Automatic milking of animals is known and disclosed in e.g.

EP-A-91 892. The automatic milking takes place in one or more combined feeding and milking stalls provided in a barn in which the animals are allowed to walk about freely and find their way voluntarily to the stalls for feeding, drinking and milking. The animals, voluntarily entering the milking stall, are automatically identified with the aid of a computer connected to identification means. By means of the computer, in which facts concerning each animal, when it was last milked, etc. are stored, an automatic handling device is activated to pick up the teatcups of a milking machine and attach them to the teats of the animal. The stall also comprises retaining gates which are automatically closed to retain the animal during milking and opened to let the animal leave the stall.

One problem in connection with such automatic milking is to determine whether an animal is present in the milking stall.

It is known to provide the animal with a so called transponder emitting a signal by which it is possible to detect when the animal enters the milking stall. However, such a transponder system is rather complicated and

expensive, and implies that the animal carries such a transponder. It is also known to provide a light beam and a photocell in the milking stall, and when said beam is interrupted by an animal a signal is generated. However, such photocell systems are rather sensitive to dirt, and therefore may not work satisfactorily.

A further problem in connection with such automatic milking is to determine the position of the teats of the animal being present in the stall in order to enable said attachment. A number of different solutions has been proposed to solve this problem. Thereby, one may differ between forcing systems and searching systems. Forcing systems are based on the idea of forcing, for example by physically pushing, the animal to a determined position in the milking stall and in which the teats then may be found by means of a sophisticated search equipment, for example including a video camera and image processing. Search systems are based on the idea that the animal may stay in any position in the milking stall and it is the task of the search system to determine the position of the animal.

Thereby, a rough determining of the position of the animal may first be performed and from this rough position the position of the teats may be determined by means of a more sophisticated search equipment. Such search systems are advantageous in connection with voluntary milking described above, since it is important for the functioning of such a milking concept that the animals are encouraged to enter the milking stall and therefore forcing the animal should be avoided as far as possible.

Furthermore, in connection with automatic milking it is known to determine the position of a cow being present in the milking stall by means of a device comprising spring biased arms abutting the cow and following her movements.

Such a device functions for the determining of a rough

position of the animal, from which position the teats of the animal then may be found by a more sophisticated search equipment. However, such devices are mechanically very complex with many moving elements, and therefore they are subjected to wear and the reliability thereof is not satisfying. Moreover, cows being fairly strong easily may damage such arms; a mere bending thereof results in an inaccurate measurement of the animal position.

SUMMARY OF THE INVENTION The object of the present invention is to overcome the disadvantages mentioned above and provide a way of monitoring an animal in a space.

This object is obtained by means of the apparatus initially defined which is characterized by at least a first conduit means provided to produce a flow of a fluid and having an outlet provided to direct said flow into said space, a first sensor provided to sense a fluid-related variable of the flow, and a processing unit adapted to determine the presence of an animal in said space in response to said sensor. By means of such an apparatus it is possible to determine in an effective and reliable way the presence of an animal in a space, for example a milking stall, a feeding stall, stall for other treatment of the animal, an animal passage, etc. Such a presence determination may be performed by sensing a first value of said variable when an animal is not present and a second value when an animal is present.

The constructive structure of the apparatus according to the invention is not very complicated, and therefore the apparatus has a high reliability and it will not be subjected to any extensive wear. Furthermore, the determining of the presence of the animal may be performed very quickly by means of the apparatus.

According to an embodiment of the present invention, a second conduit means is provided to produce a flow of a fluid and having an outlet provided to direct said flow into said space in a direction opposite the direction of the flow produced by the first conduit means and by a second sensor provided to sense a fluid-related variable of the flow in the second conduit means.

According to a further embodiment of the present invention, said second sensor comprises a pressure sensor adapted to sense the pressure of the flow in the second conduit means.

Moreover, said first sensor may comprise a pressure sensor adapted to sense the fluid pressure in the first conduit means. Thereby, each of the first and second conduit means may comprise a flow control device adapted to produce an essentially known flow through the outlets of the first and second conduit means. In this case, each of the flow control devices may be adapted to produce such a flow through the outlets of the first and second conduit means, respectively, that the pressures sensed by the first and second pressure sensors are essentially equal. Thereby, a measuring device giving the pressure difference between the pressures from the first and second pressure sensors may be of a less complicated construction and need only be adapted to exactly register when the pressures are equal. According to a further embodiment, the flow through the outlets of the first and second conduit means may be essentially equal. In this case the difference in the pressure sensed by the first and second pressure sensors may be utilized for the determining of the animal position.

According to another embodiment of the present invention, said second sensor is adapted to sense the flow rate of the fluid in the second conduit means. Moreover, said first sensor may be adapted to sense the flow rate of the fluid in the first conduit means. In this case, the first and second

conduit means may comprise a pressure control device adapted to control the pressure of the fluid in the first and second conduit means. In particular, such a pressure control device may be adapted to produce an essentially equal pressure of the fluid in the first and second conduit means. This may be obtained by conduit means having essentially identical dimensions and said common pump, or by a pressure regulating device at each conduit means.

According to a further embodiment of the present invention, the processing unit is adapted to determine the position of an animal part of the animal in said space. Such a position determination may be performed in a quick and reliable manner, i.e. the apparatus will respond almost immediately to any movements of the animal. In connection with one single sensor, the value of said variable may be used to calculate the distance from the outlet to said animal part.

Since the position of the outlet is known the position of said animal part may be determined. In this case, the positioning determination technique is based on the fact that a certain value of the variable corresponds to a certain distance between the outlet and said animal part.

Furthermore, the processing unit may be adapted to compare a first value and a second value of said variable and by means of said comparison the position of said animal part may be determined. In the case of one single sensor the first and second values may be sensed at different points of time, enabling not only to determine the position of the animal part but also to monitor the movement of the animal in said space. In connection with said first and second sensors, the position of the animal may be determined merely by means of the difference between the value of said variable of the first and second conduit means. Thereby, the processing unit may be less complex and no complicated calibrating of the apparatus is required. Thereby, the processing unit may be adapted to compare the value of said variable of the first

and second sensors and by means of said comparison determine the position of said animal between the first and second outlet. It should be noted that the movement of the animal also may be monitored in the case of two sensors by comparing the values of said variable over the time.

Preferably, the flows from the outlets of the first and second conduit means are directed into the space along a common axis essentially perpendicular to a longitudinal axis of said space and the processing unit is adapted to determine the position of the animal in relation to said longitudinal axis.

According to a further embodiment of the present invention, means are provided for performing an animal-related action regarding said animal being present in said space. Said performing means may comprise an automatic handling device and animal-related means to be handled by said automatic handling device and comprising at least one teatcup to be attached to a teat of said animal. Furthermore, enclosure means may define said space and have at least one passage permitting the animal to enter said space.

The object defined above is also obtained by the initially defined method characterized by the following steps - directing a flow of a fluid into said space, - sensing a fluid-related variable of said flow, and - determining the presence of an animal in said space in response to the variable sensed.

Preferred embodiments of the method according to the present invention are defined in the dependent claims 21 - 25.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be explained more closely by the description of different embodiments thereof and with reference to the drawings.

Fig 1 shows a view from above of a milking stall having a position determining apparatus according to a first embodiment of the present invention.

Fig 2 shows a view from above of a milking stall having a position determining apparatus according to a second embodiment of the present invention.

Fig 3 shows a view from above of a milking stall having a position determining apparatus according to a third embodiment of the present invention.

Fig 4 shows sectional side-view of a sensor of the third embodiment.

DETAILED DESCRIPTION OF DIFFERENT EMBODIMENTS With reference to Fig 1, there is disclosed a milking stall 1 for housing a cow to be milked. The milking stall 1 may be provided in a barn (not disclosed) housing many cows walking about freely. The milking stall 1 comprises enclosure means in the form of a surrounding grid device 2 defining a space in the milking stall 1. The grid device 2 comprises an inlet gate 3 and an exit gate 4. In connection to the milking stall 1, there is provided a milking machine, merely represented by a receptacle container 5, four milk conduits 6 and four schematically disclosed teatcups 7 to be attached to a respective teat of the cow being present in the milking stall 1. For said attachment, there is provided an automatic handling device 8 comprising an electronic control unit 9 and a robot arm 10 having gripping means 11 and a teat locating device 12, for example in the form of a video camera. Consequently, the robot arm 10 and the gripping means 11 may be controlled to grip successively a teatcup 7

and attach it to a teat of the cow. The automatic handling device 8 is provided on a support structure 13 and the automatic handling device 8 is movable relative to the support structure in a horizontal plane as indicated by the arrows 14.

In order to determine the position of a cow being present in the milking stall 1 there is provided a position determining apparatus comprising a first and second conduit means 15 and 16, respectively. The first and second conduit means are connected to a common inlet conduit 17 comprising a pump 18 provided to produce a fluid flow in the first and second conduit means. In the example disclosed the fluid is air.

Each of the first and second conduit means 15, 16 is provided with an outlet 19 and 20, respectively, which are adapted to direct the flow into the space of the milking stall 1. As may be seen from Fig 1 the outlet 19 is provided to direct said flow into the space of the milking stall 1 in a direction being essentially opposite the direction of the flow from the outlet 20. Preferably, the flows from the outlets 19, 20 are essentially directed into the milking stall 1 along a common axis 21 being essentially perpendicular to a longitudinal central axis 22 of the milking stall 1. Each of the first and second conduit means 15, 16 comprises a flow control device 23 and 24, respectively, which in the example disclosed in Fig 1 each comprises a throttling means. By such a throttling means it is possible to obtain an essentially identical air flow in the first and second conduit means 15, 16. It should be noted that the throttling means 23, 24 may be replaced by active flow control devices. Furthermore, there is provided in each of the first and second conduit means 15, 16, a first pressure sensor 25 and a second pressure sensor 26, respectively. The first and second pressure sensors 25, 26 are connected to a comparing means 27 adapted to deliver the difference or the ratio between the pressures sensed by the

first and second pressure sensors 25, 26 to a processing unit 28. For the co-ordination of the operation of the position determining apparatus and the automatic handling device 8, there is provided a connection 29 between the processing unit 28 and the control unit 9.

When a cow is present in the milking stall an air flow is directed to the respective sides of the cow from the outlets 19, 20. Since the air flow will be hindered by the body of the cow, the pressure in the air flow will increase. The pressure increase is dependent on the distance between the outlets 19, 20 and the cow, such that a smaller distance therebetween will result in a higher pressure increase.

Consequently, if a pressure increase is detected by at least one of the sensors 25, 26, such an increase is an indication that an animal is present in the milking stall 1.

Furthermore, if the cow is positioned exactly in the centre of the milking stall 1 the pressure increase sensed by the first and second pressure sensors 25, 26 will be equal.

Therefore, a difference signal from the comparing means 27 will be zero and by means of this value the processing unit 28 may calculate the position of the cow in the milking stall 1. Consequently, by means of general information or information stored about each individual cow it is possible, by means of the processing unit 28 and the control unit 9, to calculate the position of each teat of the cow. By means of this information the automatic handling device 8 may be moved along the arrows 14 to an appropriate position in which a teatcup 7 may be attached to a teat of the cow by the robot arm 10. If the cow is moving this will immediately be recognized by the position determining apparatus according to the present invention and thus such movement may immediately be compensated for by moving the automatic handling device 8 in relation to the support structure 13.

Alternatively, the position determining apparatus according to the present invention may be used to calculate roughly

the position of the teats, and from this position the teat locating device 12 more accurately determines the position of a teat for said teatcup attachment.

Fig 2 shows a second embodiment of the position determining apparatus according to the present invention. It should be noted that elements of the different embodiments having a corresponding function are provided with the same reference signs. The second embodiment differs from the first embodiment essentially in that the throttling means 23, 24 are replaced by adjustable control valves 30, 31. The control valves 30, 31 are connected to the processing unit 28. In the second embodiment the air flow in each of the first and second conduit means 15, 16 is adjusted such that the pressure difference sensed by the first and second pressure sensors 25, 26 is zero. By means of the information regarding the opening degree of the control valves 30, 31 the processing unit 28 may determine the position of the cow in the milking stall 1.

Moreover, the second embodiment comprises a teat locating device in the form of a conduit means 32 connected to the common inlet conduit 17 to produce a fluid flow therein. The conduit means 32 has an outlet 33 provided to direct said flow towards the udder and the teats of the animal being present in the stall. A pressure sensor 34 is provided to sense the pressure of the fluid. By means of the processing unit 28, the position of a teat then may be accurately determined in response to said pressure sensed.

Furthermore, the second embodiment comprises extendible first and second conduit means 15, 16. By means of a first and second driving member 35, 36 the first and second outlets 19, 20, respectively may be moved axially along the axis 21 in the direction towards the animal being present in the stall 1. Thereby, it is possible to minimize the

distance between the outlets and the animal and consequently to obtain a high accuracy of the determined position.

Moreover, it is advantageous that the outlets may be withdrawn from the stall, especially during entry and departure of the animal. Preferably, the driving members 35, 36 are moving the outlets 19, 20 an equal distance in order to obtain an equal pressure fall in each of the first and second conduit means 15, 16.

In the embodiments disclosed, the outlets 19, 20 are provided in the form of a linear pipe directed along the axis 21. It should be noted that the outlets 19, 20 may be provided at the height of the body of an animal in order to enable the position determination of the animal, or at the height of the udder in order to enable the position determination of the udder of the animal present in the stall 1. The pump 18 should be controlled to produce an air flow with a relatively low velocity, such that the flow may be laminar. It should be noted that the outlets 19, 20, 33 also may comprise more complicated nozzles. The pressure sensors 25, 26, 34 may be of any conventional type. They may be provided as disclosed inside the pipe but may also be provided just outside the outlets 19, 20, 33.

Fig 3 discloses a third embodiment which differs from the first and second embodiments in that the pressure sensors 25, 26 have been replaced by sensors 37, 38 for sensing the volume flow rate. Fig 4 discloses an example of such a volume flow rate sensor 37, 38 having a propeller 39 and a measuring device 40 measuring the rotational speed of the propeller 39, said speed being proportional to the volume flow rate of the fluid in the conduit means. According to the embodiment disclosed in Fig 3, the first and second conduit means 15, 16 have identical dimensions and the pump 18 is symmetrically positioned with respect to the first and second conduit means 15, 16. Consequently, the pressure fall

in each conduit means 15, 16 will be equal so that the flow rate values obtained by the sensors 37, 38 are comparable.

It should be noted, that each of the first and second conduit means 15, 16 may comprise a pressure control device (not disclosed) adapted to control the pressure of the fluid in the first and second conduit means to a known level.

Preferably, the pressure control device is adapted to produce an essentially equal pressure of the fluid in the first and second conduit means. The volume flow rate values are compared and processed in a corresponding manner as the pressure values in order to determine the position of the animal.

The present invention is not limited to the embodiments disclosed herein but may be modified within the scope of the following claims. Although the present invention has been explained in connection with a milking stall it should be understood that the inventive idea also may be applied to other animal-related actions, where it is desired to determine the presence, the position of the animal, or the position of an animal part. The present invention may be applied to other animals than cows, for example sheep, goats, horses, buffaloes.

Although the present invention has been explained for the determining of the position of a cow in a milking stall, it should be noted that the apparatus disclosed in all the above embodiments also may be utilized for detecting the presence of a cow in the milking stall or in any other place where such detection would be desired. This may easily be accomplished due to the fluid pressure increase or fluid flow rate decrease, which occurs when a cow is hindering the air flow from the outlets 19, 20, 33.

The sensors may not only include pressure sensor or volume flow rate sensors but also other sensors for sensing a fluid-related variable, e.g. a mass flow rate sensor. Also the pressure sensor 34 may be replaced by another type of sensor for sensing a fluid-related variable.

It should be noted that the present invention also applies to a position determining apparatus merely including one conduit means 32, one outlet 33, and one sensor 34, such as the teat locating device disclosed in Fig 2, and that such a device also may be used to determine the position of other animal parts than the udder and the teats of an animal or the presence of an animal.

Moreover, it should be noted that similar conduit means, outlets and pressure sensors may be provided also in the front end and the back end of the milking stall 1, in order to determine the position of a cow along the central axis 22.