WO2000004765A1

WO2000004765A1 - A device for automatically attaching a teatcup onto a teat of an animal

Info

Publication number: WO2000004765A1
Application number: PCT/SE1999/001303
Authority: WO
Inventors: Anders Gösta Axel BJÖRK
Original assignee: Alfa Laval Agri Ab
Priority date: 1998-07-24
Filing date: 1999-07-23
Publication date: 2000-02-03
Also published as: SE9802612D0; SE512611C2; AU5660499A; SE9802612L

Abstract

The present invention relates to a device and a method for automatically attaching a teatcup (8) onto a teat (19) of an animal, comprising a robot arm (4), a control means for controlling the movement of the robot arm (4), a source of structured light associated with said control means and being adapted to transmit said structured light towards said teat, an image capturing device associated with said control means and being adapted to capture images of at least one first light line (16') projected on said teat, a teatcup holding means (12) associated with said control means and being adapted to disengageably connect said teatcup thereto. According to the invention, said light source is adapted to transmit at least one second light line (18') towards said teatcup (8), said image capturing device being adapted to capture images of the second light line (18') projected on said teatcup.

Description

A device for automatically attaching a teatcup onto a teat of an animal

Technical background of the invention

The present invention relates to a device and a method for automatically attaching a teatcup onto a teat of an animal, comprising a robot arm, a control means for controlling the movement of the robot arm, a source of structured light associated with said control means and being adapted to transmit said structured light towards said teat, an image capturing device associated with said control means and being adapted to capture images of the first light line projected on said teat, a teatcup holding means associated with said control means and being adapted to disengageably connect said teatcup thereto.

Background of the invention

Such a device is known from WO 97/15900, in which a teat is located by projection of a laser plane. When the teat has been located, a teatcup is attached onto this teat.

Object of the invention

The object of the invention is to improve teatcup attachment.

Summary of the invention

This object has been achieved by a device of the initially defined kind, which is characterised in that said light source is adapted to transmit at least one second light line towards said teatcup, said image capturing device being adapted to capture images of the second light line projected on said teatcup. Hereby is achieved that not only the distance to the teat, but also to the teatcup is established, without utilisation of triangulation. Another advantage is that it is not needed that neither the image capturing device nor the source of structured light is arranged on the robot arm.

Preferably, during movement of said robot arm, said first light line is controlled to be projected on at least one teat, and said second light line is controlled to be projected on said teatcup. Hereby is achieved a full control of the teatcup attachment during the whole attachment sequence.

Suitably, said light source is adapted to simultaneously project one or several light lines on at least one teatcup and a plurality of teats. Hereby, it is possible to simultaneously identify several or all of the teats of the animal.

Suitably, said control means is adapted to establish a distance between said first light line and said second light line. Hereby, it is possible to establish the relative distance between the teat and the teatcup at every moment of the movement.

Preferably, said first line has a transversal extension, and said control means can be adapted to establish a first distance regarding said transversal extension when projected on the teat. However, when said second light line has a transversal extension, said control means can be adapted to establish a second distance regarding said transversal extension when projected on the teatcup.

Alternatively, a first pair of light lines are projected on said teat, and said control means can be adapted to establish a first distance between said first pair of light lines projected on the teat. However, when a second pair of light lines are projected on said teatcup, said control means can be adapted to establish a second distance between said second pair of light lines projected on the teatcup. Hereby, a better resolution is achieved. Preferably, said control means is adapted to establish a ratio of said first distance and said second distance, for moving said robot arm to a position where said ratio has a predetermined value. In particular, said value is substantially 1. Hereby, a precise positioning of the teatcup in relation to the teat is obtained.

Suitably, said control means is adapted to establish a third distance between said first light line or lines and said second light line or lines. Hereby, a relative distance is obtained during movement of the teatcup by means of the robot arm. The distance is established e.g. in millimetres or number of pixels of an image.

Preferably, said control means is adapted to establish a position of said first light line or lines in relation to a position of said second pair of light line or lines, for moving said teatcup with the robot arm to a point in space where said positions are symmetrical. Hereby, it is possible to establish whether a teatcup is correctly positioned in a vertical plane.

In particular, said positions are symmetrical when said first light line or lines are parallel to said second pair of at least one light line and a centrally arranged normal to said first pair of at least one light line coincide with a centrally arranged normal to said second pair of at least one light line. Hereby, is achieved a positioning of the teatcup straight underneath the teat.

Preferably, said light lines are each formed by transmission of a light plane, said light planes being divergent from the light source. Hereby, it is possible to establish which pair of teats is in front of the other, as the distance between the pairs of lines will depend on the distance from the light source.

Preferably, said light source is arranged on the robot arm. Additionally, or alternatively, said image capturing device is arranged on the robot arm. Hereby, a full control of the relative distances is achieved, as they are related to the movable robot arm.

Suitably, said source of structured light is a laser transmitter.

Preferable would be to use the apparatus here described as well as the method for carrying out the objects of the present invention in an automated milking system.

Drawing summary

The invention will now be described in more detail with reference to the accompanying drawings, in which:

Fig 1 illustrates an animal stall provided with a milking robot having a robot arm,

Fig 2 illustrates a teat locating means with a camera arranged on the robot arm,

Fig 3 illustrates a camera view of teats and a teatcup,

Fig 4 illustrates a computer view of teats and teatcup,

Fig 5 illustrates a second embodiment of the invention, and

Fig 6 illustrates a computer view according to the second embodiment.

Detailed description

Fig 1 shows an animal stall 2 provided with a robot arm 4 and a teatcup magazine 6 provided with four teatcups 8. The robot arm 4 is provided with an end portion 10 with a gripper 12 and a housing 14 for a teat and teatcup locating means. The movement of the robot arm is controlled by a control means (not shown) in response to the teat and teatcup locating means.

Fig 2 shows the end portion 10 of the robot arm 4 in more detail. The teat and teatcup locating means comprises one or two laser transmitters 14a, transmitting a first pair of diverging - upper and lower - laser planes 16 and a second pair of diverging - upper and lower - laser planes 18. The first pair 16 is above the second pair 18. The divergence is indicated in figure 2 by α_! and α₂, and the angle between the lowermost plane 16 and the uppermost plane 18 is indicated by β. It is preferable, that

= α₂.

When projected on a surface, the pairs of horizontal laser planes 16, 18 form pairs of horizontal parallel lines 16', 18'. As will be apparent below, it is^* desirable that the laser planes 16 are projected on a teat 19, and that the laser planes 18 are projected on a teatcup 8. A camera 14b, arranged in the housing 14, views in a predetermined direction, e.g. in the longitudinal extension of the robot arm.

The lines 18' created by the laser planes 18 projected on the teatcup 8 have an intermediate distance 20. Likewise, the pair of laser planes 16 projected onto the teat, creates lines 16' having an intermediate distance 22 regarding the front teats and 24 (compare with Fig 3) regarding the rear teats - due to the divergence 0 -, while assuming that both of the front teats are at the s.ame distance from the laser transmitter and that both of the rear teats are at the same distance from the laser transmitter. The lowermost plane 16 and the uppermost plane 18 have an intermediate distance 26.

When a teatcup is placed underneath a teat (compare with Fig 2), the distance 20 is preferably 5 to 15 mm, in particular 10 mm. The same relates to the distance 22. When a teatcup is ready to be attached to a teat, the distance 26 is preferably 3 to 7 mm, in particular 5 mm, provided that the lowermost line 16' is near the lower end of the teat 19, and that the uppermost line 18' is near the upper edge of the teatcup 8.

In Fig 3, a schematic representation of what is viewed by the camera 14b is shown. In this case, the pair of laser planes 16 projects four teats simultaneously.

In Fig 4 is shown the information used by an image processing system for performing calculations.

According to a second embodiment (see Fig 5 and 6), a relatively broad stripe of light is projected on the teats 19 and the teatcup 8. The transversal extension, i.e. between the outer edges 16', 16' or 18', 18', is possible to be established as distances 20, 22 and 24 (compare with the first embodiment), respectively.

It follows that in the second embodiment, the divergence αi and α₂ is the angle between the edges 16', and β is the angle between lowermost edge 16' and the uppermost edge 18'.

Operation

In order to allow milking of an animal, such as a cow, a sheep a goat, a horse or a buffalo to be automatically performed, the robot arm 4 fetches a teatcup 8 from the teatcup magazine 6 and moves it towards a region underneath a teat of the animal.

The image processing system measures the length of the lines or stripes 16' and 18' and establishes which ones belong to a rear teat, which is hereinafter named target teat. Thereafter, the distances 20 and 24 (or 20 and 22) are compared. When the teatcup is underneath a teat, the distances 20 and 24 (or 20 and 22) are substantially the same. When the teatcup has been placed somewhere underneath the target teat, it is needed to establish whether the teatcup has been placed straight underneath the target teat. This is performed by laterally moving the teat cup by means of the robot arm 4, until the lines or stripes 16' and 18' are symmetric ly underneath each other. The teatcup is now ready to be moved upwards towards the teat by means of the robot arm 4. When the teatcup has been moved upwards vertically to a predetermined distance from the teat, i.e. when the angle β has a niinimum value (or the distance 26 has a predetermined value), the interior of the teatcup is subjected to a vacuum, which causes the teat to be sucked into the teatcup. The gripper 12 of the robot arm releases the grip of the teatcup and allows the teatcup to be attached to the teat by the suction formed.

In order to attach the next teatcup onto a teat, a new target teat is chosen, and the procedure is repeated until all the teatcups have been attached to a corresponding teat.

It should be noted that teat location and teatcup attachment may be performed by projecting more than two planes 16 and two planes 18 on a teat and a teatcup, respectively. Also a combination of one plane 16 and two planes 18, or vice versa, would be possible to utilise.

It should also be noted that the laser transmitter or transmitters 14a may be arranged in or at the stall, instead of on the robot arm. Alternatively or additionally, the camera (or cameras) may be arranged in or at the stall, instead of on the robot arm. The reason for this is that there is no need for a triangulation regarding the positions of the camera, the laser transmitter and the teat or the teatcup.

It should furthermore be noted that the laser transmitter or transmitters may be substituted by any kind of source or sources of structured light, such as a lamp in front of a lens or a lens system and a slit. The line or stripe projected on the teat has been described as being created by transmitting a light plane. As an alternative, the projected line or stripe may be created by a laser beam, which is scanned in a horizontal plane.

The divergence angles

and α₂ may be compensated for parallax phenomena due to the angle β.

Claims

1. A device for automatically attaching a teatcup (8) onto a teat (19) of an animal, comprising, a robot arm (4), a control means for controlling the movement of the robot arm (4), a source of structured light associated with said control means and being adapted to transmit said structured light towards said teat, an image capturing device associated with said control means and being adapted to capture images of at least one first light line (16') projected on said teat, a teatcup holding means (12) associated with said control means and being adapted to disengageably connect said teatcup thereto, characterised in that said light source is adapted to transmit at least one second light line

(18') towards said teatcup (8), said image capturing device being adapted to capture images of the second light line (18') projected on said teatcup.

2. A device according to claim 1, characterised in that during movement of said robot arm, said first light line (16') is controlled to be projected on at least one teat (19), and said second light line (18') is controlled to be projected on said teatcup.

3. A device according to claim 1 or 2, characterised in that said light source is adapted to simultaneously project one or several light lines on at least one teatcup (8) and a plurality of teats (19).

4. A device according to anyone of claims 1 to 3, characterised in that said control means is adapted to establish a distance between said first light line (16') and said second light line (18').

5. A device according to anyone of the preceding claims, characterised in that said first line (16') has a transversal extension, said control means being adapted to establish a first distance (22, 24) regarding said transversal extension when projected on the teat, and said second light line (18') has a transversal extension, said control means being adapted to establish a second distance (20) regarding said transversal extension when projected on the teatcup.

6. A device according to anyone of claims 1 to 5, characterised in that a first pair of light lines (16', 16') are projected on said teat (19), said control means being adapted to establish a first distance (22, 24) between said first pair of light lines projected on the teat, and a second pair of light lines (18', 18') are projected on said teatcup (8), said control means being adapted to establish a second distance (20) between said second pair of light lines projected on the teatcup.

7. A device according to claim 5 or 6, characterised in that said control means is adapted to establish a ratio of said first distance and said second distance, for moving said robot arm (4) to a position where said ratio has a predetermined value.

8. A device according to claim 7, characterised in that said value is substantially 1.

9. A device according to anyone of the preceding claims, characterised in that said control means is adapted to establish a third distance (26) between said first light line or lines (16') and said second light line Or lines (18').

10. A device according to anyone of the preceding claims, characterised in that said control means is adapted to establish a position of said first light line or lines (16') in relation to a position of said second pair of light line or lines (18'), for moving said teatcup to a robot arm point in space where said positions are symmetrical.

11. A device according to claim 10, characterised in that said positions are symmetrical when said first light line or lines (16') are parallel to said second pair of light line or lines (18') and a centrally arranged normal to said first pair of light line or lines coincide with a centrally arranged normal to said second pair of light line or lines.

12. A device according to anyone of the preceding claims, characterised in that said light lines are each formed by transmission of a light plane, said light planes being divergent from the light source.

13. A device according to anyone of the preceding claims, characterised in that said light source is arranged on the robot arm (4).

14. A device according to anyone of the preceding claims, characterised in that said image capturing device is arranged on the robot arm (4).

15. A device according to anyone of the preceding claims, characterised in that said source of structured light is a laser transmitter.

16. A device according to anyone of the preceding claims, characterised in that said at least one teatcup is connectable to a pulsating vacuum and to a milk line.

17. A method of automatically attaching a teatcup (8) onto a teat (19) of an animal, comprising the steps of controlling the movement of a robot arm (4), transmitting from a light source structured light towards said teat, capturing images with an image capturing device of at least one first light line (16') projected on said teat, characterised by the further steps of transmitting at least one second light line (18') towards said teatcup (8), and capturing images of the second light line (18') projected on said teatcup.

18. Automated milking system, characterised in that said automated milking system comprises a device according to any of claims 1 to 16.

19.Automated milking system, characterised in that said automated milking system comprises means for carrying out a method according to claim 17.