AU2014101631A4

AU2014101631A4 - Fluid monitoring system

Info

Publication number: AU2014101631A4
Application number: AU2014101631A
Authority: AU
Inventors: Larry Stewart Ellison
Original assignee: Levno Ltd
Current assignee: Levno Ltd
Priority date: 2013-03-06
Filing date: 2014-03-06
Publication date: 2019-05-16
Anticipated expiration: 2022-03-06
Also published as: AU2014224190A1; WO2014136071A1; AU2014224190A2

Abstract

A fluid monitoring system for a tank comprising a fluid measuring device having a controller, a sensor arrangement, a sensor module in communication with the sensor arrangement, and a communications module. The sensor arrangement is at least partially locatable within the tank and has a sensor configured to generate an electrical signal relating to an amount of fluid in the tank. A server is configured to receive the signal from the sensor arrangement. The server is further configured to transmit the signal to a user device remote to the tank. The communications module is configured to transmit the signal to the server.

Description

FIELD OF THE INVENTION

The present invention relates to a fluid monitoring system for a tank and a method for 10 monitoring the level of fluid in a tank.

BACKGROUND

In an environment where tanks are located in remote or rural locations, a person needs to physically go to each tank to determine an amount of fluid in the tank. In 15 the case where the tank is a fuel storage tank, a person may periodically go to each tank to determine the amount of fuel in the tank, and refuel the tank if necessary. If the tank does not require refuelling, the person's time and costs of travelling to the tank are wasted.

An embodiment of the present invention seeks to provide a fluid monitoring system that overcomes one or more disadvantages of the above mentioned system.

Alternatively or additionally, an embodiment of the present invention seeks to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

The present invention provides a fluid monitoring system for a tank, the fluid monitoring system comprising:

a sensor arrangement at least partially locatable within the tank and comprising a capacitive sensor configured to generate an electrical capacitance signal relating to an amount of fluid in the tank, the capacitive sensor comprising a cylindrical capacitor having an inner cylinder and an outer hollow cylinder that surrounds the inner cylinder, the inner and outer cylinders being substantially coaxial and having a space therebetween, the outer cylinder being driven with an AC voltage;

a server being configured to receive the signal, and/or information indicating an amount of fluid in the tank based on the signal, from the sensor arrangement over a communications network, and

2014101631 07 May 2018 configured to transmit the signal, and/or information indicating an amount of fluid in the tank based on the signal, to a user device remote of the tank over the communications network; and a controller comprising or connected to a communications module, and a sensor module in communication with the sensor arrangement, the communications module being in communication with the sensor module, and configured to transmit the signal, and/or information indicating an amount of fluid in the tank based on the signal, to the server over the communications network.

The capacitance signal may relate to a height or a level of fluid in the tank.

The fluid may comprise a liquid and/or a gas. The fluid may comprise fuel. The fluid may comprise diesel or petrol.

The system may be configured to monitor the level of liquid in the tank. The sensor arrangement may be removably insertable into the tank. Alternatively, the sensor arrangement may be fixedly positioned within the tank.

The sensor arrangement may comprise an electrical circuit and the electrical circuit 20 may be configured to generate the signal relating to the amount of fluid in the tank.

The capacitive sensor may be configured to generate the capacitance signal based on a level of fluid in the space between the inner and outer cylinders, the level of fluid in the space between the inner and outer cylinders corresponding to a level of fluid in the 25 tank.

The capacitive sensor may be locatable at least partially within the tank so that the inner and outer cylinders extend vertically from at or near a top of the tank to at or near a bottom of the tank.

The capacitive sensor may comprise at least one spacer for maintaining the spacing between the outer cylinder from the inner cylinder. The spacer may be mounted to the inner cylinder.

The outer cylinder may be driven with an oscillating voltage. The outer cylinder may be driven at a peak-to-peak AC voltage of between about 20 mV and about 4 V and a current between about 20 nA and about 20 mA. The outer cylinder may be driven at a

2014101631 07 May 2018 peak-to-peak AC voltage of up to about 200mV and a current of less than about 500 μΑ.

The inner cylinder and the outer cylinder may be in a fixed spaced-apart relationship.

The capacitance sensor may comprise at least one spacer for maintaining the inner cylinder and the outer cylinder in the fixed spaced-apart relationship.

Alternatively, the capacitive sensor may be a plate capacitor with two spaced apart plates for generating a capacitance signal based on a level of fluid in the space between the plates.

The capacitive sensor may comprise aluminium. Additionally or alternatively, the capacitive sensor may comprise stainless steel or another suitable material.

The sensor arrangement may comprise a plurality of capacitive sensors positioned within the tank.

The communications module may comprise a cellular modem and an antenna. The antenna may be a radio network antenna. The radio network antenna may be a

General Packet Radio Service (GPRS) antenna, a code division multiple access (CDMA) antenna, a third generation (3G) antenna, or another suitable radio antenna.

The system may further comprise computer memory, wherein the server is configured is to store data representing a plurality of the signals generated and logged over a period of time, and/or information indicating amount(s) of fluid in the tank based on the signals, in the memory; and the server may be configured to transmit the signals, and/or information indicating amount(s) of fluid in the tank based on the signals, to the user device. The memory may be in the form of a database located remote of the tank.

The server may be accessible via a communications network, such as a local area network, a wide area network or the Internet. The communications network may comprise a private Access Port Network (APN).

The system may comprise a software platform at a user end for communication with the server. The user may access the server and the database through the software platform. The server may be configured so that a user device can access the server

2014101631 07 May 2018 via a web interface. The server may be configured to transmit the signal, and/or information indicating an amount of fluid in the tank based on the signal, to at least one of a desktop computing device, a laptop, a tablet and a smart phone device over the communications network.

The system may further comprise an identification module for generating a unique identifier of the tank. The communications module may be configured to transmit the identifier of the tank to the server. The identification module may comprise a Global Positioning System (GPS) unit and a GPS antenna, and the identifier may comprise a 10 position of the tank.

The system may comprise a power supply for providing power to at least the sensor arrangement and the communications module. The power supply unit may be located substantially outside the tank. The power supply may be in the form of a power supply unit having a battery. The power supply unit may comprise a lead-acid battery. Alternatively, the power supply unit may comprise a lithium battery, a lithium ion battery, or another suitable battery. Additionally or alternatively, the power supply unit may comprise an electrical charge storage component, such as a super capacitor for example. The power supply unit may be configured to provide a voltage of about 2 V to about 24 V. The power supply unit may be configured to provide a voltage of about 4.2 V. The system may comprise at least one solar panel or photovoltaic cell for charging the power supply unit.

The system may comprise a controller for receiving the generated signal from the sensor arrangement, wherein the controller is configured to determine the amount of fluid in the tank based on the generated signal. The controller may comprise a sensor module and/or be in electronic communication with the sensor arrangement for controlling an operation of the sensor arrangement. The controller may comprise or be in electronic communication with a solar panel module, a battery module, a power supply unit module, and the GPS unit.

The communications module may be configured to transmit an alert signal to the server when the determined amount of fluid in the tank drops below, or rises above, or substantially equals, a predetermined threshold or amount. The communications 35 module may be configured to transmit an alert signal to the server when there is an extraction or insertion of fluid from the tank. The communications module may be

2014101631 07 May 2018 configured to transmit the alert signal to the server when there is unauthorised extraction of fluid from the tank.

The system may comprise a housing that is adapted to house the controller, the battery, and the cellular modem. The housing may comprise one or more ports that are electronically connected to the controller. Alternatively, each port may be connectable to a respective one of the sensor arrangement, the cellular antenna, the GPS antenna, and the solar panel. The housing may comprise polycarbonate, other suitable polymeric materials, or other suitable materials. An example of other suitable 10 materials includes aluminium.

The present invention further provides a method for monitoring the level of fluid in a tank, the method comprising:

generating, using a capacitive sensor at least partially located within the tank, an electrical capacitance signal relating to an amount of fluid in the tank, the capacitive sensor comprising a cylindrical capacitor having an inner cylinder and an outer hollow cylinder that surrounds the inner cylinder, the inner and outer cylinders being substantially coaxial and having a space therebetween, the outer cylinder being driven with an AC voltage;

transmitting the signal, and/or information indicating an amount of fluid in the tank based on the signal, to a server over a communications network; and transmitting the signal, and/or information indicating an amount of fluid in the tank based on the signal, from the server to a user device remote of the tank over the communications network.

The capacitance signal may relate to a height or a level of fluid in the tank.

The method may be for monitoring the level of liquid in the tank. The method may comprise removably inserting the sensor arrangement into the tank. Alternatively, the method may comprise fixedly positioning the sensor arrangement within the tank.

The sensor arrangement may comprise an electrical circuit and the method may comprise generating the signal relating to the amount of fluid in the tank using the electrical circuit.

2014101631 07 May 2018

The method may comprise generating the capacitance signal based on a level of fluid in the space between the inner and outer cylinders, the level of fluid in the space between the inner and outer cylinders corresponding to a level of fluid in the tank.

The method may further comprise locating the capacitive sensor at least partially within the tank such that the inner and outer cylinders extend vertically from at or near a top of the tank to at or near a bottom of the tank.

The method may further comprise driving the outer cylinder with an oscillating voltage. The method may comprise driving the outer cylinder at a peak-to-peak AC voltage of between about 20 mV and about 4 V and a current between about 20 nA and about 20 mA. The method may comprise driving the outer cylinder at a peak-topeak AC voltage of up to about 2 V and a current of less than about 500 μΑ.

The inner cylinder and the outer cylinder may be in a fixed spaced-apart relationship. The capacitance sensor may comprise at least one spacer for maintaining the inner cylinder and the outer cylinder in the fixed spaced-apart relationship.

Alternatively, the capacitive sensor may comprise a plate capacitor having two spaced apart plates; and the method may comprise generating the capacitance signal based on a level of fluid in the space between the plates.

The method may further comprise wirelessly transmitting, using the communications module, the generated signal from the sensor arrangement and/or information indicating an amount of fluid in the tank based on the generated signal from the sensor arrangement to the server. The communications module may comprise a cellular modem and an antenna, wherein the antenna may be a radio network antenna. The radio network antenna may be a General Packet Radio Service (GPRS) antenna, a code division multiple access (CDMA) antenna, a third generation (3G) antenna, or another suitable radio antenna.

The server may be accessible via a communications network. The communications network may be a local area network, a wide area network or the Internet. The communications network may comprise a private Access Port Network (APN).

2014101631 07 May 2018

The server may be in communication with a software platform at a user end. The method may further comprise allowing a user to access the server through the software platform.

The method may further comprise generating, using an identification module, a unique identifier of the tank. The method may further comprise transmitting the identifier of the tank to the server, using the communications module. The identification module may comprise a Global Positioning System (GPS) unit and a GPS antenna, and the identifier comprises a position of the tank.

The method may further comprise the server storing data representing a plurality of the signals generated and logged over a period of time, and/or information indicating amount(s) of fluid in the tank based on the signals, in computer memory; and transmitting the logged signals, and/or information indicating amount(s) of fluid in the 15 tank based on the signals, to the user device. The memory may be in the form of a database located remote of the tank.

The method may further comprise receiving, by a controller, the generated signal from the sensor arrangement, and determining, by the controller, the amount of fluid in the 20 tank based on the generated signal. The method may further comprise controlling an operation of the sensor arrangement using the controller. The controller may comprise or be in electronic communication with a solar panel module, a battery module, a power supply unit module, and the GPS unit.

The method may further comprise transmitting an alert signal, using the communications module, to the server when the determined amount of fluid in the tank drops below, or rises above, or meets, a predetermined threshold. The method may further comprises transmitting an alert signal, using the communications module, to the server when there is an extraction or insertion of fluid from the tank. The method comprises transmitting an alert signal, using the communications module, to the server when there is unauthorised extraction of fluid from the tank.

The present invention still further provides a fluid monitoring system for a tank, the fluid monitoring system comprising:

a fluid measuring device having a controller, a sensor arrangement, a sensor module in communication with the sensor arrangement, and a communications module,

2014101631 07 May 2018 the controller comprising or being connected to, and for controlling an operation of, the communications module and the sensor module, the sensor arrangement being at least partially locatable within the tank and having a sensor configured to generate an electrical signal relating to an amount of 5 fluid in the tank;

a server being configured to receive the signal, and/or information indicating an amount of fluid in the tank based on the signal, from the sensor arrangement over a communications network, and configured to transmit the signal, and/or information indicating an amount of fluid in the tank based on the signal, to a user device remote of the tank over the communications network; and the communications module being in communication with the sensor module, and configured to transmit the signal, and/or information indicating an amount of fluid in the tank based on the signal, to the server over the communications network.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

As used herein '(s)' following a noun means the plural and/or singular forms of the noun.

As used herein the term 'and/or' means 'and' or 'or' or both.

The term 'comprising' as used in this specification means 'consisting at least in part of'. When interpreting each statement in this specification that includes the term 'comprising', features other than that or those prefaced by the term may also be present. Related terms such as 'comprise' and 'comprises' are to be interpreted in the same manner.

The term 'connected to' includes all direct or indirect types of communication, including wired and wireless, via a cellular network, via a data bus, or any other

2014101631 07 May 2018 computer structure. It is envisaged that they may be intervening elements between the connected integers. Variants such as 'in communication with', 'joined to', and 'attached to' are to be interpreted in a similar manner.

The term 'computer-readable medium' should be taken to include a single medium or multiple media. Examples of multiple media include a centralised or distributed database and/or associated caches. These multiple media store the one or more sets of computer executable instructions. The term 'computer readable medium' should also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor and that cause the processor to perform any one or more of the methods described above. The computer-readable medium is also capable of storing, encoding or carrying data structures used by or associated with these sets of instructions. The term 'computer-readable medium' includes solid-state memories, optical media and magnetic media.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example,

1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5, and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents or such sources of information is not to be construed as an admission that such documents or such sources of information, in any jurisdiction, are prior art or form part of the common general knowledge in the art.

Although the present invention is broadly as defined above, those persons skilled in the art will appreciate that the invention is not limited thereto and that the invention also includes embodiments of which the following description gives examples.

2014101631 07 May 2018

In the description in this specification reference may be made to subject matter which is not within the scope of the appended claims. That subject matter should be readily identifiable by a person skilled in the art and may assist in putting into practice the invention as defined in the presently appended claims.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the invention will now be described, by way of non-limiting example, with reference to the figures in which:

Figure 1 shows a general fluid monitoring system diagram of the system according to an embodiment of the present invention;

Figure 2 shows a simplified block diagram of a fluid measuring device of the system of figure 1;

Figure 3 shows a perspective view of a first end of a capacitive sensor according to an embodiment of the present invention;

Figure 4 shows perspective view of a second end of the capacitive sensor of figure 3 disassembled;

Figure 5 shows another perspective view of the capacitive sensor of figure 3 disassembled;

Figure 6 shows an example response of the capacitive sensor to a change in 20 liquid level in the tank;

Figure 7 shows an example response of the capacitive sensor to a change in liquid volume in the tank;

Figure 8 shows a sensor module block diagram according to an embodiment of the present invention;

Figure 9 shows a flow chart of a method for determining a level of liquid in a tank according to an embodiment of the present invention;

Figure 10 shows a perspective view of housing for the controller and a power supply according to an embodiment of the present invention;

Figure 11 shows a side view of the housing shown in figure 10;

Figure 12 shows a front view of an interior section of the housing shown in figure 10; and

Figure 13 shows a simplified block diagram of an example form of a computing device that may form at least part of the server and/or a user device for accessing the server.

2014101631 07 May 2018

DETAILED DESCRIPTION

A fluid monitoring system 100 according to an embodiment of the present invention is shown in figure 1. The system 100 is configured to monitor the level of fluid in a tank 102 using a fluid measuring device (or transceiver device) 104 that is positioned in proximity of, and at least partially within, the tank 102. With reference to figure 2, the device 104 comprises a sensor arrangement 106 which is configured to generate a signal relating to an amount of fluid in the tank 102. The device 104 further comprises a communications module 108 for transmitting the generated signal, from the sensor arrangement 106 and/or information indicating an amount of fluid in the tank 102 based on the generated signal from the sensor arrangement 106, to a server 110 via a communications network 112. The server 110 comprises or is connected to computer memory, in the form of a database 114, for storing data relating to the amount of fluid in one or more tanks. In the device 104, the communications module 108 is electronically connected to the sensor arrangement 106.

The server 110 is accessible by one or more end user devices 116 via the communications network 112. The server 110 controls access to the database 114, and is configured to store data relating to an amount of fluid in the tank 102 in the database 114, to look up data stored in the database 114, and to send data relating to 20 an amount of fluid in the tank 102 to the user device 116.

In the embodiment described, the fluid in the tank 102 to be monitored comprises fuel, such as petrol and/or diesel, and the system is configured to monitor the level of fuel in the tank 102. The system is designed to be intrinsically safe. According to other embodiments, the system may be configured to monitor other fluids, including gases, and other liquids such as water or milk.

The tank 102 may be permanently located in a single location. Alternatively, the tank may be moveable. For example, the tank may be mounted to a truck or other vehicle.

The sensor arrangement

The sensor arrangement 106 is preferably removably insertable into the tank 102. In an alternative embodiment, the sensor arrangement 106 may be fixedly positioned within the tank 102.

2014101631 07 May 2018

The preferred form of the sensor arrangement 106 comprises an electrical circuit that is configured to generate an electrical signal relating to the amount of fluid in the tank 102. The electrical circuit may comprise an arrangement of passive electronic components (such as capacitors, resistors, and inductors) and/or active electronic components (such as integrated circuits).

Referring to figures 3 to 5, the sensor arrangement 106 comprises a capacitive sensor (or 'probe') 140 that is configured to generate a capacitance signal that relates to the height of fluid in the tank 102 relative to the capacitive sensor 140. The sensor arrangement 106 may comprise more than one capacitive sensor positioned within the tank 102.

The capacitive sensor 140 comprises a cylindrical capacitor having an inner cylinder 142 and an outer hollow cylinder 144 that surrounds the inner cylinder 142. The inner and outer cylinders (or electrodes) 142, 144 are substantially coaxial with each other and have a space 146 therebetween. Referring to figure 5, a spacer 148 is provided to prevent the inner cylinder 142 from contacting the outer cylinder 144 and to maintain a uniform spacing between the inner and outer cylinders 142, 144. The spacer 148 is removably connected to the inner cylinder 142. The inner and outer cylinders 142, 144 may be located at least partially within the tank 102 to extend from at or near a top of the tank 102 to at or near a bottom of the tank 102. Alternatively, a user interested when the amount of fuel in the tank 102 is nearing empty, for example, may locate the inner and outer cylinders 142, 144 to extend vertically from a location intermediate the top and the bottom to at or near the bottom. The capacitance signal will only change when the level of the fluid is between the location intermediate the top and the bottom and at or near the bottom of the tank 102.

Referring to figure 4, the capacitive sensor 140 comprises a mount 150, which is configured to rest on a wall of the tank 102 being monitored. The mount 150 has a nose 152 that protrudes or sticks into the interior of the tank 102. The nose 152 is a hollow cylinder having an externally threaded wall for threadably engaging the outer cylinder 144, and an internally threaded wall for threadably engaging the inner cylinder 142.

The typically solid inner cylinder 142 may have a diameter of between, for example, about 3 mm and about 8 mm. According to one preferred form of the capacitive sensor 140, the inner cylinder 142 has a diameter of about 4.76 mm. The outer cylinder 144 may have an inner diameter of between, for example, about 10 mm and about 20 mm and a thickness between about 0.7 mm and 3 mm. According to one preferred form of the capacitive sensor 140, the outer cylinder 144 may have a diameter of 12.7 mm and a wall thickness of about 1.4 mm. The inner and outer cylinders 142, 144 of the capacitive sensor 140 are configured to be immersed in the liquid in the tank 102. A change in level of liquid in the space 146 between the inner and outer cylinders 142, 144 results in a change in the capacitance signal generated by the capacitive sensor 140. The capacitive sensor 140 is placed substantially vertically in the tank 102 so that the level of liquid between the cylinders 142, 144 changes as the volume of liquid in the tank 102 changes.

Capacitance is linearly dependent on the relative permittivity of the material between plates of the capacitor. When the capacitive sensor 140 is positioned in a liquid, the capacitance of the sensor 140 depends on the level of liquid in the space 146 between the cylinders 142, 144. Liquid has a different relative permittivity than air. Fuel has a relative permittivity of about 2.1, while air has a relative permittivity of about 1.0. The measured capacitance is used to determine the level or height of the liquid relative to the capacitive sensor 140. The volume of liquid in the tank 102 can be determined by multiplying the determined level or height of the liquid with geometry of the tank 102.

The formula for determining the capacitance Cprobe of a cylindrical capacitor is shown below:

probe 2&E₀£_r ln(-) where εο is the absolute permittivity (8.854e-12 Fnr¹), ε_Γ is the relative permittivity of the dielectric between the inner and outer cylinders, L is the length of the shortest of the inner and outer cylinders 142, 144, a is the radius of the inner cylinder 142, and b is the inner radius of the outer cylinder 144.

The height of the liquid Hn_qUid can be determined from the measured capacitance based on the following formula:

// = \E -E * liquid liquid air

2πε₀ measured

2014101631 07 May 2018 where Eiiquid is the permittivity of the liquid, Eair is the permittivity of air, Cmeasured IS the measured capacitance of the probe, and Cair is the measured capacitance in air.

The outer cylinder 144 may be driven at a peak-to-peak AC voltage of between about

20 mV and about 4 V and a current between about 20 nA and about 20 mA.

Preferably, the outer cylinder 144 is driven with an oscillating voltage with a peak-topeak voltage of up to about 200 mV and a current of less than about 500 μΑ.

The inner and outer cylinders (or electrodes) 142, 144 are formed of aluminium. The inner and outer cylinders 142, 144 may alternatively or additionally be formed of stainless steel and/or another suitable material.

Figure 6 shows an example capacitive response of the capacitive sensor 140 to a change in liquid level in the tank 102 from a trial run. The capacitive sensor 140 used in this run had an inner cylinder diameter of about 5 mm, an outer cylinder inner diameter of about 10 mm and a length of about 700 mm. The typical response is substantially linear. The height of liquid in the tank 102 relative to the capacitive sensor 140 can be determined from the measured capacitance of the capacitive sensor 140.

Based on the geometry of the tank 102, the volume of liquid in the tank 102 can be determined accordingly. Figure 7 shows the relationship between the capacitance measured by the capacitive sensor 140 and the volume of the tank 102. In this run, the tank 102 is substantially cylindrical with an inner radius of about 321 mm and a length of about 935 mm. The tank 102, as shown in figure 1, is a substantially horizontal cylinder tank. However, it will be understood the present system and method may be applicable to other tanks. For example the tank may be a substantially vertical cylinder tank. Alternatively, the tank may be any other suitable receptacle, container, or structure for holding a liquid or gas having other shapes.

The results of the capacitance, height, and volume measurements for the trial run are shown in the table below.

Capacitance (dF)	Heiaht (mm)	Volume fL)
57.7	13.4	1.5
61.0	50.0	10.9
63.5	78.2	21.0

2014101631 07 May 2018

69.3	143.0	50.3
73.7	193.3	76.7
79.2	255.2	112.1
82.6	292.6	134.3
86.3	334.5	159.4
90.3	379.2	186.1
94.2	423.5	211.8
95.8	440.8	221.5
97.4	459.7	231.9
101.9	510.1	257.9
109.2	592.1	291.8
112.4	627.3	300.9
111.1	613.0	297.8

According to other embodiments, the capacitive sensor may be a plate capacitor with two spaced apart plates for generating a capacitance signal based on a level of fluid between the plates.

The sensor arrangement 106 may comprise one or more other sensors, each configured to generate a signal that relates to the height and/or volume of fluid in the tank 102. For example, the sensor arrangement 106 may comprise an ultrasonic (or 'ultrasound') sensor/probe suitable for generating a signal to measure the height and/or volume of other fluids such as milk.

The sensor module

With reference to figure 8, a sensor module 154 is provided to process signals from 15 the capacitive sensor 140 and to control the operation of the capacitive sensor 140. A 'module' is a collection of analogue and digital electronics. A module may be a premade module such as a GPRS cellular module purchased from a supplier. A module may include software which controls specific parts such as a modem driver. A module may include a digital logic block, such as a field-programmable gate array (FPGA) or 20 similar configurable logic blocks. A module may be a combination of two or more of the above features.

The sensor module 154 comprises an integrated circuit (IC). An example of a suitable IC for the sensor module 154 may be a capacitance-to-digital converter sensor IC,

2014101631 07 May 2018 such as an AD7746 for example. The sensor IC of the sensor module 154 allows for two capacitances 702, 704 to be measured by a capacitance sensor 706. The first capacitance measurement 702 is a reference calibration capacitance, and the second capacitance measurement 704 is the capacitance that is measured by the sensor arrangement 106. The sensor IC additionally measures an external temperature 708, which is used in a calibration procedure described below. The sensor module 154 further comprises a communications channel 710 for communicating data to a controller or the communications module that is described in further detail below. The sensor module 154 additionally comprises memory 712 for storing calibration data for example.

The sensor module 154 comprises a range extension circuit 714 to enable a larger capacitance to be measured than the range possible with the sensor IC alone. A probe calibration procedure is carried out to compensate for large variations caused by the range extension circuit 714, manufacturing variations in the capacitive sensor 140 and also due to the inherent nature of the capacitive measurement method. This probe calibration procedure uses a reference capacitor having a known capacitance. The reference capacitor has a similar capacitance to the capacitance of the capacitive sensor 140 when the tank 102 is 'empty'. The calibration procedure essentially calibrates the sensor 140 for any offset or linearity errors.

The steps of the calibration procedure are set out below:

1) look up a unique sensor identification number from non-volatile memory 712

2) measure the calibration capacitance and the zero capacitance (no probe connected), calculate the gradient from these two points, and store the gradient in non-volatile memory 712

3) connect the capacitive sensor 140 (in air environment 25°C) and increase an offset until measurements from both the calibration capacitor and the capacitive sensor 140 are above zero, but close as possible, and store offset in non-volatile memory

4) store the offset, calibration value, and probe capacitance in air in non-volatile memory 712

5) store probe dimensions in non-volatile memory 712.

The unique sensor identification number is unique to the sensor. In one embodiment, the number comprises a EEPROM IC with built in 64-bit unique number. In an alternative embodiment, the number is assigned at factory calibration. The number is

2014101631 07 May 2018 required for identifying the sensor to the remote server 110 and enables tracking of the sensor electronics though factory calibration, to field connection to a tank 102. Additionally, each communications module 108 has a unique identification number for identifying the device 104. In one embodiment, the number is the IMEI number provided by the cellular modem. This number is used for tracking each device 104 and is sent to the server 110 with each message for message source identification such as a MAC address is used in a computer. The two different identification numbers, a unique identification number for the device 104 and a unique identification number for each sensor of the device 104, allow multiple sensors electronics (each with one probe) to be connected to one cellular module (sending device).

The calibration data variables that are gathered during this calibration procedure are stored in the calibration storage memory 712. The controller and/or software platform and/or remote server 110 described below uses these data variables to make (more 15 accurate) height calculations. Some calculations and averaging may be performed on server 110 and some may be performed on the device 104. The device 104 sends the calibration values to the server 110 when the device 104 is turned on. The device 104 calculates the capacitance from the slope and the offset. The device 104 notifies the server 110 if a capacitance threshold level change is detected. The server 110 calculates height and then volume from the sent capacitance values, the calibration values and the stored tank dimensions (on database) information to derive a tank volume.

The method 800 for the determining the liquid level is shown in figure 9. Once the device 104 is turned on 802, calibration data is read 804 from the calibration storage memory of the sensor module 154. The sensor module 154 measures 806 the raw data from the capacitive sensor 140. The raw data is converted 808 into capacitance measurements using the calibration data. The capacitance measurements are averaged 810, and a determination is made 812 if there is a change of level in the tank 102. If there is a change in level, a notification is sent 814 to the remote server 110. Once the notification is sent or if there is no change in level, the controller goes back to the step of determining 806 the raw data from the capacitive sensor.

The communications module and identification module

The communications module 108 is configured to wirelessly transmit the determined amount of fluid to the remote server 110 by the communications network 112. The

2014101631 07 May 2018 communications module 108 comprises or is in communication with a cellular modem and a radio network antenna. The type of radio network antenna that is used depends on the technology available. For example, the radio network antenna could be a Global Packet Radio Service (GPRS) antenna, a code division multiple access (CDMA) 5 antenna, or a third generation (3G) antenna, or another suitable radio antenna. The communications module 108 is configured to transmit an alert signal to the server 110 over the radio network when the determined amount of fluid in the tank 102 drops below, or rises above, or meets, a predetermined threshold.

Alternatively, the communications module may comprise or be in communication with a satellite modem and a satellite antenna, and be configured to communicate with and transmit signals to the server 110 via one or more satellites.

The device 104 further comprises an identification module 156 for generating an identifier of the tank 102. The communications module 108 is configured to transmit the identifier of the tank 102 to the remote server 110. The server 110 may store data relating to multiple sensors and multiple tanks in the database 114. The identification module 156 comprises a GPS unit and a GPS antenna, and the identifier comprises a position of the tank 102.

The server and the database

The server 110 and the database 114 are both typically located remote of the tank 102. They are accessible by user device 116 over the communications network 112, such as via a local area network, a wide area network or the Internet. The communications network may include private Access Port Network (APN).

The system comprises a software platform at the user device 116 for communication with the server 110. An end user can access the server through the software platform 30 to obtain information stored in the database 114 about the amount of fuel in the tank

102. An end user can also access the server to generate and/or view reports of historical fuel usage from one or more tanks that is stored in the database 114.

A user will typically access the server 110/database 114 via a web interface. The user 35 device 116 will typically comprise a general-purpose programming device, such as one or more of a desktop computing device, laptop, tablet or smart phone.

2014101631 07 May 2018

Figure 13 shows a simplified block diagram of an example form of a computing device 200 that may form at least part of the server 110 and/or the user device 116.

Sets of computer executable instructions are executed within device 200 that cause the device 200 to perform the methods described above. Preferably the computing device 200 is connected to other devices. Where the device is networked to other devices, the device is configured to operate in the capacity of a server or a client machine in a server-client network environment. Alternatively the device can operate as a peer machine in a peer-to-peer or distributed network environment. The device may also include any other machine capable of executing a set of instructions that specify actions to be taken by that machine. These instructions can be sequential or otherwise.

A single device 200 is shown in Figure 2. The term 'computing device' includes any collection of machines that individually or jointly execute a set or multiple sets of instructions to perform any one or more of the methods described above.

The example computing device 200 includes a processor 205. One example of a processor is a central processing unit or CPU. The device further includes read-only 20 memory (ROM) 210 and random access memory (RAM) 215. Also included is a Basic

Input/Output System (BIOS) chip 220. The processor 205, ROM 210, RAM 215 and the BIOS chip 220 communicate with each other via a central motherboard 225.

Computing device 200 further includes a power supply 230 which provides electricity to the computing device 200. Power supply 230 may also be supplemented with a rechargeable battery (not shown) that provides power to the device 200 in the absence of external power.

Also included are one or more drives 235. These drives include one or more hard drives and/or one or more solid state flash hard drives. Drives 235 also include optical drives.

Network interface device 240 includes a modem and/or wireless card that permits the computing device 200 to communicate with other devices. Computing device 200 may 35 also comprise a sound and/or graphics card 245 to support the operation of the data output device 260 described below. Computing device 200 further includes a cooling system 250 for example a heat sink or fan.

2014101631 07 May 2018

Computing device 200 includes one or more data input devices 255. These devices include a keyboard, touchpad, touchscreen, mouse, and/or joystick. The device(s) take(s) input from manual keypresses, user touch with finger(s) or stylus, spoken commands, gestures, and/or movement/orientation of the device.

Data output device(s) 260 include(s) a display and/or printer. Device(s) 260 may further include computer executable instructions that cause the computing device 200 to generate a data file such as a PDF file.

Data port 265 is able to receive a computer readable medium on which is stored one or more sets of instructions and data structures, for example computer software. The software causes the computing device 200 to perform one or more of the methods or functions described above. Data port 265 includes a USB port, Firewire port, or other 15 type of interface. The computer readable medium includes a solid state storage device. Where drives 235 include an optical media drive, the computer readable medium includes a CD-ROM, DVD-ROM, Blu-ray, or other optical medium.

Software may also reside completely or at least partially within ROM 210, within erasable non-volatile storage and/or within processor 205 during execution by the computing device 200. In this case ROM 210 and processor 205 constitute computerreadable tangible storage media. Software may further be transmitted or received over a network via network interface device 240. The data transfer uses any one of a number of well known transfer protocols. One example is hypertext transfer protocol (http).

Power supply unit

The system comprises a power supply for supplying power to the device 104 in the 30 form of power supply unit 158 that is located outside the tank 102 for safety. The power supply unit 158 comprises a lead-acid battery. According to other embodiments of the system, the power supply unit 158 comprises a lithium battery, a lithium ion battery, or another battery. According to further embodiments, the power supply unit 158 comprises an electrical charge storage component, such as a super capacitor for example. The power supply unit 158 is arranged to provide a voltage of about 2 V to about 24 V, and preferably 4.2 V.

2014101631 07 May 2018

Advantageously, the relatively low power requirements of the sensor arrangement 106 and communications module 108 enable the device 104 to substantially run off solar power. In one embodiment, the system comprises photovoltaic cells for collecting solar energy to charge the power supply unit 158.

Alternatively the power supply for supplying power to the device 104 may be a mains power supply.

Method for monitoring the level of fluid

The method for monitoring the level of fuel in the tank 102 according to an embodiment of the present invention comprises: generating a signal relating to an amount of fluid in the tank 102 using the sensor arrangement 106 locatable within the tank 102. The generated signal is representative or indicative of the level of fuel in 15 the tank 102. The sensor arrangement 106 is removably inserted into the tank 102 through an aperture in a wall of the tank 102. In an alternative embodiment, the method may comprise fixedly positioning the sensor arrangement 106 within the tank 102. Features of the sensor arrangement 106 have been previously described.

The method comprises transmitting, using the communications module 108 that is electronically coupled to the sensor arrangement 106, the generated signal from the sensor arrangement 106, and/or information indicating an amount of fluid in the tank 102 based on the generated signal from the sensor arrangement 106, to the server 110 that is accessible by a user. For example, where the sensor arrangement 106 comprises a capacitive sensor, the communications module 108 may transmit the capacitance measurements to the server 110, and the volume and/or level values are calculated based on the capacitive measurements at the user device 116 for example. Alternatively, the capacitance measurements may be converted to height or volume values of fuel in the tank 102 before the measurements are transmitted to the server

110 and remote database 114. Features of the communications module 108, server

110 and remote database 114 have been previously described above.

The method further comprises generating, using the identification module 156, an identifier of the tank 102. Features of the identification module 156 have been previously described above.

2014101631 07 May 2018

The method further comprises transmitting an electrical alert signal, using the communications module 108, to the server 110 when the determined amount of fluid in the tank 102 drops below, or rises above, or meets, a predetermined threshold.

The method can further comprise transmitting an electrical alert signal, using the communications module 108, to the server 110 when there is an extraction or insertion of fluid from the tank 102, such as an extraction or insertion of fluid from the tank 102 that exceeds a predetermined amount. The method can additionally comprise transmitting an electrical alert signal, using the communications module 108, to the server 110 any time there is an extraction of fluid from the tank 102 to alert a user to an unauthorised extraction or theft of fluid from the tank 102. The alert signal can instantly alert end users to changes in volumes of the fluid in the tank 102.

The method further comprises sending details that may include information about height or volume values of fuel in the tank 102, an identifier of the tank including the 15 tank's location and/or the alert signal to the user device 116.

The controller

With reference to figure 2, the device 104 also comprises a controller 160, which 20 comprises or is in communication with the power supply unit 158, the sensor module

154, the communications module 108, and the identification module 156 that have been previously described above. The controller 160 may be configured to control operation of the sensor module 154, the communications module 108, and the identification module 156

The controller 160 may comprise a processor, which is any suitable computing device that is capable of executing a set of instructions that specify actions to be carried out.

The term 'computing device' also includes any collection of devices that individually or jointly execute a set or multiple sets of instructions to control aspects of the system 30 including but not limited to the operation of the fluid monitoring system.

The controller 160 includes or is interfaced to a computer-readable medium on which is stored one or more sets of computer-executable instructions and/or data structures. The instructions implement one or more of the methods for controlling the operation 35 of the fluid monitoring system. The instructions may also reside completely or at least partially within the controller 160 during execution. In that case, the controller 160 comprises machine-readable tangible storage media.

2014101631 07 May 2018

Advantageously, the controller 160 is configured to obtain software updates from the server 110 over the communications network 112. For example, the controller 160 may comprise a boot loadable interface that allows new or more sensors to be added to the system.

The housing

A preferred form of the device 104 is shown in figures 10-12. The device 104 comprises a housing 180, which houses the power supply unit 158, controller 160 and the different modules that have been previously described above. The sensor module 154 is located in a separate housing 182 (not shown in figure 11). In other embodiments, the sensor module 154 may be located in the same housing 180 as the other modules. The housing 180 is formed of a polycarbonate material or another suitable polymeric material. The housing 180 may alternatively comprise another suitable material such as aluminium for example. The housing 180 has one or more ports that is/are connectable to the cellular antenna 184, and for connecting to the sensor module 154 in the separate housing 182. The GPS antenna is positioned within the housing 180.

The housing 180 is further provided with a photovoltaic cell 186 behind a substantially optically transparent face of the housing 180. The photovoltaic cell 186 is configured to charge the power supply unit 158 in the housing 180, when needed.

Referring to figure 11, silica-gel 188 may be provided in the housing 180 between the battery 190 of the power supply unit 158 and a wall of the housing 180.

The device 104 may also comprise an accelerometer (not shown) for detecting tampering with the sensor arrangement 106 and/or the device 104. For example, an 30 accelerometer may be coupled to the capacitive sensor 140. Alternatively, an accelerometer may be located in or on the housing 180. The controller 160 may be configured to cause the communications module 108 to transmit an alert signal to the remote server 110 when the accelerometer detects movement, such as unauthorised movement, of the capacitive sensor 140 and/or the housing 180.

2014101631 07 May 2018

It is not the intention to limit the scope of the invention to the abovementioned examples only. As would be appreciated by a skilled person in the art, many variations are possible without departing from the scope of the invention.

Claims

CLAIMS:

1. A fluid monitoring system for a tank, the fluid monitoring system comprising: a sensor arrangement at least partially locatable within the tank and

5 comprising a capacitive sensor configured to generate an electrical capacitance signal relating to an amount of fluid in the tank, the capacitive sensor comprising a cylindrical capacitor having an inner cylinder and an outer hollow cylinder that surrounds the inner cylinder, the inner and outer cylinders being substantially coaxial and having a space therebetween, the outer cylinder being driven with an AC voltage;

10 a server being configured to receive the signal, and/or information indicating an amount of fluid in the tank based on the signal, from the sensor arrangement over a communications network, and configured to transmit the signal, and/or information indicating an amount of fluid in the tank based on the signal, to a user device remote of the tank over the 15 communications network; and a controller comprising or connected to a communications module, and a sensor module in communication with the sensor arrangement, the communications module being in communication with the sensor module, and configured to transmit the signal, and/or information indicating an amount of fluid 20 in the tank based on the signal, to the server over the communications network.
2. The fluid monitoring system of claim 1, wherein:

the capacitive sensor is configured to generate the capacitance signal based on a level of fluid in the space between the inner and outer cylinders, and

25 the level of fluid in the space between the inner and outer cylinders corresponds to a level of fluid in the tank.
3. The fluid monitoring system of claim 1 or claim 2, wherein the inner cylinder and the outer cylinder are in a fixed spaced-apart relationship.
4. A method for monitoring the level of fluid in a tank, the method comprising: generating, using a capacitive sensor at least partially located within the tank, an electrical capacitance signal relating to an amount of fluid in the tank, the capacitive sensor comprising a cylindrical capacitor having an inner cylinder and an

35 outer hollow cylinder that surrounds the inner cylinder, the inner and outer cylinders being substantially coaxial and having a space therebetween, the outer cylinder being driven with an AC voltage;

2014101631 07 May 2018 transmitting the signal, and/or information indicating an amount of fluid in the tank based on the signal, to a server over a communications network; and transmitting the signal, and/or information indicating an amount of fluid in the tank based on the signal, from the server to a user device remote of the tank over the 5 communications network.
5. The method of claim 4, comprising generating the capacitance signal based on a level of fluid in the space between the inner and outer cylinders, the level of fluid in the space between the inner and outer cylinders corresponding to a level of fluid in the 10 tank.