The method of claim 14 wherein the base quantity is a non-wearing wheel rim inside diameter.

37. The method of claim 10 further comprising the step of visualizing the component profilograms (PG_a, PG_b, PG_c) in an indicating device such as a display.

38. The method of claim 10 further comprising the step of visualizing the overall profilogram (GPG) in an indicating device such as a display.

39. The method of claim 10 further comprising the step of visualizing the respective reference profilogram (BP1, BP2) in an indicating device such as a display.

40. The method of claim 10 further comprising the step of visualizing the respective deviations (Δ

PG) in an indicating device such as a display.

41. The method as claimed in claim 1 wherein the light of the light band has a wavelength in the range of 650 to 700 nm.

42. The method as claimed in claim 1 wherein the laser device is a VLD (visible laser diode).

43. The method as claimed in claim 1 wherein the light band has a width in the range of 0.8 mm to 2.2 mm.

44. The method as claimed in claim 1 wherein the light band has a width in the range of 200 mm to 400 mm.

45. The method as claimed in claim 1 wherein the triangulation angle (φ

) has values in the range of 20°

mm to 30°

.

46. The method as claimed in claim 1 wherein the frequency (f) with which the light reflected from the surface of the solid body is detected by means of the light receiving element is in the range of 1 kHz to 10 kHz.

47. The method as claimed in claim 1 wherein the mean working distance (L) of the laser device or of the imaging device from the area of the surface of the solid body onto which the light band is projected is less than 1.5 m/s.

48. The method as claimed in claim 1 wherein a speed of a translatory movement (v) of the solid body is in the range of 150 mm to 350 mm.

49. The method as claimed in claim 1 wherein the base distance (B) between the imaging device and the optical axis (O-O) of the laser device is in the range of 60 mm to 270 mm.

50. The method as claimed in claim 13 wherein at least one of the profilogram, the component profilograms (PG_a, PG_b, PG_c), the overall profilogram, the respective reference profilogram and the respective deviations (Δ

PG) are based on a resolution (dz_A) of less than 0.5 mm.

3. The method as claimed in claim further comprising the steps of rotating the solid body.

4. The method as claimed in claim 3 wherein the solid body is a rotationally symmetrical body and executes a rolling movement past the laser device.

5. The method as claimed in claim 3 wherein the rotating of the solid body proceeds at a constant angular velocity.

6. The method as claimed in claim 3 wherein the rotating of the solid body is at and angular velocity that is less than 15 s^{31 1}.

34. The method of claim 4 wherein the solid body is a vehicle wheel.

35. The method of claim 5 wherein the rotating of the solid body is at an angular velocity that is less than 6s⁻

1.