DE102008020715B4 - Measuring device and method for determining splitter parameters of splitter plates - Google Patents

Abstract

In the testing of ammunition the end ballistic impact assessment is an important component. For this purpose splitter plates are used. After shelling, the splinter parameters of the individual splinters of the splitter plates must be determined. The aim is to create a computer-aided, highly accurate measuring device and a corresponding method. To determine the splitter parameters of the splitter plates (40), a measuring device (1) is provided with. a light table (10) having a luminous surface (13) and a clamping device (11), with which a splitter plate (40, 50) can be clamped for transillumination,. a digital camera (20) whose optical axis (21) perpendicular to the center of the splitter plate (40) can be aligned,. a calibration splitter plate (50) which has the same outer dimensions and the same thickness as a splitter plate (40) to be examined, with reference holes (51, 51a, 51b, 52a, 52b) of defined size and defined distance from the center,. an evaluation computer (30),. an evaluation program stored in the evaluation computer (30).

Description

The The invention relates to a measuring device and a method for determining of splitter parameters of splitter plates.

at The testing of ammunition is the end-ballistic impact assessment an important component. For this purpose splitter plates are used. in the Frame of a bombardment attempt with, for example, an explosive ammunition several splitter plates are arranged one behind the other. After a shelling have to the splitter parameters of the individual fragments of the splitter plates be determined. So far, this has been done by hand.

following Letters of the prior art are appreciated.

The US 4,711,579 A relates to the determination of position and size of holes in a resting on a light table metal plate by means of an optical sensor.

The DE 198 15 573 A1 shows the detection of bullets of a target by optical means.

From the EP 0 334 263 A1 It can be seen that armored plates are photographically detected after a bombardment, with the plates being illuminated from the rear side.

From the WO 2007 129 076 A1 is known in the context of a comparable measurement task to provide measures for calibration. The measurement task refers to a camera-based measurement of holes in a paper web. The paper web is illuminated from behind.

Of the The invention is based on the object of determining splitter parameters of splitter plates as part of an ammunition assessment computer-assisted, high-precision measuring device and a related process to create.

These The object is achieved by the Features of claim 1 or by the features of the claim 2 solved.

The Advantages of the invention are that you have exactly the effect of ammunition types in target configurations. The end ballistic Effect of different types of ammunition can be compared precisely. Further can the behavior of the end-ballistic effect in terms of combat removal to be examined.

The Measuring device comprises a light table with a luminous surface and a chuck, with a splitter plate flat on the illuminated area can be clamped for fluoroscopy. With a digital camera, its optical axis perpendicular to the center of the splitter plate aligned, the recordings are created. The measuring device includes a Calibrating plate, which has the same external dimensions and the same thickness has a splinter plate to be examined. On the calibration splitter plate are reference holes of defined size and defined distance arranged to the middle. With an evaluation computer and an evaluation computer stored evaluation program, the recordings are edited and evaluated.

With a first part of the program are written with the help of a first reference picture, a recording of the light table without an attached splitter plate is calculated, first correction values. This will cause the uneven distribution of light the illuminated area at Compensated for the splitter plate recordings. Have flat light sources different brightness ranges. The splinter holes will be thus different sheds through and there are inaccurate shots, where the splinters are too light or too dark. The first correction values convert the recording of the calibration splitter plate and the individual shots of the splitter plates as if the luminance was of the illuminated table evenly high and the splinter holes illuminated with a light of uniform luminance.

Then with a second part of the program with the help of a second reference picture, which is a recording of the calibration splitter plate, second correction values calculated to compensate for the effects of the accuracy of the Minimize calculation of splitter parameters.

On the one hand, this includes the effect that the representation of the splitter holes produced by the camera is smaller when the distance of a peripheral point of a splitter surface to the center of the splitter plate is high and when the thickness of the splitter plate is large. This effect is illustrated in the context of the embodiment with drawings. On the other hand, the effect of overshoot due to the abrupt light-dark transition region is affected. The overshoot effect occurs at the edge of the hole from the illuminated to the dark area and is based in part on the light reflections on the inner wall areas of the splinter hole and on the blooming effect of the CCD chip of the camera. Blooming is an effect caused by the spillover of charges from overexposed cells. The holes of the calibration plate and their distance to the center are exactly measured and already integrated in the second part of the program. The stored data of the holes will be with the digitized holes of the recording in relation to each other to obtain the second correction values.

in the Main program will be the splitter disk recordings in which the Sliver of a buildup brighter Pixel points correspond, evaluated. First, the shots below Incorporation of the first correction values corrected so that the different ones Luminance of the illuminated area is compensated. Then the pictures are taken with the second correction values corrected. The further processing is done in such a way that the outlines the splitter can be converted into closed polygons. Everyone Traverse or any connecting line between two adjacent ones Polygon vertices is defined as a vector. Leave over the vectorization Just calculate the splitter parameters. The splitter parameters essentially comprise the number of punch holes each Splinter plate, the position, the areas and the center of gravity every split hole. Due to the correction values one achieves one high accuracy of the determined surface areas. By use a calibration plate ensures high reproducibility. The time required for the measurement and evaluation is even with extensive measurement series low. Due to the evaluation computer is a high degree of automation given. All splitter hole curves are described mathematically. This facilitates the documentation and the graphical representation.

One embodiment The invention will be described below with reference to the drawings. Hereby show:

1 a measuring device for determining splinter parameters of splitter plates, in perspective view;

2 in the 1 illustrated camera and the light table, in section;

3 a splitter plate;

3a this in 3 shown splinter hole 44 in raster format;

3b this in 3 shown splinter hole 44 in vector format;

4 a calibration splitter plate;

5 an illustration of the disturbance of the light transmission, wherein the beam path and the recorded by the camera splitter hole are located;

6 another illustration of the perturbation of the light transmission;

7 an illustration of over-the-beam effect.

The 1 shows a measuring device 1 for determining splinter parameters of splitter plates 40 , The splinter plates to be examined are obtained by bombardment tests as part of an ammunition assessment.

The measuring device initially comprises a light table 10 , a camera 20 , an evaluation calculator 30 , on which an evaluation program is stored, and a calibration splitter plate 50 , The calibration splitter plate 50 has the same outer dimensions and the same thickness as a splitter plate to be examined 40 , There are reference holes on the calibration splitter plate 51 of defined size, which have a defined distance to the center. The 4 shows the calibration splitter plate 50 on a larger scale. Signed are larger reference holes 51a and 51b as well as smaller reference holes 52a and 52b ,

The 2 goes into details. With regard to the light table 10 is the illuminated area 13 drawn in, which is formed by a diverging disk. Furthermore, a clamping device 11 with a splitter plate 40 can be clamped for fluoroscopy. With regard to the digital camera 20 is its optical axis 21 drawn perpendicular to the center of the splitter plate 40 is aligned. The bulbs are fluorescent tubes 12 ,

With With the aid of the evaluation program, three effects are compensated for to increase the accuracy.

First the effect that the light distribution of the luminous area is uneven. Because directly behind the fluorescent tube, the light intensity is higher than in the intervening areas.

Second, the effect that the two-dimensional representation of a splitter hole produced by the camera is smaller when the distance of a peripheral point of a splitter surface to the center of the splitter plate 40 high and if the thickness of the splitter plate 40 is great. Illustrate this 5 and 6 , In 5 is the camera 20 and the splitter plate 40 shown. In the splitter plate 40 is arranged a centrally located splitter hole with the diameter D. Due to the central perspective, the direct light transmission range is reduced. This means that from the camera a picture similar 5 is recorded. First, a bright circular area with a diameter of d. Then a darkened annular surface with an outer diameter D. Another example shows 6 , It illustrates a circular splitter, which is arranged from the camera angle far to the right of the center of the splitter plate is. Within the black framed circle on the left a lighter and on the right a darkened area for the camera is visible.

Third, the effect of over-radiation due to the abrupt transition from light to dark. This effect is based in part on the light reflections on the inside wall areas of the splinter hole and on charges from overexposed cells of the camera's CCD chip being dissipated to neighboring cells. The overshoot effect is in 7 shown. Shown is a circular splinter hole. It can be seen annular light-dark transition areas. Shown is the real diameter D of the splinter hole.

• • Zunächst wird ein erstes Referenzbild erstellt, das eine Aufnahme der Leuchtfläche 13 des Leuchttisches ohne eine aufgelegte Splitterplatte 40 ist.
• • Dann wird ein zweites Referenzbild erstellt, das eine Aufnahme der Kalibriersplitterplatte 50 ist.
• • Es folgt die Erstellung der Splitterplattenaufnahmen.
• • Nun berechnet man mit einem ersten Programmteil mit Hilfe des ersten Referenzbildes erste Korrekturwerte, um die ungleichmäßige Lichtverteilung der Leuchtfläche des Leuchttisches zu kompensieren.
• • Mit einem zweiten Programmteil werden zweite Korrekturwerte berechnet. Hierzu dient das zweite Referenzbild und die abgespeicherten Daten der Referenzbohrungen. Ziel ist es, Effekte zu kompensieren, die die Genauigkeit der Berechnung der Splitterparameter herabsetzen, • zum einen den Effekt, dass die von der Kamera erzeugte zweidimensionale Splitterflächenabbildung kleiner abgebildet ist, wenn der Abstand eines Umfangpunktes einer Splitterfläche bis zur Mitte der Splitterplatte 40 hoch und wenn die Dicke der Splitterplatte 40 groß ist, • zum anderen den Effekt der Überstrahlung aufgrund des abrupten Hell-Dunkel-Übergangsbereiches.
• • Berechnung der Splitterparameter der einzelnen Splitterplattenaufnahmen, in denen die Splitter einer Anhäufung heller Pixelpunkte entsprechen, mit einem Hauptprogramm, wobei jedes Bild zunächst mit den ersten Korrekturwerten und anschließend mit den zweiten Korrekturwerten korrigiert wird und wobei anschließend die Splitterparameter der Splitterplatten 40 ermittelt werden. Die Flächenermittlung der aus Polygonzügen beschriebenen Splitterlochflächen wird mit der Gaußschen Trapezformel berechnet:
  
  F Fläche n Anzahl der Stützpunkte des Polygonzuges x, y Koordinaten der Stützpunkte P₁ bis P_n Die 3 zeigt eine beispielhafte Aufnahme einer Splitterplatte 40 mit Splitterlöchern 41, 42, 43 und 44. In 3a ist das beispielhafte Splitterloch 44 im Rasterformat dargestellt. In 3b ist das Ergebnis der Vektorisierung abgebildet. Die Darstellung zeigt, dass das Splitterloch 44 durch einen geschlossenen Polygonzug mit 16 Stützpunkten beschrieben ist. Flächeninhalt und Flächenschwerpunkt sind nach einer Vektorisierung auf einfache Weise ermittelbar.

The procedure for determining the splitter parameters of splitter plates is described below:

• • First, a first reference image is created, which is a photograph of the illuminated area 13 of the illuminated table without an attached splitter plate 40 is.
• • Then a second reference image is taken, which is a picture of the calibration plate 50 is.
• • The following is the creation of the splitter plate recordings.
• • Now, with a first program part, first correction values are calculated with the aid of the first reference image in order to compensate for the uneven light distribution of the illuminated surface of the light table.
• • A second part of the program calculates second correction values. The second reference image and the stored data of the reference holes serve this purpose. The aim is to compensate for effects that reduce the accuracy of the splitter parameter calculation. • The effect is that the two-dimensional splinter area image produced by the camera is smaller if the distance from a peripheral point of a splitter surface to the center of the splitter plate is smaller 40 high and if the thickness of the splitter plate 40 is large, • on the other hand, the effect of the over-radiation due to the abrupt light-dark transition region.
• • Calculation of the splitter parameters of the individual splitter plate exposures, in which the splinters correspond to an accumulation of bright pixel dots, with a main program, wherein each image is first corrected with the first correction values and then with the second correction values and subsequently the splitter parameters of the splitter plates 40 be determined. The area calculation of the splinter hole areas described by polygons is calculated using the Gaussian trapezoid formula:
  
  F area n number of interpolation points of the traverse x, y coordinates of the points P ₁ to P _n The 3 shows an exemplary recording of a splitter plate 40 with splinter holes 41 . 42 . 43 and 44 , In 3a is the exemplary splinter hole 44 displayed in raster format. In 3b the result of the vectorization is mapped. The illustration shows that the splinter hole 44 is described by a closed polygon with 16 points. Surface area and centroid can be easily determined after vectorization.

• – Das Verfahren besitzt aufgrund der Kompensierung von drei durch theoretische und experimentelle Untersuchungen ermittelten Effekten eine sehr hohe Genauigkeit.
• – Splitterlöcher ab einem Durchmesser von 1,0 mm werden auf einer Splitterplatte von 1,0 × 2,0 m sicher erkannt. Splitterlochflächen ab einem Durchmesser von 2,0 mm werden mit einem Messfehler ≤ 1,8% ermittelt.
• – Zur Gewährleistung der Reproduzierbarkeit wird eine Kalibrierplatte verwendet.
• – Sämtliche Splitterlochparameter (Schadensflächen, Schwerpunkte, ...) werden für die weitere Bewertung je Platte in MS-Excel^®-lesbaren Textdateien gespeichert.
• – Das Verfahren nutzt ein Computerprogramm, mit dem die Splitterplattenaufnahmen stapelweise abgearbeitet werden. Die Auswertung ist automatisiert.
• – Sämtliche Splitterrandkurven liegen in exakter mathematischer Beschreibung vor.

The aforementioned determination of fragmentation splinter plate parameters is distinguished by the following points:

• The method has a very high accuracy due to the compensation of three effects determined by theoretical and experimental investigations.
• - Splitter holes with a diameter of 1.0 mm or more are reliably detected on a splitter plate of 1.0 × 2.0 m. Splinter hole areas with a diameter of 2.0 mm or more are determined with a measurement error of ≤ 1.8%.
• - To ensure reproducibility, a calibration plate is used.
• - All splinter hole parameters (damage areas, centroids, ...) are saved for further evaluation per plate in MS-Excel ^® readable text files.
• - The method uses a computer program, with the splitter plate recordings are processed in batches. The evaluation is automated.
• - All splinter edge curves are available in exact mathematical description.

1

measuring device

10

light table

11

chuck

12

Fluorescent tube

13

light area

20

camera

21

optical axis

30

evaluation computer

40

splitter plate

41 42, 43, 44

splitter hole

50

Kalibriersplitterplatte

51 51a, 51b, 52a, 52b

reference holes

Claims (2)

Measuring device ( 1 ) for the determination of split terparameters of splitter plates ( 40 ), which are obtained by bombardment tests during an ammunition impact assessment, with • a light table ( 10 ) with a luminous area ( 13 ) and a clamping device ( 11 ), with a splitter plate ( 40 . 50 ) can be clamped for fluoroscopy, • a digital camera ( 20 ) whose optical axis ( 21 ) perpendicular to the center of a splitter plate ( 40 ), • a calibration plate ( 50 ), which have the same external dimensions and the same thickness as a splitter plate ( 40 ), with reference holes ( 51 . 51a . 51b . 52a . 52b ) of defined sizes and defined distances to the center, • an evaluation computer ( 30 ), • one in the evaluation computer ( 30 ) stored evaluation program which is set up in such a way that • with a first program part with the aid of a first reference image, which is a recording of the luminous area ( 13 ) of the light table ( 10 ) without an attached splitter plate ( 40 . 50 ), first correction values are calculated in order to obtain an uneven light distribution of the luminous area ( 13 ), with a second program part with the aid of a second reference image, which contains a picture of the transilluminated calibration plate ( 50 ), second correction values are calculated to compensate for effects that reduce the accuracy of a calculation of splitter parameters, on the one hand, the effect that one of the camera ( 20 ) produced two-dimensional representation of splitter holes is smaller, when a distance of a peripheral point of a splitter surface to the center of the splitter plate high and when the thickness of the splitter plate is large, • on the other the effect of an over-radiation due to an abrupt light-dark transition region, • with a main program splitter plate recordings in which fragment holes correspond to an accumulation of bright pixel dots are evaluated taking into account the first and second correction values. Method for determining splitter parameters of splitter plates ( 40 ) obtained during the ammunition impact assessment by bombardment tests using a measuring device ( 1 ) with • a light table ( 10 ) with a luminous area ( 13 ) and a clamping device ( 11 ), with a splitter plate ( 40 . 50 ) can be clamped flat for fluoroscopy, • a digital camera ( 20 ) whose optical axis is perpendicular to the center of the splitter plate ( 40 ), • a calibration plate ( 50 ), which have the same external dimensions and the same thickness as a splitter plate ( 50 ), with reference holes ( 51 . 51a . 51b . 52a . 52b ) of defined sizes and defined distances to the center, • an evaluation computer ( 20 ), • one in the evaluation computer ( 20 ), with the steps: • Creation of a first reference image, which records the illuminated area of the illuminated table without an attached splitter plate ( 40 ), • creation of a second reference image which contains a picture of the calibration splitter plate ( 50 ), • compilation of splitter disk recordings, • calculation of first correction values with a first program part on the basis of the first reference image, in order to obtain an uneven light distribution of the luminous area ( 13 ) of the light table ( 10 • Compute second correction values with a second program part based on the second reference image and data describing the size and location of reference holes to compensate for effects that reduce the accuracy of splitter parameter computation the effect that a two-dimensional representation of splinter holes generated by the camera is shown smaller, when a distance of a peripheral point of a fragment surface to the middle of the splitter plate ( 40 ) and if the thickness of the splitter plate ( 40 • large, • the effect of an overshadow due to an abrupt light-dark transition region, • calculation of the splitter parameters with the help of splitter plate recordings, in which the splitter holes correspond to an accumulation of bright pixel dots, with a main program, each recording first with the first Correction values and then corrected with the second correction values and then the splitter parameters of the splitter plates ( 40 ) be determined.