GB2463518A

GB2463518A - Automated meter reading device

Info

Publication number: GB2463518A
Application number: GB0816706A
Authority: GB
Inventors: Paul Fellows
Original assignee: Alertme com Ltd
Current assignee: Alertme com Ltd
Priority date: 2008-09-12
Filing date: 2008-09-12
Publication date: 2010-03-24
Also published as: GB0816706D0; WO2010029339A3; WO2010029339A2

Abstract

Remotely reading a utility meter wherein consumption of a utility is indicated by the movement of a mechanical component which is illuminated with coherent light which reflects off the mechanical component in a speckle pattern which is detected to produce a light detection signal. The light detection signal is processed to identify changes in the speckle pattern due to movements of the mechanical component. The processing may comprise identifying a set of features in the light detection signal, storing data representing the set of features and matching the stored data with the identified set of features. Other independent claims comprise; the mechanical component having at least one fiducial mark and detecting the movement of one or more fiducial marks through two successive spatial locations or twice optically detecting the movement of a fiducial mark through a spatial location during a cycle of the mechanical component and; determining the energy consumption using two time periods, the first time period being the time taken for a rotation of a rotating element depending on variations in a detection signal and the second time period being a time between two variations in at least one detection signal during the rotation of the rotating element.

Description

Automated meter reading device

FIELD OF THE INVENTION

The invention relates to a method and apparatus for remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, and to an automated meter reading apparatus and a method for use with a rotating element that rotates according to energy consumption.

The invention is particularly applicable to automatically monitoring electricity consumption at a user's meter, for the purpose of encouraging energy efficiency by enabling feedback to the user showing their energy consumption.

BACKGROUND TO THE INVENTION

Electricity meters typically provide a human-readable display showing cumulative electricity usage in the form of numerals indicated on a series of dials or drums. This is ill adapted to modern requirements such as automated meter reading and frequent feedback of electricity usage to users.

The majority of electricity meters installed today utilise an electromechanical measurement system comprising a metal disc, known as a Ferraris disc, which rotates under the impulsion of induced electromagnetic forces. The Ferraris disc is almost always mounted horizontally with one edge visible through the face of the meter. One sector of the disc is blackened so that the rotation of the disc can be observed by eye, each rotation of the disc corresponding to a given amount of electrical energy, the size of the electric current passing through the meter therefore being indicated by the disc's rate of revolution.

Numerous studies have shown that providing users with frequent feedback of their energy usage motivates them to efficient behaviours and typically leads to reductions of 5-15%. Giving feedback every few seconds allows customers to see and respond to their electricity usage immediately. It also becomes easy to determine the energy usage of particular appliances. Being clearly beneficial to both the customer and the environment, rapid feedback is widely desired. However, there is a disadvantage in that because meters and their associated wiring are unsightly, they are usually sited in out-of-the-way and consequently hard to access locations unsuited to this feedback role.

Deploying smart meters' capable of communicating with remote displays remains a significant capital and engineering project, a work of many years. However, they are not strictly necessary for the purposes of providing rapid feedback to electricity users, for whom exact usage measurements may not be essential. These can be obtained cheaply and easily by means of a clip-on' device placed around one of the mains cables entering the fiduciary meter. Such devices are typically part of a user-installable system which measures current using a simple inductive coil, calculates power consumption and feeds back some representation of it to the user via a display of some kind. Cheap and easy to set up, these systems often rely heavily on assumptions about the supply voltage and power factor of connected loads.

The supply voltage is of most concern, as it varies significantly between locations. Near an electricity substation, voltage may be high -up to 253.OV in the UK. Far from the local substation, after resistive losses in the distribution network, the supply voltage can fall significantly -as low as 216.2V in the UK.

Because it represents a variation up to +10% above and -6% below the expected 230V any clip-on' power monitoring device based on an inductive coil and assuming a 230V supply may report power consumption up to 10% in error. Supply voltage can also vary during the day, falling slightly during high-load periods, and varying moment by moment as loads are connected and disconnected.

These assumptions can be rendered unnecessary if frequent usage readings are instead obtained from the fiduciary meter. In this regard, a known technique involves shining an infra-red light beam from a light emitting diode (LED) onto the edge of the Ferraris disc and recovering a measurement of the reflected light by means of a photo diode (PD), in which a voltage is generated proportional to the incident light. When the black sector passes beneath the beam, a dip in the amount of reflected light leads to a dip in the diode voltage which can be detected by a level-detect circuit or micro controller. The time between voltage dips corresponds to the rotational period of the Ferraris disc, each rotation of which corresponds to the consumption of a given amount of electrical energy. Having an amount of energy and a time, the present rate of energy consumption can be calculated. This rate is necessarily an average over the preceding rotational period.

At low but not atypical consumption rates, the Ferraris disc may take many seconds, or even minutes, to complete each revolution, thus severely limiting the rate at which updates can be provided to the user.

SUMMARY

According to a first aspect of the invention, there is provided a method of remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, the method comprising: illuminating said mechanical component with coherent light; detecting a portion of said coherent light reflected from said mechanical component to produce a light detection signal, said reflected portion of coherent light having a speckle pattern; processing said light detection signal to identify changes in said speckle pattern due to movement of said mechanical component; and determining a measurement of consumption of said utility from said identified changes.

Thus, the present invention may advantageously provide an automated meter reading device for responsive electricity consumption feedback.

There may further be provided the above method, wherein said processing comprises identifying a set of features in said light detection signal, storing data representing said set of features, and matching a later light detection signal to said identified set of features using said stored data.

According to a second aspect of the invention, there is provided a method of remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, said mechanical component having at least one fiducial mark, the method comprising optically detecting movement of one or more said fiducial marks through two successive spatial locations, determining the speed or time duration of a fractional part of a complete cycle of movement of said mechanical component between said two spatial locations, and using said determined speed or duration to estimate a consumption of said utility.

According to a third aspect of the invention, there is provided a method of remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, said mechanical component having at least one fiducial mark, the method comprising: twice optically detecting movement of a said fiducial mark though a spatial location during a complete cycle of movement of said mechanical component; determining the speed or time duration of a fractional part of said complete cycle of movement of said mechanical component between two spatial locations; and using said determined speed or duration to estimate a consumption of said utility.

According to further aspects and embodiments of the invention there may be provided apparatus comprising means for performing themethod steps of any one of the above methods.

According to a fourth aspect of the present invention, there is provided an automated meter reading apparatus for use with a rotating element that rotates according to energy consumption, comprising; at least one light detector arranged to output a detection signal based on light received from the rotating element; and a process arranged to determine a fast time period, which is the time taken for a rotation of the rotating element, independence on variations in a said detection signal wherein the processor is further arranged to: determine a second time period, which is a time between two variations in at least one detection signal during said rotation of said rotating element; and determine a measure of energy consumption in dependence on the first and second time periods.

In such an apparatus, there may further be provided at least one light source arranged to transmit the light received by the at least one light detector. Such a light source could be, for example, a light emitting diode (LED) or a filament lamp. In other embodiments, the received light may be ambient light.

The above apparatus may further be provided with the processor arranged to divide the second time period by the first time period, in order to estimate the measure of energy consumption.

Alternatively, such a division may be carried out at an external processor. Further alternatively, the estimation may be obtained by use of a look-up table (LUT) that stores reference values of first and second time periods. Further still, the processor of the above automated meter reading apparatus, or an external processor, may multiply the results, e.g., of the above division or look-up, by a predetermined amount of total energy consumed during the rotation of the rotating element. In this regard, it is noted that the rotation corresponding to the first time period in any of the embodiments described herein may for example be a complete revolution of the rotating element.

There may be further provided the above automated apparatus, wherein the received light is light reflected from the rotating element. Alternatively, the received light may have been transmitted through the rotating element. Further still, the received light may be ambient light or may be provided by a light source included in the apparatus. Where such a light source is included in the apparatus, there may be one light source for each respective light detector.

The above automated apparatus may further be arranged such that each of the variations in the detection signal corresponds to the movement past a respective detector of a portion of the rotating element, the portion being distinguished by colour from neighbouring portions of the rotating element. For example, the portion may be a blackened or darkened portion relative to the remainder of the rotating element, and the portion may for example be a sector of the rotating element surface or a mark on the edge of the element.

Furthermore, light received by a detector in any of the embodiments described herein may be reflected any part of the mechanical component, e.g., from an edge or from a flat radially extending surface. For example, where the mechanical component is a disk such as a Ferraris disc, the light may be reflected from the circumferential edge of the disc.

In one preferred embodiment of the above automated apparatus, at least one detector comprises two detectors and these detectors are arranged to detect the movement of the same distinguished portion of the rotating element as that portion passes the respective detector. In other words, one distinguished portion of the element is detected twice, once when it passes the first detector and the second time when it passes the second detector.

Similarly, an embodiment of the automated apparatus may alternatively comprise a single detector, the rotating element having more than one portion distinguished by colour from the background colour of the rotating element, the more than one portions being separated by the background colour of the rotating element. In this case, the single detector outputs a variation in a detection signal every time one of the distinguished portions passes the detector.

In some preferred embodiments of the automated reading apparatus, the above light source is a coherent light source (e.g. an infra-red laser diode), this light source transmitting the light received by the at least one light detector. In this case, variations of the detection signal are preferably determined by a speckle pattern of the reflected light, such a speckled pattern changing according to the roughness of the surface of the rotating element from which the coherent light is reflected.

In any embodiment of the above automated meter reading apparatus, in particular the preferred embodiment having a coherent light source and using the speckled pattern of reflected light, a feature detection algorithm may be applied to a trace of the detection signal during a rotation of the rotating element.

Depending on the required accuracy of energy consumption determination, this trace may be obtained as the rotating element rotates under substantially constant load. The trace is then analysed to identify and store characteristics of features within the trace. Features that are identified in subsequent traces of the detection signal can then be identified by comparing the stored characteristics to characteristics of the features of the subsequent traces. Such characteristics may be the magnitude and ordinate (i.e., angular position on the rotating element) of the feature. The feature characteristics may further be stored in such as way as to indicate the order in which the characteristics are identified in the original trace, e.g., may be stored in a memory in the same order as their time order of identification.

According to further aspects and embodiments of the invention there may be provided methods corresponding to any one of the above automated meter reading apparatuses.

The present invention as described above is particularly applicable to the monitoring of electricity consumption using, for example, a Ferraris disc as the mechanical component. However, the consumed resource i.e. utility or energy, may be consumed electricity, gas or water, or for that matter any other utility, and the skilled person will recognised that alternative mechanical component may be used, e.g., a band, wheel, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to Fig. 1, which illustrates acquisition of rotational rate data from a Ferraris disc using a laser diode, a photo-diode and signal processing.

DETAILED DESCRIPTION

An embodiment of this invention may advantageously provide means of obtaining increased update rates and on demand' updates from a retrofittable optical monitoring system adapted to observe a Ferraris disc, otherwise similar to those described above.

In one implementation, a second photo diode and associated light beam are placed close to the first, such that the black sector must pass through both in close succession. Two averaging periods are available for power readings obtained using this arrangement -a short one of typically few or less than one seconds, and a longer one being the rotation period of the disc.

In well-controlled installations where the angle subtended by the points of intersection of the two beams with the edge of the Ferraris disc and its centre, it is trivial to calculate the energy corresponding to the partial rotation of the disc between the two points of intersection. In cases where the positions of the beams relative to the centre of the disc are not initially known, it can be determined by dividing the time taken for a complete revolution under a constant load by the time taken to rotate through the two beams, multiplying the result by the energy indicated by a complete revolution.

In a second implementation a single light source and photo diode are retained, but the light source used is an infrared semiconductor laser diode (LD) (see label 1 in accompanying Fig. 1) . Reflected laser light exhibits a characteristic speckle pattern' arising from constructive and destructive interference created by microscopic irregularities on the reflecting surface, regardless of its innate reflectivity. Such irregularities are unique to each part of each surface, so that as the Ferraris disc rotates through each revolution the PD will output a corresponding periodic voltage pattern. This pattern is the same for each revolution (see label 2, Fig. 1), scaled in time according to the rate of revolution.

By shining the laser on the edge of the Ferraris disc for a short period and recording the time evolution of the reflected laser light by means of the PD (see label 4, Fig. 1), whose output voltage may be fed in to a micro controller for logging and processing, it is possible to determine the present rate of energy consumption in short order and on demand.

The micro controller's task is to identity features in the present signal in order to ascertain from their time progression the rate of rotation of the Ferraris disc. By applying a feature-detection algorithm to a trace of an entire rotation under constant load (again, see label 2, Fig. 1), and recording the results, the micro controller can establish a canonical, sequential list of features, each feature having a voltage magnitude and being assigned an ordinate on the edge of the disc (see label 3, Fig. 1) . Applying the same algorithm to subsequent short traces, a short series of features can be obtained and matched with a portion of the stored list (see label 5, Fig. 1) . The present power usage is then obtained by an analysis similar to that for the paired photo diodes above, in which the time between two features subtending a known angle at the centre of the disc is converted into a power reading.

One example algorithm may involve processing, e.g. digital signal processing (DSP), of a signal from a detector provided as a series of values or images, so as to detect patterns in the values or images and see how these patterns have moved since the previous value/image. In the case of values, the detector could be the above PD. In the case of images, the PD could be replaced by a camera or CMOS sensor. On the basis of changes in the patterns over a series of values/images, features can be tracked and movement, e.g. speed, distance or angle of a disc, determined.

Characteristics of the tracked features may be identified by the processing of the signal to enable the tracking.

In many implementations, it may not be possible to arrive at a power measurement in absolute units, owing to the necessity of knowing the amount of energy indicated by one disc revolution.

Although this is frequently one of a number of standard values, it may be convenient to leave the final multiplication by this factor to be performed elsewhere, for instance at the feedback display device, which may also have facilities for the user to enter the necessary figure, which is typically printed on the face of the meter.

Advantageously, the present invention may allow updates of consumption at arbitrary intervals. These may be pre-determined or on-demand. Moreover, where the update frequency is relatively low, power consumption of the invention including processing may be sufficiently low to allow the invention to be battery powered over a long life span, e.g., using a lithium battery.

Alternatively, the invention may be powered by mains electricity, e.g., by induction such as through a transformer.

While the above refers to advantages such as automated meter reading for responsive electricity consumption feedback, the invention is further applicable to numerous other applications, e.g., for shaft encoders for position or movement sensing, in particular when using a speckle pattern as described above.

Particularly advantageously, the invention may provide a retro-fittable solution in many applications, e.g., the method or apparatus of the present invention may be applied to a pre-existing utility meter.

Claims

CLAIMS: 1. A method of remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, the method comprising: illuminating said mechanical component with coherent light; detecting a portion of said coherent light reflected from said mechanical component to produce a light detection signal, said reflected portion of coherent light having a speckle pattern; processing said light detection signal to identify changes in said speckle pattern due to movement of said mechanical component; and determining a measurement of consumption of said utility from said identified changes.
2. The method as claimed in claim 1, wherein said processing comprises identifying a set of features in said light detection signal, storing data representing said set of features, and matching a later light detection signal to said identified set of features using said stored data.
3. Apparatus for remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, the apparatus comprising: means for illuminating said mechanical component with coherent light; means for detecting a portion of said coherent light reflected from said mechanical component to produce a light detection signal, said reflected portion of coherent light having a speckle pattern; means for processing said light detection signal to identify changes in said speckle pattern due to movement of said mechanical component; and means for determining a measurement of consumption of said utility from said identified changes.
4. The apparatus as claimed in claim 3, wherein said means for processing comprises means for identifying a set of features in said light detection signal, means for storing data representing said set of features, and means for matching a later light detection signal to said identified set of features using said stored data.
5. A method of remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, said mechanical component having at least one fiducial mark, the method comprising: optically detecting movement of one or more said fiducial marks through two successive spatial locations; determining the speed or time duration of a fractional part of a complete cycle of movement of said mechanical component between said two spatial locations; and using said determined speed or duration to estimate a consumption of said utility.
6. Apparatus for remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, said mechanical component having at least one fiducial mark, the apparatus comprising: means for optically detecting movement of one or more said fiducial marks through two successive spatial locations; means for determining the speed or time duration of a fractional part of a complete cycle of movement of said mechanical component between said two spatial locations; and means for using said determined speed or duration to estimate a consumption of said utility.
7. A method of remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, said mechanical component having at least one fiducial mark, the method comprising: twice optically detecting movement of a said fiducial mark though a spatial location during a complete cycle of movement of said mechanical component; determining the speed or time duration of a fractional part of said complete cycle of movement of said mechanical component between two spatial locations; and using said determined speed or duration to estimate a consumption of said utility.
8. Apparatus for remotely reading a utility meter, the utility meter being of the type in which consumption of a utility is indicated by movement, typically rotational movement, of a mechanical component, said mechanical component having at least one fiducial mark, the apparatus comprising: means for twice optically detecting movement of a said fiducial mark though a spatial location during a complete cycle of movement of said mechanical component; means for determining the speed or time duration of a fractional part of said complete cycle of movement of said mechanical component between two spatial locations; and means for using said determined speed or duration to estimate a consumption of said utility.
9. Automated meter reading apparatus, for use with a rotating element that rotates according to energy consumption, comprising: at least one light detector arranged to output a detection signal based on light received from said rotating element; and a processor arranged to determine a first time period, which is the time taken for a rotation of the rotating element, in dependence on variations in a said detection signal, wherein said processor is further arranged to: determine a second time period, which is a time between two variations in the at least one detection signal during said rotation of said rotating element; and determine a measure of energy consumption in dependence on the first and second time periods.
10. Automated meter reading apparatus of claim 9, wherein said processor is arranged to divide said second time period by said first time period.
11. Automated meter reading apparatus of claim 10, wherein said processor is further arranged to multiply the result of said dividing by a predetermined amount of total energy consumed during said rotation of the rotating element.
12. Automated meter reading apparatus of any of claims 9 -11, wherein said received light is light reflected from said rotating element.
13. Automated meter reading apparatus of any of claims 9 -12, wherein each said variation corresponds to the movement, past a said detector, of a portion of the rotating element that is distinguished by colour from neighbouring portions of the rotating element.
14. Automated meter reading apparatus of claim 13, wherein said at least one detector comprises: a first said detector arranged to output a said variation in a said detection signal when one said distinguished portion moves past the first detector; and a second said detector arranged to output a said variation in a said detection signal when said one distinguished portion moves past the second detector.
15. Automated meter reading apparatus of claim 12, further comprising a coherent light source arranged to transmit said light received by said at least one light detector, wherein said variations of said detection signal are determined by a speckle pattern of said reflected light.
16. Automated meter reading apparatus of any of claims 9 -15, wherein said processor is further arranged to: apply a feature-detection algorithm to a trace of the detection signal during a rotation of the rotating element; store characteristics of features identified by said algorithm; and identify features in subsequent traces of the detection signal by comparing the stored characteristics to characteristics of features in the subsequent traces.
17. Automated meter reading apparatus of claim 16, wherein said characteristics of features include magnitude and ordinate of the or each said identified feature.
18. Method for automated meter reading, for use with a rotating element that rotates according to energy consumption, comprising: receiving light from said rotating element; outputting a detection signal based on said light received from said rotating element; determining a first time period, which is the time taken for a rotation of the rotating element, in dependence on variations in a said detection signal, determining a second time period, which is a time between two variations in the at least one detection signal during said rotation of said rotating element; and determining a measure of energy consumption in dependence on the first and second time periods.
19. Method of claim 18, further comprising dividing said second time period by said first time period.
20. Method of claim 19, further comprising multiplying the result of said dividing by a predetermined amount of total energy consumed during said rotation of the rotating element.
21. Method of any of claims 18 -20, wherein said received light is light reflected from said rotating element.
22. Method of any of claims 18 -20, wherein each said variation corresponds to the movement, past a said detector, of a portion of the rotating element that is distinguished by colour from neighbouring portions of the rotating element.
23. Method of claim 22, wherein said detecting comprises: outputting from a first detector a said variation in a said detection signal when one said distinguished portion moves past the first detector; and outputting from a second detector a said variation in a said detection signal when said one distinguished portion moves past the second detector.
24. Method of claim 21, further comprising a coherent light source transmitting said light received by said at least one light detector, wherein said variations of said detection signal are determined by a speckle pattern of said reflected light.
25. Method of any of claims 18 -24, further comprising: applying a feature-detection algorithm to a trace of the detection signal during a rotation of the rotating element; storing characteristics of features identified by said algorithm; and identifying features in subsequent traces of the detection signal by comparing the stored characteristics to characteristics of features in the subsequent traces.
26. Method of claim 25, wherein said stored characteristics of features include magnitude and ordinate of the or each said identified feature.