A method and a system for obtaining information from a utility meter

Abstract

The present invention provides a method for obtaining information from a utility meter, the method comprising steps of directing emitted radiation on to a rotating element of the utility meter, receiving incident radiation, the incident radiation comprising reflected radiation from a reflective surface of the rotating element, the reflective surface having a marker, determining an instant value of intensity of the incident radiation, determining a reference value from earlier ones of the determined values of the intensity of the incident radiation and detecting passing of the marker, as a function of the reference value and the instant value.

Claims

1. A method for obtaining information from a utility meter, the method comprising steps of: emitting radiation on to a rotating element of the utility meter; receiving incident radiation comprising reflected radiation from a reflective surface of the rotating element, the reflective surface having a marker; at each of a plurality of points in time: determining, at the point of time, an instant value of intensity of the incident radiation; determining a reference value from values of the intensity of the incident radiation determined at other points in time of the plurality of points in time, the other points in time being earlier than the time; and detecting passing of the marker, as a function of the reference value and the instant value.

2. The method as claimed in claim 1, wherein the step of determining the instant value comprises a step of determining the instant value continuously or intermittently.

3. The method as claimed in claim 1, wherein the reference value is a running mean of the values determined at the other points in time.

4. The method as claimed in claim 1, wherein the detecting step further comprises a step of determining a first threshold value from the reference value.

5. The method as claimed in claim 4, wherein the detecting step further comprises a step of updating the first threshold value so as to ensure that the first threshold value is always at a first minimum offset from the reference value.

6. The method as claimed in claim 4, wherein the detecting step further comprises a step of determining a second threshold value from the reference value or the first threshold value, the second threshold value being at a second minimum offset from the first threshold value, wherein the first minimum offset and the second minimum offset are in a same direction.

7. The method as claimed in claim 1, wherein the passing of the marker is detected when the instant value first crosses the second threshold value in the direction of the first and the second minimum offsets followed by the instant value crossing the first threshold value in a direction opposite to the direction of the first and the second minimum offsets.

8. The method as claimed in claim 7, wherein the detecting step further comprises a step of keeping the first threshold value and the second threshold value constant, between the instant value crossing the second threshold value and then crossing the first threshold value.

9. A system for obtaining information from a utility meter, the system comprising: a radiation emitter configured to direct emitted radiation on to a rotating element of the utility meter; a radiation detector configured to receive incident radiation comprising reflected radiation from a reflective surface of the rotating element, the reflective surface having a marker; a control module configured to, at each of plurality of points in time: determine, at the point in time, an instant value of intensity of the incident radiation; determine a reference value from values of the intensity of the incident radiation determined at other points in time of the plurality of points in time, the other points in time being earlier than the point in time; and detect passing of the marker as a function of the reference value and the instant value.

10. The system as claimed in claim 9, wherein the control module is further configured to determine the instant value continuously or intermittently.

11. The system as claimed in claim 9, wherein the reference value is running mean of the values determined at the other points in time.

12. The system as claimed in claim 9, wherein the control module is further configured to determine a first threshold value from the reference value.

13. The system as claimed in claim 12, wherein the control module is further configured to determine a second threshold value from the reference value or the first threshold value, the second threshold value being at a second minimum offset from the first threshold value, wherein the first minimum offset and the second minimum offset are in a same direction.

14. The system as claimed in claim 13, wherein the control module is further configured to detect the passing of the marker when the instant value first crosses the second threshold value in the direction of the first and second minimum offsets followed by the instant value crossing the first threshold value, in a direction opposite to the direction of the first and the second minimum offsets.

15. The system as claimed in claim 14, wherein the control module is further configured to keep the first threshold value and the second threshold value constant, between the instant value crossing the second threshold value and then crossing the first threshold value.

16. The method as claimed in claim 2, wherein the reference value is a running mean of the values determined at the other points in time.

17. The method as claimed in claim 5, wherein the detecting step further comprises a step of determining a second threshold value from the reference value or the first threshold value, the second threshold value being at a second minimum offset from the first threshold value, wherein the first minimum offset and the second minimum offset are in a same direction.

18. The system as claimed in claim 10, wherein the reference value is running mean of the values determined at the other points in time.

Description

[0076] These and other features, benefits, and advantages of the present invention will become apparent by reference to the following text figure, with like reference numbers referring to like structures across the views, wherein:

[0077] FIG. 1 illustrates a system for obtaining information from a utility meter, In one embodiment;

[0078] FIG. 2 illustrates an IntensityTime plot of incident radiation, received at a radiation detector, In one embodiment;

[0079] FIG. 3 illustrates the IntensityTime plot of incident radiation, received at the radiation detector, in accordance with another embodiment of the present invention; and

[0080] FIG. 4 illustrates a method for obtaining information from a utility meter, In one embodiment.

[0081] As shown in FIG. 1, a system 100 for obtaining information from a utility meter 160 In one embodiment, comprises a radiation emitter 120, a radiation detector 130 and a control module 140. Further, the system 100 comprises a battery 150, configured to provide power to the radiation emitter 120, the radiation detector 130 and the control module 140. The radiation emitter 120 is configured to direct emitted radiation on to a rotating element 110 of the utility meter 160.

[0082] Positioning of the system may be seen in the Applicant's co-pending application with the title A SENSOR AND A METHOD FOR READING A UTILITY METER filed on even date. A suitable set-up of the system may be seen in Applicant's co-pending application with the title A UTILITY METER READER FOR READING A UTILITY METER AND A METHOD OF READING A UTILITY METER filed on even date. Both references are incorporated herein in their entireties by reference.

[0083] In one embodiment, the radiation emitter 120 is a laser. The use of a laser allows sufficient amount of radiation on the rotating element 110, when the rotating element 110 is at a substantial distance from the radiation emitter 120. Further, In one embodiment, the rotating element 110 is a rotating disc or a rotating needle. Usually, the radiation is emitted toward and reflected from an edge of the rotating element 110. Often, the radiation emitter 120 and radiation detector 130 are positioned in a plane of the rotating disc. When the rotating element 110 is a rotating needle, the emitted radiation may be directed toward a position which is passed by the needle so that the passing of the needle may be determined from the reflected radiation.

[0084] The radiation detector 130 is configured to receive incident radiation. The incident radiation comprises reflected radiation from a reflective surface 1102 of the rotating element 110. Further, the reflective surface 1102 has a marker 1104, such as, but not limited to a black dot. As to the needle, the marker 1104 may be a portion of the needle passing the beam of radiation. The marker 1104 has a lower reflectivity compared to a remaining portion of the reflective surface 1102. Alternatively, the marker 1104 may have a higher reflectivity compared to other portions of the reflective surface 1102. Therefore, an intensity of the reflected radiation from the marker 1104 will be different from that from the rest of the reflective surface 1102.

[0085] Consequently, the intensity of the incident radiation during passing of the maker 1104 will also be different compared to the rest of the reflective surface 1102. Additionally, the incident radiation may not only comprise reflected radiation but also ambient light, such as light from light bulbs, the sun and other light sources. Variations in the detected radiation thus stems not only from the passing of the marker but also from variations in ambient light, such as the light turned on/off and the amount of sunlight available at different times of the day or during different weather conditions.

[0086] The control module 140 is configured to determine an instant value of the intensity of the incident radiation. The control module 140 is configured to determine the instant value continuously, in real time. Continuous determination has the advantage that detection of the marker 1104 is ensured. This is suitable in applications where the rotating element 110 is rotating at a fairly high rate. However this gives a higher power consumption and is rather inefficient in applications where the rotating element 110 is rotating with a moderate or a very small angular velocity.

[0087] Alternatively, the control module 140 is configured to determine the instant value intermittently, such as at short intervals. This may still be seen as being in real time. The control module 140 is configured to determine the instant value with a frequency of 60 Hz. However, the interval may vary in various embodiments, as per the design requirements. Intermittent determination reduces power consumption and is suitable where the rotating element 110 is not expected to be rotating at a high rate. The frequency may be increased at points in time where the marker is expected to pass or when a high consumption (rotational velocity) is expected or determined.

[0088] Further, the control module 140 is configured to determine a reference value from historic values of the determined intensity of the incident radiation. The reference value is a running mean of the historic values of the intensity of incident radiation, such as a running mean of historic values obtained over a predetermined period of time or simply a predetermined number of historic numbers/values (typically the latest ones). For example, the running mean may be calculated over the latest sixteen values. Running means are simple to calculate and may be determined during the latest 1-1000 seconds, 5-100 seconds or 5-20 seconds. Further, the control module 140 may be configured to update the reference value after every first predetermined period of time. The first predetermined period of time may be 500 milliseconds. Other such periods may be selected as per design requirements. The control module 140 is further configured to detect passing of the marker 1104 as a function of the reference value and the instant value.

[0089] FIG. 2 illustrates an IntensityTime plot of the incident radiation received at the radiation detector 130, where the marker 1104 has a lower reflectivity compared to the rest of the reflective surface 1102. Plot 210 denotes the instant value of the intensity of the incident radiation. Plot 220 denotes the reference value. As can be seen from FIG. 2, trough 230 denotes passing of the marker 1104.

[0090] FIG. 3 illustrates the IntensityTime plot of the incident radiation received at the radiation detector 130, where the marker 1104 has higher reflectivity compared to the rest of the reflective surface 1102. Plot 310 denotes the instant value of the intensity of the incident radiation. Plot 320 denotes the reference value. As can be seen from FIG. 3, crest 330 denotes passing of the marker 1104.

[0091] The control module 140 is further configured to determine a first threshold value from the reference value. The first threshold value is denoted by plot T.sub.1 240 in FIG. 2 and by plot T.sub.12 340 in FIG. 3. The control module 140 is further configured to update the first threshold value so as to ensure that the first threshold value is always offset at least a first minimum from the reference value. In FIG. 2, the first minimum offset is a negative value, whereas in FIG. 3, the first minimum offset is a positive value.

[0092] Taking the example of embodiment 300, each time an instant value is determined or each time the reference value is updated, the reference value is compared to the first threshold value, and if a difference value obtained from subtracting the reference value from the first threshold value is smaller than the first minimum offset, the first threshold value is re-calculated. The first minimum offset may take into account for example a situation where the instant value becomes higher than the reference value (the reference value preferably adapts slower to changes than the instant value). For not too large changes, the control module 140 should not assume that the marker is passing. In this manner, the first threshold value is so high that if the instant value passes it (becomes higher), the marker may be passing or another event takes place, such as when ambient light is turned off.

[0093] Naturally, it will be possible to determine the passing of the marker using the first threshold value, but it is preferred that the control module 140 is further configured to determine a second threshold value from reference value or the first threshold value. The second threshold value is at a second minimum offset from the first threshold value. Further, the first minimum offset and the second minimum offset are in a same direction. This means that both the first minimum offset are either positive or negative. The second threshold value is denoted by plot T.sub.2 250 in FIG. 2 and by plot T.sub.22 350 in FIG. 3. The second threshold is calculated to ensure that the detection of the marker is not a result of variations in the ambient light. Hence a second minimum offset is maintained with the first threshold to ensure that rather small variations caused in the intensity of incident radiation due to ambient conditions are ruled out.

[0094] Further, the control module 140 is further configured to determine a third threshold value from the historic values. Lowest values of the historic values corresponding to a second predetermined period of time are considered in embodiment 200. For example, the third threshold value may be a lowest value of the historic values for a period of time in order of days or weeks. In another embodiment, the third threshold value is a low running average over a number of lowest values, determined over, for example, a fifteen minute interval.

[0095] Highest values of the historic values corresponding to a second predetermined periods of time are considered in embodiment 300. For example, in one embodiment, the third threshold value is a highest value of the historic values for a period of time in order of days or weeks. In another embodiment, the third threshold value is a high running average over a number of highest values, determined over, for example, a fifteen minute interval. The third threshold value represents a boundary for the second threshold value so that second threshold value preferably never is smaller or larger, as the case may be, than the third threshold value.

[0096] However, false reflections and other intensity increases may be seen during the passing of the marker 1104. This is seen at the bottom of the trough of the curve 210 in FIG. 2 or at the top of the crest 310 in FIG. 3. Thus, the marker is preferably determined only when the instant value again exceeds the first threshold. The control module 140 is further configured to detect the passing of the marker 1104 when the instant value first crosses the second threshold value in the direction of the first and second minimum offsets followed by the instant value crossing the first threshold value, in a direction opposite to the direction of the first and the second minimum offsets.

[0097] In embodiment 200, as shown in FIG. 2, the marker 1104 is detected when the instant value first becomes smaller than the second threshold value, followed by the instant value becoming greater than the first threshold value. In embodiment 300, as shown in FIG. 3, the marker 1104 is detected when the instant value first becomes larger than the second threshold value, followed by the instant value becoming smaller than the first threshold value.

[0098] The control module 140 is further configured to keep the first threshold value and the second threshold value constant, between the instant value crossing the second threshold value and then crossing the first threshold value. Thus, the first threshold value and the second threshold value are fixed during the trough 230 in FIG. 2 and crest 330 in FIG. 3. This is to, among other things, take into account the fact that the running mean will deviate from an expected trend, due to the reduced reflection at the marker 1104. In fact, the updating of the threshold(s) may be postponed to also a period of time 270 after the end of the marker (the instant value exceeding the first threshold) in order to allow the reference value to recover from the lower intensity caused by the marker.

[0099] Alternatively, the reference value may be determined only on the basis of instant values not within the marker, so that when the curve 210 passes the second threshold value on its way into the trough 230, updating of the reference values is stopped, and when the curve 210 again exceeds the first threshold value, values of the curve 210 between these two passings are not used in the calculation of the reference value. Then, the thresholds may be re-determined as soon as the trough 230 has passed.

[0100] In one embodiment, the control module 140 is further configured to assign a predefined set of values to the reference value and any of the first, the second and the third thresholds used, when the reference value is smaller than a predefined design constant. This may be the situation if the sensor head is positioned wrongly in relation to the utility meter, so that the reflected radiation is much less than ideal or if the ambient lighting is excessive. Then the predefined set of values ensure that the passing of the marker 1104 would still be detected for most of the occurrences.

[0101] The control module 140 is further configured to determine a marker width interval between the instant value crossing the second threshold value and then crossing the first threshold value. Periods 260 in FIGS. 2 and 360 in FIG. 3 illustrate the respective marker width intervals of embodiment 200 and 300. Then, a next detection of the passing of the marker may be discarded, if a determined marker width thereof is smaller than a predetermined fraction of the width interval of a previous marker detected. This helps discarding spurious signals or false positives of the passing of the marker 1104. Naturally, the marker width interval will depend on the speed of the rotating element 110 and may therefore vary. This may be taken into account in the determination of the fraction, so that some speed deviations may be accepted but very large speed deviations will result in a width variation too large and thus are discarded. A too wide or too narrow crest or trough may be caused by other effects, such as a cloud passing before the sun. this expected width or expected marker width interval may be determined from historical widths (rotation speeds), use patterns of the utility (more power used at points in time of cooking than in the middle of the day or in the middle of the night) or the like.

[0102] Further, the control module 140 is configured to instruct the radiation emitter 120 to adapt intensity of the emitted radiation based on the reference value. This saves power, which is especially desirable when the system 100 is powered by the battery 150. The control module 140 is further configured to deactivate the radiation emitter 120 for a third predetermined period of time. Deactivating the radiation emitter 120 for a period of time will, naturally, save power. On the other hand, it is desired to ensure that a next passing of the marker 1104 is detected, so that the radiation emitter 120 is deactivated for only a portion of the time expected between passings of the marker.

[0103] Further, it may be desired to reduce the intensity of emitted radiation, at least partially or intermittently. The control module 140 may be configured to instruct the radiation emitter 120 to emit the emitted radiation as pulses of a predetermined pulse width interval and at a predetermined frequency. For example in FIG. 2, during period 270, the radiation emitter 120 emits radiation in pulses of very low pulse width duration and at a fairly low frequency. This reduces the intensity of the emitted radiation between the detection of the passing of the marker and the next detection of the passing of the marker. This will again save power, while still being able to receive radiation reflected from the reflective portion of the rotating element.

[0104] The predetermined frequency lies in a range of 30-100 Hz and the pulse width duration lies in a range of 2 microseconds to 3.5 milliseconds. The lower pulse width duration may be maintained for e.g. 0-80%, or 0-60%, or 0-50% of a period of time from the passing of the marker to an expected next point in time of passing of the marker. This next point in time may be determined from points in time of subsequent passings of the marker, the time it took for the marker to pass the last time or the like.

[0105] Power may also be saved during detection of the passing of the marker 1104. The control module 140 is further configured to instruct the radiation emitter 120 to adapt the intensity of the emitted radiation as a function of the instant value. If the instant value of the intensity of the incident radiation is higher than required, the intensity of emitted radiation may be lowered to save power. Various embodiments of a method for adapting intensity of emitted radiation during operation of a utility meter, may now be understood taking the embodiments of the system 100 as reference.

[0106] FIG. 4 illustrates a method 400 for obtaining information from the utility meter 160. The method begins at step 410 by emitting radiation on the rotating element 110 of the utility meter 160. The emitted radiation is projected by the radiation emitter 120. At step 420, the incident radiation is received at the radiation detector 130. As mentioned above, the incident radiation comprises the reflected radiation from the reflective surface 1102 of the rotating element 110. At step 430, the instant value of the intensity of the incident radiation is determined by the control module 140. The instant value is determined continuously, in real time, by the control module 140. Alternatively, the instant value is determined intermittently, by the control module 140.

[0107] At step 340, the reference value is determined by the control module 140, from the historic values of the intensity of the incident radiation. At step 350, the passing of the marker 1104 is detected, as a function of the reference value and the instant value, by the control module 140. The control module 140 determines the first threshold value from the reference value. Further, the control module 140 updates the first threshold value so as to ensure that the first threshold value is always at at least a first minimum offset from the reference value. Then, the control module 140 determines the second threshold value from the reference value or the first threshold value and the third threshold value from the historic values, corresponding to the second predetermined period of time.

[0108] The passing of the marker 1104 is detected by the control module 140, when the instant value first crosses the second threshold value in the direction of the first and the second minimum offsets followed by the instant value crossing the first threshold value in a direction opposite to the direction of the first and the second minimum offsets. The control module (140) keeps the first threshold value and the second threshold value constant, between the instant value crossing the second threshold value and then crossing the first threshold value.

[0109] The control module 140 further assigns the predefined set of values to the reference value and any of the first, second and the third thresholds used, when the reference value is smaller than the predefined design constant.

[0110] Also, the control module 140 determines the marker width interval between the instant value crossing the second threshold value and then crossing the first threshold value.

[0111] To save power the control module 140 adapts the intensity of the emitted radiation based on the reference value. The control module 140 deactivates the emitted radiation by deactivating the radiation emitter 120 for a third predetermined period of time. The control module 140 instructs the radiation emitter 120 to emit the emitted radiation as pulses of the predetermined pulse width duration and at the predetermined frequency. The control module 140 instructs the radiation emitter 120 to adapt the intensity of the emitted radiation also on basis of the instant value.

[0112] The method and the system discussed above allow cancellation of noise caused due to environmental or ambient conditions. Also, power can be saved using a number of strategies, making the invention suitable for battery operation. A number of variables can be introduced at any time to enhance the overall accuracy of the invention even further.

[0113] Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be providing broadest scope of consistent with the principles and the novel and inventive features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention and appended claim.