Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
  • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
  • G01B11/2518—Projection by scanning of the object
  • G01B11/2522—Projection by scanning of the object the position of the object changing and being recorded

Definitions

• the present invention relates to a method for non-contact dynamic detection of the profile of a, in particular moving, solid body, wherein a widened to a linear light band laser beam from a laser device is projected onto a region of the surface of the solid and reflected light from there in an imaging device whose optical axis is at a fixed triangulation angle to the projection direction of the laser device and which is arranged at a fixed base distance to the laser device, focused and in particular detected with a relation to a speed of movement of the solid high frequency by means of a sheet-like light receiving element, after which emitted from the light receiving element signals, as a function of the triangulation angle and the base distance in a data processing device, the measured values of the profile are obtained by trigonometric relationships and used as profile be stored.
• Profiling of solids ie the extraction of profilograms of the surface, can be known to be carried out by tactile methods or contactless.
• tactile methods or contactless.
• An extension of the laser triangulation represents a known, also described in said monograph method, in which the laser light beam is expanded to a linear band of light, a so-called light section.
• DE 103 13 191 A1 describes a method of the aforementioned type, according to which - for the purpose of determining wear on railway vehicle wheels in particular - such light cuts are used for non-contact dynamic detection of the profile of a, in particular moving, solid.
• a planar detector may be used, such as a video camera.
• the detection time of the measured values also plays an essential role, because a wrong choice of this time provides measured values that are no longer accessible even after a correction.
• the profilogram of a rolling solid is obtained from three of the two top surfaces and on the lateral surface at the same time determined Operafilogrammen, wherein the detection time of the individual Operafilogramme is selected such that a measured at this detection time measurement of at least three on a circular arc with a radius in one of Covering lying, each at successive times and unidirectionally from the respective length of the line-shaped light band determined measurements, each corresponding to half the length of a chord through the arc, a maximum assumes.
• the present invention has for its object to provide a non-contact method for dynamic detection of the profile of a solid of the type described above, which allows short measurement times and ensures a high measurement accuracy under harsh operating conditions, but at the same time by a simplified determination of an optimal detection time of the measured values and an increased efficiency.
• this is achieved by such a method, in which at an initial time, a determination of initial conditions of the solid, in particular a distance to the laser device, a temporal change of this distance and / or a light intensity distribution, and then from the initial conditions, a detection time is determined for the signals emitted by the light receiving element are selected to obtain the measured values of the profile.
• an acceleration of the measured value detection is achieved because, as is known, three basic steps, namely recording of three measured value sets, comparison of the measured values, selection of the maximum value, are necessary by determining the detection time from the initial conditions, but only two steps namely, the detection of the initial conditions, wherein only a single set of measured values needs to be recorded, and the determination of the detection time.
• the determination of the detection time from the initial conditions can be carried out in particular by means of a digital signal processor (DSP), which can be integrated into the existing data processing device.
• DSP digital signal processor
• Fig. 3 is a program flowchart for the application of the invention
• Fig. 4 is a perspective view of a wear test stand for wheels of a rail vehicle, such as railway wheels, wherein the inventive method is applied.
• the light beam is widened to a light band 3, as shown in three-dimensional view Fig. 2.
• z A of the light band on the surface of the solid 1 is formed by diffuse light scattering (Reflected light RL), a measuring spot, which also out Directions can be perceived that differ from the direction of incidence determined by the optical axis 0-0 of the laser device 2.
• Reflected light RL diffuse light scattering
• the geometry of the structure of the device used for the method according to the invention is determined next to the fixed triangulation angle ⁇ by a fixed base distance B of the optical axis A-A focusing optics 4 of the imaging device 5 to the position of the laser device 2 - determined by the optical axis O-O.
• the base distance B may be in the range of 30 mm to 450 mm, in particular in the range of 60 mm to 270 mm.
• H is a distance of the focusing lens 4 of the imaging device 5 to its light receiving element 6, as illustrated in FIG.
• the quantity dz A in equation (2) represents an absolute value of the measurement accuracy.
• the final measured values z B of the profile (denoted by P in FIGS. 1 and 2) can be obtained by combining the values z A with correction values Kv determined in accordance with the movement speed v of the solid 1, which are in particular vectorial which is movement speed v proportional factors and / or summands.
• a correlation of the movement speed v with the frequency f of the detection of the reflected light RL takes place.
• the measuring range Dz and, associated therewith, the measuring accuracy dz A / z A can be freely adjusted simply by the appropriate choice of the geometrical sizes of the structure.
• the individual devices need not necessarily, as shown in Fig. 1, to be covered by a common housing 7. An enlargement of the measuring range Dz causes a reduction of the measuring accuracy and vice versa.
• the mean working distance L can be in the range from 20 mm to 650 mm, in particular in the range from 150 mm to 350 mm.
• a camera with an image-recording frequency of much less than about 60 images / s is sufficient. Since the resolution of the size of the measuring range, ie the measuring range Dz, depending, this means for the dimensioning of an apparatus for performing the method according to the invention that the number of detecting camera heads is directly dependent on the required or selected resolution.
• the system which has hitherto only been considered in two dimensions, is in three dimensions considered. That is, it is worked with a flared to a light band 3 laser beam. This is called a light-section method.
• a data processing device not shown, such as a PC
• the measured values of the profile P determines and in the data processing system as Profilogram PG are stored. Representing such a profileogram PG is in the schematic representation of Fig. 2, the correspondingly designated polyline on the light receiving element. 6
• a commercial line laser for example, designated L200 with a line length LB (Fig. 2) of 300 mm and a line width b (Fig. 1) of 1, 5 mm used become.
• the program flow chart shown in FIG. 3 for the application of the method according to the invention is particularly tailored to the non-contact detection of the profile of wheels of a rail vehicle, such as railway wheels.
• a rail vehicle such as railway wheels.
• Such a wheel is - provided with the reference numeral 1a - shown on a rail vehicle 10 in Fig. 4 by way of example.
• the program flowchart comprises a pick-up loop 100 for the dynamic detection of the profile P of the solid 1 or 1 a, which is started after a request 90 by a server after the system start processes, which are indicated by the reference numeral 95 in FIG Box are symbolized and include the activation of a traffic light for the rail vehicle 10, the activation of a trigger for image triggering in the light receiving element 6 and switching on the laser device 2.
• a distance signal 103 is provided by a laser distance sensor 101, which is in particular the light receiving element 6, after a signal conditioning 102, ie an initial time to is determined to determine the initial conditions of the solid pers 1, 1a, such as the distance to the laser device 2, a light intensity distribution and optionally a change in time of this distance as the first and - with accelerated movement - also second derivative of the way after the time.
• step "signal evaluation" 104 the determination of a detection time tfi as h from the initial conditions-in particular from the distance signal 103-is then selected for the signals emitted from the light receiving element 6 to obtain the measured values z B of the profile P.
• the detection time tfl aS h determined from the initial conditions should be determined with the criterion of the greatest possible proximity to the starting time to, since in this case the signals present at the initial time to and the detection time tfi as h differ only slightly in an advantageous manner for the signal evaluation ,
• the determination of the detection time tfi aS h from the initial conditions can be carried out in particular by means of a digital signal processor (DSP), which can preferably be integrated into an existing data processing device. This may require the pre-connection of an analog-to-digital converter if the laser distance sensor 101 does not provide a digital signal.
• DSP digital signal processor
• a digital signal processor is predestined for real-time, ie continuous, signal processing because of its accurate predictability and extremely short time required to perform the desired operations.
• Its use for signal evaluation 104 advantageously allows the data present in the form of digital signals to be optimally processed in terms of both data manipulation, such as data movement, storage and / or validation, and mathematical calculations, such as additions and multiplications.
• data manipulation such as data movement, storage and / or validation
• mathematical calculations such as additions and multiplications.
• 104 evaluations, convolutions as well as Fourier, Laplace and / or z transformations in the millisecond range can be carried out in the signal evaluation.
• DSP prevents data storage or data corruption.
• Remote transmission - also in the millisecond range - a highly efficient data compression possible.
• the time change of the distance of the solid 1, 1a to the laser device 2, ie, for example, the speed of individual for the dynamic profile acquisition particularly relevant portions of the solid 1, 1a, preferably for the determination of the detection time tfi as h can be used to determine from the initial conditions, if this speed is not detected as being part of the initial conditions by direct determination or fixed or set.
• a light intensity distribution present on the solid body 1, 1a at the initial time to and / or at the time of acquisition tfi aS h can advantageously be recorded in a histogram and, preferably, using a look-up, in particular in the form of a transparency distribution Table (LUT), an image transformation, in particular a threshold operation, such as a, preferably by means of Laplace transform high-pass filtering, subjected.
• LUT transparency distribution Table
• a threshold operation such as a
• a known LUT is, for example, the so-called color map or palette.
• the binary coded mask in particular an alpha channel, preferably a binary alpha channel
• a binary alpha channel is a minimized alpha channel that relies on the use of only one bit to encode the transparency and therefore can only indicate whether a pixel is either completely transparent (black) or completely opaque (white).
• the image triggering 106 takes place at the detection time tfi aS h, in particular an image matrix 107 is detected, in particular as the first complete image after the trigger trigger pulse 105, and the captured image is sent to a storage 108. At the same time, the reset 109 of a timer takes place. The described processes repeatedly occur, as illustrated by pick-up loop 100.
• the termination criteria for the processes in the receiving loop 100 are the condition checks illustrated by the boxes labeled 110 and 111. It is on the one hand checked (box 110), whether the Timer is running for more than 10 s, and on the other hand, whether all axes of the rail vehicle 10 are included (box 111). If one of these conditions applies, the image acquisition is stopped (box 112). The question of whether the timer is already running for more than 10 s, aims to determine whether the solid 1 or 1a may have come to a standstill. After stopping 112 image capture, the stored image data 108 may be sent to the server (box 113). At the same time, the system stop operations "turn off trigger”, “turn off laser device 2" and "traffic light control for the rail vehicle 10", which are symbolized by the marked with the reference numeral 195 box.
• Fig. 4 shows a typical application of the method according to the invention, namely for the determination of wear.
• the illustration shows a perspective view of a wear test stand 8, which is designed for rolling on rails 9, with a translational speed v and an angular velocity ⁇ over, moving wheels 1a designed as to be measured solid 1.
• the corresponding hardware can be incorporated into the test bench 8, whereby advantageously a client-server circuit can be realized in which the client is on the track 9 and the server is located in a remote location.
• the wheel 1a of the rail vehicle 10 represents a rotationally symmetrical, in the basic shape substantially cylindrical or annular solid 1, wherein the areas onto which the light bands 3a, 3b are projected lie on the two cover surfaces Di, D 2 and on the lateral surface M of the cylinder or of the ring.
• the respective light band 3 a, 3 b can be widened with the use of a cylinder optics such that - as shown - with a corresponding positioning - distance B - the laser device 2 more than one of the different sides Di, D 2 , M of the surface of the solid 1 is irradiated by a light band 3a, 3b.
• the light band 3a in particular irradiates the front cover surface Di and the lateral surface M of the wheel 1a and the light band 3b in particular the rear cover surface D 2 and the lateral surface M of the wheel 1a.
• the advantage of the use of two light bands 3a, 3b consists in the following: The fact that according to the invention at an initial time to a determination of the initial conditions 103 of the solid 1, 1a is carried out and then determined from the initial conditions 103 of the detection time tfl aS h, for the If the signals emitted from the light receiving element 6 are selected for obtaining the measured values z B of the profile P, it is possible for the light bands 3a, 3b to be simultaneously or else displaced by the laser device (s) 2 to one and the same measuring location with respect to one position to project on the lateral surface M.
• correction values Ko may be, in particular, factors determined by the area of the surface of the solid 1, 1a or specified factors and / or summands.
• a determined profilogram PG such as the partial profilograms and the overall profilogram determined in the above case, as well as optionally a respective reference profilogram and / or the respective deviations between the determined profilogram PG and the reference profilogram, in particular representing wear values, can advantageously be based on a fixed, unchanging, long-term geometric base size, such as a non- wearing wheel rim inner diameter D flx .
• the non-wearing wheel rim inner diameter Dflx can on the one hand serve as a baseline for the measured values z B of the profile height which are determined on the lateral surface M of the wheel 1a, on the other hand it is possible for him to determine the correction values Ko corresponding to that of the light band 3 or 3a, 3b illuminated area of the surface of the solid 1 are considered to be used.
• the wheel rim inner diameter Dn x can be determined, for example, from three measured values which are made by contactless dynamic measurements on the moving wheel 1a in the same manner, but in particular unidirectionally, ie with the same orientation of the respective light bands 3a, 3b, as the detection of the Profilogram PG.
• the measured values can be, three located on a circular arc with the wanted Radkranzinnen butmesser D f j x measured values thereby to be determined as the ordinate in a Cartesian coordinate system and that are transformed in such a way that they in each case half the length of a chord of the circular arc represent.
• the notver Tearing wheel rim inner diameter D f i X of the rolling wheel 1a can then be determined by solving a system of equations which contains the respective transformed ordinate values, the associated abscissa values and the wheel rim inner diameter Dflx.
• non-wear wheel rim inside diameter D f i X which - if available - from a technical drawing of the solid 1 or from an earlier, z. B. stored, measurement is derived.
• the method according to the invention advantageously makes it possible to detect a profile P in an exceptionally short determination time.
• a resolution dz A of less than 2.0 mm, in particular a resolution of less than 0.2 mm, can be achieved.
• the present invention is not limited to the illustrated embodiment, in particular not to the use of a DSP for signal evaluation 104 or processing, but includes all the same means and measures in the context of the invention. Furthermore, the skilled person can supplement the invention by additional advantageous measures - for example, the connection of machining processes for the solid 1, which are based on the determined profilograms PG - without departing from the scope of the invention.
• FIG. 4 which shows approximately the size ratios of the aforementioned test bench 8 in relation to a rail vehicle wheel 1a
• a test bench 8 designed for use with the method according to the invention has a much smaller and smaller footprint more compact size than that shown - for example, about twice the size of a shoe box - may have. Therefore, in most cases advantageously in the implementation of the test bench 8 in a track system on consuming concrete work can be dispensed with.
• the invention is not limited to the feature combination defined in claim 1, but may also be defined by any other combination of certain features of all individually disclosed features. This means that in principle virtually every individual feature of claim 1 can be omitted or replaced by at least one individual feature disclosed elsewhere in the application. In this respect, the claim 1 is to be understood only as a first formulation attempt for an invention.
• corrected measured value from z A For example, corrected measured value from z A

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• Engineering & Computer Science (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Length Measuring Devices By Optical Means (AREA)

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• 2005
  • 2005-09-19 US US12/067,400 patent/US20080204765A1/en not_active Abandoned
  • 2005-09-19 EP EP05794432A patent/EP1926968A1/de not_active Withdrawn
  • 2005-09-19 CN CNA2005800516245A patent/CN101283234A/zh active Pending
  • 2005-09-19 ES ES05794432T patent/ES2304909T1/es active Pending
  • 2005-09-19 JP JP2008530338A patent/JP2009509131A/ja active Pending
  • 2005-09-19 WO PCT/EP2005/054664 patent/WO2007033702A1/de active Application Filing

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