CA2065775A1 - Measuring system for the non-contact determination of the shape of long objects having diffusely reflecting surfaces - Google Patents
Measuring system for the non-contact determination of the shape of long objects having diffusely reflecting surfacesInfo
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- CA2065775A1 CA2065775A1 CA002065775A CA2065775A CA2065775A1 CA 2065775 A1 CA2065775 A1 CA 2065775A1 CA 002065775 A CA002065775 A CA 002065775A CA 2065775 A CA2065775 A CA 2065775A CA 2065775 A1 CA2065775 A1 CA 2065775A1
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- 238000005259 measurement Methods 0.000 claims abstract description 76
- 238000004458 analytical method Methods 0.000 claims description 6
- 238000010191 image analysis Methods 0.000 claims description 3
- 238000012634 optical imaging Methods 0.000 claims 1
- 238000005286 illumination Methods 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 6
- 238000009966 trimming Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 241000763859 Dyckia brevifolia Species 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 101150061972 zur gene Proteins 0.000 description 1
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
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/024—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by means of diode-array scanning
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- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
ABSTRACT
The present invention is intended particularly for use in sawmills in order to cut sharp-edged boards from side slabs.
Using opto-electronical structural elements, it is intended to construct a measurement system for long objects having diffusely reflecting surfaces and to do this in a simple manner, said measurement system requiring no additional space in order to make these measurements. To this end, a plurality of beam sources are installed at a specific interval from each other, said interval growing larger from the reference point to the detector row, and parallel to the longitudinal axis of the object to be measured, outside the reference plane of the analysing detector row, so that, viewed from the detector row, a triangle is formed in its illumination plane. The object to be measured is guided transversely to the plans of observation, whereupon measurement points of the particular shape at this point are recorded for each beam source.
The present invention is intended particularly for use in sawmills in order to cut sharp-edged boards from side slabs.
Using opto-electronical structural elements, it is intended to construct a measurement system for long objects having diffusely reflecting surfaces and to do this in a simple manner, said measurement system requiring no additional space in order to make these measurements. To this end, a plurality of beam sources are installed at a specific interval from each other, said interval growing larger from the reference point to the detector row, and parallel to the longitudinal axis of the object to be measured, outside the reference plane of the analysing detector row, so that, viewed from the detector row, a triangle is formed in its illumination plane. The object to be measured is guided transversely to the plans of observation, whereupon measurement points of the particular shape at this point are recorded for each beam source.
Description
20~7~
~ present invention relates to a measuring system for the non-contact determination of long objects having diffusely reflecting surfaces, in particular for use in sawmills, in order to cut sharp-edged boards from slabbed stock.
A number of optical co-ordinate measuring devices are known, amongst others, for making non-contact measurements. In these, the basic principle is that, as in known electro-mechanical measuring systems, one proceeds such that the geometry of the workpiece is determined by measuring the co-ordinates of individual points on the surface of the workpiece. However, the surface is scanned optically, i.e., without physical contact.
Once again, there are many methods of doing this, e.g., those involving interference, defraction, triangulation, or image analysis. In addition to these, DE-OS 29 03 529 and DE-OS 21 13 522 describe a procedure for non-contact measurement of objects, in which the optical scanning of workpieces is effected according to the triangulation principle. To this end, a spot of light is projected at an angle onto the object to be measured and the distance from the source of the beam to the measurement object is determined according to the displacement of the image of the spot of light that is measured by means of a position-sensitive detector. The desired additional analysis and processing of the value~ so obtained is effected with the help of an image analysis apparatus that is associated with the detector. The projector and the imaging system are combined into one structural group in the form of a so-called optical scanning head.
In order to measure longer objects, this is then moved over the object by means of suitable guide systems. However, using this process, the distance to the object can only be determined without error if the angle subtended between the surface of the object and the axis of the scanning head does not change, or if the scanning head approaches the wor~piece in such a way that the 20~7~5 i.._ge of the projected spot of light is always at the centre of the detector.
However, guiding the scanning head along the shape of the object entails high mechanical and control-technology costs. In addition, the speed with which such measurements are made depends not only on the electronic organization but also on the mechanical construction, i.e., it is prejudiced by the latter.
In order to eliminate guidance of the scanning head, DE-OS 33 42 675 shows that the scanning head can be set into dif~erent angular positions by means of a detent system. However, measurement of longer objects would require constantly renewed angular adjustment which, in its turn, entails considerable mechanical costs.
For this reason, in practice, in order to determine the shape of longer workpieces, a plurality of scanning heads are used, which means that measurements can then be made very quickly. This then becomes a question of economics if a large number of scanning heads are required. In order to measure long objects, such as, for example, boards and tree trunks, a parabolic laser scanner is used in sawmills (M. Wolleston, ed.: Computer Control Systems for Log Processing and Lumber Manufacturinq, 1985, page 127).
Here, a parabolic mirror that is acted upon by a laser through a rotating mirror must lie above the total width of the board that is to be processed. The laser beams are then guided perpendicularly from the parabolic mirror onto a reference plane in which the object to be measured is guided transversely to the direction of scan. Above this reference plane, on both sides there are detectors that receive the beams that are reflected from the object to be measured. This system is only suitable for a major operation with a high throughput because it involves major costs.
20~a7~5 1. order to measure board stock that is to be squared, and to do this as it is being fed into a sawmill longitudinally there are, of course, cost-effective procedures using laser scanning systems. In these, the measurement of the board stock is effected by a series of sensors arranqed after an in-feed table.
However, because of the fact that measurement and sawing are serial processes, additional space that corresponds to the length of the board to be processed is required. Very frequently, small sawmills do not have such space. In addition, there are problems connected with the transition from the cross conveyor to the in-feed table.Since, in this case, measurement is only concluded once the board has passed through its entire length, it is not possible to align the board precisely. Because of this fact, the board stock cannot be used optimally in each case, i.e., there are economic losses for the operator.
If measurement and sawing are now to be so managed that there is no requirement for additional space, as has been described above, one has to accept greater expenditures for sensors and analysis systems. These increased electro-mechanical costs may not make the total system appear economical, for example, for a smaller sawmill, for in addition component downtime costs increase.
Thus, it is one task of the present invention to find an economical measurement system for longer objects having diffusely reflecting surfaces, that uses only opto-electronic structural element~, in which connection the measurement system is not to take up any additional space in order to make the required measurements.
This ta~k has ~een solved using the features set out in the preamble to the main claim. In doing this, in order to determine the shape of the object to be measured, a plurality of beam sources are arranged at a specific measurement distance from each other, said distance growing greater from the reference point to 20~7~
tlla detector row and parallel to the longitudinal axis of the object to be measured, but outside the plane of observation of the plotting detector row so that a triangle is formed in their illuminatinq planes, as seen from the detector row, and the measurement object is guided transversely to the plane of observation, measurement points of the particular contour being recorded at this point for each beam source.
The advantages of this system, as viewed from the standpoint of the prior art, is that the measurement system incorporates no moving parts, and that only one detector is required.
Additional developments of the present invention are set out in the sub-claims.
The present invention will be described in greater detail below on the basis of one embodiment that is shown in the drawings appended hereto. These drawings show the following:
igure 1: a view of the beam paths or light intersections of the individual measurement points;
Figure 2: a detailed drawing of the CCD row as in figure l;
Figure 3: a sector of two measurement points as in figure 1;
Figure 4: a drawing of the object field of the CCD row camera on the surface of the board;
Figure 5: a light intersection with the surface of the object of one pixel;
Figure 6: a drawing of the individual planes;
Figure 7: a possible measurement ob;ect:
Figure 8: the cross section of a mea~urement;
Figure 9: a view of the curves of the pixels for each measurement point in conjunction with the CCD row signal;
Figure 1~: one possible use of the measurement system in a sawmill.
~ present invention relates to a measuring system for the non-contact determination of long objects having diffusely reflecting surfaces, in particular for use in sawmills, in order to cut sharp-edged boards from slabbed stock.
A number of optical co-ordinate measuring devices are known, amongst others, for making non-contact measurements. In these, the basic principle is that, as in known electro-mechanical measuring systems, one proceeds such that the geometry of the workpiece is determined by measuring the co-ordinates of individual points on the surface of the workpiece. However, the surface is scanned optically, i.e., without physical contact.
Once again, there are many methods of doing this, e.g., those involving interference, defraction, triangulation, or image analysis. In addition to these, DE-OS 29 03 529 and DE-OS 21 13 522 describe a procedure for non-contact measurement of objects, in which the optical scanning of workpieces is effected according to the triangulation principle. To this end, a spot of light is projected at an angle onto the object to be measured and the distance from the source of the beam to the measurement object is determined according to the displacement of the image of the spot of light that is measured by means of a position-sensitive detector. The desired additional analysis and processing of the value~ so obtained is effected with the help of an image analysis apparatus that is associated with the detector. The projector and the imaging system are combined into one structural group in the form of a so-called optical scanning head.
In order to measure longer objects, this is then moved over the object by means of suitable guide systems. However, using this process, the distance to the object can only be determined without error if the angle subtended between the surface of the object and the axis of the scanning head does not change, or if the scanning head approaches the wor~piece in such a way that the 20~7~5 i.._ge of the projected spot of light is always at the centre of the detector.
However, guiding the scanning head along the shape of the object entails high mechanical and control-technology costs. In addition, the speed with which such measurements are made depends not only on the electronic organization but also on the mechanical construction, i.e., it is prejudiced by the latter.
In order to eliminate guidance of the scanning head, DE-OS 33 42 675 shows that the scanning head can be set into dif~erent angular positions by means of a detent system. However, measurement of longer objects would require constantly renewed angular adjustment which, in its turn, entails considerable mechanical costs.
For this reason, in practice, in order to determine the shape of longer workpieces, a plurality of scanning heads are used, which means that measurements can then be made very quickly. This then becomes a question of economics if a large number of scanning heads are required. In order to measure long objects, such as, for example, boards and tree trunks, a parabolic laser scanner is used in sawmills (M. Wolleston, ed.: Computer Control Systems for Log Processing and Lumber Manufacturinq, 1985, page 127).
Here, a parabolic mirror that is acted upon by a laser through a rotating mirror must lie above the total width of the board that is to be processed. The laser beams are then guided perpendicularly from the parabolic mirror onto a reference plane in which the object to be measured is guided transversely to the direction of scan. Above this reference plane, on both sides there are detectors that receive the beams that are reflected from the object to be measured. This system is only suitable for a major operation with a high throughput because it involves major costs.
20~a7~5 1. order to measure board stock that is to be squared, and to do this as it is being fed into a sawmill longitudinally there are, of course, cost-effective procedures using laser scanning systems. In these, the measurement of the board stock is effected by a series of sensors arranqed after an in-feed table.
However, because of the fact that measurement and sawing are serial processes, additional space that corresponds to the length of the board to be processed is required. Very frequently, small sawmills do not have such space. In addition, there are problems connected with the transition from the cross conveyor to the in-feed table.Since, in this case, measurement is only concluded once the board has passed through its entire length, it is not possible to align the board precisely. Because of this fact, the board stock cannot be used optimally in each case, i.e., there are economic losses for the operator.
If measurement and sawing are now to be so managed that there is no requirement for additional space, as has been described above, one has to accept greater expenditures for sensors and analysis systems. These increased electro-mechanical costs may not make the total system appear economical, for example, for a smaller sawmill, for in addition component downtime costs increase.
Thus, it is one task of the present invention to find an economical measurement system for longer objects having diffusely reflecting surfaces, that uses only opto-electronic structural element~, in which connection the measurement system is not to take up any additional space in order to make the required measurements.
This ta~k has ~een solved using the features set out in the preamble to the main claim. In doing this, in order to determine the shape of the object to be measured, a plurality of beam sources are arranged at a specific measurement distance from each other, said distance growing greater from the reference point to 20~7~
tlla detector row and parallel to the longitudinal axis of the object to be measured, but outside the plane of observation of the plotting detector row so that a triangle is formed in their illuminatinq planes, as seen from the detector row, and the measurement object is guided transversely to the plane of observation, measurement points of the particular contour being recorded at this point for each beam source.
The advantages of this system, as viewed from the standpoint of the prior art, is that the measurement system incorporates no moving parts, and that only one detector is required.
Additional developments of the present invention are set out in the sub-claims.
The present invention will be described in greater detail below on the basis of one embodiment that is shown in the drawings appended hereto. These drawings show the following:
igure 1: a view of the beam paths or light intersections of the individual measurement points;
Figure 2: a detailed drawing of the CCD row as in figure l;
Figure 3: a sector of two measurement points as in figure 1;
Figure 4: a drawing of the object field of the CCD row camera on the surface of the board;
Figure 5: a light intersection with the surface of the object of one pixel;
Figure 6: a drawing of the individual planes;
Figure 7: a possible measurement ob;ect:
Figure 8: the cross section of a mea~urement;
Figure 9: a view of the curves of the pixels for each measurement point in conjunction with the CCD row signal;
Figure 1~: one possible use of the measurement system in a sawmill.
2~a77~
Figure 1 shows the concept of the measuring system with its light intersections and beam paths. In the whole of the following description, the point of departure is the drawing showing measurement of board stock l so that maximum exploitation is made possible during the squaring process. Of course, the system is equally suitable for determining the shapes of other long and flat objects.
Above the board 1 there are a number of beam sources 4.m (m = 1, 2, 3 ...) that are arranged, for example, on a rail 2 above the reference plane 3 and outside the detector observation plane 30 (Translator's note: this reference number does not appear in figure l), the light beams of which fall perpendicularly onto the Z-axis in the reference plane 3 and which are shown as light intersections 5.m. The light intersection 5.1 of the first beam source 4.1 forms the reference point 6 for the null intersection.
The lens 9 of a CCD row camera 10 is arranged above the reference plane 3 at a distance (1) 7 and at a height (h) 8. The measurement section 11 is limited by the number of light intersections 5.m. The total measurement length 12 can extend beyond this, however, if it can be ensured that the start of the board 1 lies at the null intersection 6.
Figure 2 i8 a detailed drawing of the CCD row 10 that is shown in figure 1 and its beam paths through the lens 9. The pixels from 0 to 2048 are recorded in the CCD row although, of course, another number of pixels is also possible. A median beam path serves as optical axis 13. The total beam area is covered by the len~ field angle 2~. The angle subtended between two beam paths is desiqnated as field angle ~m for the measurement points. A
further angle y is subtended between the optical axis 13 and the perpendiculars.
Figure 3 shows a section of two measurement points as in figure l. This shows the reference plane 3 and the sections for the two 2Q6~77~
1 ,~t intersections 5.9 and 5.10, i.e., for the ninth and tenth beam sources 4.9 and 4.10. In this example, the light intersection of the ninth beam source 4.9 coincides with the optical axis 13 on the reference plane 3. The angle subtended by the optical axis 13 and the light intersection is designated ~.
This shows that the optical axis 13 is the reflected beam of the light intersection 5.9 that is picked up by the detector. The reflected beam of light intersection 5.10 intersects the light intersection 5.9 at pointl6. The distance of the pointl6 to the reference plane 3 represents the possible measurement range height 17 at this point. ~he reflected beam 15 of the light intersection 5.11 (not shown herein) intersects the light intersection 5.10 at pointl8. The distance of pointl8 from the reference plane 3 represents the measurement range height 19 that is possible at this point. An additional light intersection 20 is shown at an angle ~9 at the point of intersection of the optical axis 13 with the reference plane 3 and the light intersection 5.9. This light intersection 20 displays an inclination (expressed by the angle ~9) that is possible for the light intersections 5.m in order to permit more precise measurement. The point of intersection 21 of this light intersection 20 with the reflected beam 14 of the light intersection 5.10 represents the maximal measurement range height 22. The distance of the two light intersections 5.9 and 5.10 is designated ~zm.
Reference is made to the following formulae in order to provide a clear dexcription of the individual relationships:
Key to fo,,~m~ ae text 2 ~ 7 ~
(1) Cm - ~rc tan - ~_ z - Distance of the measurement points from the null inter-section.
M - Number of measurement points.
m - m. measurement points.
~m - Angle of the distance of the object am-perpendicular.
1, h - See drawing.
Np - Number of pixels of the CCD row.
LCCD ~ Length of the CCD row.
- Picture ratio pixel width/pixel length.
(2) CJ s~ M ~1 ~ - Field angle for measurement mm --f~ m points m.
Figure 1 shows the concept of the measuring system with its light intersections and beam paths. In the whole of the following description, the point of departure is the drawing showing measurement of board stock l so that maximum exploitation is made possible during the squaring process. Of course, the system is equally suitable for determining the shapes of other long and flat objects.
Above the board 1 there are a number of beam sources 4.m (m = 1, 2, 3 ...) that are arranged, for example, on a rail 2 above the reference plane 3 and outside the detector observation plane 30 (Translator's note: this reference number does not appear in figure l), the light beams of which fall perpendicularly onto the Z-axis in the reference plane 3 and which are shown as light intersections 5.m. The light intersection 5.1 of the first beam source 4.1 forms the reference point 6 for the null intersection.
The lens 9 of a CCD row camera 10 is arranged above the reference plane 3 at a distance (1) 7 and at a height (h) 8. The measurement section 11 is limited by the number of light intersections 5.m. The total measurement length 12 can extend beyond this, however, if it can be ensured that the start of the board 1 lies at the null intersection 6.
Figure 2 i8 a detailed drawing of the CCD row 10 that is shown in figure 1 and its beam paths through the lens 9. The pixels from 0 to 2048 are recorded in the CCD row although, of course, another number of pixels is also possible. A median beam path serves as optical axis 13. The total beam area is covered by the len~ field angle 2~. The angle subtended between two beam paths is desiqnated as field angle ~m for the measurement points. A
further angle y is subtended between the optical axis 13 and the perpendiculars.
Figure 3 shows a section of two measurement points as in figure l. This shows the reference plane 3 and the sections for the two 2Q6~77~
1 ,~t intersections 5.9 and 5.10, i.e., for the ninth and tenth beam sources 4.9 and 4.10. In this example, the light intersection of the ninth beam source 4.9 coincides with the optical axis 13 on the reference plane 3. The angle subtended by the optical axis 13 and the light intersection is designated ~.
This shows that the optical axis 13 is the reflected beam of the light intersection 5.9 that is picked up by the detector. The reflected beam of light intersection 5.10 intersects the light intersection 5.9 at pointl6. The distance of the pointl6 to the reference plane 3 represents the possible measurement range height 17 at this point. ~he reflected beam 15 of the light intersection 5.11 (not shown herein) intersects the light intersection 5.10 at pointl8. The distance of pointl8 from the reference plane 3 represents the measurement range height 19 that is possible at this point. An additional light intersection 20 is shown at an angle ~9 at the point of intersection of the optical axis 13 with the reference plane 3 and the light intersection 5.9. This light intersection 20 displays an inclination (expressed by the angle ~9) that is possible for the light intersections 5.m in order to permit more precise measurement. The point of intersection 21 of this light intersection 20 with the reflected beam 14 of the light intersection 5.10 represents the maximal measurement range height 22. The distance of the two light intersections 5.9 and 5.10 is designated ~zm.
Reference is made to the following formulae in order to provide a clear dexcription of the individual relationships:
Key to fo,,~m~ ae text 2 ~ 7 ~
(1) Cm - ~rc tan - ~_ z - Distance of the measurement points from the null inter-section.
M - Number of measurement points.
m - m. measurement points.
~m - Angle of the distance of the object am-perpendicular.
1, h - See drawing.
Np - Number of pixels of the CCD row.
LCCD ~ Length of the CCD row.
- Picture ratio pixel width/pixel length.
(2) CJ s~ M ~1 ~ - Field angle for measurement mm --f~ m points m.
(3) 2~ ~16 ~ ~ 2~ - Object field angle.
~4) ~CCO f' - Focal length of the image.
c~ ~
(S) ~J pm Np ~pm ~ Pixel field angle at measure-ment point m.
(6) oC n~l + (m - 1)~ fur 2 < m ~ M
r ~ - See drawing.
(8) Z ~ h ~ tsn cC - 1 m m ( ) ~ Zm Zm+l Zm ~Z - Measurement point interval length-measurement range and reference plane.
1 ~ Z
~10) ~m ~ am ~ Dlstance to ob~ect outside the optical axis.
7a ` 2063775 ~Z
(11) dm = ~ dm - Maximally detectable board thickness at measurement point m.
(12) a dp~ dpm ~ Mean thickness resolution for each pixel at measurement point m.
Np Number of pixels per measure-M ment point.
(am - f~ Zeilcnbreite Z - Mean board (= object) length ~ per pixel at measurement point m.
am - Distance of the object.
f - Object focal length.
~4) ~CCO f' - Focal length of the image.
c~ ~
(S) ~J pm Np ~pm ~ Pixel field angle at measure-ment point m.
(6) oC n~l + (m - 1)~ fur 2 < m ~ M
r ~ - See drawing.
(8) Z ~ h ~ tsn cC - 1 m m ( ) ~ Zm Zm+l Zm ~Z - Measurement point interval length-measurement range and reference plane.
1 ~ Z
~10) ~m ~ am ~ Dlstance to ob~ect outside the optical axis.
7a ` 2063775 ~Z
(11) dm = ~ dm - Maximally detectable board thickness at measurement point m.
(12) a dp~ dpm ~ Mean thickness resolution for each pixel at measurement point m.
Np Number of pixels per measure-M ment point.
(am - f~ Zeilcnbreite Z - Mean board (= object) length ~ per pixel at measurement point m.
am - Distance of the object.
f - Object focal length.
4 ) A Zpm = ~P~ ~ Xpm ~ Mean board (= object) width per pixel at measurement point m.
(15) ~ m r tgn a 2m (dg dmax) ~m - Maximally possible inclination Q ' m~x of the light intersection to the board surface normal for measurement point m.
dma ~ Nominal measurement range for the board thickness plus safety (curvature).
~16)C~ = Width of the CCD row/pixel 7 interval (pitch)~
7b 26793~ 7 75 Figure 4 shows the object field of the CCD row camera of the surface on the board.
In the plan view of the board 1, one can recognize the object field 23 of the CCD row camera 10. The lens 9 of the CCD row camera 10 is arranged at the distance 7 from the null inter-section 6 of the board 1. Eccentrically in the object field 20~7~
23, the beam sources 4.m lie at a small distance above the board 1. The direction of feed 25 of the board runs in the X-direction as seen from the reference plane 3.
In figure 5, a light intersection is shown with the surface of a pixel. The beam source 4.m that lies eccentrically to the object field 23 projects its beam at a specific width 28 onto the surface of the board 1. The object field 23 is defined by its object field borders 26, 27. The intersection 28 of the path of the beam source 4.m with the object field 23 produces the part of the area that is conjugate to the surface 29 of a pixel, which is to be irradiated.
In order to illustrate the basic principle still more clearly figure 6 shows the individual planes. The board 1 lies on the reference plane and is moved in the feed direction 25. The lens 9 of the CCD row camera 10 lies at distance 7 and height 8 from the null intersection. This CCD row camera has a plane of observation 30 which is shown in total. This plane of observation 30 impinges vertically on the light intersection 5.m formed by the beam sources 4.m, and which, seen in the direction of the reference plane, are of triangular shape. The plane of observation 30 now impinges in the approximate centre of these beam Qections formed by the beam sources 4.m. The point of intersection 31, in conjunction with the intersection point of the observation plane 30 with the reference plane 3, forms the maximum height 22 of the board 1 that is to be measured.
Figure 7 shows a possible measurement object with the recorded measurement points. A section of the board 1 is sufficient for this representation, and this is guided in the board feed direction 25 into the intersection points of the light intersections 5.1 and the object field 23. If the lower edge of the rough slab 32 impinge on such an intersection point, a measurement point 35.m, 35.m~1 is stored in an analysis unit (not 20~5775 shown herein). The same thing applies when the upper edge of the rough slab 32 is reached. Then, the measurement points 36.m, 36.m+1 are stored. If the upper edge of the second rough slab 33 of the board 1 reaches the intersection point, a third measurement point 37.m, 37.m+1 is stored. The last measurement point 38.m, 38.m+1 is stored when the lower edge leaves the point of intersection of the light beams.
Figure 8 once again shows the associated section for a measurement in detail. Viewed in the direction of feed 25, the first measurement point 35.m is picked up on the lower edge of the rough slab 32. The next measurement point 36.m that is to be stored is picked up when the upper edge of the board is reached.
As soon as the upper edge of the second rough slab edge 32 passes through the plane of observation 30 of the CCD row camera 10, the third measurement point 37.m is picked up. Finally, the fourth measurement point 38.m is stored when the lower edqe of the board 1 leaves the observation plane 30. ~his result is achieved by serial analysis of the CCD row signals at equally spaced time and distance intervals.
Figure 9 shows the curves of the pixels for each measurement point combined with the CCD row signals. The starting point is once again a board 1 which is moved in the direction of movement 25. The light intersections are associated with the individual pixel numbers 39. Selected measurement curves are shown for the light intersections 5.1, 5.9, and 5.16. The possible measurement heights 22.1, 22.9 or 22.16, respectively, correspond to the intervals between the pixels. Also associated are the CCD row signals 40. If the individual measurement points 36.m or 37.m, respectively, of the upper edge of the slab goods are observed, one can see that rectilinear sections 51, 52 can be drawn, ~o that all rough slab edge pieces fall out.
20~57~
Figure 10 shows one possible use of the measuring system in a sawmill. Processing timber in a sawmill begins with a slabbing machine, as a rule a rift saw, after which the main and side slabs are separated. After the separation of these main and side slabs, the side slabs are cut to an appropriate length and the waste slabs are rejected.
Sharp-edged boards must be cut on at least one cut surface from the side slabs, i.e., the outside surface or a part thereof must be separated. These boards are squared by a trimming saw.
Generally speaking, the trimming saw consists of a plurality of adjustable saws that can be so positioned that the optimal board can be cut for maximal use of the slabs. Because of the fact that the boards can be of any width and can be curved, on being inserted into the trimming saw each board has to be aligned.
Side slabs are moved through a separator 50 and a waste hopper 41 that removes the waste material, to a cross-conveyor 42. The board passes over appropriate conveying systems of the transverse conveyor 42 to the measuring table 43 that is arranged on the transverse conveyor. The CCD row camera 10 is arranged above this measuring table 43. In the same way, the corresponding beam sources 4.m are also arranged over this table. The measured board 44 is then moved optionally to a holding station 45. The board is then moved to the in-feed table 47, either by means of a positioner 46 or directly by means of the transverse conveyor 44.
Alignment cylinders 48 are arranged on this in-feed table and these align the measured board according to the measurement points that have been calculated. When the board 44 is aligned, it is fixed on the in-feed table 47 by the pressure rollers 49.
Then the board is sawn, in that it i~ fed through an arrangement of saws (not shown herein). An analysis unit (not shown herein) then computes the sawblade adjustment from the control signals that are generated by the width of the board.
e mid-line of the board that is to be sawn is design ~ ~
ideal line when this is done and must be oriented towards the saw adjustment.
Alignment is effected on the in-feed table of the trimming saw.
To this end, this saw contains a special alignment unit. The alignment unit, i.e., the alignment cylinders 48, consist, for example, of a stop that can be lowered and which is fitted with defined extendable pistons. The pistons are so positioned that they lie on a board length that is equal to the measurement points. Depending on the length of the board, two pistons are so positioned that the board is automatically aligned when it lies against these pistons. In order to control the pistons, in each instance the distance of the outer rought edge ideal line is calculated. In order to ensure a high throughput for the machine, the alignment pistons are installed on a stop that can be lowered. As soon as the board has been aligned and fixed in position, the pistons are lowered and the board is fed into the trimmer.
(15) ~ m r tgn a 2m (dg dmax) ~m - Maximally possible inclination Q ' m~x of the light intersection to the board surface normal for measurement point m.
dma ~ Nominal measurement range for the board thickness plus safety (curvature).
~16)C~ = Width of the CCD row/pixel 7 interval (pitch)~
7b 26793~ 7 75 Figure 4 shows the object field of the CCD row camera of the surface on the board.
In the plan view of the board 1, one can recognize the object field 23 of the CCD row camera 10. The lens 9 of the CCD row camera 10 is arranged at the distance 7 from the null inter-section 6 of the board 1. Eccentrically in the object field 20~7~
23, the beam sources 4.m lie at a small distance above the board 1. The direction of feed 25 of the board runs in the X-direction as seen from the reference plane 3.
In figure 5, a light intersection is shown with the surface of a pixel. The beam source 4.m that lies eccentrically to the object field 23 projects its beam at a specific width 28 onto the surface of the board 1. The object field 23 is defined by its object field borders 26, 27. The intersection 28 of the path of the beam source 4.m with the object field 23 produces the part of the area that is conjugate to the surface 29 of a pixel, which is to be irradiated.
In order to illustrate the basic principle still more clearly figure 6 shows the individual planes. The board 1 lies on the reference plane and is moved in the feed direction 25. The lens 9 of the CCD row camera 10 lies at distance 7 and height 8 from the null intersection. This CCD row camera has a plane of observation 30 which is shown in total. This plane of observation 30 impinges vertically on the light intersection 5.m formed by the beam sources 4.m, and which, seen in the direction of the reference plane, are of triangular shape. The plane of observation 30 now impinges in the approximate centre of these beam Qections formed by the beam sources 4.m. The point of intersection 31, in conjunction with the intersection point of the observation plane 30 with the reference plane 3, forms the maximum height 22 of the board 1 that is to be measured.
Figure 7 shows a possible measurement object with the recorded measurement points. A section of the board 1 is sufficient for this representation, and this is guided in the board feed direction 25 into the intersection points of the light intersections 5.1 and the object field 23. If the lower edge of the rough slab 32 impinge on such an intersection point, a measurement point 35.m, 35.m~1 is stored in an analysis unit (not 20~5775 shown herein). The same thing applies when the upper edge of the rough slab 32 is reached. Then, the measurement points 36.m, 36.m+1 are stored. If the upper edge of the second rough slab 33 of the board 1 reaches the intersection point, a third measurement point 37.m, 37.m+1 is stored. The last measurement point 38.m, 38.m+1 is stored when the lower edge leaves the point of intersection of the light beams.
Figure 8 once again shows the associated section for a measurement in detail. Viewed in the direction of feed 25, the first measurement point 35.m is picked up on the lower edge of the rough slab 32. The next measurement point 36.m that is to be stored is picked up when the upper edge of the board is reached.
As soon as the upper edge of the second rough slab edge 32 passes through the plane of observation 30 of the CCD row camera 10, the third measurement point 37.m is picked up. Finally, the fourth measurement point 38.m is stored when the lower edqe of the board 1 leaves the observation plane 30. ~his result is achieved by serial analysis of the CCD row signals at equally spaced time and distance intervals.
Figure 9 shows the curves of the pixels for each measurement point combined with the CCD row signals. The starting point is once again a board 1 which is moved in the direction of movement 25. The light intersections are associated with the individual pixel numbers 39. Selected measurement curves are shown for the light intersections 5.1, 5.9, and 5.16. The possible measurement heights 22.1, 22.9 or 22.16, respectively, correspond to the intervals between the pixels. Also associated are the CCD row signals 40. If the individual measurement points 36.m or 37.m, respectively, of the upper edge of the slab goods are observed, one can see that rectilinear sections 51, 52 can be drawn, ~o that all rough slab edge pieces fall out.
20~57~
Figure 10 shows one possible use of the measuring system in a sawmill. Processing timber in a sawmill begins with a slabbing machine, as a rule a rift saw, after which the main and side slabs are separated. After the separation of these main and side slabs, the side slabs are cut to an appropriate length and the waste slabs are rejected.
Sharp-edged boards must be cut on at least one cut surface from the side slabs, i.e., the outside surface or a part thereof must be separated. These boards are squared by a trimming saw.
Generally speaking, the trimming saw consists of a plurality of adjustable saws that can be so positioned that the optimal board can be cut for maximal use of the slabs. Because of the fact that the boards can be of any width and can be curved, on being inserted into the trimming saw each board has to be aligned.
Side slabs are moved through a separator 50 and a waste hopper 41 that removes the waste material, to a cross-conveyor 42. The board passes over appropriate conveying systems of the transverse conveyor 42 to the measuring table 43 that is arranged on the transverse conveyor. The CCD row camera 10 is arranged above this measuring table 43. In the same way, the corresponding beam sources 4.m are also arranged over this table. The measured board 44 is then moved optionally to a holding station 45. The board is then moved to the in-feed table 47, either by means of a positioner 46 or directly by means of the transverse conveyor 44.
Alignment cylinders 48 are arranged on this in-feed table and these align the measured board according to the measurement points that have been calculated. When the board 44 is aligned, it is fixed on the in-feed table 47 by the pressure rollers 49.
Then the board is sawn, in that it i~ fed through an arrangement of saws (not shown herein). An analysis unit (not shown herein) then computes the sawblade adjustment from the control signals that are generated by the width of the board.
e mid-line of the board that is to be sawn is design ~ ~
ideal line when this is done and must be oriented towards the saw adjustment.
Alignment is effected on the in-feed table of the trimming saw.
To this end, this saw contains a special alignment unit. The alignment unit, i.e., the alignment cylinders 48, consist, for example, of a stop that can be lowered and which is fitted with defined extendable pistons. The pistons are so positioned that they lie on a board length that is equal to the measurement points. Depending on the length of the board, two pistons are so positioned that the board is automatically aligned when it lies against these pistons. In order to control the pistons, in each instance the distance of the outer rought edge ideal line is calculated. In order to ensure a high throughput for the machine, the alignment pistons are installed on a stop that can be lowered. As soon as the board has been aligned and fixed in position, the pistons are lowered and the board is fed into the trimmer.
Claims (6)
1. A measuring system for the non-contact determination of the shape of long objects with diffusely reflecting surfaces, which works according to the triangulation principle using a detector row and beam sources, the detector row having a subsequent analysis unit for image analysis and storing the measurement points, characterized in that in order to determine the shapes of the object to be measured a plurality of beam sources (4.m) are arranged at a specific interval, which grows greater from the reference point (6) of the detector row (10), and parallel to the longitudinal axis of the object to be measured (1), but which are outside the plane of observation (30) of the analysing detector row (10) so that, viewed from the detector row (10), a triangle is formed in its beam plane: and in that the object (1) to be measured is guided transversely to the plane of observation, when measurement points (35.m...38.m) of the particular shape are recorded at this point for each beam source (4.m).
2. A measurement system as defined in claim 1, characterized in that a lens (9) for the detector row (10) is arranged, viewed in the longitudinal direction to the reference plane (3) at interval 1 (7) to the null intersection (6) and at a height h (8) above the object to be measured (1), the first beam source (4.1) being arranged approximately perpendicularly over the null intersection (6) and the distance Zm of the beam source (4.m), viewed from the reference point for the null intersection (6), is calculated according to the equation Zm = h ? tan(.alpha.m) - 1 the angle .alpha.m standing for the angle between the object beam for the light intersection (5.m) and the normal to the reference plane.
3. A measurement system as defined in claims 1 to 2, characterized in that on arranging the beam source perpendicularly on the reference plane longitudinal axis, the possible measurement range height dm (22) of the object (1) to be measured is calculated according to the equation wherein .DELTA.Zm stands for the measurement point interval in the longitudinal measurement range of the reference plane (3).
4. A measurement system as defined in the claims 1 to 3, characterized in that the possible inclination of the light intersection (5.m) to the object to be measured--surface normal--is calculated according to the equation wherein dmax stands for the nominal measurement range for the thickness of the object to be measured.
5. A measurement system as defined in claims 1 to 3, characterized in that the detector row (10) is configured as a CCD row which covers all the light intersections at once by optical imaging.
6. A measurement system as defined in claim 1 to claim 3, characterized in that laser diode systems are used as beam sources (4.m), these being arranged above and very close to the reference plane.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4112009.4 | 1991-04-12 | ||
| DE4112009A DE4112009A1 (en) | 1991-04-12 | 1991-04-12 | MEASURING SYSTEM FOR CONTACT-FREE DETECTION OF THE CONTOUR OF LONG OBJECTS WITH DIFFUSING REFLECTING SURFACE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2065775A1 true CA2065775A1 (en) | 1992-10-13 |
Family
ID=6429478
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002065775A Abandoned CA2065775A1 (en) | 1991-04-12 | 1992-04-10 | Measuring system for the non-contact determination of the shape of long objects having diffusely reflecting surfaces |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0508339B1 (en) |
| CA (1) | CA2065775A1 (en) |
| DE (2) | DE4112009A1 (en) |
| FI (1) | FI921569A7 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3186876B2 (en) * | 1993-01-12 | 2001-07-11 | 株式会社東芝 | Surface profile measuring device |
| DE102010021951A1 (en) * | 2010-05-28 | 2011-12-01 | Weber Maschinenbau Gmbh Breidenbach | Scanning device for determining partial cross-sectional profiles of meat product that is cut by heavy-duty slicer, has detection device detecting images containing light lines, where scanning planes and lines are separated from each other |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2113522C3 (en) * | 1971-03-19 | 1974-05-09 | Siemens Ag | Method for non-contacting measurement of a surface profile |
| US3787700A (en) * | 1971-07-27 | 1974-01-22 | Atmospheric Sciences Inc | Automatic system for measuring selected dimensions |
| SE412286B (en) * | 1978-07-10 | 1980-02-25 | Saab Scania Ab | SET AND DEVICE FOR PHOTOELECTRIC DIMENSION OF WIDES OR SIMILAR GEOMETRICALLY DETERMINED FORMS |
| DE2903529A1 (en) * | 1979-01-31 | 1980-08-07 | Schlatter Ag | METHOD FOR MEASURING DISTANCES AND DEVICE FOR CARRYING OUT THE METHOD |
| DE3342675A1 (en) * | 1983-11-25 | 1985-06-05 | Fa. Carl Zeiss, 7920 Heidenheim | METHOD AND DEVICE FOR CONTACTLESS MEASUREMENT OF OBJECTS |
| DE3817387A1 (en) * | 1988-05-19 | 1989-11-30 | Mannesmann Ag | METHOD AND DEVICE FOR DETECTING THE EXTERNAL DESIGN OF A LONG STRETCHED, CROSS-SECTION PRISMATIC BODY |
| US4943157A (en) * | 1989-05-18 | 1990-07-24 | Corning Incorporated | Fiber optic triangulation gage |
-
1991
- 1991-04-12 DE DE4112009A patent/DE4112009A1/en active Granted
-
1992
- 1992-04-04 DE DE59202777T patent/DE59202777D1/en not_active Expired - Fee Related
- 1992-04-04 EP EP92105868A patent/EP0508339B1/en not_active Expired - Lifetime
- 1992-04-09 FI FI921569A patent/FI921569A7/en not_active Application Discontinuation
- 1992-04-10 CA CA002065775A patent/CA2065775A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| FI921569A7 (en) | 1992-10-13 |
| DE4112009A1 (en) | 1992-10-22 |
| DE59202777D1 (en) | 1995-08-10 |
| DE4112009C2 (en) | 1993-07-15 |
| EP0508339A2 (en) | 1992-10-14 |
| FI921569A0 (en) | 1992-04-09 |
| EP0508339B1 (en) | 1995-07-05 |
| EP0508339A3 (en) | 1993-04-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |