WO2020169955A1

WO2020169955A1 - Monitoring apparatus, system and method

Info

Publication number: WO2020169955A1
Application number: PCT/GB2020/050373
Authority: WO
Inventors: Florin Cosmin MANGU; Joseph Finn
Original assignee: Remote Tech Ltd
Priority date: 2019-02-18
Filing date: 2020-02-17
Publication date: 2020-08-27
Also published as: GB2581395B; GB2581395A; GB201902196D0

Abstract

According to the invention there is provided a sensor device comprising: a temperature sensing element configured to take temperature measurements at configured intervals; memory for processing data; a power source for powering the device; a wireless transceiver for allowing data transfer to and from the device; and a controller configured to: operate in a high-performance mode and an ultra-low power mode, the controller operating at full speed in the high-performance mode and at reduced speed in the ultra-low power mode; operate a data collection phase, for collecting the temperature measurements, and a data transmission phase, for transmitting temperature data from the device via the wireless transceiver, the temperature data corresponding to the collected temperature measurements; and operate in the ultra-low power mode during the data collection phase and the high-performance mode during the data transmission phase; there is also provided a monitoring system comprising at least one sensor device as described above, a gateway, a broker and a cloud platform; there is also provided a monitoring method comprising: a) providing a monitoring system as described above; b) operating the controller of the at least one sensor device in high-performance mode; c) providing the at least one sensor device with configuration data comprising a temperature range to be monitored, frequency at which to take temperature readings and a frequency at which to report the temperature readings; d) switching the controller of the at least one sensor device into ultra-low power mode; e) at the time at which to take temperature readings, taking a temperature reading with the temperature sensing element; and f) comparing the temperature reading with the temperature range to be monitored.

Description

MONITORING APPARATUS, SYSTEM AND METHOD

FIELD OF THE INVENTION

This invention relates to apparatus, system and method for monitoring and reporting the risk of Legionnaires' disease in a given environment.

BACKGROUND OF THE INVENTION

Legionella bacteria is commonly found in water. The bacteria multiply when temperatures are between 20-45 °C and nutrients are available. The bacteria are dormant below 20 °C and do not survive above 60 °C.

Legionnaires’ disease, which is a form of legionellosis, is a potentially fatal type of pneumonia, contracted by inhaling airborne water droplets containing viable Legionella bacteria. Such droplets can be created, for example, by: hot and cold-water outlets; atomisers; wet air conditioning plant; and whirlpool or hydrotherapy baths.

Currently, in order to monitor temperatures in such systems a monthly water temperature reading is taken using a manual method. This manual technique typically requires an engineer to arrive to his designated site and designated sentinel outlets or sources of water within a building, and physically using a handheld thermometer take the water temperatures and record the temperatures taken in the site water log book (cold water must be run for two minutes and hot water for one minute using this technique).

This method relies heavily on the human aspect involved of physically driving to site, physically taking and logging the temperature and then relaying information to the relevant personnel to rectify any problems (if need be) and then to take further action and maintenance. This adds to the carbon footprint and also is solely reliant on the human factor involved and the individual who is taking the readings at the particular moment in time. Therefore, there could potentially be many different scenarios where an incorrect temperature is recorded such as faulty equipment, incorrect procedure, fatigue (due to the amount of hours worked in a day), time of day at which the temperatures are taken, usage elsewhere within a building, water system failure, failure to record, not physically taking the temperatures however recording an estimated temperature. The major flaw within this technique, however, other than the error potentials set out above is the fact there are 28-31 days in any one calendar month and an engineer will only record one temperature per month per outlet leaving potentially a further 30 days from recording a compliant temperature for legionella bacterium to grow within the water systems being monitored. Legionella can multiply by the million within a few days and can potentially proliferate, infect and then cause a potential fatality within 10 days (in the correct conditions and temperatures). This manual method has been an industry standard for many years, however, the cases of reported incidents have been on the rise year upon year, with temperatures being one of the main factors that aids in the proliferation of the legionella bacterium.

In order to try and overcome some of these short comings, remote sensors have begun to be employed, however these temperature sensors are of low level intelligence and technology. Typically, the remote sensors use the same set up scenario as sensors used to track a building’s water systems (temperature data) and these sensors will then in turn connect to a gateway and the gateway will then send this data onto a server which is then displayed upon a website.

The sensors on the market currently take temperatures on a timed basis, the temperature sensors are set up at manufacturing stage with a particular time frame to ‘turn off and‘turn on’ (or wake up) at predetermined timed intervals to take the water temperature reading. Whether the temperature (in regards to legionella control) is compliant or not, the sensor will take the temperature at its timed interval stage and send the data onto the gateway, this data is then analysed by the software within a web platform to advise the end client whether the temperature is compliant or not and then alert the responsible person.

There are many flaws with the current remote sensors available. When the sensors are commissioned they are typically set up to take temperature readings frequently, usually every 5 minutes. This dramatically drains battery and only allows for about 6 months to 2 years maximum autonomy, which in turn creates an expense for the client of continuously changing the battery along with the associated call out charges to replace the battery. In addition water can change temperature very quickly and therefore one can reach non-compliance and/or compliance within a hot or cold water system within a short period of time. However, due to the timed interval wake up technique the system may take the temperature when the hot water has cooled too much or when the cold water has been heated, this will in turn give non-compliant reading, whereas only 1 minute before the temperatures would have been compliant and the timer missed the reading. These two factors combined will result in the web platform providing the client with numerous non-compliant readings and cost the client in call out charges and amendments to the water systems or in higher priced maintenance regimes to rectify such “non-compliance”. There is also a large potential that legionella proliferation temperatures (along with other potential parameters such as stagnation and system hygiene) could be missed and legionella could have started to grow due to these continuously missed temperatures due to the timed interval technique and that reactive measures needed to be taken.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a sensor device comprising a temperature sensing element, memory, a power source, a wireless transceiver, and a microcontroller unit configured to operate in a high-performance mode and an ultra-low power mode.

Preferably the memory comprises read only memory (RAM) and flash memory.

Preferably the microcontroller unit comprises two microcontroller units; an ultra-low power microcontroller unit, and a high-performance microcontroller unit.

Preferably the high-performance microcontroller unit and the ultra-low power microcontroller unit are part of the same chip and are preferably interconnected together by a high-speed bus matrix.

Preferably the ultra-low power microcontroller unit is a 16-bit or an 8-bit ultra-low power microcontroller unit.

Preferably the high-performance microcontroller unit is a dual core 32-bit microcontroller unit. Alternatively, the sensor device comprises one or more high-performance microcontroller units that are configured to operate at different speeds during the different phases of operation, preferably the phases of operation comprise a data transmission phase and a data collection phase.

Preferably the one or more high-performance microcontroller units are configured to operate at full speed (high-performance mode) during data transmission phase and are configured to operate at reduced speed (ultra-low power mode) during data transmission phase.

Preferably the speed reduction is obtained by configuring the one or more high- performance microcontroller units to operate at different clock frequencies during the different phases of operation.

Preferably the one or more high-performance microcontroller units are configured to operate at, at least about 100 MHz during the data transmission phase and the one or more high-performance microcontroller units are configured to operate between about 1/8th to about 1/10th of the clock speed during the data collection phase, preferably at about 10MHz.

In this way it is possible that a single high-performance microcontroller unit is provided which is able to switch between operations at different speeds, or in the alternative to provide two high-performance microcontroller units one which is configured to run at normal speed and one of which is configured to run at a reduced speed.

Preferably the battery is a non-rechargeable lithium battery.

Preferably the wireless transceiver utilises long range (LoRa) technology.

Preferably the temperature sensing element comprises an analogue temperature probe, preferably of the negative temperature coefficient (NTC) type.

Preferably the temperature sensing element is configured to take temperature measurements at configured intervals. Preferably, the temperature sensing element is configured to take temperature measurements continuously at intervals of 1 to 5 seconds, preferably at intervals of 2 seconds.

Preferably sensor device further comprises a high precision voltage reference and the temperature sensing element is powered by the high precision voltage reference. Preferably the high precision voltage reference is enabled and disabled by the microcontroller unit operating in ultra-low power mode. This enables reduced power consumption between temperature measurements.

Preferably, the voltage produced by the temperature sensing element can be sampled by the microcontroller unit when operating in both high-performance mode and ultra-low power mode. Preferably the sensor device further comprises an analogue to digital converter peripheral and the temperature sensing element can be sampled by the microcontroller unit when operating in both high-performance mode and ultra-low power mode via the analogue to digital converter peripheral.

Preferably when the microcontroller unit is operating in high-performance mode the microcontroller unit converts the voltage value to a temperature value using a polynomial equation.

Preferably when the microcontroller unit is operating in ultra-low power mode the microcontroller unit converts the voltage value to a temperature value using a look up table.

Preferably in the case that the temperature crosses a previously configured threshold, the microcontroller unit operating in ultra-low power mode will wake-up or switch to the microcontroller unit operating in high-performance mode in order to enter the data transmission phase.

According to a second aspect of the invention there is provided a monitoring system comprising at least one sensor device as described in the first aspect of the invention, a gateway, a broker and a cloud platform.

Preferably the at least one sensor device is configured to communicate with the gateway, and the gateway is configured to communication with the at least one sensor device. Preferably the gateway is configured to communicate with the cloud platform and the cloud platform is configured to communication with the gateway.

In one alternative the gateway is configured to communicate with the cloud platform through the broker and the cloud platform is configured to communicate with the gateway through the broker.

Preferably the gateway comprises a microprocessor unit, a non-volatile memory (NVM), a modem to provide internet connectivity, a wireless transceiver and a power source.

Preferably the modem has wireless (Wi-Fi), cellular or Ethernet connectivity.

Preferably the wireless transceiver utilises long range (LoRa) technology.

Preferably the power source comprises an AC-DC power source.

Preferably the power source comprises a battery, preferably the battery is a rechargeable battery preferably a rechargeable lithium polymer (LiPo) battery.

Preferably the power source further comprises a battery charging system.

Preferably the broker comprises an application which is configured to communicate with the cloud platform and the gateway in order to coordinate the source and the destination of certain data packets.

The cloud platform comprises a MQTT broker, a database system and an application programming interface (API).

According to a third aspect of the present invention there is provided a monitoring method comprising:

a) providing a monitoring system according to the second aspect of the present invention;

b) operating the microcontroller unit of the at least one sensor device in high- performance mode; c) providing the at least one sensor device with configuration data comprising a temperature range to be monitored, frequency at which to take temperature readings and a frequency at which to report the temperature readings;

d) switching the microcontroller unit of the at least one sensor device into ultra- low power mode;

e) at the time at which to take temperature readings, taking a temperature reading with the temperature sensing element; and

f) comparing the temperature reading with the temperature range to be monitored.

Preferably the method further comprises where the temperature reading is a predetermined distance from the temperature range boundary being monitored switching the operation of the microcontroller unit into high-performance mode and transmitting the data to the gateway.

Preferably the predetermined distance may be outside, at or close to the temperature range boundary.

Preferably the method further comprises where the frequency to report is reached switching the operation of the microcontroller unit into high-performance mode and transmitting the data to the gateway.

Preferably once the data has been transmitted to the gateway the sensor device will wait for a predetermined period of time for new configuration data.

Preferably if new configuration data is received the current configuration data will be overwritten, preferably the microcontroller unit will then switch into ultra-low power mode.

Preferably if no new configuration data is received the microcontroller unit will then switch into ultra-low power mode.

According to a fourth aspect of the present invention there is provided a sensor device comprising:

a temperature sensing element configured to take temperature measurements at configured intervals; memory for processing data;

a power source for powering the device;

a wireless transceiver for allowing data transfer to and from the device; and a controller configured to:

operate in a high-performance mode and an ultra-low power mode, the controller operating at full speed in the high-performance mode and at reduced speed in the ultra-low power mode;

operate a data collection phase, for collecting the temperature measurements, and a data transmission phase, for transmitting temperature data from the device via the wireless transceiver, the temperature data corresponding to the collected temperature measurements; and

operate in the ultra-low power mode during the data collection phase and the high-performance mode during the data transmission phase. Preferably the data transmission phase occurs at configured intervals.

Preferably wherein the memory comprises random access memory (RAM) and flash memory. Preferably wherein the operational speed of the controller is obtained by configuring the controller to operate at different clock frequencies during the different modes of operation.

Preferably the controller is configured to operate at, at least 100 MHz in the high- performance mode and 1 /8th to 1/10th of the clock speed in the ultra-low power mode, preferably at about 10MHz.

Preferably the wireless transceiver utilises long range technology such as LoRa. Preferably the temperature sensing element comprises an analogue temperature probe, preferably of the negative temperature coefficient (NTC) type.

Preferably the sensor device further comprises a high precision voltage reference and wherein the temperature sensing element is powered by the high precision voltage reference. Preferably the high precision voltage reference is enabled and disabled by the controller operating in ultra-low power mode. Preferably the voltage produced by the temperature sensing element can be sampled by the controller when operating in both high-performance mode and ultra-low power mode.

Preferably the sensory device further comprises an analogue to digital converter peripheral and wherein the temperature sensing element can be sampled by the controller when operating in both high-performance mode and ultra-low power mode via the analogue to digital converter peripheral.

Preferably wherein when the controller is operating in high-performance mode the controller converts the voltage value to a temperature value using a polynomial equation.

Preferably when the controller is operating in ultra-low power mode the controller converts the voltage value to a temperature value using a look up table.

Preferably the controller is further configured to:

switch the operation of the controller into the high-performance mode when a temperature measurement is a predetermined distance from one or more predetermined temperature range boundaries provided to the controller; and

transmit the temperature data from the device via the wireless transceiver. Preferably the controller is one or more microcontroller units.

Preferably the one or more microcontroller units are high-performance microcontroller units. Preferably the controller is two microcontroller units, an ultra-low power microcontroller unit for operating the ultra-low power mode, and a high-performance microcontroller unit for operating the high-performance mode. Preferably the high-performance microcontroller unit and the ultra-low power microcontroller unit are part of the same chip and are preferably interconnected together by a high-speed bus matrix.

Preferably the ultra-low power microcontroller unit is a 16-bit or 8-bit ultra-low power microcontroller unit.

Preferably the high-performance microcontroller unit is a dual core 32-bit high- performance microcontroller unit.

According to a fifth aspect of the present invention there is provided a monitoring system comprising at least one sensor device according to the fourth aspect of the invention, a gateway, a broker and a cloud platform.

Preferably the at least one sensor device is configured to communicate with the gateway, and the gateway is configured to communication with the at least one sensor device.

Preferably the gateway is configured to communicate with the cloud platform and the cloud platform is configured to communication with the gateway.

Preferably the gateway is configured to communicate with the cloud platform through the broker and the cloud platform is configured to communicate with the gateway through the broker.

Preferably the modem has wireless, cellular or Ethernet connectivity.

Preferably the wireless transceiver utilises long range technology such as LoRa.

Preferably the power source comprises an AC-DC power source. Preferably the power source comprises or further comprises a battery, preferably the battery is a rechargeable battery preferably a rechargeable lithium polymer (LiPo) battery.

Preferably the power source further comprises a battery charging system.

Preferably the cloud platform comprises a MQTT broker, a database system and an application programming interface (API).

According to a sixth aspect of the present invention there is provided a monitoring method comprising:

a) providing a monitoring system according to the fifth aspect of the present invention;

b) operating the controller of the at least one sensor device in high- performance mode;

c) providing the at least one sensor device with configuration data comprising a temperature range to be monitored, frequency at which to take temperature readings and a frequency at which to report the temperature readings;

d) switching the controller of the at least one sensor device into ultra-low power mode;

Preferably the method further comprises where the temperature reading is a predetermined distance from the temperature range boundary switching the operation of the controller into high-performance mode and transmitting the temperature data to the gateway. Preferably the predetermined distance may be outside, at or close to the temperature range boundary.

Preferably the method further comprises where the time to report is reached switching the operation of the controller into high-performance mode and transmitting the temperature data to the gateway.

Preferably once the temperature data has been transmitted to the gateway the sensor device will wait for a predetermined period of time for new configuration data.

Preferably if new configuration data is received the current configuration data will be overwritten, preferably the controller will then switch into ultra-low power mode.

Preferably if no new configuration data is received the controller will then switch into ultra-low power mode.

The main advantage of the invention is the technology behind the sensor device waking up on a temperature threshold being reached while it’s in deep sleep, and this is only possible because it has the ability to monitor temperatures with a 1 % accuracy while only consuming 20uA of current. Other sensors wake up only on a timer to take the temperature, every 5 minutes for example, and to then go back to sleep again. This is considered ineffective from a property point a view where water loses its properties (heath) very quickly and the timer will only pick a snapshot at that point in time. Also, from a cost perspective they send useless information every 5 min if nothing is happening in the water system, where the system admin will have to pay more for the data transmission and data storage cost, battery replacement, and likely the cost of analysis of so much data as well. Last but not least, our system allows to achieve 10 years’ of battery life for the sensors since the periodic report interval can be configured in the range of hours and the system will still be able to detect temperature values outside of the allowed range and report them to the cloud in real time.

Using technology and ingenuity the present invention results in the ability to increase the information monitoring granularity from once every 28 days (the minimum legal requirement) to as low as every minute, using a combination of modern microcontrollers with ultra-low power modes, batteries, radio platforms and algorithm technology. On top of that, the present invention is capable of monitoring the temperature constantly, taking a measurement preferably every 2 seconds in order to detect sudden temperature changes and notify them in real time.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

Figure 1 illustrates an overview of the general components of the monitoring system; Figure 2 illustrates a flow chart illustrating the operating steps of the monitoring system according to a first embodiment;

Figure 3 illustrates a flow chart illustrating the operating steps of the monitoring system according to a second embodiment;

Figure 4 illustrates a flow chart illustrating the operating steps of the monitoring system according to a third embodiment;

Figure 5 illustrates a block diagram of an exemplary sensor device according to a first embodiment of the present invention;

Figure 6 illustrates a block diagram of an exemplary sensor device according to a second embodiment of the present invention;

Figure 7 illustrates a block diagram of an exemplary sensor device according to a third embodiment of the present invention; and

Figure 8 illustrates a block diagram of an exemplary gateway according to an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The monitoring system 10 comprises at least one sensor device 12 a gateway 14, a broker 16 and a cloud platform 18.

The sensor device 12 comprises a temperature sensing element 22 which takes temperature measurements at configured intervals and transmits the values using wireless technology to a central hub called the“gateway” 14. The gateway 14 receives the data collected by the at least one sensor device 12 and transmits it to the cloud platform 18 via the internet. The gateway 14 also receives configuration information from the cloud platform 18 that needs to be transmitted to the at least one sensor device 12. Some of these transactions are performed directly between the gateway 14 and the cloud platform 18, and in some other cases the data passes through the broker 16 first so that the broker can choose the correct destination for the data to be transmitted where there are for example multiple sensor devices 12.

Block diagrams of sensor devices 12, 1 12, 212 according to embodiments of the present invention are illustrated in Figures 5 to 7. The sensor device 12 illustrated in Figure 5 comprises a temperature sensing element 22, a high precision voltage reference 24, read only memory (RAM) and flash memory, a power source preferably a non- rechargeable lithium battery 26, a wireless transceiver 28, an analogue to digital converter peripheral 36 and a controller 31.

The controller 31 is an arrangement of microcontroller units 30, 32 that are configured to operate each device 12, 1 12, 212. In this embodiment, the controller 31 comprises an ultra-low power microcontroller unit 30, preferably 16-bit or 8-bit and a high-performance microcontroller unit 32, preferably dual core 32-bit. Preferably the high-performance microcontroller unit 30 and the ultra-low power microcontroller unit 32 are part of the same chip 34 and are preferably interconnected together by a high-speed bus matrix. The temperature sensing element 22 is powered by the high precision voltage reference 24 which is enabled and disabled by the ultra-low power microcontroller unit 32 in order to reduce power consumption between temperature samples. The voltage produced by the temperature sensing element 22 can be sampled by both the microcontroller units 30, 32 via the analogue to digital converter peripheral 36 which is preferably also located on the same chip as the microcontroller units. Once this value has been sampled, the high-performance microcontroller unit 32 proceeds to convert the voltage value to a temperature value using mathematic calculations (polynomial equations).

In this document, the term‘high performance microcontroller’ means a microcontroller able to operate at a clock frequency in the order of l OOMFIz and/or has a current consumption in the order of milliamps. The term ‘high-performance mode’ means a mode whereby the operating or clock frequency is at‘full speed’, the term‘full speed’ meaning at substantially a maximum clock frequency, or more specifically, a clock frequency in the order of 100MHz and/or a current consumption in the order of milliamps.

In this document, the term‘ultra-low power microcontroller’ means a microcontroller able to operate at a clock frequency of 10MHz or less and/or has a current consumption in the order of tens of microamps. The term‘ultra-low power mode’ means a mode whereby the operating or clock frequency is at‘reduced speed’, the term‘reduced speed' meaning a clock frequency that is substantially less than the maximum clock frequency such as 1/8 to 1/10 of the maximum clock frequency, or more specifically, a clock frequency of 10MHz or less and/or a current consumption in the order of tens of microamps. Therefore, a controller or microcontroller operating in a high-performance mode means the controller or microcontroller is operating at full speed, i.e. maximum clock frequency, and a controller or microcontroller operating in an ultra-low power mode means the controller or microcontroller is operating at a reduced speed, i.e. a clock frequency of 1/8 to 1/10 of the maximum clock frequency.

In this document, the term‘high precision voltage reference’ means a voltage reference that has an error of less than 0.1%.

Preferably the electronic components of the sensor device 12 described are located on the same printed circuit board which also has a connector into which the battery 26 is connectable.

Preferably the wireless transceiver 28 utilises long range technology such as LoRa.

Preferably the temperature sensing element 22 comprises an analogue temperature probe preferably of the negative temperature coefficient (NTC) type, rather than a digital probe, this is due to the characteristics of the ultra-low power microcontroller unit 30 that is used to monitor the temperature in a quasi-real time fashion. The ultra-low power microcontroller unit 30 has access to the same analogue digital convertor peripheral 36 that the high-performance microcontroller unit 32 can access; however, this would not be the case with a digital communication interface, which would not have been accessible by the ultra-low power microcontroller unit 30. The fact that the sensor device 12 does not run from a mains power supply and is not connected via wires to any other pieces of equipment during normal operation to communicate information collected by the sensor device 12 means that the sensor device 12 can be placed in a remote environment.

In order to enable long life of the sensor device 12 before the power supply, i.e. the battery 26, needs to be replaced the sensor device 12 is configured to be able to manage power consumption and as such the life expectancy of the battery of the sensor device 12. This is brought about by either allowing the sensor device 12 to execute its instructions (programming) at different speeds or in the alternative by providing the sensor device 12 with a controller 31 having two processors one of which works at higher speed and therefore consumes more power and one of which works at lower speed and therefore consumes less power which the sensor device can switch between or even a controller 31 which is a single microcontroller unit which can switch between operation at different speeds. In the case of the embodiment described and illustrated in Figure 5 the sensor device 12 is provided with a controller 31 having a high-performance microcontroller unit 32 such as Cortex-M4 and an ultra-low power microcontroller unit 30 such as Cortex M0.

In the case of executing instructions at different speeds the sensor device 212 can a controller 31 that is one high-performance microcontroller unit 42 as illustrated in Figure 7 or the sensor device 1 12 can have a controller 31 that is two high-performance microcontroller units 32, 34 as illustrated in Figure 6, which can be configured to run at different clock frequencies. During the radio transmit/receive states, the microcontroller unit would run at full speed (e.g. 100 Mhz or more) but during the low power temperature sensing state, the microcontroller unit would run at 1 /8^th or 1/10^th of the clock speed (around 10MFIz), which would allow the sensor device to maintain the average current consumption during the temperature sensing state below 50uA. Clock speed switching is performed on the fly before going to deepsleep (ultra-low power) modes. RAM retention during the deepsleep state is also required in order to guarantee a fast wake up and to avoid flash write/operations to store the temperature measured values.

In other words, in some embodiments, the controller 31 of the sensor device is single microcontroller unit that is configured to operate in both the ultra-low power mode and the high-performance power mode, and in other embodiments, the controller 31 of the sensor device is two microcontroller units, one of which operates in the ultra-low power mode and the other operates in the high-performance power mode. In yet other embodiments, the controller 31 of the sensor device may be one or more microcontrollers, each microcontroller being configured to operate in the ultra-low power mode and/or the high-performance power mode and/or a combination of the modes.

In order to enable the sensor device 12, 1 12, 212 to operate effectively the sensor device 12, 1 12, 212 is configured to be able to read the temperature from both microcontroller units 32, 34, 38, 40 if more than one microcontroller unit is provided an at both operating speeds if a single microcontroller unit 42 is provided and this is achieved because each microcontroller unit 32, 34, 38, 40, 42 is configured to access the analogue to digital convertor peripheral 36.

The microcontroller unit operating in high-performance mode is able to convert an analogue to digital reading through a polynomial as it has a larger processing power, and as such is able to know and compare the temperature value readily. This, however, is not the case for the microcontroller unit operating in ultra-low power mode, as it cannot easily calculate and compare temperature values as these are features that have been omitted from its capabilities in order for the microcontroller unit to operate at ultra-low power.

In order to solve this problem values for the trigger from the look-up table are provided to the microcontroller unit operating in ultra-low power mode wherein the microcontroller unit operating in ultra-low power mode can compare these values with the measurements being taken. The look up table provides references to the values which correlate to temperature points which would normally be obtained through the analogue to digital convertor peripheral. This provides a coarse temperature measurement ability to the microcontroller unit operating in ultra-low power mode.

The normal operations of the sensor device 12, 1 12, 212 according to embodiments of the present invention are illustrated in Figures 2 to 4 respectively. Once the sensor device 12, 1 12, 212 has powered up it will set up the temperature ranges it will be monitoring and the report frequency at which the sensor device 12, 1 12, 212 is to take temperature readings and to send the temperature readings to the gateway 14. The sensor device 12, 1 12, 212 will then evaluate the raw analogue to digital conversation values for the various temperature ranges that it will be monitoring and which it will then store in memory that is accessible by the sensor device 12, 1 12, 212 by the microcontroller unit operating in ultra-low power mode. The sensor device 12, 1 12, 212 will then enter into power saving mode, during the power saving mode the sensor device12, 1 12, 212 will operate using the microcontroller unit operating in ultra-low power mode and will take temperature readings between about 0 to about 100 degrees Celsius (continuously every about 2 seconds). In the case of a system for monitoring for legionella the temperatures of interest to be monitored are around the values of 20, 25, 35, 50, 55 and 60 degrees Celsius. These are the temperature values configured as trigger points for the microcontroller operating in ultra-low power mode unit to wake-up the microcontroller unit operating in high-performance mode or in the case of the provision of a single microcontroller unit for it to switch to operating an normal speed from reduce speed. Once the coarse temperature values have been determined they are then compared with given temperature range that is being monitored. If the temperature values are close to the end points of given range / fall within given range / fall outside given range then the sensor device 12, 1 12, 212 will report the values to the gateway 14 or if the frequency has been reached to report the temperature to the gateway 14 anyway then the sensor device 12, 1 12, 212 will switch to use the microcontroller unit operating in high-performance mode and transmit the data wirelessly to the gateway 14. The sensor device 12, 1 12, 212 will then await return data from the gateway 14 which might be in the form of a new configuration (i.e. new temperature range or reporting frequency), and if no data is received then the sensor device 12, 1 12, 212 will switch back to the power saving mode and go back to using the microcontroller unit operating in ultra-low power mode.

By using a wireless transceiver 28 with long range such as LoRa technology the sensor device 12, 1 12, 212 will be able to initiate communication and should the user need to change the update frequency or the temperature risk points of the sensor device 12, 1 12, 212, then this can be done during boot up of the sensor device 12, 1 12, 212 or through a command issued from the gateway 14. Preferably the temperature values are stored within the sensor device 12, 1 12, 212 so that at power up or during operation in ultra-low power mode, the configuration can be retrieved and used once in high-performance mode. A block diagram of the gateway 14 according to an embodiment of the invention is illustrated in Figure 8. The gateway 14 comprises a microprocessor unit 44, a modem 48 to provide internet connectivity, a long range radio such as a LoRa radio 46 to allow communication with the at least one sensor device 12, 1 12, 212, an AC-DC power source 50 that can be connected to mains power, a battery 52, such as a lithium polymer (LiPo) battery for back-up power and a battery charging system 54 in to keep the battery recharged whenever mains power is available.

The gateway 14 typically uses the same platform as the sensor device 12, 1 12, 212 without a temperature sensor attached and without the need to run solely off a battery. The main purpose of the gateway 14 is that of data conglomeration. The gateway 14 collects messages from the at least one sensor device 12, 1 12, 212 and forwards them through a single pipe line. Preferably the single pipe line is a message queuing telemetry transport (MQTT) protocol-based connection to the cloud platform 18, preferably running a service such as Amazon Web Services (AWS). The connection to the cloud platform 18 is either through wireless means such as Wi-Fi or some form of cellular communication like long term evolution (LTE). The present invention preferably uses an IP based protocol (such as MQTT) to act as the trunk service to the cloud platform 18 running back-end AWS service.

The gateway 14 itself has a configuration state, however, unlike the sensor device 12, 1 12, 212 it does not need to switch between microcontroller units operating in high- performance mode and ultra-low power mode, however it does need to manage where its power is coming from, using a rechargeable lithium ion battery 52 and a smart power supply unit (PSU) 56, the gateway 14 can run from mains power 50 and charge the lithium ion battery 52, whilst indicating to the back-end service if the PSU 56 has dropped out whilst continuing to run on the battery 52 for a finite time limit.

The gateway 14 has a non-volatile memory (NVM) which is used to store configuration, encryption keys and endpoints URLs. Using the long range radio such as LoRa radio 46, the at least one sensor device 12, 1 12, 212 will attach to the gateway 14 in a star topology and each message received will be forwarded to the cloud platform 18 running the back-end service that connects to the monitoring software 20. The broker 16 comprises an application which runs on a remote server that communicates with the cloud platform 18 and the gateway 14 in order to coordinate the source and the destination of certain data packets. Preferably the application is written in Python.

The broker 16 is preferably an internet of things (loT) message broker and is configured to receive/transmit messages from/to the gateway 14 from/to the cloud platform 18.

The cloud platform 18 comprises a MQTT broker, a database system and an application programming interface (API) to allow accessing the sensor data from other applications.

The cloud platform 18 contains a shadow of each of the at least one sensor devices 12, 1 12, 212 and the gateway 14 which identifies the characteristics and current configuration of the devices. It also holds databases to store the data received from the at least one sensor device 12, 1 12, 212. This data can then be accessed by other parts of the system.

The monitoring system 10 utilises wireless technology which has MQTT as the trunk communication protocol and LoRa as the distributed wireless protocol. The monitoring system 10 preferably uses a plurality of sensor devices 12, 1 12, 212 which are distributed around key monitoring points for risk reduction with respect to Legionella bacteria growth.

Claims

1 . A sensor device comprising:

a temperature sensing element configured to take temperature measurements at configured intervals;

memory for processing data;

a power source for powering the device;

operate in the ultra-low power mode during the data collection phase and the high-performance mode during the data transmission phase.

2. A sensor device as claimed claim 1 wherein the data transmission phase occurs at configured intervals.

3. A sensor device as claimed in claim 1 or claim 2 wherein the memory comprises random access memory (RAM) and flash memory.

4. A sensor device as claimed in any of claims 1 to claim 3 wherein the operational speed of the controller is obtained by configuring the controller to operate at different clock frequencies during the different modes of operation.

5. A sensor device as claimed in claim 4 wherein the controller is configured to operate at, at least 100 MHz in the high-performance mode and 1/8th to 1/10th of the clock speed in the ultra-low power mode, preferably at about 10MHz.

6. A sensor device as claimed in any preceding claim wherein the wireless transceiver utilises long range technology.

7. A sensor device as claimed in any preceding claim wherein the temperature sensing element comprises an analogue temperature probe, preferably of the negative temperature coefficient (NTC) type.

8. A sensor device as claimed in any preceding claim further comprising a high precision voltage reference and wherein the temperature sensing element is powered by the high precision voltage reference.

9. A sensor device as claimed in claim 8 wherein the high precision voltage reference is enabled and disabled by the controller operating in ultra-low power mode.

10. A sensor device as claimed in any preceding claim wherein the voltage produced by the temperature sensing element can be sampled by the controller when operating in both high-performance mode and ultra-low power mode.

1 1. A sensor device as claimed in any preceding claim further comprising an analogue to digital converter peripheral and wherein the temperature sensing element can be sampled by the controller when operating in both high-performance mode and ultra-low power mode via the analogue to digital converter peripheral.

12. A sensor device as claimed in Claim 10 or Claim 1 1 wherein when the controller is operating in high-performance mode the controller converts the voltage value to a temperature value using a polynomial equation.

13. A sensor device as claimed in Claim 10 or Claim 1 1 wherein when the controller is operating in ultra-low power mode the controller converts the voltage value to a temperature value using a look up table.

14. A sensor device as claimed in any of the preceding claims wherein the controller is further configured to:

transmit the temperature data from the device via the wireless transceiver.

15. A sensor device as claimed in any preceding claim, wherein the controller is one or more microcontroller units.

16. A sensor device as claimed in claim 15, wherein the one or more microcontroller units are high-performance microcontroller units.

17. A sensor device as claimed in any of claims 1 to 14 wherein the controller is two microcontroller units, an ultra-low power microcontroller unit for operating the ultra-low power mode, and a high-performance microcontroller unit for operating the high- performance mode.

18. A sensor device as claimed in claim 17 wherein the high-performance microcontroller unit and the ultra-low power microcontroller unit are part of the same chip and are preferably interconnected together by a high-speed bus matrix.

19. A sensor device as claimed in claim 17 or claim 18 wherein the ultra-low power microcontroller unit is a 16-bit or 8-bit ultra-low power microcontroller unit.

20. A sensor device as claimed in any of claims 16 to 19 wherein the high- performance microcontroller unit is a dual core 32-bit high-performance microcontroller unit.

21. A monitoring system comprising at least one sensor device as claimed in any of claims 1 to 20, a gateway, a broker and a cloud platform.

22. A monitoring system as claimed in claim 21 wherein the at least one sensor device is configured to communicate with the gateway, and the gateway is configured to communication with the at least one sensor device.

23. A monitoring system as claimed in claim 21 or claim 22 wherein the gateway is configured to communicate with the cloud platform and the cloud platform is configured to communication with the gateway.

24. A monitoring system as claimed in claim 21 or claim 22 wherein in the gateway is configured to communicate with the cloud platform through the broker and the cloud platform is configured to communicate with the gateway through the broker.

25. A monitoring system as claimed in any of claims 21 to 24 wherein the gateway comprises a microprocessor unit, a non-volatile memory (NVM), a modem to provide internet connectivity, a wireless transceiver and a power source.

26. A monitoring system as claimed in claim 25 wherein the modem has wireless, cellular or Ethernet connectivity.

27. A monitoring system as claimed in claim 25 or claim 26 wherein the wireless transceiver utilises long range technology.

28. A monitoring system as claimed in any of claims 25 to 27 wherein the power source comprises an AC-DC power source.

29. A monitoring system as claimed in any of claims 25 to 28 wherein the power source comprises or further comprises a battery, preferably the battery is a rechargeable battery preferably a rechargeable lithium polymer (LiPo) battery.

30. A monitoring system as claimed in claim 29 wherein the power source further comprises a battery charging system.

31. A monitoring system as claimed in any of claims 21 to 30 wherein the broker comprises an application which is configured to communicate with the cloud platform and the gateway in order to coordinate the source and the destination of certain data packets.

32. A monitoring system as claimed in any of claims 21 to 31 wherein the cloud platform comprises a MQTT broker, a database system and an application programming interface (API).

33. A monitoring method comprising:

a) providing a monitoring system according to any of claims 21 to 32; b) operating the controller of the at least one sensor device in high- performance mode;

34. A monitoring method as claimed in claim 33 wherein the method further comprises where the temperature reading is a predetermined distance from the temperature range boundary switching the operation of the controller into high- performance mode and transmitting the temperature data to the gateway.

35. A monitoring method as claimed in claim 34 wherein the predetermined distance may be outside, at or close to the temperature range boundary.

36. A monitoring method as claimed in any of claims 33 to 35 wherein the method further comprises where the time to report is reached switching the operation of the controller into high-performance mode and transmitting the temperature data to the gateway.

37. A monitoring method as claimed in any of claims claim 34 to 36 wherein once the temperature data has been transmitted to the gateway the sensor device will wait for a predetermined period of time for new configuration data.

38. A monitoring method as claimed in claim 37 wherein if new configuration data is received the current configuration data will be overwritten, preferably the controller will then switch into ultra-low power mode.

39. A monitoring method as claimed in claim 37 wherein if no new configuration data is received the controller will then switch into ultra-low power mode.