A METHOD AND A DEVICE FOR MANOEUVRING TEAT CUPS FOR MILKING DAIRY ANIMALS

Abstract: The present invention relates to a robot for the milking of dairy animals in which a teat cup gripping means (15) is pivotably arranged on the robot arm (13).

Description: Technical Field of the Invention A method and a device for manoeuvring teat cups for milking dairy animals. Description of Related Art Continuous efforts are being made in order to reduce the costs of producing milk. One way of doing this is by automating the milking of dairy animals thereby reducing the labour costs of producing milk. In order to achieve this it is proposed to use robots to automatically attach the teat cups to the teats of the diary animals once they have entered a milking stall. Consequently robots arms with gripping means for releasably holding teat cups and control means for guiding the robot arm to a position where it can slide a teat cup onto a teat have been developed. A problem which occurs with automated mounting of teat cups is that teats often do not hang vertically but, depending on the quantity of milk and hence pressure in the udder, project out sideways somewhat. If a teat cup approaches such an inclined teat vertically from below then there is a risk that the teat does not correctly enter the teat cup but becomes bent or is pushed away by the rim of the teat cup. In order to prevent this it has been proposed in the device known from EP-A 0 824 857 to approach the teat with vertically aligned teat cups which move altematingly with small vertical and horizontal steps so that it zigzags about an oblique path. A problem with this device is that there is still a risk that teats inclined at a large angle from the vertical, e.g. 30° or more, will be bent or pushed aside by the teat cup if the tip of the teat is not accurately aligned with the centre of the teat cup. Summary The object of the invention is to solve the above stated problems. The present invention solves the above stated problems by means of a device having the features mentioned in the characterising part of claim 1 and a method having the characterising features of claim 9. In a method and device in accordance with the present invention, teat cups in a milking apparatus are manoeuvred by a robot arm which is provided with gripping means which can grip a teat cup wherein said gripping means is provide with means for changing the angle that a teat cup is inclined to the vertical. In this way the angle to the vertical of the teat cup can be adjusted to approach that of the teat which it is intended to be attached to. In a second embodiment of the invention the means for changing the angle can selectively move a teat cup between two or more predetermined angles. In this way the operation of the device is simplified as it is possible to provide stops at the selected positions instead of needing to use some form of feedback or position deteπmning means. In a further embodiment of the invention the means for changing the angle of inclination of the teat cup is infinitely variable between its end limits. In this way the angle of the teat cup can more exactly correspond to that of the teat and thereby reduce the risk of the teat not being correctly fed into the teat cup. Brief Description of the Figures The invention will be described more closely in the following by means of examples of embodiments and figures in which., Figure 1 shows an example of a milking stall with an embodiment of a milking robot in accordance with the present invention; Figure 2 shows a vertically aligned teat cup which is moved upwards towards a an inclined teat so that the teat is not fed into the teat cup; Figure 3 is a schematic view of one embodiment of a teat cup inclining means in accordance with the invention with the teat cup in a first position; Figure 4 is a schematic view of one embodiment of a teat cup inclining means in accordance with the invention with the teat cup in a second position; Figures 5a) and 5b) show schematically lateral views of a robot arm in accordance with the present invention; Figure 6 shows a perspective schematic view of a second embodiment of a teat cup mclining means in accordance with the invention. Detailed Description of Embodiments Figure 1 shows an example of a milking stall S provided with a milking robot R. Robot R has a robot arm 13 which has pivotable teat cup gripping means 15 in accordance with one embodiment of the present invention at its distal end. Figure 2 shows schematically a lateral view of the udder 1 of an animal. Two of the teats 3, 5 of the udder are shown and they are inclined in opposite directions to the vertical. Teat 3 is inclined approximately 30° to the left of the vertical while teat 5 inclines approximately 45° to the right of the vertical. In the rest of this application for the sake of brevity an inclination to the left will be called a positive inclination while an inclination to the right will be called a negative inclination. A teat cup 7 is shown approaching teat 3 from below. Teat cup 7 is held firmly with its longitudinal axis vertical by openable and closable gripping means 9 on a prior art robot arm 1 1. It is moved in the direction of the arrow by the robot arm and is intended to fit around teat 3. As can be seen from the lower position of the teat cup 7 shown in dotted lines it is possible that the teat is not correctly fed into the teat cup but is instead caught on the edge of the teat cup. If this occurs and is not detected then as the teat cup advances upwards the teat 3 may be come bent and end up lying on top of the teat cup instead of inside it, or, even worse, it may become folded and sucked sideways into the teat cup, possibly injuring the teat. When the milking operation subsequently starts then no milking of the teat 3 will occur and it is also conceivable that the teat 3 could be damaged if it is sucked sideways down into the teat cup 7 when the milking vacuum is applied to the teat cup 3. If the incorrect alignment of the teat 3 is detected then the fitting of the teat cup 7 onto the teat 3 has to be repeated which is time consuming. Figure 3 shows schematically one embodiment of a robot arm 13 provided with pivotable gripping means 15 shown in a first operative position. In this embodiment pivotable gripping means 15 comprises bell-crank means such as an L-shaped support 17 pivotably mounted about a horizontal axis 19 attached to the distal end 21 of robot arm 13. Bell crank has a short arm 23 which is attached to an actuating rod 25 of actuating means 27 which can be a linear actuator of any suitable type such as a pneumatic actuator, an hydraulic actuator, a solenoid, a rack and pinion drive or the like. Bell crank 17 also has a long arm 29 which is attached to short arm 23 at any suitable angle, e.g. for the sake of example 90°. Long arm 29 comprises teat cup gripping means 31 which can be any suitable type known in the art and which are not part of the inventive concept of the present invention and which are not shown in detail for the sake of ease of comprehension of the figures. In this figure the actuating rod 25 is retracted so that long arm 29 inclines downwards from horizontal axis 19 at an angle of approximately 30°. Teat cup 7 is held substantially perpendicular to long arm 29 and consequently it makes an angle of positive 30° to the vertical. This is approximately the same as the angle that teat 3 makes to the vertical. This means that when robot arm 13 is moved to a position below and to the left of teat 3 it is easy to align the teat cup 7 with the projected longitudinal axis of teat 3. It can then be moved obliquely approximately along said projected centreline towards the udder until it encloses teat 3. As the longitudinal axis of the teat cup 7 is substantially aligned with the longitudinal axis of the teat 3 there is a minimum chance of the teat catching on an edge of the teat cup 7 and therefore there is a maximum chance that the teat cup 7 will be correctly mounted on the teat 3. Figure 4 shows the robot arm 13 from figure 2 in a second operative position when it is preparing to attach a teat cup 7 to teat 5. In this case teat 5 is on the opposite side of the udder from teat 3 and extends at an angle of approximately negative 45° to the vertical. Actuating rod 25 has been extended so that long arm 29 inclines upwards from horizontal axis 19 at an angle of approximately 45°. Teat cup 7 is still held substantially perpendicular to long arm 29 and consequently it makes an angle of negative 45° to the vertical. This is approximately the same as the angle that teat 5 make to the vertical. Thus in a similar manner to that described above for teat 3 it becomes easy to align teat cup 7 with teat 5. The amount which actuator rod 25 extends of retracts can be controlled by the normally present control device not shown) which controls the movement of robot arm 13 or by an additional control means (not shown). The information on the angle which the teats 3, 5 make to the vertical (or to the horizontal or to some other frame of reference) can be derived from the normally present teat recognition means such as, for example, a laser light emitter and detectors, or cameras 24 (shown schematically). In order to prevent actuator rod 25 retracting or extending too far it and/or robot arm 13 can be provided with stops shown symbolically by 33, 35, 37. If the actuator 27 has a freely moving actuator rod 25 it can be biased by for example spring means 39 so that when no power is supplied to actuator 27 it is takes up an intermediate position so that long arm 29 is substantially horizontal. In a simple embodiment of the invention it is possible that the actuator rod 27 has no positive position control and is either fully retracted (maximum positive angle of inclination) or fully extended (maximum negative angle of inclination). This however means that there is no simple way of positioning the long arm 29 horizontally in order to pick up a teat cup 7 and it is therefore preferable to have a biasing means 39 in order to provide a third distinct arm inclination, namely, no inclination (neutral position). This can be easily arranged if actuator 27 is a solenoid in which case the neutral position can be obtained when the solenoid is not energised, the maximum negative inclination can be obtained with a potential difference having one polarity applied and the maximum positive inclination can be obtained with the reverse polarity. Latching means (not shown) can be provided in order to releasably hold the long arm 29 in the respective maximum positions. Preferably the actuating means produce a substantially linear effect on the inclination of the gripping means, in other words, a certain displacement of the actuator always causes the same angular change in the position of the gripping means irrespective of the actual angle of inclination of the gripping means. For example the actuator could be a stepper motor or an actuator influence by a stepper motor (e.g. by means of a treaded rod and moving nut or a rack-and-pinion system increasing or decreasing the pressure exerted on a piston in the actuator) in which one revolution of the motor always causes the same angular displacement of the gripping means e.g. 1 revolution of the stepper motor causes a 2° rotation of the gripping means. Alternatively it could be a hydraulic actuator system in which the addition or removal of a certain volume of fluid has a linear effect on the displacement of the gripping means. In this way the control of the pivoting is simplified as it is possible to accurately move the gripping means without using a feedback system. For example if a rotation of 8° is required then the stepper motor is controlled to rotate 4 revolutions in the appropriate direction. This also means that the command required to achieve a desired rotation is the same irrespective of the angle that the robot arm makes with the frame of reference. An example of such a system is shown schematically in figure 5. Figure 5a) shows a lateral view of a robot arm 41 which supports a gripping means 43. Gripping means 43 is pivotably mounted at an end of robot arm 41 and is connected to a parallel arm 45 which is pivoted in such a way that when robot arm 41 moves up and down the angle that the gripping means to the horizontal remains the same as is shown by the image in dashed lines. Parallel arm 45 has length adjusting means 47 which can be, for example, a threaded rod and nut arrangement or a telescopic hydraulic cylinder or actuator or the like which can lengthen or shorten parallel arm 45. The length adjusting means can be operated by any suitable control means (not shown). Figure 5b) shows how the angle that the gripping means 43 makes to the horizontal can be simply changed by adjusting the length of the parallel arm 45. In this figure length adjusting means 47 has been operated so as to lengthen parallel arm 45 so that gripping means 43 is at an angle of α° to the horizontal. As before when robot arm 41 moves up and down the angle that the gripping means 43 to the horizontal remains the same as is shown by the image in dashed lines. While the inventive concept has been illustrated here by means of a mechanical parallel arm it is also possible to provide a similar effect by using hydraulic master cylinder and slave cylinder arrangement in which movement of the robot arm in the vertical direction causes the piston of the master cylinder to move against a cam. The movement of the master cylinder piston is then transmitted by a hydraulic line to the cylinder of the slave cylinder. This causes the slave cylinder piston to move and by means of suitable linkages and/or cams the movement of the slave cylinder piston can be transmitted to the gripping means in order to compensate for the movement of the robot arm. Preferably when a robot arm is moved along an inclined path it is moved with simultaneous vertical and horizontal displacements so that it follows a smooth inclined line and does not follow a series of steps. In this way the risk of it snubbing on the tip of a teat is reduced and accordingly the risk that it incorrectly engages a teat is reduced. Figure 6 shows a perspective schematic view of a second embodiment of a robot arm 51 provided with gripping means 53 in accordance with the invention. This embodiment is substantially similar to the previous embodiment except that the gripping means 53 is rotatable about the longitudinal axis L of the robot arm 51 in addition to being rotated about a horizontal axis H. This can be achieved in various ways, for example by rotating the robot arm 51 about its longitudinal axis L or by providing a rotary joint 55 and gripping means rotating means 57 on the robot arm 51. In this way the gripping means 53 has more freedom of movement. It is also conceivable to provide gripping means which are only rotatable about the longitudinal axis L of the robot. This is simpler to construct but can make it more difficult to align a teat cup with a teat. While the invention has been illustrated with respect to the use of a robot arm for gripping and moving teat cups it is naturally also applicable to robot arms for moving other tools such as teat cleaning means or the like. While the invention has been illustrated by embodiments in which a bell crank is rotated by a actuator rod operated by a linear actuator it also possible to use rotary actuators such as air motors, vacuum motors, hydraulic motors or electrical motors or the like to accomplish the desired pivoting of the gripping means. Furthermore the pivoting action of the gripping means from a positive angle with respect to a frame of reference to a negative angle with respect to the frame of reference can be accomplished in another ways for example by providing a horizontal hinge in the robot arm in order to enable the distal end of the robot arm and associated gripping means to pivot with respect to the other end of the robot arm.

Claims: Claims 1. Milking robot for the milking of dairy animals (9), comprising a robot arm (13) and gripping means (15) for gripping for example teat cups and the like, characterised in that said gripping means (15) are controllably pivotable about a substantially horizontal axis (19) from a first operative position inclined at a positive angle to a frame of reference to a second operative position inclined at a negative angle to the frame of reference, for adjusting the angle of an individual teat cup relative to the frame of reference. 2. Milking robot according to claim 1 characterised in that it said gripping means (15) comprises a bell-crank means (17) pivotably mounted around a substantially horizontal axis (19). 3. Milking robot in accordance with any of the previous claims characterised in that said first operative position and second operative position are deteπnined by means of stops (33, 35, 37). 4. Milking robot in accordance with any of the previous claims characterised in that said gripping means (15) is biased by biasing means (39) into a neutral position with respect to said frame of reference. 5. Milking robot according to any of the previous claims characterised in that said gripping means are pivotable by means of an actuator rod (25) operated by an actuator (27). 6. Milking robot in accordance with claim 5 characterised in that said actuator (27) is a linear actuator such as a pneumatic piston and cylinder actuator, a hydraulic piston and cylinder actuator, a rack and pinion drive, a solenoid or the like. 7. Milking robot in accordance with claim 5 characterised in that said actuator (27) is a rotary actuator such as an air motor, a hydraulic motor, a vacuum motor, an electric motor or the like. 8. Milking stall (S) comprising a milking robot in accordance with any of the above claims. 9. Method for attaching a device such as a teat cup (7) or a cleaning device or the like supported by a robot arm (13) to a teat (3) comprising the step of deterrnining the angle of inclination that the teat (3) makes to a frame of reference and characterised by the further step of mclining said device (7) to an angle of inclination substantially the same as the angle of inclination of said teat (3), and moving said device (7) obliquely towards said teat (3). 10. Method according to claim 9, characterised in that said device (7) is moved obliquely along the projected longitudinal axis of said teat (3) towards said teat (3).

Inventors: ERIKSSON JAN, ERIKSSON, JAN
Applicants: ALFA LAVAL AGRI AB, ERIKSSON JAN, ERIKSSON, JAN
Application year: 1999
Main classification: A01J5
IPC codes: A01J5