WO2007051659A1

WO2007051659A1 - Apparatus for optical recording of piece goods

Info

Publication number: WO2007051659A1
Application number: PCT/EP2006/063174
Authority: WO
Inventors: Erwin Herre
Original assignee: Robert Bosch Gmbh
Priority date: 2005-07-28
Filing date: 2006-06-14
Publication date: 2007-05-10
Also published as: DE102005035410A1

Abstract

An apparatus for optical recording of piece goods (12) which are carried in an organized or unorganized form on a conveyer (10), has an image recording unit (40) which can be used to record images of the piece goods (12) being supplied on the conveyor (10). In this case, at least one mirror (41, 42) is arranged in the beam path of the image recording unit (40) and can be used to deflect the beam path of the image recording unit (40) in order to make the beam paths (31, 32, 33) which run in the housing (26) longer than a vertical dimension of the housing (26).

Description

Device for optical detection of piece goods

State of the art

The invention relates to a device for the optical detection of piece goods and their location on transport devices, in particular piece-like food, for controlling downstream gripping devices.

From the prior art, a number of such devices are known. For example, EP 0 847 838 shows such a device according to the preamble of claim 1. The product scanner described therein is intended to be the optical one

Keep positioning simple and cost-effective without optical distortion. For this purpose, photosensitive bar sensors are arranged below a transparent transport device, while above the

Transporting light strips and cameras are arranged. The photosensitive bar sensors cover the entire width of the conveyor belt. When using this device, the elements to be used are each tuned exactly to the transport device.

Advantages of the invention

It is, starting from this prior art, object of the invention to provide an apparatus for optically detecting piece goods, the modular compact design while allowing high depth of field to capture from flat to higher products.

This object is achieved by a device having the features of claim 1.

The inventive scanning device has a folded beam path, so that there is a large object image distance.

Preferably, the image scanning devices are configured one-dimensional across the conveyor, so that the angle of view is small, and thus there are almost parallel beams, without the line scan cameras having to cover the full width of the conveyor.

The high depth of field of the device allows the modular use of the same in any transport facilities and directly for a variety of products, which can be very flat or very high, with "flat" products generally has a height of less than 5 millimeters and "high" products Height over a conveyor belt up to, for example, 80 or 100 millimeters may include. These image scanning results are ensured with the same mounting height of the device, so that the device can be used modularly in the construction of packaging equipment, without the device needs to be specially adapted to the different piece goods to be detected.

Such a device is excellently suited for optically detecting piece-like foods and their location on transport means for controlling downstream gripping devices in a packaging plant of the food industry.

Further advantageous embodiments of the inventive device and variants with inventive method from the dependent claims,

drawing

Embodiments of the invention are illustrated in the figures. Show it:

Fig. 1 is a schematic perspective view in view of a Bildabtastvorrichtung with modules according to an embodiment of the invention;

FIG. 2 shows a schematic cross-sectional view through a module according to the invention of the image scanning apparatus according to FIG. 1; FIG.

Fig. 3 is a schematic partially sectioned front view of a device similar to that of Fig. 1;

4 shows a further embodiment of a module for a device according to FIG. 1 or 3.

5 shows a further embodiment of a module for a device according to FIG. 1 or 3.

Description of the embodiments

1 shows a schematic perspective view of an apparatus for image scanning with modules according to a first exemplary embodiment of the invention. Such an image scanning module shown in FIG. 2 is used in conjunction with a conveyor 10, which is simply shown here as a planar surface. The conveyor 10 moves in the direction of the arrow 11, so that here with the Reference numeral 12 provided piece goods are moved under the device 20 therethrough. The piece goods 12 may be ordered or disordered. Here, six piece goods are arranged arranged side by side, which just pass through the direction indicated by the trapezoid 33 scanning zone. The conveyor 10 may be a single conveyor belt or may comprise a plurality of conveyor belts. These can be moved at the same speed or at different speeds.

Above the conveyor belt 10, the scanning device 20 is arranged, which advantageously extends over the entire width of the conveyor belt 10. It is arranged at such a height above the conveyor belt 10, so that in addition to rather flat piece goods, such as the illustrated piece goods 12, even relatively high piece goods, for example up to 10 centimeters in height, can pass under the housing 16 of the device 20. The device 20 according to FIG. 1 comprises three scanning modules 30, which are arranged in the transverse direction to the conveyor belt 10 at regular intervals from each other. The modules 30 may be arranged in individual housings 26, as indicated for the modules 25 and 35 in FIGS. 2 and 4, or altogether in an overall housing 16 of the device 20. The scanning modules 30 may also be arranged at an angle at an angle to the conveyor belt 10.

1 also shows cameras 40 and mirrors 41 and 42, which are arranged at right angles to one another and at a 45 "angle to the plane of the conveyor belt 10. The camera-like mirror 41 and the transport-near one Mirror 42 are configured here continuously, that is, there is a single long mirror for the three cameras 40. Thus - in reverse light propagation direction - the camera 40 each have a portion 31 of the beam path, mirrored over the mirror 41 in the area 32 passes, which is aligned parallel to the conveyor belt 10, which area 32 via the further mirror 42 in a direction perpendicular to Conveyor belt 10 and transverse thereto beam path 33 and 33 'passes. In this case, the beam path running within the housing 16 is referred to as the beam path 33 and the beam path extending outside the housing 16 is referred to as the beam path 33 '.

When talking about housing 16 or 26 in this context, this is not necessarily to be understood as a physical housing. Nevertheless, the principles of the invention can also be implemented without a housing enclosing a space; It is therefore to be understood by the term housing 16, 26 and the space surrounding such a structure, in other words the virtual cuboid or space that the device needs to accommodate its components. In particular, the device may be embedded in a grid structure comprising only the edges of the cuboid and connecting and supporting elements.

This last beam path 33 'intersects as the field of view of several cameras 40 and thus results in a total field of view. Each camera 40 is connected via the line 51, which is simply shown here for simplicity only with a module 51, which is also connected to a sensor 60 which receives the speed of the conveyor belt 10 or connected to a drive wheel or integrated into such the propulsion is responsible. This element is identified by the reference numeral 60. The image processing system 50 is therefore able to determine from the recorded data of the cameras 40 and the information from the sensor 60 with respect to the progress of the conveyor belt 10 at any time the location of parcels 12 downstream of the scanning device 20. This information is transferred via the control line 52 to the gripper control device 70, which is then connected in a known manner with gripping devices and controls this, which is not shown in the drawings for simplicity. Such gripping devices may be known delta robots or other pick and place robots act.

In accordance with the principle circuit diagram of FIG. 1, a scanning module 25 which is shown very diagrammatically and which has its own housing 26 is shown in FIG. The line camera 40 is mounted in the downstream direction of the housing 26 and has its field of view away from the conveyor belt 10. In an advantageous because sufficient design of the camera 40 is a single line of, for example, CCD or CMOS sensors, this line is aligned transversely to the conveyor belt 10. The line thus extends perpendicular to the drawing plane of FIG. 2. The camera 40 receives images of a piece goods 12 via the beam path 31, 32, 33 and 33 'shown in FIG. 1, wherein the light is deflected at the two planar mirrors 41 and 42 becomes. As a light source for lighting the piece goods 12 33 two LED lines 13 and 14 are arranged on both sides of the transverse and perpendicular to the conveyor belt 10 extending beam path, with which the cargo 12 are illuminated. Of course, only one LED row 13 or 14 can be arranged on one of the two sides of the field of view 33. The LED lines 13 and 14 are aligned parallel to the line scan camera 40.

Preferably, the respective LED's are stroboscopic, ie intermittently switched to increase their life. The duration of the connection must be sufficiently long to ensure a corresponding sufficient temporal resolution for the line scan camera 40. In other embodiments, the conveyor belt 10 may be arranged to be transparent and the lighting elements may be arranged below the conveyor belt. It would also be possible to align the light lines at an angle to one another, so that their optical axis intersects with the beam path plane 33 'at the level of the conveyor belt 10. However, the embodiment shown in Fig. 2 has the advantage of very compact design within of the housing 26.

The advantage of LED rows 13 and / or 14 is also in the low heat emission, so that within the housing 26 no heat release problems exist. But it could be provided instead of the LED lines and lines of light with other lighting fixtures.

FIG. 3 shows a very schematic cross-sectional view of the three modules 25 of a device similar to the device according to FIG. 1, the mirrors 42 being shown here as individual units. In particular, it can be clearly seen here that in each case two adjacent cameras 40 form with their beam path plane 33 'an overlapping region 34 in which image information from two adjacent cameras 40 is relayed on. Thus, it is possible in a simple manner to create a coherent image over the entire width of the conveyor belt 10 with an image-merging program (so-called stitch software) and then process it further as an image. This generation of a single image regardless of the number of modules 25 allows high scalability of the plant.

FIG. 4 shows a further exemplary embodiment of a scanning module 35 for use in a device according to FIG. 1 or 3. In this case, the camera 40 is oriented transversely in the direction of the conveyor belt 10. Thus arise between the first beam path 31 and the beam path plane 33 and 33 ', which finally cuts the conveyor belt 10, three folded beam paths 32, 132 and 232, which are thus deflected by the mirrors 41, 42, 43 and 44 in each case by 90 ° , This results in the illustrated in Fig. 4 spiral beam path.

Finally, FIG. 5 shows a further exemplary embodiment of a scanning module 55 for use in a device according to FIG. 1 or 3. The camera 40 in this case is almost longitudinal in FIG Direction of the conveyor belt 10 aligned. Thus arise between the first beam path 31 and the beam path plane 33 and 33 ', which finally cuts the conveyor belt 10, four folded beam paths 32, 132, 232 and 332, which are thus deflected by the mirrors 41, 43 and 44 each by a few degrees to then be deflected by the mirror 42 by 90 ° to exit the housing 26. This results in the zigzag-shaped beam path shown in FIG.

For the modules 25, 30, 35 and 55 it is essential that at least one folding of the beam path exists. In the simplest embodiment, not shown in the drawings, the camera 40, if one proceeds from the training of FIG. 4, at the location of the mirror 43 and looks with its optical axis directly on the mirror 42, which then in another, acute angle reflects the beam path in the plane 33. Here, too, there is an extension of the light path over the real distance camera conveyor belt.

Preferably, a unit consists of two deflecting mirrors, which each deflect the beam path by 90 °, as shown in Fig. 2. As shown in Fig. 4 and Fig. 5, three or more folds are possible. It is also possible to arrange the camera substantially horizontally and to keep the main weight of the extended beam path analogous to the beam path 232 in the horizontal over a series of mirror deflections, which deflect the beam path only by a few degrees.

It is essential in all embodiments, which can form the skilled person based on the present invention, that a relatively limited in depth and height housing 26 can be specified, in which the emitted from the object 12 or conveyor belt 10 reflected radiation with a narrow field of view or redirected several times mirrored is to achieve the highest possible optical distance from the said conveyor belt 10 to the camera 40, which distance is in particular far above the simple distance from the upper edge of the housing 26 to the conveyor belt 10. The optical distance is therefore significantly greater than the vertical dimension of the housing 26. The housing 26 may be slightly inclined relative to the vertical.

The cameras 40 are in particular line cameras which operate monochromatically or in color, for example CCD sensors whose state is evaluated. Through the use of a line camera, which has only a single element in the direction of movement of the conveyor belt 10, there are thus no perspective errors in the product movement direction 11. In addition, high resolution is possible with line cameras. By providing the folded light paths, which form a small angle of view with still large field of view, can be dispensed with in particular on the provision of CCD sensors in the number and order of the width of the conveyor belt. The possibility of not arranging cameras 40 over the entire width of the conveyor belt 10, it is possible to fit the corresponding circuits and elements in separate housing 26, which results in excellent scalability.

The illumination bodies may in particular consist of LEDs, which are lined up linearly. In particular, these can be applied to printed circuit boards.

Advantageously, there are white emitting LEDs. However, in alternative embodiments, green, red or IR LEDs may also be used.

One way of operating the light sources is constant operation, which, however, severely limits the life of white LEDs since LEDs are subject to aging. A better alternative is the stroboscopic operation, which in addition to a longer life also to a lower heat development results. The stroboscopic operation must be correlated with the images of the line cameras. As a result, the stroboscopic operation may be defined such that the LEDs do not light each other when the conveyor belt 10 is stationary.

Optionally, pure polarization filters can be provided in front of the LEDs to reduce reflections. In addition to juxtaposed LED's also discrete LED's with superior optics can be used. Thus, the light output of the LEDs can be bundled in the predetermined direction, so that there is a uniform light over the entire width of the conveyor belt. The housing 26 is particularly compact and splash-proof, since only one opening (a slot) is provided for the entry of the light rays corresponding to the plane 33. This opening can also be covered with glass. Such a spray water protection is associated with the term "wash down" or standard IP67 for the person skilled in the art.

As is apparent from the above, the corresponding system is independent of the other means used in the packaging plant. This applies both to the type of conveyor belt 10 and the upstream supply units or downstream gripper or pick and place robots. In particular, due to the advantageous optical conditions always a same mounting height of the modules 25, 30, 35 is possible, so that the system can be used both for different installation widths of the band as well as for different cargo 12, which may have a wide range of heights.

The invention also permits minimization of perspective errors without requiring full camera coverage of the transverse direction of the conveyor belt 10. Such a picture requires the smallest possible angle of view. For a given image size, therefore, the focal length must be maximized. This leads by the reverse proportionality to an increase in the working distance.

Claims

claims

1. A device for optically detecting piece goods (12), which are ordered or randomly guided on a conveyor (10), with at least one image pickup unit

(40), with which on the conveyor (10) supplied piece goods (12) are detectable, characterized in that in a the image pickup unit (s) (40) receiving housing (16, 26) in the beam path of the image pickup unit (s) (40) at least one mirror (41, 42, 43, 44) is arranged with which the beam path (s) of the image pickup unit (s) (40) are deflectable to the in the housing (16, 26) extending beam paths (31, 32, 131, 132, 33) longer than a vertical dimension of the housing (16, 26) form.

2. Apparatus according to claim 1, characterized in that the housing has a closed housing (16, 26) with an oblong cuboidal shape or a cuboidal grid structure or that of the image recording unit (40) and the one or more mirrors (41, 42, 43, 44 ) and the associated beam paths (31, 32, 131, 132, 33) is surrounded space.

3. Device according to one of claims 1 or 2, characterized in that the image recording unit (s) (40) comprise linearly formed image sensors, which are arranged obliquely or transversely to the transport direction (11) of the conveyor (10).

4. Apparatus according to claim 3, characterized in that a plurality of image recording units (40) obliquely at intervals or transversely to the transport direction (11) of the conveyor (10), in particular at approximately constant distances from each other, are arranged.

5. Device according to one of claims 3 or 4, characterized in that at least one linearly formed lighting unit (13, 14) is provided, which is arranged parallel to the linearly formed image sensors.

6. Apparatus according to claim 5, characterized in that on both sides of the transition of the beam path between within

(33) and outside (33 ') of the housing (16, 26) each have a lighting unit (13, 14) is arranged.

7. Device according to one of claims 3 to 6, characterized in that the beam paths (33 ') juxtaposed image recording units (40) in the region of the transport plane (10) overlap (33').

8. Apparatus according to claim 7, characterized in that an image processing system (50) is provided, with which the overlapping beam paths (34) are connectable to a composite image.

9. Device according to one of claims 1 to 8, characterized in that the image pickup unit (40) in the lower region of the housing (16, 26) and is aligned upward, and that the beam paths (31, 32, 33) spaced over two Mirror (41, 42) in the upper region of the housing (16, 26) are foldable twice.

10. The device according to claim 9, characterized in that the mirrors (41, 42) are arranged obliquely, in particular at 45 degrees relative to the transport plane (10).

11. Device according to one of the preceding claims, characterized in that the image recording units (40) are line scan cameras for monochrome or multicolored light.

12. Device according to one of the preceding claims, characterized in that each illumination unit (13, 14) consists of light-emitting diodes.

13. The apparatus according to claim 12, characterized in that the lighting units (13, 14) are provided with polarizing filters.

14. Device according to one of the preceding claims, characterized in that the housing (16, 26) is substantially closed and in particular "washdown" compliant (IP67) is executed.

15. Use of a device according to one of claims 1 to 14 in a production line for controlling downstream gripper devices.