TITLE: CONNECTED MEASURING DEVICE FOR AN AIRCRAFT

TECHNICAL AREA

The present invention relates to the technical field of surveillance systems for an aircraft.

STATE OF THE PRIOR ART

French patent application No. 17 58213 filed on September 6, 2017 discloses a monitoring system for an aircraft, the monitoring system comprising measuring devices and a reception terminal conforming to a low consumption wide area network standard (or LPWAN for “Low Power Wide Area Network” in English) installed in an aircraft. This network is for example a so-called “LoRaWAN” network as defined by the “Lora Alliance” (see https://lora-alliance.org/). Each disclosed measuring device includes:

a sensor designed to measure at least one parameter of the aircraft,

an antenna conforming to the low power wide area network standard and a transmitter conforming to the same standard,

an autonomous power source which supplies power to the measuring device, a main cut-off module mounted between the power source and the transmitter, a management module arranged to monitor operating parameters of the transmitter and to open and close selectively the cut-off module according to the operating parameters.

Thus, each measuring device can physically cut the power supply to its transmitter in the event of a problem, which guarantees that the transmitter can in no case emit radio energy that does not comply with an aeronautical standard such as for example RTCA DO-160 Section 21.

This patent application discloses that the measuring devices include two operating modes: a first operating mode corresponding globally to a phase in which the aircraft is moving (phase of taxiing, takeoff, climb, flight, descent, landing and final taxiing) and a second operating mode corresponding to a phase in which the aircraft is stationary (or “parking” phase). The measuring devices include means (for example accelerometer and / or gyroscope) for detecting the phase of flight in which the aircraft in which the measuring device is installed is located. According to this document, the transmission of a radio signal by a measuring device is deactivated when the measuring device is in the first operating mode, that is to say when the aircraft is in flight or in motion. So, obviously,

However, the system disclosed by the cited document makes it necessary to wait for an immobilization phase of the aircraft (i.e. the second operating mode of the measuring devices) in order to be able to collect data measured by the sensors of the devices. of measurement. This is particularly problematic if, for example, the measuring device is supposed to allow the monitoring of a physical parameter such as the temperature of a refrigerated container, and to alert if this temperature exceeds a certain threshold: the device is then not able to 'emits an alert only once the aircraft has come to a stop on the runway. If this can make it possible to know a posteriori that a temperature problem has occurred with the container during the flight, it is however probably too late to act and correct the problem. Otherwise,

DISCLOSURE OF THE INVENTION

The invention relates to a measuring device for a surveillance system intended to be installed in an aircraft, the measuring device being adapted to operate according to a first operating mode called “on the ground” or a second operating mode known as “in flight”. ". The measuring device includes:

- a sensor suitable for measuring at least one physical parameter of the environment of the aircraft,

- a radio module conforming to a low consumption wide area network standard, the radio module being suitable for sending messages comprising measurement data from the sensor to a radio access point, the radio module being suitable for sending each message with a transmit power chosen from a predefined plurality of transmit powers,

- an electrical power source,

a power supply management module mounted in cut-out between the radio module and the power supply module, the power supply management module comprising an energy storage element making it possible to supply the radio module with power,

a control module, the control module being suitable for switching the operating mode of the measuring device between the first operating mode called “on the ground” and the second operating mode known as “in flight”.

Said measuring device is suitable for:

in the first operating mode called "on the ground":

o before sending each message, charge the energy storage element with a predefined energy,

in the second operating mode called "in flight":

o for each message to be sent, choose a transmission power of the radio module,

o determining, as a function of this transmission power, an energy necessary for the transmission of the message by the radio module, o before the transmission of the message, charging the energy storage element with the determined necessary energy.

According to a complementary embodiment of the invention, the radio module also being adapted to send a message as a function of a spreading factor, the spreading factor being chosen from among a predefined plurality of spreading factors, the measuring device is suitable for, in the second operating mode called "in flight":

- for each message to be sent, choose a transmission power of the radio module and a spreading factor,

- determine the energy required for the transmission of the message by the radio module as a function of the transmission power and the spreading factor chosen.

According to a complementary embodiment of the invention, the measuring device is suitable for, in the second so-called “in-flight” operating mode, following the transmission of a message by the radio module with a first power and according to a first spreading factor, and in the absence of an acknowledgment response from the radio access point:

- choose a second transmission power of the radio module and a second spreading factor, to re-transmit the message,

the second transmission power and the second spreading factor corresponding to an entry of a predetermined list, the list comprising the plurality of pairs formed by the plurality of transmission powers and the plurality of spreading factors, each pair being associated with an energy necessary to send a message with the emission power of the torque and according to the spreading factor of the torque, the list being ordered according to the energy necessary to send the message associated with each pair, the second power d 'emission and the second spreading factor corresponding to the torque following the torque formed by the first transmission power and the first spreading factor.

According to a complementary embodiment of the invention, the list does not include the pairs formed by a transmission power and a spreading factor requiring energy to send a message greater than a predetermined energy threshold.

According to a complementary embodiment of the invention, a list is associated with each size of message to be sent.

According to a complementary embodiment of the invention, the power supply management module comprises a Coulomb counter.

The invention also relates to a system for monitoring an aircraft, the system comprising:

- a plurality of measuring devices according to one of the preceding claims,

a radio access point, the radio access point being connected to an item of equipment on the aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention mentioned above, as well as others, will emerge more clearly on reading the following description of an exemplary embodiment, said description being given in relation to the accompanying drawings, among which:

[Fig. 1] schematically illustrates the hardware architecture of a measuring device according to one embodiment of the invention,

[Fig. 2] schematically illustrates a method of sending a message by a measuring device according to one embodiment of the invention.

DETAILED EXPOSURE OF EMBODIMENTS

Fig. 1 schematically illustrates the hardware architecture of a measuring device 100 according to one embodiment of the invention.

The measuring device 100 is intended to be integrated into a monitoring system installed in an aircraft. The measuring device 100 is adapted to operate according to a first operating mode called “on the ground” or a second operating mode known as “in flight”. The first operating mode corresponds to a phase in which the aircraft is moving (taxiing, takeoff, climb, flight, descent, landing and final taxiing phase). The second operating mode corresponding to a phase in which the aircraft is stationary (or “parking” phase).

The measuring device 100 comprises:

- one or more sensors 110, 111 adapted to measure physical parameters of the environment of the aircraft,

- a radio module 104 conforming to a low consumption wide area network standard, the radio module 104 being suitable for sending messages comprising measurement data from one of the sensors 110, 111 to a radio access point, the radio module being adapted to transmit each message with a transmission power chosen from among a predefined plurality of transmission powers,

- an electrical power source 102,

- a management module 103 of the electrical supply mounted in cut-off between the radio module 104 and the electrical supply module 102, the supply management module 103 comprising an energy storage element making it possible to supply the power to the radio module,

a control module 101, the control module 101 being adapted to switch the operating mode of the measuring device between the first operating mode called “on the ground” and the second operating mode called “in flight”.

The control module 101 can comprise or be connected to detection means 120, these detection means being adapted to detect whether the aircraft is in flight or immobilized on the ground. These detection means 120 typically comprise a gyroscope and / or an accelerometer.

The power management module 103 ensures that the radio module 104 is only powered by a controlled amount of electrical energy. According to one embodiment of the invention, the power supply management module 103 comprises an electric capacitor. This capacitor can be charged with a variable amount of electrical energy, this variable amount of electrical energy being determined for example by the control module 101. The maximum amount of energy that can be stored by the capacitor, that is- that is, the maximum capacitance of the capacitor, can be chosen so as to prevent the radio module 104 from emitting more than a certain radio frequency energy in order to comply with a radio interference standard.

According to a complementary embodiment of the invention, the power supply management module 103 can include a so-called Coulomb counter in order to measure the electrical energy transmitted to the radio module 104. Thus, the power supply management module can cut the power supply to the radio module as soon as a predefined quantity, or defined by the control module 101, of energy has been transmitted to the radio module 104 for sending a message.

Thus, the measuring device 100 is suitable for, in the first so-called “ground” operating mode:

o before sending each message, charge the energy storage element with a predefined energy.

The measuring device 100 can thus send a message via the radio module 104, the power management module 103 guaranteeing that the radio module cannot send more than the maximum authorized energy corresponding to the energy stored in the. storage element, modulo the energy losses inherent in the operation of the radio module 104.

Likewise, the measuring device 100 is suitable for, in the second so-called “in-flight” operating mode:

o for each message to be sent, choose a transmission power of the radio module,

o determine, according to this transmission power, an energy necessary for the transmission of the message by the radio module,

o before sending the message, charge the energy storage element with the determined necessary energy.

When the measuring device 100 is in the second operating mode called “flight”, it is desirable to start by transmitting a message with the lowest possible transmission power. If the message sent is not received by the access point, which can be deduced if the measuring device 100 does not receive an acknowledgment message from the access point following the transmission of the message , then the transmission power of the radio module 104 is gradually increased until the moment when an acknowledgment is finally received. The transmission power can then be kept for future messages. Periodically, this sequence of transmitting a message with increasing transmission power may be repeated in order to ensure that the radio module 104 transmits with minimum power.

According to one embodiment, the measuring device 100 is characterized in that the radio module is also suitable for transmitting a message as a function of a radio spectrum spread factor (“spread factor”). This "spreading" technology allows a radio signal to be spread over a wide spectrum of frequencies through the use of a code. This is for example the case for a radio technology called “LoRa” developed by the “LoRa Alliance”. The spreading factor can be chosen from a predefined plurality of spreading factors.

The measuring device 100 is then suitable for, when it operates in the second so-called “in-flight” operating mode:

- for each message to be sent, choose a transmission power of the radio module and a spreading factor,

- determine the energy required for the transmission of the message by the radio module as a function of the transmission power and the spreading factor chosen.

The relationship between the transmission power of a radio signal transmitted by the radio module 104, the spreading factor used for this transmission and the electrical energy required (here in nA.h) for this transmission is not trivial. as shown in the table below:

transmit power

(dBm) 14 13 12 il 10 9 8 7 6 5 4 3 2 î O -î -2 -3 transmit power

(mW) 25 20 16 12.5 10 8 6.3 5 4 3.2 2.5 2 1.6 1.3 1 0.8 0.6 0 5

Spread

Bit / s factor

SF7 5470

SF8 3Î25

SF9 1760

SF10 980

SF11 540

SF12 290
This table gives, for a given pair of a transmission power and a spreading factor, the energy necessary for the transmission of a message of a predetermined size, the size of a message depending particularly the payload of the message. Note that this table is an example for a given message size, another table to be determined for a different message size.

This table must be determined in a preliminary configuration phase for a radio module 104 and for each size of message potentially sent by the radio module 104.

This table can be generated from a few measurements, the other data can then be calculated.

This table can be presented in a different form, but equivalent, of a list comprising pairs of transmission power and spreading factor, each pair being associated with an energy necessary for transmission of a message of a predefined size. .

This list is advantageously ordered, from the lowest energy required to the highest.

For example, the list can start here with the couple (P = -3dBm; SF = 7) associated with the energy O.OôlnA.h. The last element in the list here is the torque (P = 14 dBm; SF = 12), associated with the energy required 57,471 nA.h (with "P" for "transmit power" and "SF" for "factor spread ”- or“ spread factor ”in English).

Note that at the same transmission power, the transmission of a message with a high spreading factor (SF = 12 for example) decreases the available bandwidth (here 290 bits / s against 5470 bits / s with a SF of 7) and therefore needs to emit longer, which explains the greater energy required. On the other hand, the transmission range of the message is then greater.

Once the table - or the ordered list - has been produced, the measuring device 100 can choose the pairs (transmission power; spreading factor) in an increasing order of the energy required, and test each pair until the one making it possible to find it. receive an acknowledgment. This pair is then that which allows a good reception of a message transmitted with an energy consumed during the minimum transmission. The power consumption of the measuring device 100 is then minimal. The power supply 102 is then preserved for better longevity.

Thus, when in the second so-called “in-flight” operating mode, the measuring device 100 is suitable for, following the transmission of a message by the radio module with a first power and according to a first spreading factor, and in the absence of an acknowledgment response from the radio access point:

- choose a second transmission power of the radio module and a second spreading factor, to re-transmit the message.

The second transmission power and the second spreading factor correspond to an entry of the predetermined list (or of the table), the list comprising the plurality of pairs formed by the plurality of transmission powers and the plurality of transmission factors. spreading, each pair being associated with an energy necessary to transmit a message with the torque transmission power and according to the torque spreading factor, the list being ordered according to the energy required to transmit the message associated with each pair, the second transmission power and the second spreading factor corresponding to the torque following the torque formed by the first transmission power and the first spreading factor.

A list is associated with each size of message to be sent. Each list is generated or predetermined during a configuration phase of the measuring device 100.

According to a complementary embodiment of the invention, the list does not include the pairs formed by a transmission power and a spreading factor requiring energy to send a message greater than a predetermined energy threshold. In other words, it is possible to refrain from using transmitting power and spreading factor pairs which would lead to excessive consumption of electrical energy and / or to transmitting radio signals exceeding a predetermined radio energy.

Fig. 2 schematically illustrates a method of sending a message by a measuring device 100 according to one embodiment of the invention.

In a first step 201, the measuring device 100 determines that a message is to be sent. The message can include data from measurements made by one of the sensors 110, 111. The need to send a message can be triggered by the exceeding of a threshold by one of the measurements of one of the sensors. 110, 111 or be triggered periodically.

In a following step 202, the measuring device 100 determines its operating mode. This operating mode is determined by the control module 101, possibly according to data coming from the detection means 120, which may include a gyroscope and / or an accelerometer. The operating mode can correspond to a state of a so-called “flag” memory, this memory being updated periodically or on demand according to the data of the detection means 120.

If the measuring device 100 determines that it is in the first operating mode, corresponding to an aircraft on the ground (immobilized on the ground or “parking”), the measuring device 100 goes to a step 210.

If the measuring device 100 determines that it is in the second operating mode, corresponding to a flying aircraft, the measuring device 100 goes to a step 220. Note that according to one embodiment of the invention, failing this to be able to determine an operating mode, the measuring device considers itself to be in the second operating mode.

In the first mode of operation, following step 210, according to one embodiment of the invention, the measuring device 100, in a step 211, charges the electrical energy storage element of the control module. the power supply 103 with a predetermined energy. This predetermined energy corresponds to a maximum transmission energy that must not exceed the radio module 104 when transmitting messages.

In a following step 212, the radio module 104 can transmit the message, the energy made available by the power supply management module 103 guaranteeing that the radio module 104 cannot exceed a maximum energy during this transmission, for example. defined by a standard.

In the second mode of operation, following step 220, according to one embodiment of the invention, the measuring device 100, in a step 221, determines transmission parameters for the message. These transmission parameters include, for example, a transmission power and a spreading factor. These parameters can be found in a table or an ordered list comprising, for example, pairs (transmission power; spreading factor) ordered according to the energy required for transmission according to the parameters defined by each pair. Typically, the measuring device chooses during a first step 221 the first element of the ordered list corresponding to a minimum necessary energy.

In a following step 222, the measuring device 100 determines the energy necessary for sending the message with the previously determined parameters. This necessary energy can be defined in association with each couple in the list, so it can be easily found. Alternatively, the measuring device 100 can apply correction factors to take account of the energy loss during the transmission of a message.

In a following step 223, the measuring device 100 configures the power supply management module 103 so that the latter cannot supply more electrical energy than the energy previously determined to the radio module 104. According to a mode of operation. embodiment of the invention, the measuring device 100 charges an electrical energy storage element with the necessary energy previously determined. This storage element is for example a capacitor. According to a complementary embodiment, the measuring device 100 configures a Coulomb type counter - included in the power supply management module 103 - so that the power supply to the radio module 104 is cut off as soon as a threshold value of energy transmitted to radio module 104 is exceeded.

In a following step 224, the radio module 104 transmits the message. The radio module 104 cannot exceed a maximum value of transmitted energy, which is controlled according to the necessary energy configured by the power management module 103 during step 223.

In a following step 225, and possibly after a predetermined waiting time, the measuring device 100 checks whether an acknowledgment has been received indicating the correct reception of the message sent.

If the message is acknowledged (return to step 201 or else to step 220 as long as the measuring device remains in the second operating mode), then the method ends until the transmission of a next message. Possibly then, the pair of emission power and spreading factor is kept in memory. During a new step 221 carried out for a new message to be sent of the same size, the measuring device can advantageously use these parameters kept in memory. This can avoid restarting a test phase of several parameters which in the end do not allow good reception of the messages. Conversely, it may be useful to periodically validate that the parameters chosen are indeed the most economical in terms of energy required. So,

If the message is not acknowledged, then the measuring device 100 recommences a step 221 by choosing from the table or the ordered list the following parameters or torque (transmission power; spreading factor), that is to say those requiring just higher energy. The process is thus repeated, each time with an increasing necessary energy, until the moment when an acknowledgment is received. It is thus possible to determine the transmission power and spreading factor parameters guaranteeing minimum consumption of the radio module 104, and therefore of the measuring device 100.

CLAIMS

1. Measuring device (100) for a surveillance system intended to be installed in an aircraft, the measuring device being adapted to operate according to a first operating mode called “on the ground” or a second operating mode known as “in flight” ", The measuring device comprising:

- a sensor suitable for measuring at least one physical parameter of the environment of the aircraft,

- a radio module conforming to a low consumption wide area network standard, the radio module being suitable for sending messages comprising measurement data from the sensor to a radio access point, the radio module being suitable for sending each message with a transmit power chosen from a predefined plurality of transmit powers,

- an electrical power source,

a power supply management module mounted in cut-out between the radio module and the power supply module, the power supply management module comprising an energy storage element making it possible to supply the radio module with power,

a control module, the control module being suitable for switching the operating mode of the measuring device between the first operating mode called “on the ground” and the second operating mode known as “in flight”,

the measuring device being suitable for:

- in the first operating mode called "on the ground":

o before sending each message, charge the energy storage element with a predefined energy supplied by the electrical power source,

- in the second operating mode called "in flight":

o for each message to be sent, choose a transmission power of the radio module,

o determine, according to this transmission power, an energy necessary for the transmission of the message by the radio module,

o before sending the message, charge the energy storage element with the necessary energy determined and supplied by the power supply source.

2. Measuring device according to claim 1, the measuring device being characterized in that the radio module further comprises means for transmitting a message as a function of a spreading factor, the spreading factor being chosen from among a predefined plurality of spreading factors, the measuring device being suitable for, in the second so-called “in-flight” operating mode:

- for each message to be sent, choose a transmission power of the radio module and a spreading factor,

- determine the energy required for the transmission of the message by the radio module as a function of the transmission power and the spreading factor chosen.

3. Measuring device according to claim 2, characterized in that the measuring device further comprises means for, in the second operating mode called "in flight", following the transmission of a message by the radio module. with a first power and according to a first spreading factor, and in the absence of an acknowledgment response from the radio access point:

- means for choosing a second transmission power of the radio module and a second spreading factor, to re-transmit the message,

the second transmission power and the second spreading factor corresponding to an entry of a predetermined list, the list comprising the plurality of pairs formed by the plurality of transmission powers and the plurality of spreading factors, each pair being associated with an energy necessary to send a message with the emission power of the torque and according to the spreading factor of the torque, the list being ordered according to the energy necessary to send the message associated with each pair, the second power d 'emission and the second spreading factor corresponding to the torque following the torque formed by the first transmission power and the first spreading factor.

4. Measuring device according to claim 3, characterized in that the list does not include pairs formed by a transmission power and a spreading factor requiring energy to transmit a message greater than a predetermined energy threshold.

5. Measuring device according to claim 3 or 4, characterized in that the measuring device comprises a list associated with each size of message to be sent.

6. Measuring device according to one of the preceding claims, characterized in that the power supply management module comprises a Coulomb counter.

7. A surveillance system for an aircraft, the system comprising:

- a plurality of measuring devices according to one of the preceding claims,

a radio access point, the radio access point being connected to an item of equipment on the aircraft.