Method for Contactless Dynamic Detection of the Profile of a Solid Body

• US 20080204765A1
• Filed: 09/19/2005
• Published: 08/28/2008
• Est. Priority Date: 09/19/2005
• Status: Abandoned Application

• Current Assignee: Gutehoffnungshütte Radsatz GmbH
• Original Assignee: Gutehoffnungshütte Radsatz GmbH
• Inventors: Hoffmann, Manfred, Walter, Michael J., Hoffmann, Dieter, Brinkmann, Andreas, Nowaczyk, Christian
• Application Number:
  US12/067,400
• Publication Number:
  US 20080204765A1
• Time in Patent Office: Days
• US Class Current: 356/606
• CPC Class Codes: G01B 11/2522 the position of the object changing and being recorded

Abstract

The present invention relates to a method for contactless dynamic detection of the profile of a solid body, particularly a moving one, a laser beam, expanded to form a linear light band, from a laser device being projected onto a region of the surface of the solid body, and the light reflected therefrom being focused in an imaging device, whose optical axis is at a fixed triangulation angle to the projection direction of the laser device and that is arranged at a fixed base distance from the laser device, and is detected by means of a planar light receiving element, in particular at a frequency that is high by compariosn with a speed of movement of the solid body, whereupon signals output by the light receiving element are used in a data processing device as a function of the triangulation angle and the base distance to obtain the measured values of the profile by means of geometric relationships, the values being stored as a profilogram.

Claims

1. A method for contactless dynamic detection of the profile (P) of a solid body (1, 1a), including a moving one, comprising a laser beam, expanding the beam to form a linear light band (3, 3a, 3b, 3c, 3c1, 3c2, 3c3), projecting the light band onto a region of the surface of the solid body (1, 1a), the light (RL) reflected from the surface being focused in an imaging device (5) whose optical axis (A-A) is at a fixed triangulation angle (φ

) to the projection direction (O-O) of the laser device (2) and that is arranged at a fixed base distance (B) from the laser device (2), and is reflected by means of a planar light receiving element (6), whereupon signals output by the light receiving element (6) are used in a data processing device as a function of the triangulation angle (φ

) and the base distance (B) to obtain measured values (z_B) of the profile (P) by means of geometric relationships, the values being stored as a profilogram (PG), the initial conditions of the solid body (1, 1a), including a distance from the laser device (2), a temporal variation in this distance and a light intensity distribution is determined at an initial instant (t₀), and thereafter there is determined from the initial conditions a detection instant (t_flash) for which signals output by the light receiving element (6) are selected in order to obtain the measured values (z_B) of the profile (P).

2. The method as claimed in claim 1, wherein a digital signal processor (DSP) is used to determine the detection instant (t_flash) for which signals output from the light receiving element (6) are selected in order to obtain the measured values (z_B) of the profile (P).

3. The method as claimed in claim 1, wherein the detection instant (t_flash) determined from the initial conditions is determined with the aid of the criterion of greatest possible temporal proximity to the initial instant (t₀).

4. The method as claimed in claim 1, wherein to determine the initial conditions of the solid body (1, 1a) at the initial instant (t₀) the signals output by the light receiving element (6) are used in order to obtain a pattern in the form of a binary coded mask, and the detection instant (t_flash) is fixed with the aid of the criterion of the recognition of this pattern.

5. The method as claimed in claim 4, wherein that in order to obtain and recognize the pattern, a light intensity distribution in the form of a transparency distribution, present on the solid body (1, 1a) at the initial instant (t₀) or at the detection instant (t_flash) is detected in a histogram and, using a lookup table (LT), is subjected to an image transformation, in the form of a threshold value operation including a highpass filtering.

6. The method as claimed in claim 4, wherein an alpha channel, in the form of a binary alpha channel, is used to obtain and recognize the binary coded mask pattern.

7. The method as claimed in claim 4, further comprising methods including filter operations in the form of intelligent image processing of the type including one or more of sharpening an image or producing a chrome effect, are used in order to obtain and recognize the pattern.

8. The method as claimed in claim 1, wherein the solid body (1, 1a) is a substantially rotationally symmetrical body, and undergoes a translatory and simultaneously rotating movement.

9. The method as claimed in claim 1, wherein the measured values (z_B) of the profile (P) of the body in the form of a vehicle wheel are obtained in combination with correction values (Ko) determined in accordance with the region of the surface of the solid body (1, 1a).

10. The method as claimed in claim 9, wherein the correction values (Ko) determined in accordance with the region of the surface of the solid body (1, 1a) are vectorial factors, determined as a function of a non-wearing wheel rim inside diameter (D_fix) of the rotationally symmetrical body.

11. The method as claimed in claim 1, wherein a number of profilograms (PG) are determined as component profilograms by using two light bands (3, 3a, 3b) projected on regions (D₁/M, D₂/M) lying on different sides (D₁, D₂, M) of the surface of the solid body (1, 1a), and an overall profilogram (GPG) is obtained therefrom.

12. The method as claimed in claim 11, wherein the light bands (3, 3a, 3b) are projected, simultaneously or with a time offset, onto one and the same measuring location, with reference to a position on a peripheral face (M) of the solid body (1, 1a), there being determined from the initial conditions for the two light bands (3, 3a, 3b) the detection instant (t_flash) for which signals output from the light receiving element (6) are selected in order to obtain the measured values (z_B) of the profile (P).

13. The method as claimed in claim 11, wherein the solid body (1, 1a) in the form of a vehicle wheel of substantially cylindrical or annular basic shape and the regions onto which the light bands (3, 3a, 3b) are projected lie on the two end faces (D₁, D₂) and on the peripheral face (M) of the cylinder or annulus.

14. The method as claimed in claim 1, wherein a determined profilogram (PG) and reference profilogram (PG) are referred to a fixed geometric basic size of long term invariability, including a nonwearing wheel rim inside diameter (D_fix).

15. The method as claimed in claim 1, wherein a device supplying digitized signals in the form of a trigger controlled CCD camera is used as light receiving element (6).

16. The method as claimed in claim 1, wherein the light band (3, 3a, 3b) has a width (b) in the range from 0.3 mm to 6.5 mm.

17. The method as claimed in claim 1, wherein the light band (3, 3a, 3b) has a length (LB) in the range from 50 mm to 750 mm.

18. The method as claimed in claim 1, wherein the light band (3, 3a, 3b) has a divergent angle (δ

) that is greater than 45°

.

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

) has values in the range from 15°

to 40°

C.

20. The method as claimed in claim 1, wherein the frequency (f) at which the light (RL) reflected by the surface of the solid body (1, 1a) is detected by means of the light receiving element (6) lies in the range from 25 Hz to 100 kHz.

21. The method as claimed in claim 1, wherein a translatory movement speed (v) of the solid body is greater than 4.0 m/s.

22. The method as claimed in claim 1, wherein a mean working distance (L) of the laser device (2) or of the imaging device (5) from the region of the surface of the solid body (1, 1a) after which the light band (3, 3a, 3b) is projected lies in the range from 20 mm to 650 mm.

23. The method as claimed in claim 1, wherein the base distance (B) between the imaging device (5), in particular the midpoint of a focusing lens (4) of the imaging device (5), and the optical axis (O-O) of the laser device lies in the range from 30 mm to 450 mm.

24. The method as claimed in claim 1, wherein the determination of the detection instant (t_flash) for which signals output by the light receiving element (6) are selected in order to obtain the measured values (z_B) of the profile (P) is performed in a receiving loop (100) for whose implementation a hardware component is incorporated in a test stand (8) located on a track (9).

25. The method as claimed in claim 24, wherein the receiving loop (100) is implemented in a client of a client-server circuit with a spatially remote server, system start processes (95) including actuating traffic lights for a rail vehicle (10), activating a trigger for image triggering (106) or switching on the laser device (2) being set in motion by means of a request (90) from the server.

26. The method as claimed in claim 25, wherein the measured values (z_B), in the form of stored image data (108), are sent (113) to the server after the obtaining of the measured values (z_B) of the profile (P), after stopping (112) imaging.

27. The method as claimed in claim 24, wherein a laser distance sensor (101, 6) after signal conditioning (102) with the inclusion of analog-to-digital conversion is a signal (103) for the initial conditions from which there is determined by a signal evaluation (104) a detection instant (t_flash) at which a triggering pulse (105) is output to the light receiving element (6), as a result of which image triggering (106) is performed, an image matrix (107) being acquired and the acquired image being fed to a storage means (108).

28. The method as claimed in claim 24, wherein the receiving loop (100) includes as abort criteria condition checks (110, 111) that are connected to a timer or to a number of predetermined measurements.