WO2010023121A2

WO2010023121A2 - Arrangement and method for determining positions of the teats of a milking animal

Info

Publication number: WO2010023121A2
Application number: PCT/EP2009/060581
Authority: WO
Inventors: Bohao Liao; Uzi Birk; Emil HÄLLSTIG
Original assignee: Delaval Holding Ab
Priority date: 2008-08-29
Filing date: 2009-08-14
Publication date: 2010-03-04
Also published as: WO2010023121A3

Abstract

An arrangement for determining positions of the teats of a milking animal (8) is provided in a milking system (3) including a robot arm (15) for automatically attaching teat cups (11) to the teats of a milking animal and a control device for controlling the movement of the robot arm based on determined positions of the teats of the milking animal. The arrangement comprises a light source and speckle generating arrangement (12, 13), a camera pair (21), and image processing means (22). The light source and speckle generating arrangement is provided for illuminating the udder of the milking animal by light having a speckle pattern. The camera pair is provided to repeatedly record image pairs of the udder of the milking animal while being illuminated by the light having the speckle pattern. The image processing means is provided for repeatedly detecting the teats of the milking animal and determining their positions by a stereoscopic calculation method based on the repeatedly recorded image pairs.

Description

ARRANGEMENT AND METHOD FOR DETERMINING POSITIONS OF THE TEATS OF A MILKING ANIMAL

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to dairy farm robot milking and to automatic attachment of teat cups related thereto.

DESCRIPTION OF RELATED ART AND BACKGROUND OF THE INVENTION

WO 2005/094565 discloses an arrangement for determining positions of the teats of an animal in a robot-based milking system. The arrangement comprises a camera pair directed towards the teats of the animal for repeatedly recording pairs of images, and an image processing device for repeatedly detecting the teats of the animal and determining their positions by a stereoscopic calculation method based on the recorded pairs of images. The image processing device may be provided to initially determine the absolute position of a teat of the milking animal in a coordinate system of the milking system, and to later determine the position of the teat of the milking animal relative to the robot arm or the teat cup repeatedly, wherein the position of the teat of the milking animal relative to the robot arm or the teat cup is more exact than the absolute position. The camera pair may be comprised of a pair of thermal or infrared cameras.

A drawback of the approach disclosed in WO 2005/094565 is that the stereo vision measurements are very difficult to perform in a milking environment; it is non-clean and dirt may easily settle on camera lenses and deteriorate images recorded.

Further the milking animals are moving, and teats may not be visible to the cameras due to self-occlusion.

Still further, both color and texture of the teats are similar to those of the rest of the udder, which means that teat detection will be an arduous task: the contrast is low and color filters are of no use. The situation is even more complicated by the fact that the size, shape, color structure, morphological structure and texture may vary quite much from animal to animal.

SUMMARY OF THE INVENTION

High capacity automatic milking requires attachment of teat cups at a very high speed. A goal is to reduce the teat cup attachment procedure to fractions of a minute. This is hardly achievable by the above described prior art teat detection approach.

Accordingly, it is an object of the present invention to provide a stereo vision based arrangement and method for determining positions of the teats of a milking animal in a milking system, which arrangement and method alleviate at least some of the problems and drawbacks of the prior art as set forward above.

It is a particular object of the invention to provide such an arrangement and method, which improves the matching of images in each image pair recorded.

It is a further object of the invention to provide such an arrangement and method, which are robust, effective, fast, precise, accurate, reliable, safe, easy to use, and of low cost.

It is still a further object of the invention to provide such an arrangement and method, which are capable of obtaining a very high number of correct teat cup attachments at high speed.

These objects among others are, according to the present invention, attained by arrangements and methods as claimed in the appended patent claims.

According to one aspect of the invention, an arrangement for determining positions of the teats of a milking animal is provided in a milking system including a robot arm for automatically attaching teat cups to the teats of a milking animal and a control device for controlling the movement of the robot arm based on determined positions of the teats of the milking animal. The arrangement comprises a light source and speckle generating arrangement, a camera pair, and image processing means.

The light source and speckle generating arrangement is provided for illuminating the udder of the milking animal by light having a speckle pattern, preferably a steady or constant speckle pattern. The camera pair is provided to repeatedly record image pairs of the udder of the milking animal while the udder of the milking animal is illuminated by the light having the speckle pattern. The image processing means is provided for repeatedly detecting the teats of the milking animal and determining their positions by a stereoscopic calculation method based on the repeatedly recorded image pairs.

Preferably, the image processing means is provided, in the stereoscopic calculation method, to align the images of each of the repeatedly recorded image pairs to one another based on the speckle pattern as found on the udder of the milking animal in the images, that is, the texture patterns generated on the udder and teats of the milking animal is used to improve speed, accuracy and reliability of the provided stereo vision.

By such arrangement, the control device may control the robot arm very fast and accurately. The stereo vision measurements, which employ speckle light illumination of the udder of the milking animal and the subsequent processing of the measurement data provide high quality information extremely fast and as a result the milking system is capable of operating at higher speed. The milking time will be shorter and the throughput of animals is increased.

In one embodiment the light source and speckle generating arrangement comprises a coherent light source such as e.g. a laser, and a speckle pattern generating device arranged in front of the coherent light source. The speckle pattern generating device may comprise a fiber optic bundle, a holographic element, or a patterned filter arrangement.

In another embodiment the inventive arrangement is implemented in a rotary milking system, wherein the camera pair is located at a fixed position with respect to a floor, on which the rotary milking system is installed and with respect to which a rotary platform of the rotary milking system rotates during milking. By such provisions a single camera pair is capable of serving several or all of the milking stalls of the milking system. The fast operation of the inventive arrangement is required since the milking stalls are moving (rotating) with respect to the camera pair.

In such a milking system the position of the teat cups when being stored in e.g. a magazine, i.e. when not being used, may not be known. However, the camera pair of the inventive arrangement may be directed towards teat cups located in the magazine and provided to record image pairs of the teat cups.

Hereby, the image processing means is capable of detecting the teat cups and determining their positions in all three spatial dimensions in the magazine by the stereoscopic calculation method based on the image pairs of the teat cups.

In yet another embodiment of the invention the camera pair is mounted on the movable robot arm and the image processing means determines the positions of the teats of the milking animal in all three spatial dimensions relative the movable robot arm. Additionally positions for other objects such as legs, udders, bodies, magazines, and teats may be determined by the camera pair mounted on the movable robot arm.

In still another embodiment of the invention the camera pair is mounted in a fixed position with respect to the milking stall and the image processing means determines the positions of the teats of the milking animal in all three spatial dimensions relative the milking stall.

The camera pair may be located at a side of the milking animal and be directed essentially sideways, i.e., horizontally, towards the udder of the milking animal. Alternatively, the camera pair may be located below the milking animal and be directed upwards towards the udder of the milking animal.

The light source and speckle generating arrangement may be arranged fixed with respect to the camera pair, fixed with respect to the floor of a rotary milking system, or fixed with respect to a milking stall. The light source and speckle generating arrangement is preferably arranged for illuminating the udder with light having the speckle pattern in a direction which is essentially parallel with one of the optical axes of the cameras of the camera pair, but preferably the direction of the illumination and the optical axes of the cameras of the camera pair define acute angles.

The above positions/orientations of the camera pair and the light source and speckle generating arrangement seem to be the most favorable ones in order to fast locate the udder and the teats of the milking animals. The camera positions/orientations seem to provide the best contrast between the udder/teats and other objects in the view field of the cameras.

Further, the camera pair and/or the light source and speckle generating arrangement may be movable between several positions/orientations depending on the application or status of the camera pair and/or the light source and speckle generating arrangement.

Further embodiments of the inventive arrangement are set out in the dependent claims. According to a second aspect of the invention a method for determining positions of the teats of a milking animal is provided in a milking system of the above disclosed kind. According to the method the udder of the milking animal is illuminated by light having a speckle pattern. Image pairs of the udder of the milking animal are repeatedly recorded by a stereo vision system while the udder of the milking animal is illuminated with the speckle pattern. The teats of the milking animal are repeatedly detected and their positions are repeatedly determined by a stereoscopic calculation method based on the repeatedly recorded image pairs.

An advantage of the present invention is that the determination of the positions of the teats of an animal in all three spatial coordinates is made very fast. The invention provides in particular for the recording of image pairs of all visible teats, and the positions of all such teats may be determined simultaneously. Hence, teat cup attachment may be made very fast .

Further characteristics of the invention, and advantages thereof, will be evident from the following detailed description of preferred embodiments of the present invention given hereinafter and the accompanying Figs. 1-3, which are given by way of illustration only, and are thus not limitative of the present invention .

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1-3 display each a schematically outlined milking system including an arrangement for determining positions of the teats of a milking animal according to a respective embodiment of the present invention. Figs. 1 and 3 are top views while Fig. 2 is a perspective view.

DETAILED DESCRIPTION OF EMBODIMENTS In Fig. 1 is shown a milking system, in which an arrangement for determining positions of the teats of milking animals according to an embodiment of the invention is implemented. The rotary milking system 3 comprises a plurality of milking stalls 5, which milking animals 8 enter in a sequential order. Each of the milking stalls 5 comprises milking equipment including teat cups that are attached to the teats of the milking animal 8 present in the milking stall 5 prior to milking. For sake of simplicity teat cups 11 are illustrated only for one of the milking stalls 5. The rotary milking system 3 may be of parallel, tandem, or herringbone configuration. In the herringbone configuration, which is illustrated in Fig. 1, the longitudinal directions x of the milking stalls and of the milking animals 8 therein extends partly radially, partly circumferentially .

A robot 14 provided with a robot arm 15 is provided for automatically attaching teat cups 11 to the teats of the milking animals 8 present in the milking stalls 5 under the control of a control device 19, which is operatively connected to the milking robot 14. The milking robot 14 is preferably stationary with respect to a rotatable carousel or rotating platform 20 of the rotary milking system 3, which forms the support for the milking stalls 5. Alternatively, the milking robot 14 is movable back and forth in e.g. a circumferential direction.

The rotating platform 20 may, for each of the milking animals 8, be kept still while the milking robot 14 automatically attaches teat cups 11 to the teats of the milking animal 8, and is rotated there in between. Alternatively, the rotating platform is rotated continuously during the attachment of the teat cups 11 and the milking of the milking animals 8.

In order to determine positions of the teats of the milking animals 8 present in the milking stalls 5, and thus be capable of moving the teat cups 11 to the teats of the milking animals 8, a camera pair 21 and a light source and speckle generating arrangement 12, 13 are provided.

The camera pair 21 may comprise two CCD cameras arranged adjacent one another and directed towards the udder of a milking animal 8. Typically their optical axes are slightly non-parallel in order to view the object from two slightly different angles. The camera pair 21 is arranged to repeatedly record image pairs of the udder of the milking animal 8.

The light source and speckle generating arrangement 12, 13 comprises typically a coherent light source 12 such as e.g. a laser and a speckle pattern generating device 13 arranged in front of the coherent light source 12. The speckle pattern generating device 13 may comprise a fiber optic bundle, a holographic element, or a patterned filter arrangement.

The light source and speckle generating arrangement 12, 13 is directed towards the udder of the milking animal 8 and is arranged to illuminate the udder of the milking animal 8 by light having a speckle pattern during the repeated recordings of the image pairs.

Preferably, the speckle pattern of the light from the light source and speckle generating arrangement 12, 13 is steady or constant during the repeated recordings of the image pairs. The speckle pattern may be structured or random.

The light source and speckle generating arrangement 12, 13 has preferably a controllable light intensity and is strong enough to enable the camera pair 21 to differentiate the speckle pattern on the udder/teats of the milking animal 8 against background light. In particular, the light source and speckle generating arrangement 12, 13 may be arranged to adjust the intensity of its light in response to the color or light reflectivity of the udder/teats of the milking animal 8 and/or the distance between the camera pair 21 and the udder/teats of the milking animal 8.

The light source and speckle generating arrangement 12, 13 is preferably arranged for illuminating the udder of the milking animal 8 with the speckle patterned light in a direction which define acute angles with respect to the optical axes of the cameras of the camera pair 21.

Image processing means 22 is arranged to repeatedly detect the teats of the milking animal 8 and determine their positions by a stereoscopic calculation method based on the repeatedly recorded image pairs of the udder of the milking animal 8.

The image processing means 22 is arranged to align the images of each of the repeatedly recorded image pairs to one another based on the speckle pattern as found on the udder of the milking animal 8 in the images.

The image processing means 22 is preferably implemented as a software module in the control device 19, which thus is operatively connected to the camera pair 21, or in any other device operatively connected to the camera pair 21 and the control device 19.

The camera pair 21 and the light source and speckle generating arrangement 12, 13 may be mounted in fixed positions with respect to the different parts of the milking system 3 depending on the application in question. The camera pair 21 and the light source and speckle generating arrangement 12, 13 may be located at a fixed position with respect to a floor, on which the rotary milking system 3 is installed and with respect to which the rotary platform 20 of the rotary milking system 3 rotates during milking. In such instance, the camera pair 21 and the light source and speckle generating arrangement 12, 13 may be mounted in a ceiling of a building in which the milking system 3 is installed. Alternatively, the camera pair 21 and the light source and speckle generating arrangement 12, 13 are mounted on the rotating platform 20 or on the robot arm 15. Still alternatively, the camera pair 21 and optionally the light source and speckle generating arrangement 12, 13 are movable along some path. In one version, for instance, the camera pair 21 may be movable between a first position, in which the camera pair 21 is located during the detections of the image pairs, and a second position, in which the camera pair 21 is located there in between, that is, when being idle.

The camera pair 21 and the light source and speckle generating arrangement 12, 13 may further be located in a number of different positions and orientations depending on the application in question. The camera pair 21 and the light source and speckle generating arrangement 12, 13 may be located at a side of the milking animal 8 and be directed essentially sideways in the horizontal plane and perpendicular to a longitudinal direction of the milking animal 8. Alternatively, the camera pair 21 and the light source and speckle generating arrangement 12, 13 may be located below the milking animal 8 and be directed upwards.

Still further, two or more camera pairs 21 may be provided operatively connected to the image processing means 22 and the control device 19 in order to provide further detailed information of the positions and orientations of the teats of the milking animal 8.

For instance, several of the camera pairs 21 seem to be advantageous if they are not mounted fixedly on the robot arm 15 since at least one teat would always be obscured. Further, one or several camera pairs 21 arranged stationary on the floor or on the rotating platform 20 could be combined with one camera pair 21 mounted on the robot arm 15, or a single camera pair mounted on the robot arm 15 could be used in the invention.

The speed and accuracy of the arrangement for determining teat positions as provided by the invention are of outermost importance in order to provide a milking system 3 with accurate and fast automatic attachments of teat cups 11 to teats of milking animals 8. This is of particular importance in a rotary milking system 3 where not only the robot arm 15 for attaching the teat cups 11 is movable, but also the entire robot 14 may be movable. Further, the rotating platform 20 and the milking stalls 5 are moving (rotating) .

Since also the milking stalls 5 and the milking equipments belonging to the milking stalls 5 are moving it is typically not known - at least not in a fixed coordinate system - where the teat cups 11 are located, particularly when they are stored in a magazine (not illustrated in Fig. 1) in each of the milking stalls 11.

In a rotary milking system 3 it may be particularly difficult to find the magazines since they may appear in different positions in different milking stalls, and the position of a magazine in a milking stall may be stored only if the position of the milking stall is monitored.

The camera pair 21 of the inventive arrangement may thus be provided to record image pairs of the teat cups 11, particularly when the teat cups 11 are located in the magazine, and the image processing means 22 detects the teat cups 11 and determines their positions by the above calculation method based on the recorded image pairs of the teat cups 11 when being located in the magazine.

In another embodiment of the present invention the camera pair 21 may be used to establish a position of each of the milking animals 8 in at least one spatial dimension, e.g. a longitudinal direction x or in a direction perpendicular thereto, with respect to the milking stalls in which they are housed. Thus, the camera pair 21 is, for each of the milking animals 8, directed towards a leg or an outer contour of the milking animal 8 in the milking stall, wherein the camera pair 21 records an image pair of the leg or the outer contour of the milking animal 8. The image processing means 22 detects the milking animal 8 and determines its position in the spatial dimension by the calculation method based on the recorded image pair of the leg or the outer contour of the milking animal 8.

Such embodiment may be advantageous in a milking system 3 where a detection device is used to detect the teats 11 of a milking animal 8 in a milking stall based on the prior knowledge of where in the milking stall the milking animal 8 is located and possibly on the physical dimensions of the milking animal 8 itself .

Thus, the control device 19 may, for each of the milking animals 8, hold information in, or receive information from, a database 23 regarding the position of the udder of the milking animal 8 relative the milking animal 8 itself. This may be a single approximate figure valid for all the animals. Further, the control device 19 directs the camera pair 21 and controls the robot arm 15 of the milking robot 14 to move towards the udder of the milking animal 8 based on the information of the position of the at least one teat of the milking animal 8 relative the milking animal 8 itself, and on the detected position of the milking animal 8 in the spatial dimension relative the milking stall.

The information of the position of the at least one teat of the milking animal 8 relative the milking animal 8 itself may be deduced from the recording of visual detections of the milking animal 8 in connection with an earlier milking of the milking animal 8.

With reference next to Fig. 2, a further embodiment of the present invention will be described. The arrangement for determining teat positions is here implemented in a voluntary milking system or station 3 comprising an enclosure having an inlet gate 4a and an outlet gate 4b, which are both capable of being opened automatically. The front end of the milking station 3 is denoted by 3a, the back end is denoted by 3b, the sides are denoted by 3c and 3d.

The milking station 3 comprises further an automatic milking machine (not explicitly illustrated) including teat cups 11 connected to an end unit by means of milk lines (only the portions attached to the teat cups 11 are shown in Fig. 2) . The milking station further includes a milking robot 14 having a movable robot arm 15 provided with a gripper. The milking robot 14 is arranged to automatically apply the teat cups 11 of the milking machine to the teats of a milking animal 8 present in the milking station 3 prior to milking. In Fig. 2 three of the teat cups 11 are arranged in a teat cup rack or magazine 16, whereas the fourth one is held by the gripper of the robot arm 15. Typically, a teat cleaning device including e.g. a teat cleaning cup 24 or brushes 25 may be provided for cleaning the teats of the milking animal 8 prior to milking.

Further, the milking station 3 comprises an identification device (not illustrated) provided to identify a milking animal 8 approaching the milking station 3, and a control device 19, which is responsible for controlling of the milking system 3, which inter alia includes the initiation of various activities in connection with the milking such as e.g. opening and closing of the gates 4 and 5, and control of the milking machine and its handling device 14

The arrangement for determining teat positions comprises a camera pair 21 for repeatedly recording image pairs of the udder of the milking animal 8 and a light source and speckle generating arrangement 12, 13 for illuminating the udder of the milking animal 8 by light having a speckle pattern during the repeated recordings of the image pairs. Image processing means 22 of e.g. the control device 19 detects repeatedly the teats of the milking animal 8 and determines their positions by digital image processing including a stereoscopic calculation method based on the repeatedly recorded image pairs of the udder of the milking animal 8.

The camera pair 21 is mounted on the movable robot arm 15 of the milking robot 14 and the control device 19 is thus provided for determining the positions of the teats of the milking animal 8 in all three spatial dimensions relative the movable robot arm 15.

The inventive arrangement may further be arranged for determination of the positions and orientations of the teat cups 11, the teat cleaning cup 24, and the brushes 25.

Fig. 3 illustrates a further embodiment of the invention wherein the arrangement for determining teat positions is implemented in a voluntary milking system 3 of the above kind. Here, two camera pairs 21 are mounted in fixed positions with respect to the milking station 3. One camera pair 21 is arranged to record image pairs of the udder of a milking animal 8 from behind and one camera pair 21 is arranged to record image pairs of the udder of the milking animal 8 from a side. A light source and speckle generating arrangement 12, 13 is located between the camera pairs 21 and is provided for illuminating the udder of the milking animal by light having a speckle pattern during the repeated recordings of the image pairs by the two camera pairs.

The image processing means 22 of the control device 19, to which the camera pairs 21 are operatively connected, is provided for determining the positions of the teats of the milking animal 8 relative the milking station 3 based on image pairs recorded by the two camera pairs.

It shall be appreciated that the inventive arrangement for determining teat positions of the present invention may be implemented in virtually any kind of milking system where the teat positions need to be found automatically. There are many prior art techniques for determining the identities of milking animals, however, many of them being complex or requiring the providing of each of the milking animals to be identified with a transducer or tag.

This is eliminated by using the inventive stereoscopic measurement arrangement for animal identification. Thus, the camera pair 21 and the light source and speckle generating arrangement 12, 13 are directed towards a milking animal 8, or a part thereof. The light source and speckle generating arrangement 12, 13 is arranged to illuminate the milking animal 8 with light having a speckle pattern. The camera pair 21 is arranged to record a further image pair of the milking animal 8, or the part thereof. Finally, the image processing means 22 is arranged to image process the further image pair, which includes a stereoscopic calculation, and to determine the identity of the milking animal 8 based on comparisons between the image processed further image pair and (i) physical parameters characteristic for each of a group of milking animals or (ii) previously recorded images of each of the group of milking animals, wherein the milking animal 8, whose identity is to be determined, is comprised in the group of milking animals.

Preferably, the camera pair 21 is provided to record the image pair to be image processed as an image pair of the udder/teats of the milking animal 8 from a position below the udder of the milking animal 8. Alternatively, the camera pair 21 is positioned elsewhere and/or oriented differently.

The physical parameters characteristic for the milking animals may be found by detailed analysis of digital images of the milking animals, e.g. as recorded by the camera pair 21.

The above arrangement is less complicated than prior art systems. The milking animals have not to be provided with transducers or tags. A camera pair, which may already be provided for other purposes such as e.g. the above determination of teat positions, may be used for the identification. Thus, less equipment is needed for the achievement of a certain number of functions of the milking system.

Further, the above disclosed imaging technology provides for rapid and direct identification of milking animals.

Still further, the arrangement may be provided for detecting damaged or swollen teats or any other abnormal teat condition and to alert a dairy farmer of such condition.

It shall be appreciated that the above arrangement may be implemented in a milking system or a milking stall, but alternatively it may be implemented in a feeding station, at a gate arrangement, or elsewhere at a dairy farm.

In the prior art the weights of milking animals are typically determined by weighing devices, onto which the milking animals are led or guided. Such devices, however, are bulky and costly.

This is eliminated by using the inventive stereoscopic measurement arrangement for animal weighing. Thus the camera pair 21 and the light source and speckle generating arrangement 12, 13 are directed towards a milking animal 8 to be weighed. The light source and speckle generating arrangement 12, 13 is arranged to illuminate the milking animal 8 with light having a speckle pattern. The camera pair 21 is arranged to record a yet further image pair of the milking animal 8. Finally, the image processing means 22 is arranged to image process the yet further image pair, which includes a stereoscopic calculation, and to determine the weight of the milking animal 8 based on the image processed yet further image pair and a table which correlates dimensions or volumes with weights for the species or breed, to which the milking animal 8 belongs.

Preferably, the camera pair 21 is located above the milking animal 8 and is directed downwards towards the milking animal 8. The camera pair 21 may be located at an angle with respect to a vertical plane parallel with a longitudinal direction of the milking animal 8.

In one version, the arrangement comprises a second camera pair (not illustrated) directed towards the milking animal 8, wherein the camera pairs are provided to record image pairs of the milking animal 8 at different view angles, wherein the image processing device 22 is provided to digitally process the recorded image pairs and to determine the weight of the milking animal 8 based on the digitally processed image pairs and the table which correlates dimensions with weights for the breed, to which the milking animal 8 belongs.

Alternatively, the image pairs of the milking animal 8 at different view angles may be recorded by a single camera pair, which is movable between at least two positions. For instance, the camera pair may be movable between two positions located at each side of a vertical plane parallel with a longitudinal axis of the animal.

The above arrangement is less bulky than a conventional weighing device and the arrangement may be used for other purposes as well. The arrangement may be implemented at any location of a dairy farm.

It shall be noted that the above arrangement may be arranged for determining or calculating a body score index (BSI) , which may be used as a parameter related to the health of the milking animal. While any of the above described camera locations may be used for body score index determinations, it seems like that locating the camera pair above the milking animal at an angle with respect to a vertical plane parallel with a longitudinal direction of the milking animal and directing the camera pair diagonally downwards towards the milking animal is a preferred option. By placing the camera pair so that the important body parts for body score index may be exposed and then making a computer "cut out" of the model, a calculation of the volume may be made. From a reference value for each milking animal stored in a database, a current body score index may be determined.

It shall be appreciated by a person skilled in the art that various features of the above embodiments may be combined to form yet further embodiments of the present invention.

Claims

1. An arrangement for determining positions of the teats of a milking animal (8) in a milking system (3) comprising a robot arm (15) for automatically attaching teat cups (11) to the teats of a milking animal when being located in the milking stall, and a control device for controlling the movement of said robot arm based on determined positions of the teats of the milking animal, said arrangement comprising:

- a camera pair (21) provided to repeatedly record image pairs of the udder of the milking animal;

- image processing means (22) provided for repeatedly detecting the teats of the milking animal and determining their positions by a stereoscopic calculation method based on said repeatedly recorded image pairs, characteri zed in that said arrangement comprises

- a light source and speckle generating arrangement (12, 13) provided for illuminating the udder of the milking animal by light having a speckle pattern during the repeated recordings of the image pairs.

2. The arrangement of claim 1 wherein said image processing means is provided, in said stereoscopic calculation method, to align the images of each of said repeatedly recorded image pairs to one another based on the speckle pattern as found on the udder of the milking animal in the images.

3. The arrangement of claim 1 or 2 wherein the speckle pattern of the light is steady during the repeated recordings of the image pairs .

4. The arrangement of any of claims 1-3 wherein said light source and speckle generating arrangement (12, 13) comprises a coherent laser source (12) and a speckle pattern generating device (13) arranged in front of the coherent laser source.

5. The arrangement of claim 4 wherein said speckle pattern generating device (13) comprises a fiber optic bundle, a holographic element, or a patterned filter arrangement.

6. The arrangement of any of claims 1-5 wherein said light source and speckle generating arrangement (12, 13) is provided for adjusting the intensity of the light having the speckle pattern, preferably in response to a light reflectivity of the udder of the milking animal (8) and/or in response to a distance between the camera pair (21) and the udder of the milking animal.

7. The arrangement of any of claims 1-6 wherein

said camera pair and said a light source and speckle generating arrangement are directed towards teat cups located in a magazine (16) ;

the light source and speckle generating arrangement is provided for illuminating the teat cups with light having a speckle pattern;

- the camera pair is provided for repeatedly recording images of the teat cups; and

- the image processing means is provided for repeatedly detecting the teat cups and determining their positions by a stereoscopic calculation method based on said repeatedly recorded image pairs of the teat cups.

8. The arrangement of any of claims 1-7 wherein said arrangement is provided for determining positions of the teats of the milking animal in a rotary milking system.

9. The arrangement of claim 8 wherein said a camera pair is, during the recordings of image pairs, located at a fixed position with respect to a floor, on which said rotary milking system is installed and with respect to which a rotary platform of said rotary milking system rotates during milking.

10. The arrangement of any of claims 1-8 wherein

- said camera pair is mounted on said movable robot arm; and

- said image processing means is provided for determining the positions of the teats of the milking animal relative said movable robot arm.

11. The arrangement of any of claims 1-8 wherein

- said camera pair is mounted in a fixed position with respect to said milking stall; and

- said image processing means is provided for determining the positions of the teats of the milking animal relative said milking stall.

12. The arrangement of any of claims 1-11 wherein said camera pair and/or said light source and speckle generating arrangement are/is, during each of the recordings of said image pairs, located at a side of the milking animal and are/is directed essentially sideways.

13. The arrangement of any of claims 1-11 wherein said camera pair and/or said light source and speckle generating arrangement are/is, during each of the recordings of said image pairs, located below the milking animal and are/is directed upwards.

14. The arrangement of any of claims 1-13 wherein

- said camera pair and said light source and speckle generating arrangement are directed towards the milking animal, or a part thereof; the light source and speckle generating arrangement is provided for illuminating the milking animal, or the part thereof, with light having a speckle pattern;

- the camera pair is provided for recording a further image pair of the milking animal, or the part thereof; and

- the image processing means is provided for image processing the further image pair, which includes a stereoscopic calculation; and for determining the identity of the milking animal based on comparisons between the image processed further image pair and (i) physical parameters characteristic for each of a group of milking animals or (ii) previously recorded images of each of the group of milking animals, wherein the milking animal, whose identity is to be determined, is comprised in the group of milking animals.

15. The arrangement of any of claims 1-14 wherein

- said camera pair and said light source and speckle generating arrangement are directed towards the milking animal;

the light source and speckle generating arrangement is provided for illuminating the milking animal with light having a speckle pattern;

- the camera pair is provided for recording a yet further image pair of the milking animal; and

- the image processing means is provided for image processing the yet further image pair, which includes a stereoscopic calculation; and for determining the weight of the milking animal based on the image processed yet further image pair and a table which correlates dimensions or volumes with weights for the species or breed, to which the milking animal belongs.

16. A method for determining positions of the teats of a milking animal (8) in a milking system (3) comprising a robot arm (15) for automatically attaching teat cups (11) to the teats of a milking animal when being located in the milking stall, and a control device for controlling the movement of said robot arm based on determined positions of the teats of the milking animal, said method comprising:

- directing a camera pair (21) towards the udder of the milking animal in the milking stall and repeatedly recording image pairs of the udder of the milking animal by the camera pair;

repeatedly detecting the teats of the milking animal and determining their positions by a stereoscopic calculation method based on said repeatedly recorded image pairs, characteri zed by the step of :

- illuminating the udder of the milking animal by light having a speckle pattern during the repeated recordings of the image pairs by means of a light source and speckle generating arrangement (12, 13) .