SYSTEM AND COMPUTER-IMPLEMENTED METHOD FOR MONITORING OPERATING PRESSURE IN A MILKING INSTALLATION, COMPUTER PROGRAM AND NON-VOLATILE DATA CARRIER

Abstract

A system and method for monitoring at least one operating pressure in a milking installation by a pressure sensor measuring values of a pressure level in a component of a milking point of the milking installation, the pressure level being indicative of the at least one operating pressure to be monitored. A processing node generates monitoring data representing a series of measured values of the pressure level, and the monitoring data contains temporal indicators designating a respective timestamp indicative of a point in time when a value of the pressure level was measured. The temporal indicators serve as a basis for triggering at least one alarm, such as when a timestamp indicates that the pressure level was measured to a value outside of an acceptable range of values at the point in time indicated by the timestamp.

Claims

1. A system for monitoring at least one operating pressure in a milking installation, the system comprising: a pressure sensor (115) configured to measure values of a pressure level in a component (110) of a milking point of the milking installation, said pressure level being indicative of said at least one operating pressure; and a processing node (125) communicatively connected (120) to the pressure sensor (115) and configured to generate monitoring data representing a series of measured values of the pressure level, the monitoring data comprising temporal indicators designating a respective timestamp indicative of a point in time when a value of the pressure level was measured, and the temporal indicators serving as a basis for triggering at least one alarm.

2. The system according to claim 1, wherein the processing node (125) is configured to trigger at least one local alarm based on the temporal indicators, at least one of the at least one local alarm being triggered if one of said timestamps indicates that the pressure level was measured to a value outside of an acceptable range of values at the point in time indicated by said timestamp.

3. The system according to claim 1, further comprising: a central node (140), the processing node (125) being configured to forward the monitoring data to the central node (140), and the central node (140) being configured to trigger at least one central alarm based on the temporal indicators, at least one of the at least one central alarm being triggered if one of said timestamps indicates that the pressure level was measured to a value outside of an acceptable range of vlues at the point in time indicated by said timestamp.

4. The system according to claim 3, further comprising: a storage resource (145) communicatively connected to the central node (140), said storage resource (145) configured to store the monitoring data and at least one of the at least one central alarm.

5. The system according to claim 3, wherein the processing node (125) is configured to initiate forwarding of the monitoring data to the central node (140) in response to a start signal (S) indicating a beginning of a milking session to be carried out by the milking installation.

6. The system according to claim 5, wherein the processing node (125) is configured to continue forwading the monitoring data to the central node (140) until an abort signal (E) is received, said abort signal (E) indicating an end of said milking session.

7. The system according to claim 6, wherein the central node (140) is configured to trigger at least one of the at least one central alarm if the monitoring data indicates that one of the at least one operating pressure has been applied during a total extension of a high-pressure part of a milking time, said high-pressure part exceeding a threshold measure.

8. The system according to claim 1, wherein the pressure sensor (115) is arranged in a dry space (111) of the component (110), said dry space (111) being in direct fluid connection with at least one conduit in which said at least one operating pressure exists.

9. The system according to claim 1, wherein the pressure sensor (115) is arranged in a liquid-containing space (113) of the component (110), said liquid-containing space (113) being in indirect fluid connection with at least one conduit in which said at least one operating pressure exists.

10. The system according to claim 1, wherein the pressure sensor (115) is configured to measure the values of the pressure level at a first frequency, and to transmit representative data reflecting the measured values of the pressure level to the processing node (125) at a second frequency being lower than the first frequency.

11. The system according to claim 10, wherein the representative data comprises at least one of: a rolling average of the measured values of the pressure level since a previous transmission, a maximum of the measured values of the pressure level since a previous transmission, and a minimum of the measured values of the pressure level since a previous transmission.

12. A computer-implemented method of monitoring at least one operating pressure in a milking installation, the method comprising: receiving from a pressure sensor (115) measured values of a pressure level in a component (110) of a milking point of the milking installation, said pressure level being indicative of said at least one operating pressure; and processing the measured values of the pressure level and generating monitoring data representing a series of measured values of the pressure level, the monitoring data comprising temporal indicators designating a respective timestamp indicative of a point in time when a value of the pressure level was measured, and the temporal indicators serving as a basis for triggering at least one alarm.

13. The method according to claim 12, further comprising: determining if a timestamp of one of said timestamps indicates that the pressure level was measured to a value outside of an acceptable range of values at the point in time indicated by said timestamp; and determining that said timestamp indicates that the pressure level was measured to a value outside of an acceptable range of values at the point in time indicated by said timestamp, and subsequently triggering local alarm.

14. The method according to any one of the claim 12, further comprising: forwarding the monitoring data to a central node (140); determining if a timestamp of one of said timestamps indicates that the pressure level was measured to a value outside of an acceptable range of values at the point in time indicated by said timestamp; and determining that said timestamp indicates that the pressure level was measured to the value outside of the acceptable range of values at the point in time indicated by said timestamp, and subsequently triggering in the central node a central alarm.

15. The method according to claim 14, further comprising: determining receipt of a start signal (S) indicating a beginning of a milking session to be carried out by the milking installation, and subsequently initiating the forwarding of the monitoring data to the central node.

16. The method according to claim 15, further comprising: determining receipt of an abort signal (E), said abort signal (E) indicating an end of said milking session, and subsequently stopping the forwarding of the monitoring data to the central node.

17. The method according to claim 16, further comprising: determining if the monitoring data indicates that one of the at least one operating pressure has been applied during a total extension of a high-pressure part of a milking time, said high-pressure part exceeding a threshold measure; and determining that the monitoring data indicates that the one of the at least one operating pressure has been applied during the total extension of a high-pressure part of the milking time, and subsequently triggering in the central node an other central alarm.

18. The method according to claim 12, further comprising: measuring the values of the pressure level in a dry space (111) of the component (110), said dry space (111) being in direct fluid connection with at least one conduit in which said at least one operating pressure exists.

19. The method according to claim 12, further comprising: measuring the values of the pressure level in a liquid-containing space (113) of the component (110), said liquid-containing space (113) being in indirect fluid connection with at least one conduit in which said at least one operating pressure exists.

20. The method according to claim 12, further comprising: measuring, in the pressure sensor (115), the values of the pressure level (P.sub.md, P.sub.mw) at a first frequency; and transmitting representative data reflecting the measured values of the pressure level (P.sub.md, P.sub.mw) from the pressure sensor (115) at a second frequency lower than the first frequency.

21. The method according to claim 20, wherein the representative data comprises at least one of: a rolling average of the measured values of the pressure level since a previous transmission, a maximum of the measured values of the pressure level since a previous transmission, and a minimum of the measured values of the pressure level since a previous transmission.

22. (canceled)

23. A non-transitory computer-readable data medium (526) having recorded thereon a computer program (527) that, upon execution by a processor of a computer, executes the method according to claim 12.

24. The system according to claim 1, wherein the component is any one of a milk conduit, a claw of a milking device, a teat cup, and a shut-off valve.

25. The method according to claim 12, wherein the component is any one of a milk conduit, a claw of a milking device, a teat cup, and a shut-off valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] FIG. 1 shows a block diagram over a system according to a first embodiment of the invention;

[0026] FIG. 2 shows a graph illustrating how a measured pressure level may vary over time during the milking of an animal according to the embodiment of FIG. 1;

[0027] FIG. 3 shows a block diagram over a system according to a second embodiment of the invention;

[0028] FIG. 4 shows a graph illustrating how a measured pressure level may vary over time during the milking of an animal according to the embodiment of FIG. 3;

[0029] FIG. 5 schematically represents the processing node according to one embodiment of the invention; and

[0030] FIG. 6 illustrates, by means of a flow diagram, the general method according to the invention.

DETAILED DESCRIPTION

[0031] In FIG. 1, we see a system for monitoring the operating pressures P.sub.1OP, P.sub.2OP and P.sub.3OP that exist in first, second and third conduits 151, 152 and 153 respectively of a milking installation. Valves 161, 162 and 163 connect each of the conduits 151, 152 and 153 to a common control valve 160 via which either of the operating pressures P.sub.1OP, P.sub.2OP and P.sub.3OP is applied to a component 110 of the milking installation, for instance a shut-off valve for controlling the extraction of milk at a milking point.

[0032] Alternatively, each of the operating pressures P.sub.1OP, P.sub.2OP and P.sub.3OP may be produced based on a basic pressure P that is regulated by a pressure regulator 160b to the respective levels P.sub.1OP, P.sub.2OP and P.sub.3OP and delivered to the component 110 as shown by the dashed lines. Naturally, this design may also be used for a dynamic adjustment of the pressure level P.sub.DYN being delivered to the component 110, i.e. delivery of any other fixed pressure level or a varying pressure, which for example is adjusted in response to one or more measured parameters.

[0033] A pressure sensor 115 is arranged in the component 110, which pressure sensor 115 is configured to measure values of a pressure level P.sub.md in the component 110. The pressure level P.sub.md is indicative of the at least one operating pressure P.sub.1OP, P.sub.2OP and/or P.sub.3OP depending on which operating pressure that is being applied via the common control valve 160, or the pressure regulator 160b. Here, the pressure sensor 115 is arranged in a dry space 111 of the component 110, which dry space 111 connects to a wet space, i.e. a liquid-containing space 113 of the component 110, via a diaphragm 112, so as to effect milk extraction via conduits M connected to the animal. The dry space 111 is in direct fluid connection with the conduits 151, 152 and 153 in which the operating pressures P.sub.1OP, P.sub.2OP P.sub.3OP respectively exist.

[0034] A processing node 125 is communicatively connected 120 to the pressure sensor 115, for instance via a wireless connection based on radio or optical technique, or a wired connection implemented by electric cable or optic fiber. The processing node 125 is configured to generate monitoring data P.sub.md(t.sub.s) representing a series of measured values of the pressure level P.sub.md. The monitoring data P.sub.md(t.sub.s) includes temporal indicators t.sub.s designating a respective timestamp indicative of a point in time when a value of the pressure level P.sub.md was measured. The temporal indicators t.sub.s are included to serve as a basis for triggering at least one alarm as will be explained below.

[0035] During a milking procedure, 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 animal's udder. For example, to instigate the milk flow, a so-called stimulation vacuum 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. 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 animal's teats.

[0036] The applicant has found that the milk extraction can be made even more efficient, if yet another 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. Thus, a total of three different vacuum levels are applied in addition to the atmospheric pressure level exerted on the teats when they are not being milked. For example, a first operating pressure P.sub.1OP, a so-called stimulation vacuum, may be applied to instigate the milking. Then, a second operating pressure P.sub.2OP, a so-called standard vacuum, may be applied to match a subsequently increased milk flow. Thereafter, during a top-flow period, the boost vacuum is applied. Analogous to the above, towards the end of the milking procedure the sub pressure applied is preferably gradually decreased, for instance in three steps corresponding to the levels applied at the beginning of the procedure.

[0037] As mentioned above, the operating pressures P.sub.1OP, P.sub.2OP and P.sub.3OP may either originate from separate fluid connection with the conduits 151, 152 and 153 respectively, or be produced based on a common basic pressure P that is regulated by a pressure regulator 160b to the said levels P.sub.1OP, P.sub.2OP and P.sub.3OP.

[0038] When varying the vacuum pressure like this, it is important that the variations are adequately timed relative to the animal's milk-flow curve, i.e. that the vacuum pressure level follows the differing quantities of milk flowing from the teats. Such monitoring is especially critical if a boost vacuum is used.

[0039] FIG. 2 shows a graph illustrating how a measured pressure level P.sub.md may vary over time t during a milking procedure effected via the milking installation of FIG. 1. Here, it should be noted that measured pressure level P.sub.md represents a vacuum pressure, i.e. a sub-atmospheric pressure, where zero represents the atmospheric pressure level and a pressure level P.sub.md of larger vacuum magnitude is represented by a larger positive value than a pressure level P.sub.md of smaller vacuum magnitude. In other words, the P.sub.md axis represents negative pressure deviations from the atmospheric pressure level. A dotted line symbolizes an estimated milk flow F as a function of time t corresponding to the measured pressure level P.sub.md.

[0040] In FIG. 2, a first reference level P.sub.1d designates a measured pressure level P.sub.md constituting the stimulation vacuum, which is provided by the first operating pressure P.sub.1OP in the first conduit 151; a second reference level P.sub.2d designates a measured pressure level P.sub.md constituting the standard vacuum, which is provided by the second operating pressure P.sub.2OP in the second conduit 152; and a third reference level P.sub.3d designates a measured pressure level P.sub.md constituting the boost vacuum, which is provided by the third operating pressure P.sub.3OP in the third conduit 153. According to embodiments of the invention, the atmospheric pressure level is preferably defined as any pressure below 4 kPa; the first reference level P.sub.1d is typically around 34 kPa, and preferably between 20 and 50 kPa, however at least 3 kPa below the second reference level P.sub.2d; the second reference level P.sub.2d is typically around 43 kPa, and preferably between 20 and 50 kPa, however at least 2 kPa below the third reference level P.sub.3d; and the third reference level P.sub.3d is typically around 49 kPa, and preferably between 40 and 55 kPa.

[0041] Above and below each of the reference levels P.sub.1d, P.sub.2d and P.sub.3d a respective upper and lower threshold P.sub.1dL, P.sub.1dH; P.sub.2dL, P.sub.2dH; and P.sub.3dL, P.sub.3dH respectively define intervals outside which the processing node 125 will trigger alarms. In particular, according to one embodiment of the invention, the temporal indicators form a basis for triggering at least one alarm as follows. The processing node 125 is configured to trigger a local alarm A.sub.L based on the temporal indicators if a timestamp indicates that the pressure level P.sub.md was measured to a value outside of an acceptable range of values as defined by the upper and lower thresholds P.sub.1dL, P.sub.1dH, P.sub.2dL, P.sub.2dH and P.sub.3dL, P.sub.3dH, indicated by the timestamp in question.

[0042] For example, the milking procedure may be prescribed to start by applying the first operating pressure P.sub.OP1 for a first period, say 30 seconds. Then, the second operating pressure P.sub.OP2 shall be applied for a second period, say 25 seconds. Thereafter, the third operating pressure P.sub.OP3 is applied until an end criterion is fulfilled, for instance relating to the milk flow. In response to the end criterion being fulfilled, the pressure is stepwise decreased analogous to how it was elevated in the beginning of the procedure. We assume that the processing node 125 generates monitoring data containing a first timestamp t.sub.1 when the measured pressure level P.sub.md indicates that the pressure increases from the atmospheric level to the first reference levels P.sub.1d representing the first operating pressure P.sub.OP1 providing the stimulation vacuum In a nominal scenario, the processing node 125 should generate monitoring data containing a second timestamp t.sub.2 when the measured pressure level P.sub.md indicates that the pressure increases from the first operating pressure P.sub.OP1 to the second operating pressure P.sub.OP2 providing the standard vacuum, where the second timestamp t.sub.2 designates a point in time around one second later than the point in time designated by the first timestamp t.sub.1. In the nominal scenario, the processing node 125 should further generate monitoring data containing a third timestamp t.sub.3 when the measured pressure level P.sub.md indicates that the pressure increases from the second operating pressure P.sub.OP2 to the third operating pressure P.sub.OP3 providing the boost vacuum, where the third timestamp t.sub.3 designates a point in time around one second later than the point in time designated by the second timestamp t.sub.2.

[0043] To monitor the timing of the above pressure changes, the processing node 125 may perform temporal checks as follows. If, at a point in time t.sub.1a after the point in time indicated by the first timestamp t.sub.1, say two seconds later, the measured pressure level P.sub.md is not within the acceptable pressure range P.sub.2dL-P.sub.2dH for the second reference level P.sub.2d, the processing node 125 is configured to trigger a first alarm A1, for instance in the form of a local alarm A.sub.L. Analogously, if, at a point in time t.sub.2a after the point in time indicated by the second timestamp t.sub.2, say three seconds later, the measured pressure level P.sub.md is not within the acceptable pressure range P.sub.3dL-P.sub.3dH for the third reference level P.sub.3d, the processing node 125 is configured to trigger a second alarm A2, for instance in the form of a local alarm A.sub.L.

[0044] According to one embodiment of the invention, the system also includes a central node 140. The processing node 125 is further configured to forward the monitoring data P.sub.md(t.sub.s) to the central node 140. Analogous to the processing node 125, the central node 140 is configured to trigger alarms. Specifically, the central node 140 is configured to trigger at least one central alarm A.sub.C based on the temporal indicators t.sub.s. At least one of the at least one central alarm A.sub.C is triggered if one of the timestamps t.sub.1, t.sub.2, t.sub.2a, t.sub.3, t.sub.3a, t.sub.4, t.sub.5 or t.sub.6 indicates that the pressure level P.sub.md was measured to a value outside of an acceptable range of values at the point in time indicated by the timestamp in question. For example, if, at the point in time t.sub.1a after the point in time indicated by the first timestamp t.sub.1, the measured pressure level P.sub.md is not within the acceptable pressure range P.sub.2dL-P.sub.2dH for the second reference level P.sub.2d, the central node 140 is configured to trigger a first alarm A1, for instance in the form of a central alarm A.sub.L. Further, if, at the point in time t.sub.2a after the point in time indicated by the second timestamp t.sub.2, the measured pressure level P.sub.md is not within the acceptable pressure range P.sub.3dL-P.sub.3dH for the third reference level P.sub.3d, the central node is configured to trigger a second alarm A2, for instance in the form of a central alarm A.sub.C.

[0045] Preferably, a storage resource 145, for example a digital memory unit, is communicatively connected to the central node 140. The storage resource 145 is configured to store the monitoring data P.sub.md(t.sub.s) and any central alarm A.sub.C that have been generated. Thus, service personnel and/or the farmer may gain access to log data describing how the operating pressure has fluctuated during historic milking sessions in the milking installation. Thereby, decisions can be taken relating to when service and repair actions should be taken.

[0046] According to one embodiment of the invention, the pressure sensor 115 is configured to measure the values of the pressure level P.sub.md at a first frequency, say 100 Hz, or at least within a range from 10 to 1000 Hz, and transmit representative data reflecting the measured values of the pressure level P.sub.md to the processing node 125 at a second frequency that is lower than the first frequency, say 1 Hz, or at least within a range from 0.001 to 10 Hz. The representative data may here contain: a rolling average of the measured values of the pressure level P.sub.md since a previous transmission, a maximum of the measured values of the pressure level P.sub.md since a previous transmission, and/or a minimum of the measured values of the pressure level P.sub.md since a previous transmission. The previous transmission is preferably a most recent previous transmission of the representative data. However, according to the invention, various overlap in the transmitted data are also conceivable, meaning that the above-mentioned previous transmission is the penultimate, or an even earlier transmission.

[0047] According to one embodiment of the invention, the processing node 125 is configured to initiate forwarding of the monitoring data P.sub.md(t.sub.s) to the central node 140 in response to a start signal S, which indicates a beginning of a milking session to be carried out by the milking installation. The start signal S, in turn, may be produced by a cleaning unit for the milking installation, for example a signal indicating that a milking session has started or a cleaning procedure has been completed. Alternatively, the start signal S may originate from any other device or function in the milking system indicating that a milking session has started. For example, a milking point controller may generate the start signal S individually for each milking cluster. In such a case, an accelerometer output caused by a movement of the milking cluster may form a basis for the start signal S. As yet another alternative, an operator may cause the start signal S by manually activating a milking session.

[0048] The processing node 125 is further preferably configured to continue forwarding the monitoring data P.sub.md(t.sub.s) to the central node 140 until an abort signal E is received, which abort signal E indicates an end of the milking session. Thus, it can be ensured that the central node 140 exclusively receives monitoring data P.sub.md(t.sub.s) generated during the milking session. For example, any monitoring data collected during cleaning can be excluded from the basis for triggering alarms.

[0049] According to one embodiment of the invention, the central node 140 is configured to trigger at least one of the at least one central alarm A.sub.C if the monitoring data P.sub.md(t.sub.s) indicates that one or more of the operating pressures P.sub.1OP, P.sub.2OP and/or P.sub.3OP has been applied during a total extension of a high-pressure part of a milking time, which high-pressure part exceeds a threshold measure. For example, the central node 140 may be configured to trigger such a central alarm A.sub.C if the pressure level P.sub.md has been measured to the third reference level P.sub.3d, i.e. representing the boost vacuum, during more than 90% of the milking session. Preferably, the threshold measure for the high-pressure part of a milking time is between 60% and 99% of the total duration of a milking session.

[0050] FIG. 3 shows a block diagram over a system according to a second embodiment of the invention. Here, all parts, units and signals that also occur in FIG. 1 designate the same parts, units and signals as described above with reference to FIG. 1. As can be seen, the design in FIG. 3 differs from that in FIG. 1 with respect to where the pressure level is measured, which pressure level is indicative of the operating pressures P.sub.1OP, P.sub.2OP and P.sub.3OP respectively.

[0051] In FIG. 3, this pressure level P.sub.mw is measured in a liquid-containing space 113 of the shut-off valve component 110, i.e. on the opposite side of the diaphragm 112 relative to where the pressure sensor 115 is arranged in FIG. 1. According to the invention, the pressure sensor 115 may equally well be arranged at any other point on the so-called wet, or milk-containing, side schematically illustrated by conduits M, such as beneath the tip of the animal's teat in a teat cup.

[0052] It is somewhat more complicated to measure the pressure level P.sub.mw on the wet side because here the pressure level varies depending on the magnitude of the milk flow although the operating pressure applied P.sub.1OP, P.sub.2OP or P.sub.3OP is constant. This, in turn, is due to the fact that the liquid-containing space 113 is only in indirect fluid connection with the conduits 151, 152 or 153 where the operating pressures P.sub.1OP, P.sub.2OP and P.sub.3OP respectively exist.

[0053] On the other hand, the pressure level P.sub.mw more accurately reflects the pressure level to which the animal's teats are subjected.

[0054] FIG. 4 shows a graph illustrating how the measured pressure level P.sub.mw may vary over time t during the milking of an animal according to the design shown in FIG. 3. As can be seen, here, for each operating pressure P.sub.1OP, P.sub.2OP and P.sub.3OP, a reference level must be allowed to vary between first and second values P′.sub.1 to P″.sub.1, P′.sub.2 to P″.sub.2 and P′.sub.3 to P″.sub.3 respectively due to said variations in the milk flow.

[0055] Nevertheless, the processing node 115 and/or the central node 140 may be configured to trigger first and/or second alarms A1 and/or A2 respectively as described above if, at the points in time t.sub.1a and/or t.sub.2a the measured pressure level P.sub.mw is not within an acceptable pressure range P.sub.2wL-P.sub.2wH or P.sub.3wL-P.sub.3wH respectively.

[0056] FIG. 5 shows a block diagram over the processing node 125 according to one embodiment of the invention. The processing node 125 is configured to receive measured values of a pressure level, for example P.sub.md as described above with reference to FIG. 1, or P.sub.mw as described above with reference to FIG. 3, and assign timestamps to generate corresponding the monitoring data P.sub.md(t.sub.s) or P.sub.mw(t.sub.s) respectively. It is generally advantageous if the processing node 125 is configured to effect the above-described procedure in an automatic manner by executing a computer program 527. Therefore, according to this embodiment, the processing node 125 includes a memory unit 525, i.e. non-volatile data carrier, storing the computer program 527, which, in turn, contains software for making processing circuitry in the form of at least one processor 525 in the central control unit 520 execute the above-described actions when the computer program 527 is run on the at least one processor 525.

[0057] In order to sum up, and with reference to the flow diagram in FIG. 6, we will now describe the general computer-implemented method according to the invention of monitoring at least one operating pressure in a milking installation.

[0058] In a first step 610, at least one measured pressure value is received from one or more pressure sensors. The at least one measured pressure value is indicative of the at least one operating pressure in the milking installation.

[0059] A following step 620 assigns a respective timestamp to each of the measured pressure values received. The monitoring data represent a series of measured values of the pressure level including the timestamps indicating a respective time when a particular value of the pressure level was measured, and serve as a basis for triggering at least one alarm.

[0060] Subsequently, a step 630 checks if at least one alarm criterion is fulfilled. If so, a step 640 follows; and otherwise, the procedure loops back to step 610.

[0061] Step 640 generates at least one alarm in response to an output from step 630. Thereafter, the procedure loops back to step 610.

[0062] All of the process steps, as well as any sub-sequence of steps, described with reference to FIG. 6 may be controlled by means of a programmed processor. Moreover, although the embodiments of the invention described above with reference to the drawings comprise processor and processes performed in at least one processor, the invention thus also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source code, object code, a code intermediate source and object code such as in partially compiled form, or in any other form suitable for use in the implementation of the process according to the invention. The program may either be a part of an operating system, or be a separate application. The carrier may be any entity or device capable of carrying the program. For example, the carrier may comprise a storage medium, such as a Flash memory, a ROM (Read Only Memory), for example a DVD (Digital Video/Versatile Disk), a CD (Compact Disc) or a semi-conductor ROM, an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a magnetic recording medium, for example a floppy disc or hard disc. Further, the carrier may be a transmissible carrier such as an electrical or optical signal which may be conveyed via electrical or optical cable or by radio or by other means. When the program is embodied in a signal which may be conveyed directly by a cable or other device or means, the carrier may be constituted by such cable or device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant processes.

[0063] The term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components. However, the term does not preclude the presence or addition of one or more additional features, integers, steps or components or groups thereof.

[0064] The invention is not restricted to the described embodiments in the figures, but may be varied freely within the scope of the claims.