Arrangement and method for controlling milking vacuum levels

Abstract

A milking arrangement and method of controlling a milking arrangement where a milking unit is configured to be attached to teats of a dairy animal during a milking operation. A vacuum supply system is arranged to provide a milking vacuum to the milking unit for extracting milk from the dairy animal. A sensor is configured to measure at least one property of milk, such as conductivity, extracted from the dairy animal and provide an output. A control unit is configured to control the vacuum supply system to provide a first milking vacuum level. The control unit is further configured to obtain the output from the sensor and control the vacuum supply system to change from the first milking vacuum level to a second milking vacuum level when at least one condition is fulfilled.

Description

[0001] ARRANGEMENT AND METHOD FOR CONTROLLING MILKING VACUUM LEVELS

[0002] TECHNICAL FIELD

[0003] The present invention relates to milking of dairy animals. More specifically the invention relates to a milking arrangement and a method for controlling milking vacuum levels.

[0004] BACKGROUND

[0005] During a milking operation, milk is extracted from a dairy animal by attaching teat cups to the teats of the dairy animal and applying, by means of a vacuum supply system, a milking vacuum to the teat cups for extracting the milk. Each teat cups comprises a liner wherein the liner is exposed to a pulsating vacuum which makes it open and close. The opening and closing of the liner massages the teats of the dairy animal which stimulates the teats and causes an oxytocin release. This activates the milk ejection reflex which results in milk letdown. The first milk to be extracted from the dairy animal is the cisternal milk which is followed by the alveolar milk. The transition between the cisternal milk and the alveolar milk can be a gradual transition, i.e. the extracted milk may be a mix between cisternal milk and alveolar milk.

[0006] During a milking operation, a modern milking machine typically applies a vacuum pressure level that varies over time in order to match the variations in milk flow from the dairy animal’s udder. For example, to instigate the milk flow, a so-called stimulation milking vacuum level may be applied. Shortly thereafter, it is expected that a considerable milk flow has been brought about, and therefore a standard milking vacuum level is applied. The milk extraction can be made even more efficient, if yet another milking vacuum level is introduced, namely a so-called boost vacuum, where the sub pressure is further increased in relation to the standard milking vacuum level, i.e. to a level even further below the atmospheric pressure. Analogously, when the milk flow decreases towards the end of the milking procedure, it is often preferable to reduce the vacuum pressure, i.e. adjust the sub pressure to a level closer to the atmospheric pressure, in order to not risk harming the dairy animal’s teats.

[0007] During the extraction of the cisternal milk, which is extracted prior to the alveolar milk, the milk flow is relatively low and thus the milking vacuum level should be low. During the extraction of alveolar milk the milk flow is higher and thus the milking vacuum level can be increased. So, during the milking operation the milk extraction starts with a milking vacuum at a first milking vacuum level and when the milk flow has increased and reached a threshold limit the milking vacuum is elevated, i.e. the sub atmospheric pressure is increased, to a second vacuum level. This elevated milking vacuum level may be a boost phase where the vacuum pressure is increased to preferably 48-60 kPa. When varying the vacuum pressure it is important that the variations are adequately timed, especially when boost vacuum is used.

[0008] Thus in the known solutions, the flow of the milk is used as an indicator for controlling the milking vacuum levels during the milking operation. Usually, the milk flow is measured by a milk meter.

[0009] SUMMARY

[0010] It is important that the milking vacuum level during the boost phase is not applied excessively or in inappropriate stages of the milking procedure. The object of the invention is to provide a solution that enables an animal-friendly, simple and efficient milking operation of the dairy animal where especially the milking time can be decreased.

[0011] There are differences in the constituent of the cisternal milk and the alveolar milk, e.g. the alveolar milk has a higher fat content than the cisternal milk. Other differences could be protein content, cell count, salinity etc.

[0012] Consequently, the cisternal milk and the alveolar milk has different intrinsic properties, e.g. different electrical properties like conductivity, different optical properties, etc. For example, the conductivity in the alveolar milk is lower than in the cisternal milk.

[0013] According to one aspect of the invention, the object is achieved by a milking arrangement comprising a milking unit configured to be attached to teats of a dairy animal during a milking operation. The dairy animal may be a dairy cow, but it can also be other dairy animals like sheep or goats etc. The milking arrangement may be an automatic milking arrangement consisting of e.g. at least one milking robot or it may be a conventional milking arrangement, e.g. a milking parlour. The milking arrangement may also be a rotary system. A vacuum supply system is arranged to provide milking vacuum to the milking unit for extracting milk from the dairy animal. A sensor is configured to measure at least one property of the milk, which may be any intrinsic property of the milk, extracted from the dairy animal and provide an output. The sensor measures the at least one property of milk, extracted from the dairy animal, during the milking operation. A control unit is configured to control the vacuum supply system to provide a first milking vacuum level. The control unit is further configured to obtain the output from the sensor, during the milking operation, and control the vacuum supply system to change from the first milking vacuum level to a second milking vacuum level when at least one condition, during the milking operation, is fulfilled.

[0014] The measurement of the sensor, the obtaining of the output from the sensor and the controlling of the vacuum supply system to change from the first milking vacuum level to a second milking vacuum level when at least one condition is fulfilled takes place during one and the same milking operation. This milking arrangement is advantageous because it enables a simple and efficient milking operation of the dairy animal. Further, the milking time of the dairy animal will decrease since the vacuum levels are adequately timed relative the milk ejection, especially relative the transition between cisternal and alveolar milk.

[0015] The term milking vacuum refer to a vacuum pressure, i.e. a sub atmospheric pressure. It should be noted that a zero value represents the atmospheric pressure level and a pressure level of larger vacuum magnitude is represented by a larger positive value than a pressure level with smaller vacuum magnitude.

[0016] The control unit is configured to obtain the output from the sensor and control the vacuum supply system to change from the first milking vacuum level to a second milking vacuum level when at least one condition is fulfilled. The condition being related to a value of the sensor output. The condition may be that the sensor output indicates that a change of the at least one property of milk extracted from the dairy animal exceeds a threshold value and / or when the at least one property of milk extracted from the dairy animal reaches a preset value. Hence, the control unit is configured to obtain the output from the sensor and control the vacuum supply system to change from the first milking vacuum level to a second milking vacuum level when the sensor output indicates that a change of the at least one property of milk extracted from the dairy animal exceeds a threshold value and / or when the at least one property of milk extracted from the dairy animal reaches a preset value.

[0017] The preset value being a predetermined value, a threshold, which the measurement from the sensor is compared with in real-time during the milking operation. The change exceeding a threshold value refers to a real-time determination, during the milking operation, where it is possible to determine if there is a sudden, abrupt, change of the at least one property of milk. The change exceeding a threshold value, i.e. the sudden change, may be determined by rate of change, time derivative, or by the difference between two values of the at least one property of milk exceeding a threshold. In one embodiment the two conditions are separate and only one of them may be used in the milking arrangement, i.e. when the sensor output indicates that there is a change of the at least one property of milk extracted from the dairy animal exceeding a threshold value or when the at least one property of milk extracted from the dairy animal reaches a preset value the control unit performs the action of changing from the first milking vacuum level to a second milking vacuum level. In another embodiment, the two conditions both needs to be fulfilled for the control unit to perform the action of changing from the first milking vacuum level to a second milking vacuum level, i.e. when the sensor output indicates that there is a change of the at least one property of milk extracted from the dairy animal exceeding a threshold value and when the at least one property of milk extracted from the dairy animal reaches a preset value.

[0018] The second milking vacuum level may be higher than the first milking vacuum level. In other words, the second milking vacuum level has a pressure level with larger vacuum magnitude than the first milking vacuum level.

[0019] The first milking vacuum level may be a stimulation phase where vacuum levels are preferably between 32-34 kPa and the second milking vacuum level may be a standard phase where the vacuum levels are preferably between 38-44 kPa.

[0020] The first milking vacuum level may be a standard phase where the vacuum levels are preferably between 42-44 kPa and the second milking vacuum level may be a boost phase where the vacuum levels are preferably between 42-60 kPa.

[0021] It is to be understood that one milking operation according to the invention could consist of a stimulation phase followed by a standard phase or a standard phase followed by a boost phase or all three phases, i.e. first a stimulation phase which is then followed by a standard phase which in turn is followed by a boost phase.

[0022] According to another aspect of the invention, the second milking vacuum level may be lower than the first milking vacuum level. Before detaching the milking unit the milking vacuum levels are decreased. This is referred to as the exit phase. During the exit phase the milking vacuum level is changed from a first, higher, milking vacuum level to a second, lower, milking vacuum level. In other words, the second milking vacuum level has a pressure level with lower vacuum magnitude than the first milking vacuum level. During the exit phase the milking vacuum level may be changed from the standard or boost phase to a second, lower, milking vacuum level. According to a further aspect of the invention, the milking operation could consist of a stimulation phase followed by a standard phase or a standard phase followed by a boost phase or all three phases and then followed by an exit phase.

[0023] According to one embodiment of the invention the at least one property of milk extracted from the dairy animal comprises conductivity. Since the value of the conductivity is different between the cisternal milk and the alveolar milk, this may be used as an indicator for the transition between cisternal and alveolar milk. Consequently, the conductivity is an indicator for when to change from the first milking vacuum level to the second milking vacuum level. This solution provides a simple and more efficient milking operation of the dairy animal where the milking vacuum levels are adequately timed to the milk ejection and thus leading to a decreased milking time.

[0024] Thus, when the at least one property of milk extracted from the dairy animal comprises conductivity the control unit is configured to obtain the output from the sensor and control the vacuum supply system to change from the first milking vacuum level to a second milking vacuum level when the sensor output indicates that there is a decrease of the conductivity of milk extracted from the dairy animal exceeding a threshold, i.e. a sudden decrease, and / or when the conductivity of milk extracted from the dairy animal reaches (i.e. falls below) a preset value.

[0025] The conductivity may be measured by any type of sensor configured to measure conductivity, such as comprising two or more electrode elements arranged in contact with the milk.

[0026] According to another embodiment of the invention the at least one property of milk extracted from the dairy animal comprises an optical property. Optical properties may be e.g. absorbance, color, reflectivity, scattering, turbidity etc. The sensor to measure the optical property may be an I R sensor, preferably a NIR sensor or a MIR sensor, or any other type of optical sensor configured to measure optical properties.

[0027] The sensor configured to measure at least one property of milk may be arranged at a teat cup of the milking unit, e.g. the sensor may be arranged at the mouthpiece or the barrel of a teat cup. This enables a reading of the milk directly after it has been ejected from the teats of the dairy animal. Thus, the second milking vacuum level may be triggered almost instantly when there is a change of the at least one property of milk extracted from the dairy animal exceeding a threshold and / or when the at least one property of milk extracted from the dairy animal reaches a preset value. This enables a more efficient milking operation of the dairy animal where the milking time will be decreased.

[0028] In another embodiment of the invention the milking unit comprises a milking cluster which comprises a plurality of teat cups, a central claw and a short milk tube extending between the central claw and the respective plurality of teat cups, wherein the sensor is arranged at the short milk tube or the central claw. This enables a more efficient milking operation of the dairy animal where the milking time will be decreased. This embodiment is used for udder milking.

[0029] In a further embodiment the milking unit comprises a plurality of teat cups each connected to a respective milk conduit, and wherein the milking arrangement comprises a plurality of sensors configured to measure at least one property of milk extracted from the dairy animal, wherein each of the sensors are arranged at a respective milk conduit. This enables a more efficient and individually controlled milking operation, e.g. during quarter milking, of the dairy animal where the milking time will be decreased.

[0030] The control unit may be configured to obtain an identity of the dairy animal, and the milking arrangement further comprises a storage unit configured to store the measurements of the at least one property of milk extracted from the dairy animal. This enables that the sensor measurements may be connected to a specific dairy animal and that the measurements of the at least one property of milk from that dairy animal may be stored. Due to this, a simple and more efficient milking operation is provided. The control unit is communicatively connected to the storage unit. The control unit may be configured to retrieve data from the storage unit so that the condition on when to change to the second milking vacuum level may be based on historical data from at least one previous milking operation.

[0031] The control unit may comprise a processing unit configured to perform all necessary calculations from the obtained sensor output.

[0032] The preset value can be determined by the stored measurements and the obtained identity of the dairy animal. The preset value may be based on individual historical data of the measured at least one property of milk extracted from the dairy animal, i.e. the preset value may be a specific value for individual dairy animals, or on common historical data of the measured at least one property of milk extracted from a plurality of dairy animals, e.g. the entire herd of dairy animals or a selected group of dairy animals. Thus, a simple and more efficient milking operation is provided. The preset value may be varied depending on the stored measurements from the last milking operation or on any number of previous milking operations. It is to be understood that when the preset value is based on common historical data of the measured at least one property of milk extracted from a plurality of dairy animals it is not necessary that the control unit obtains the identity of the dairy animals.

[0033] The milking arrangement may further comprise a milk meter configured to measure milk flow of milk extracted from the dairy animal. Then, the sensor registers a value of the at least one property of milk corresponding to a high milk flow, the high milk flow may be determined by a preset threshold limit. The preset value is based on that registered value, i.e. the value of the at least one property of milk registered by the sensor when the milk meter indicates a high milk flow. This solution will provide a simple and more efficient milking operation.

[0034] The preset value based on the registered value of the at least one property of milk corresponding to a high milk flow may be dependent on the obtained identity of the dairy animal and thus the preset value is based on individual historical data, i.e. the preset value is individually set. However, in another aspect, the preset value may also be based on measurements from a plurality of dairy animals and it is to be understood that then the preset value based on the registered value of the at least one property of milk corresponding to a high milk flow is not necessary dependent on that the control unit obtains the identity of the dairy animals.

[0035] All preset values may be adjusted depending on the stored measurements from the last milking operation or on any number of previous milking operations.

[0036] During the milking operation the measurements from the sensor measuring the property of milk are compared with the preset value in real-time during the milking operation.

[0037] In yet another aspect of the invention, measurements from the milk meter measuring the flow of milk and the sensor measuring the at least one property of milk may be taken separately but at approximately the same time and used in combination to determine when there has been e.g. a transition from cisternal to alveolar milk. Thus, they are both used as indicators, i.e. both a condition of milk flow and a condition of the at least one property of milk needs to be fulfilled for the control unit to change from the first milking vacuum level to a second milking vacuum level. Consequently, e.g. the change to the second vacuum level will start when the milk flow has reach a threshold limit and the sensor output indicates that the change of the at least one property of milk extracted from the dairy animal has exceeded a threshold and / or when the at least one property of milk extracted from the dairy animal reaches a preset value. This solution will provide a more efficient milking operation.

[0038] The milk flow may be determined by the milk meter or any other technic known to measure flow of liquid.

[0039] According to one further embodiment, the change of the at least one property of milk extracted from the dairy animal is determined by the time derivative of the at least one property of milk, or the rate of change or the difference between two values of the at least one property of milk, this will indicate when there is a sudden change of the at least one property of milk. The change corresponds to a real-time measurement, i.e. the at least one property of milk extracted from the dairy animal will be measured during the milking operation and the control unit will, during the same milking operation, control the vacuum supply system based on the change of the at least one property of milk extracted from the dairy animal exceeding a threshold. This enables a control of the vacuum supply system based on the present status of the dairy animal, i.e. the control of the vacuum supply system does not need to be based on historical data. The present status of the dairy animal may be e.g. a health status, mastitis for example may lead to a change in constituent of milk and then the measured milk properties will be affected. This embodiment will provide a simpler and more efficient milking operation.

[0040] The threshold for the change of the at least one property of milk extracted from the dairy animal may be determined by training a machine learning model to be able to determine when a sudden change for the at least one property of milk has occurred. The threshold may also be a predetermined threshold.

[0041] In a further aspect the control unit may be configured to change from the first milking vacuum level to the second milking vacuum level at a predetermined delay time after the at least one condition is fulfilled. For example, if the sensor is arranged adjacent to the teats of the dairy animal there may be a longer predetermined delay time. Hence, the further away from the teats that the sensor is arranged the shorter predetermined delay time before changing to the second milking vacuum level. This prevents the second milking vacuum level from being triggered too early in the milking operation. This provides a solution where the vacuum levels are adequately timed relative the milk ejection. Thus, providing a more efficient milking of the dairy animal.

[0042] According to another aspect of the invention, the object is achieved by a method of controlling a milking arrangement, the method comprising the steps of attaching a milking unit to teats of a dairy animal to be milked, providing a first milking vacuum level to the milking unit for extracting milk from the dairy animal, obtaining a measurement of at least one property of milk extracted from the dairy animal, changing from the first milking vacuum level to a second milking vacuum level when the obtained measurement fulfills at least one condition. This method is advantageous because it enables a simple and efficient milking operation of the dairy animal. Further, the milking time of the dairy animal will decrease. Further advantages of the method are described in relation to the milking arrangement disclosed herein.

[0043] The method may further be configured to perform the various embodiments of the milking arrangement as described herein.

[0044] BRIEF DESCRIPTION OF DRAWINGS

[0045] The invention is now to be explained more closely by means of preferred embodiments, which are disclosed as examples, and with reference to the attached drawings.

[0046] Figure 1 shows the milking arrangement for a milking operation performed on udder level.

[0047] Figure 2 shows the milking arrangement for a milking operation performed on quarter level.

[0048] Figure 3 shows the milking vacuum level over time when changing between two milking vacuum levels.

[0049] Figure 4 shows the milking vacuum level over time when changing between three milking vacuum levels.

[0050] Figure 5 shows the method of controlling the milking arrangement. DETAILED DESCRIPTION

[0051] Figure 1 shows a milking arrangement for udder milking with a milking unit 1 comprising a milking cluster 100, which milking cluster 100 comprises a plurality of teat cups 111, 112, 113, 114, a central claw 115 and short milk tubes 116, 117, 118, 119 extending between the central claw 115 and the respective plurality of teat cups 111, 112, 113, 114. The teat cups 111 , 112, 113, 114 are attached to a respective teat of an udder of a dairy animal. Milk is extracted from each of the teats of the dairy animal by applying a milking vacuum level P to the teat cups 111, 112, 113, 114. Each teat cups 111 , 112, 113, 114 comprises a liner (not shown) wherein the liner is exposed to a pulsating vacuum which makes it open and close. The opening and closing of the liner massages the teats of the dairy animal which stimulates the teats and causes an oxytocin release. The pulsating vacuum is not illustrated herein. The milking unit 1 is connected to a milk line 120 which leads the extracted milk to a milk tank (not shown). A sensor 121, 122, 123, 124 is configured to measure at least one property of milk extracted from the dairy animal. The sensor 121 , 122, 123, 124 is arranged in each of the short milk tubes 116, 117, 118, 119. Alternatively, the sensor 121, 122, 123, 124 may be arranged in one or several short milk tubes 116, 117, 118, 119, in one or several teat cups 111, 112, 113, 114, e.g. it may be arranged in the mouthpiece or in the barrel of the teat cup 111, 112, 113, 114, or it may be arranged in the central claw 115 or in the milk line 120. An optional milk meter 125 may be arranged in the milk line 120.

[0052] Figure 2 shows a milking arrangement with a quarter milking setup where the milking unit 2 comprising a plurality of teat cups 111, 112, 113, 114 each connected to a respective teat of an udder of the dairy animal. Each teat cup 111, 112, 113, 114 is connected to a respective milk conduit 211, 212, 213, 214. Milk is extracted from each of the teats of the dairy animal by applying a milking vacuum level P to the teat cups 111, 112, 113, 114 and the milk is extracted to a milk tank (not shown). A sensor 121, 122, 123, 124 configured to measure at least one property of the milk is arranged at each respective milk conduit 211, 212, 213, 214. This provides that each teat may be measured individually. Alternatively, the sensor 121, 122, 123, 124 may be arranged in one or several teat cups 111 , 112, 113, 114, e.g. it may be arranged in the mouthpiece or in the barrel of the teat cup 111, 112, 113, 114. An optional milk meter 215, 216, 217, 218 may be arranged in the respective milk conduit 211 , 212, 213, 214.

[0053] The at least one property measured by the sensor 121, 122, 123, 124 may be conductivity or an optical property of the milk. The sensor 121, 122, 123, 124 is communicatively connected to a control unit 126, via a wireless connection or a wired connection. The measurements measured by the sensor 121 , 122, 123, 124 are provided as an output, which output is obtained by the control unit 126.

[0054] The sensor 121, 122, 123, 124 may be a conductivity sensor comprising two or more electrode elements arranged in contact with the milk. Alternatively, the sensor 121, 122, 123, 124 may be a NIR sensor or a MIR sensor configured to measure an optical property of the milk.

[0055] A vacuum supply system 127, 219 may comprise of any type of vacuum pump configured to generate a vacuum pressure, valve devices, regulators and vacuum lines.

[0056] For example, the vacuum supply system 127, 219 may comprise valve device(s) 128, 220, 221, 222, 223, preferably shut-off valve(s), for controlling the extracting of milk from the dairy animal. The valve device(s) 128, 220, 221, 222, 223 is located downstream the milking unit 1, 2. The vacuum supply system 127, 219 is communicatively connected to the control unit 126, which is indicated by a dashed line, via a wireless connection or a wired connection. The control unit 126 is configured to control the vacuum supply system 127, 219 to provide certain milking vacuum levels P to the milking unit 1, 2 for extracting milk from the dairy animal based on the received output from the at least one sensor 121, 122, 123, 124. To provide the different milking vacuum levels P, the vacuum supply system 127, 219 may further comprise a vacuum regulator 129 which is connected to the control unit 126, wherein the control unit 126 generates a command to the vacuum regulator 129 to adjust the milking vacuum level P at the milking unit 1, 2, via the valve device(s) 128, 220, 221 , 222, 223. Thus, the valve device(s) 128, 220, 221, 222, 223 is connected to the vacuum regulator 129. The regulator 129 may be connected to at least one vacuum line which is provided with a certain vacuum pressure level generated by a vacuum pump (not shown). The vacuum regulator 129 and the valve device(s) 128, 220, 221, 222, 223 will in conjunction provide the milking vacuum level P corresponding to the stimulation phase, standard phase and boost phase respectively to the milking unit 1, 2. Alternatively, different milking vacuum levels P are provided by having at least two vacuum lines, i.e. conduits which have respectively different vacuum pressure levels. The pressure levels in the vacuum lines substantially correspond with the milking vacuum levels at the stimulation phase, standard phase and boost phase respectively. The at least two vacuum lines are connected to the valve device(s) 128, 220, 221, 222, 223 via a common control valve so that either of the vacuum pressure levels in the at least two vacuum lines may be applied to the valve device(s) 128, 220, 221, 222, 223 and thus, the preferred milking vacuum level P may be provided to the milking unit 1, 2. The common control valve and the valve device(s) 128, 220, 221, 222, 223 will in conjunction provide the milking vacuum level P corresponding to the stimulation phase, standard phase and boost phase respectively to the milking unit 1, 2.

[0057] In Figure 2 the vacuum supply system 219 comprises several valve devices 220, 221 , 222, 223, preferably shut-off valves, located downstream the milking unit 2, one for each respective milk conduit 211 , 212, 213, 214. Each valve device 220, 221, 222, 223 is connected to the vacuum regulator 129 or to a common control valve which in turn are connected to vacuum lines and the control unit 126 as previously described. Thus, the control unit 126 generates a command to the vacuum regulator 129, or the common control valve, to adjust the milking vacuum level P at the milking unit 2, via each of the valve devices 220, 221, 222, 223. This provides that the milking vacuum level P can be controlled individually for each teat cup 111 , 112, 113, 114. The vacuum regulator 129 may be configured such that it can provide adjustment to each valve device 220, 221 , 222, 223 separately, via e.g. different air tubes in the vacuum regulator 129 connected to each valve device 220, 221 , 222, 223. The control unit 126 is configured to provide each valve device 220, 221, 222, 223 with a preferred vacuum pressure through each air tube. Alternatively, each valve device 220, 221, 222, 223 is connected to a respective vacuum regulator which are all connected to the control unit 126.

[0058] The vacuum supply system 127, 219 is configured to implement adjustments of the milking vacuum level P applied to the teat cups 111, 112, 113, 114. The vacuum supply system 127, 219 arranged to provide milking vacuum P to the milking unit 1, 2 for extracting milk from the dairy animal may vary and is not further described herein.

[0059] The milking vacuum levels P may vary between a stimulation phase where the vacuum levels are preferably between 32-34 kPa, a standard phase where the vacuum levels are preferably between 42-44 kPa and a boost phase where the vacuum levels are preferably between 42-60 kPa.

[0060] The control unit 126 is configured to control the vacuum supply system 127, 219 to provide a first milking vacuum level P1. The control unit 126 is configured to obtain the output from the sensor 121, 122, 123, 124 and control the vacuum supply system 127, 219 to change from the first milking vacuum level P1 to a second milking vacuum level P2 when at least one condition of the sensor output is fulfilled. The at least one condition to be fulfilled for the control unit 126 to change from the first milking vacuum level P1 to the second milking vacuum level P2 is that the sensor output indicates that there is a change of the at least one property of milk extracted from the dairy animal exceeding a threshold and / or when the at least one property of milk extracted from the dairy animal reaches a preset value.

[0061] As can be seen in Figure 1, four sensors 121, 122, 123, 124 are arranged at each short milk tube 116, 117, 118, 119. Sensor output from all four sensors 121, 122, 123, 124 needs to indicate that the at least one property of milk extracted from the dairy animal has fulfilled the at least one condition before the control unit 126 can send a signal to the vacuum supply system 127 so that it changes from the first milking vacuum level P1 to the second milking vacuum level P2. The sensor 121, 122, 123, 124 may be arranged at one, two or three of the short milk tubes 116, 117, 118, 119 and thus the milking vacuum level P is controlled for the entire milking unit 1 based on measurements from one, two or three sensors 121 , 122, 123, 124.

[0062] In Figure 2, the sensors 121 , 122, 123, 124 are arranged at each of the four milk conduits 211, 212, 213, 214 respectively. These sensors 121 , 122, 123, 124 may be controlled individually so that when sensor output from at least one sensor 121, 122, 123, 124 indicates that the at least one property of milk extracted from the dairy animal has fulfilled the at least one condition the control unit 126 can send a signal to the vacuum supply system 219 to change from the first milking vacuum level P1 to the second milking vacuum level P2 for that particular teat cup 111 , 112, 113, 114. All teat cups 111 , 112, 113, 114 are thus independently controlled. The sensor(s) 121, 122, 123, 124 may be arranged at one, two or three of the milk conduits 211 , 212, 213, 214 and thus the milking vacuum level P is controlled for the entire milking unit 2 based on measurements from one, two or three sensors 121 , 122, 123, 124.

[0063] Figure 3 shows two milking vacuum levels P wherein the second milking vacuum level P2 is higher than the first milking vacuum level P1. The first milking vacuum level P1 may be a stimulation phase and the second milking vacuum level may be a standard phase or the first milking vacuum level P1 may be a standard phase and the second milking vacuum level P2 may be a boost phase.

[0064] Figure 4 shows an embodiment where three milking vacuum levels P are provided during the same milking operation. The first milking vacuum level P1 is prevailing during the stimulation phase Tstim which is, when at least one condition of the sensor output is fulfilled at a point in time ti , raised to a second milking vacuum level P2. The second milking vacuum level P2 is prevailing during the standard phase Tstand. The standard phase is then indicated as the first milking vacuum level P1 which is raised, when at least one condition of the sensor output is fulfilled at a point in time t2, to the second milking vacuum level P2 which is the milking vacuum level prevailing during the boost phase TbOost.

[0065] Note that a zero value in Figure 3 and 4 represents the atmospheric pressure level and a pressure level of larger vacuum magnitude is represented by a larger positive value than a pressure level with smaller vacuum magnitude.

[0066] In one embodiment of the invention the at least one property of milk extracted from the dairy animal is conductivity. The conductivity of the milk is higher for the cisternal milk than for the alveolar milk and can thus be used as an indicator for when to apply a higher milking vacuum P. During the extraction of the cisternal milk a lower milking vacuum P, preferably a vacuum level corresponding to the stimulation phase, is applied. But when there is a decrease in conductivity, which is an indicator that there has been a transition to alveolar milk, a higher milking vacuum P can be applied. Thus, during a milking operation the control unit 126 is configured to obtain the output from the sensor 121 , 122, 123, 124 configured to measure conductivity and control the vacuum supply system 127, 219 to change from the first milking vacuum level P1 to the second milking vacuum level P2 when the sensor output indicates that there is a decrease of the conductivity of milk extracted from the dairy animal which exceeds a threshold and / or when the conductivity of milk extracted from the dairy animal falls below a preset value. Preferably, when the sensor output indicates that there is a decrease of the conductivity of milk extracted from the dairy animal exceeding a threshold and / or when the conductivity of milk extracted from the dairy animal falls below a preset value, which indicates that extraction of alveolar milk has started, the vacuum supply system 127, 219 changes from a first milking vacuum level P1 to a higher second milking vacuum level P2, where the second milking vacuum level may be the boost phase.

[0067] In a further embodiment, the control unit 126 is configured to obtain the identity of the dairy animal. The animal may be identified by using an identity device attached to the dairy animal, e.g. an ear tag or a collar. The animal may also be identified using a camera. The control unit 126 may be connected to a storage unit 130 configured to store the measurements of the at least one property of milk extracted from the identified dairy animal, i.e. the storage unit 130 stores the sensor output.

[0068] The control unit 126 may comprise a processing unit configured to retrieve data from the storage unit 130 and to perform all necessary calculations from the obtained sensor output.

[0069] In one example the identity of the dairy animal is obtained and the stored historical data for conductivity of the milk extracted from the identified dairy animal is obtained by the control unit 126, i.e. previous conductivity measurements, for previous milking operations, of the milk extracted from the identified dairy animal is stored in the storage unit 130 and is obtained by the control unit 126. The preset value for conductivity is then based on the historical conductivity data of the milk extracted from the identified dairy animal. The historical data may be based on at least one previous milking operation but preferably several milking operations. During a milking operation, when the control unit 126 detects, based on the output from the conductivity sensor 121, 122, 123, 124, that the conductivity falls below the preset value it sends a signal to the vacuum supply system 127, 219 so that it changes from the first milking vacuum level P1 to the second milking level P2. Preferably, the vacuum supply system 127, 219 changes to a boost phase when the conductivity value falls below the preset value. A further option is that the preset value based on the individual historical conductivity data for one particular dairy animal is used as the preset value for the entire herd or a selected group of dairy animals.

[0070] Alternatively, the measurements of the conductivity of milk for a plurality of dairy animals is stored in the storage unit 130 and obtained by the control unit 126, i.e. a common historical data. The preset value is then based on these measurements from a plurality of dairy animals, e.g. the preset value could be a mean value for all measurements from a plurality of animals. The plurality of dairy animals could be the entire herd of dairy animals or a selected group of dairy animals. For this alternative, the identity of the dairy animals could be obtained but it is not necessary.

[0071] In a further embodiment, the milking arrangement may comprise a milk meter 125, 215, 216, 217, 218 configured to measure milk flow of milk extracted from the dairy animal. The milk meter 125 may be arranged in the milk line 120 as in Figure 1 when the milking operation is udder milking. The milk meter 215, 216, 217, 218 may be arranged in the respective milk conduits 211, 212, 213, 214 when the milking operation is quarter milking, as can be seen in Figure 2. For example, during the milking operation the milk meter 125, 215, 216, 217, 218 registers a high milk flow, which is determined by a threshold limit, and then the conductivity sensor 121, 122, 123, 124 registers a value of the conductivity corresponding to the high milk flow. The preset value, for when to change from the first milking vacuum level P1 to the second milking vacuum level P2, is then based on that registered conductivity value. The control unit 126 may obtain the identity of the dairy animal and the registered conductivity value may be used as a preset value for that identified dairy animal, thus the preset value is based on individual historical conductivity and milk flow data. A further option is that the preset value based on the individual historical conductivity and milk flow data for one particular dairy animal is used as the preset value for the entire herd or a selected group of dairy animals. It is thus possible to use the same conductivity value corresponding to high milk flow for one dairy animal and use it as the preset value for other dairy animals with e.g. similar expected milk yield or milk flow. Alternatively, measurements of conductivity values corresponding to a high milk flow may be taken for a plurality of dairy animals, i.e. the entire herd or a selected group, and the preset value may be based on these measurements. For example, a mean value for the conductivity measurements for the plurality of dairy animals may be used as the preset value.

[0072] All described embodiments on how to determine the preset value may be adjusted depending on the stored measurements from the last milking operation or on any number of previous milking operations. The preset value is determined in the same way as described above when the at least one property is an optical property.

[0073] The change of the at least one property of milk extracted from the dairy animal exceeding a threshold corresponds to a real-time measurement and may be determined by the time derivative of the at least one property of the milk, rate of change or the difference between two values of the at least one property of the milk. This would correspond to detecting a sudden, abrupt, change of the at least one property of milk extracted from the dairy animal. For example, the conductivity sensor 121 , 122, 123, 124 measures the conductivity of the milk during the milking operation of the dairy animal. When the control unit 126 detects a decrease of the conductivity, determined by for example that the change between two measured conductivity values exceeds a threshold, which indicates a sudden change of the conductivity, it sends a signal to the vacuum supply system 127, 219 so that it changes from the first milking vacuum level P1 to the second milking vacuum level P2. This embodiment does not require the identity of the dairy animal or storing data of the measured conductivity for the dairy animal since the control unit 126 will, during the same milking operation, control the vacuum supply system 127, 219 based on the real-time measurement of the conductivity values of the milk. Thus, when indicating a sudden change for the conductivity of the extracted milk during the milking operation the milking vacuum level will change from the first milking vacuum level to the second milking vacuum level.

[0074] In yet another aspect of the invention, measurements from the milk meter 125, 215, 216, 217, 218 measuring the flow of milk and the sensor 121, 122, 123, 124 measuring the at least one property of milk may be taken separately but at approximately the same time and used in combination to determine when there has been a transition from cisternal to alveolar milk. For example, when the milk meter 125, 215, 216, 217, 218 detects a high milk flow, determined by a threshold, that is registered by the control unit 126. Further, the control unit 126 detects when the conductivity values, measured by the conductivity sensor, falls below the preset value and / or indicates a decrease. When the milk flow has reached its threshold and the sensor output from the conductivity sensor 121, 122, 123, 124 indicates that the conductivity falls below the preset value and / or indicates a decrease the control unit 126 is configured to change from the first milking vacuum level P1 to the second milking vacuum level P2.

[0075] The control unit 126 may be configured to change from the first milking vacuum level P1 to the second milking vacuum level P2 at a predetermined delay time after the at least one condition is fulfilled. For example, if the conductivity sensor 121, 122, 123, 124 is arranged in the short milk tube 116, 117, 118, 119 or the teat cups 111, 112, 113, 114 or arranged close to the teat cups 111 , 112, 113, 114 in respective milk conduit 211, 212, 213, 214 the control unit 126 will be configured to change to the second milking vacuum level P2 after a predetermined delay time which is longer than if the conductivity sensor 121 , 122, 123, 124 is arranged further away from the teats of the dairy animal. This prevents the second milking vacuum level P from being triggered too early in the milking operation.

[0076] A flow diagram in Figure 5 describes the method 500 of controlling the milking arrangement, the method comprising the steps of: attaching 501 a milking unit 1 , 2 to teats of a dairy animal to be milked, providing 502 a first milking vacuum level P1 to the milking unit 1, 2 for extracting milk from the dairy animal, obtaining 503 a measurement of at least one property of milk extracted from the dairy animal, changing 504 from the first milking vacuum level P1 to a second milking vacuum level P2 when the obtained measurement fulfills at least one condition. According to some embodiments, the at least one condition is that the obtained measurement indicates that there is a change of the at least one property of milk extracted from the dairy animal exceeding a threshold and / or when the at least one property of milk extracted from the dairy animal reaches a preset value.

[0077] The second milking vacuum level P2 may be higher than the first milking vacuum level P1. The at least one property of the milk extracted from the dairy animal is conductivity or an optical property.

[0078] According to some embodiments the method comprises: obtaining 505 the identity of the animal, and storing 506 the measurements of the at least one property of milk extracted from the dairy animal.

[0079] The preset value may be based on individual historical data of the measured at least one property of milk extracted from the dairy animal or on common historical data of the measured at least one property of milk extracted from a plurality of dairy animals.

[0080] According to some embodiments the method comprises: measuring 507 milk flow of milk extracted from the dairy animal, and registering 508 a value of the at least one property of milk corresponding to a high milk flow, wherein the preset value is based on that registered value.

[0081] The change of the at least one property of milk extracted from the dairy animal may be determined by the time derivate of the at least one property of the milk, the rate of change or the difference between two values of the at least one property of the milk.

[0082] According to some embodiments the method comprises: changing 509 from the first milking vacuum level P1 to the second milking vacuum level P2 at a predetermined delay time after the at least one condition is fulfilled.

[0083] The invention is not restricted to the described embodiments in the figures but may be varied freely within the scope of the claims.

Claims

CLAIMS1. A milking arrangement comprising a milking unit (1, 2) configured to be attached to teats of a dairy animal during a milking operation, a vacuum supply system (127, 219) arranged to provide milking vacuum (P) to the milking unit (1, 2) for extracting milk from the dairy animal, a sensor (121, 122, 123, 124) configured to measure at least one property of milk extracted from the dairy animal and provide an output, and a control unit (126) configured to control the vacuum supply system (127, 219) to provide a first milking vacuum level (P1 ), characterized in that the control unit (126) is configured to obtain the output from the sensor (121, 122, 123, 124) and control the vacuum supply system (127, 219) to change from the first milking vacuum level (P1) to a second milking vacuum level (P2) when at least one condition is fulfilled.

2. The milking arrangement according to claim 1, wherein the at least one condition is that the sensor output indicates that a change of the at least one property of milk extracted from the dairy animal exceeds a threshold value and / or when the at least one property of milk extracted from the dairy animal reaches a preset value.

3. The milking arrangement according to any one of claims 1 or 2, wherein the second milking vacuum level (P2) is higher than the first milking vacuum level (P1).

4. The milking arrangement according to any one of claims 1-3, wherein the at least one property of milk extracted from the dairy animal comprises conductivity.

5. The milking arrangement according to any one of claims 1-3, wherein the at least one property of milk extracted from the dairy animal comprises an optical property.

6. The milking arrangement according to any one of claims 1-5, wherein the sensor (121, 122, 123, 124) is arranged in a teat cup (111, 112, 113, 114) of the milking unit (1, 2).

7. The milking arrangement according to any one of claims 1-5, wherein the milking unit (1, 2) comprises a milking cluster (100) which comprises a plurality of teat cups (111 , 112, 113, 114), a central claw (115) and a short milk tube (116, 117, 118, 119) extending between the central claw (115) and the respective plurality of teat cups (111 , 112, 113, 114), wherein the sensor (121, 122, 123, 124) is arranged in the short milk tube (116, 117, 118, 119) or the central claw (115).

8. The milking arrangement according to any one of claims 1-5, wherein the milking unit (1 , 2) comprises a plurality of teat cups (111, 112, 113, 114) each connected to a respective milk conduit (211 , 212, 213, 214), and wherein the milking arrangement comprises a plurality of sensors (121 , 122, 123, 124) configured to measure at least one property of milk extracted from the dairy animal, wherein each of the sensors (121 , 122, 123, 124) are arranged in a respective milk conduit (211, 212, 213, 214).

9. The milking arrangement according to any one of claims 1-8, wherein the control unit (126) is configured to obtain an identity of the dairy animal, and wherein the milking arrangement comprises a storage unit (130) configured to store the measurements of the at least one property of milk extracted from the dairy animal.

10. The milking arrangement according to claims 2 and 9, wherein the preset value is based on individual historical data of the measured at least one property of milk extracted from the dairy animal or on common historical data of the measured at least one property of milk extracted from a plurality of dairy animals.

11. The milking arrangement according to any one of claims 2-9, comprising a milk meter (125, 215, 216, 217, 218) configured to measure milk flow of milk extracted from the dairy animal, wherein the sensor (121, 122, 123, 124) registers a value of the at least one property of milk corresponding to a high milk flow measured by the milk meter (125, 215, 216, 217, 218), and the preset value is based on that registered value.

12. The milking arrangement according to any one of claims 1-11, wherein the control unit (126) is configured to change from the first milking vacuum level (P1) to the second milking vacuum level (P2) at a predetermined delay time after the at least one condition is fulfilled.

13. A method (500) of controlling a milking arrangement, the method comprising the steps of attaching (501) a milking unit (1 , 2) to teats of a dairy animal to be milked, providing (502) a first milking vacuum level (P1) to the milking unit (1, 2) for extracting milk from the dairy animal, obtaining (503) a measurement of at least one property of milk extracted from the dairy animal, changing (504) from the first milking vacuum level (P1) to a second milking vacuum level (P2) when the obtained measurement fulfills at least one condition.

14. The method of controlling a milking arrangement according to claim 13, wherein the at least one condition is that the obtained measurement indicates that a change of the at least one property of milk extracted from the dairy animal exceeds a threshold value and / or when the at least one property of milk extracted from the dairy animal reaches a preset value.

15. The method of controlling a milking arrangement according to any one of claims 13 or14, wherein the second milking vacuum level (P2) is higher than the first milking vacuum level (P1).

16. The method of controlling a milking arrangement according to any one of claims 13-15, wherein the at least one property of the milk extracted from the dairy animal is conductivity.

17. The method of controlling a milking arrangement according to any one of claims 13- 15, wherein the at least one property of the milk extracted from the dairy animal is an optical property.

18. The method of controlling a milking arrangement according to any one of claims 13- 17, comprising the steps ofObtaining (505) the identity of the animal, and storing (506) the measurements of the at least one property of milk extracted from the dairy animal.

19. The method of controlling a milking arrangement according to claims 14 and 18, wherein the preset value is based on individual historical data of the measured at least one property of milk extracted from the dairy animal or on common historical data of the measured at least one property of milk extracted from a plurality of dairy animals.

20. The method of controlling a milking arrangement according to any one of claims 14- 18, comprising the steps of measuring (507) milk flow of milk extracted from the dairy animal, and registering (508) a value of the at least one property of milk corresponding to a high milk flow, wherein the preset value is based on that registered value.

21. The method of controlling a milking arrangement according to any one of claims 13- 20, comprising the step of changing from the first milking vacuum level (P1) to the second milking vacuum level (P2) at a predetermined delay time after the at least one condition is fulfilled.

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