Patent Description:
Such methods are particularly useful to predict corrosion events in a vehicle based on vehicle usage and severity of the conditions it experiences, notably linked to weather conditions and salt exposure. They can be applied to cars or any other type of vehicle.

Corrosion undergone by parts of a vehicle is highly dependent on the vehicle usage and the conditions it undergoes. Particularly, corrosion is greatly influenced by the weather conditions and the presence of salt in the vehicle environment. For instance, rain, especially when accompanied by wind, and proximity to sea promote corrosion. Also, salt spread on the roads during snow events further promotes corrosion.

However, to date, these corrosion observations are mainly based on experience: particularly, no clear correlation has been found between the corrosion undergone by some part of the vehicles and objective data based on the weather conditions, the salt exposure and the vehicle usage. Therefore, for lack of a mathematical relationship linking corrosion with weather data, salt exposure and/or vehicle usage, corrosion predictions are very challenging to undertake. Document <NPL> deals with a multi-factor mining and corrosion rate prediction model construction of carbon steel under dynamic atmospheric corrosion environment.

As a result, to date, the only reliable manner to prevent failures due to corrosion is to regularly inspect the vehicle. However, of course, most of these inspections are carried out as a precaution by non-technical people that are not skilled to understand severity of usage of a vehicle based on visual inspection. Alternatively, a skilled engineer would require a great number of inspections to link corrosion events to the severity of environment experienced by a vehicle, given the wide range of weather conditions, salt usage and vehicle usage in a single country. The efficiency of this method is therefore rather low.

As a result, there is a need for another method to predict corrosion events in a more reliable manner and on a large scale.

The present invention relates to a training method for a machine learning model intended to carry out corrosion estimations about a vehicle, according to claim <NUM>.

As a result, thanks to this training method, it is possible to record in a training database a whole history of weather conditions in the area of the vehicle and to associate with it, for each moment of this history, data about the corrosion actually undergone by said vehicle as measured by the corrosion sensor.

Thus, thanks to such a training database, it is possible to train a machine learning model to make it able, once the training completed, to carry out corrosion estimations on the basis of the weather conditions that the vehicle actually faces at the current moment. In this respect, it should be understood that the training database is supplied by one or several test vehicles which are equipped with one or several corrosion sensors but that, of course, the actual commercial vehicles are generally devoid of corrosion sensors: the trained machined learning model will therefore help to predict corrosion events for such commercial vehicles.

Of course, the more numerous are the sets of data in the training database, the more reliable will be the corrosion estimations made by the trained machine learning model. Also, because the method always determines the closest weather station to the vehicle, the accuracy of the weather data is increased.

In some embodiments, said several moments are set at a regular time interval, this time interval being comprised between <NUM> minute and <NUM> minutes, preferably comprised between <NUM> minutes and <NUM> minutes. These values constitute a good comprise between the need to have a great number of sets of data and the need to reduce the amount of redundant data so as to reduce the risk of overfitting. Also, such intervals are well adapted to prevent the battery of the corrosion sensor from being depleted too quickly.

In some embodiments, said several moments spread over at least one month, preferably over at least <NUM> months. Indeed, the longest the duration of the data collection, that is to say of the test phase, the more numerous and the more varied the collected data, which improves the training efficacy. Also, preferably, the test phase is carried out in winter, for instance from December to February. Indeed, the snow events are more likely to happen in winter so that the salt exposure is also more important in those months.

In some embodiments, the method comprises determining the moving state of the vehicle. Particularly, the moving state of the vehicle may be determined between at least two states: "still" and "moving".

In some embodiments, the moving state of the vehicle is recorded in the training database for at least some moments of said several moments, and preferably for each of them. The movement of the vehicle may indeed influence the corrosion phenomenon, as the vehicle experiences more salts due to splashing, particularly in winter periods.

In some embodiments, the step of determining the vehicle location is carried out only when the moving state of the vehicle is equal to "moving". For instance, when the moving state is equal to "still", the last known vehicle location is used to determine which weather station is the closest weather station.

In some embodiments, the method comprises determining the moving speed of the vehicle. The speed of the vehicle may indeed influence the corrosion phenomenon, particularly during rain.

In some embodiments, a data representative of the moving speed is recorded in the training database for at least some moments of said several moments, and preferably for each of them. This data is preferably the average moving speed over the last time interval. Alternatively, it could be the instantaneous moving speed at the time of the recorded moment.

In some embodiments, the method comprises determining the moving direction of the vehicle. The moving direction of the vehicle may indeed influence the corrosion phenomenon, particularly in relation with the wind direction.

In some embodiments, a data representative of the moving direction is recorded in the training database for at least some moments of said several moments, and preferably for each of them. This data is preferably the average moving direction over the last time interval. Alternatively, it could be the instantaneous moving direction at the time of the recorded moment.

In some embodiments, the closest weather station is selected in the weather station database among the weather stations which are available. An available weather station is a weather station which provides available and updated weather data. In the meaning of the present disclosure, the weather data are believed to be up to date if they have been updated in the last two hours, preferably in the last hour.

In some embodiments, the method comprises, when the time interval at which the weather data are available from the closest weather station is longer than the time interval of the training database, building intermediate weather data based on weather data actually retrieved from the closest weather station at other moments. For instance, these intermediate weather data can be interpolated on the basis of the previous and the next available weather data. Alternatively, the last available weather data can be reused until new weather data are available at the closest weather station.

In some embodiments, the weather data comprises the amount of precipitations. For instance, the amount of precipitation is the amount of precipitation from the last recorded moment. Indeed, rain is a factor having great influence on corrosion.

In some embodiments, the weather data comprises the wind speed. Indeed, wind may promote corrosion under certain circumstances, especially in relation with rain.

In some embodiments, the weather data comprises the wind direction. Indeed, the direction of the wind with respect to the vehicle may influence corrosion.

In some embodiments, the weather data comprises the cloud cover. Indeed, the inventors have identified a correlation between cloud cover and corrosion experienced by the vehicle.

In some embodiments, the weather data comprises the air pressure.

In some embodiments, the weather data comprises the air temperature.

In some embodiments, the corrosion sensor is configured to measure the free corrosion, the galvanic corrosion and/or the total free and galvanic corrosion. Particularly, the corrosion sensor may be configured to measure corrosion current.

In some embodiments, at least one corrosion sensor is attached on a part to be monitored of the vehicle. This helps to monitor the corrosion of a particular part which is for instance known to be particularly sensible to corrosion or which is particularly critical for the correct functioning of the vehicle. Of course, several corrosion sensors may be used to monitor different parts. For instance, the parts of interest may include stabilizer bars, coil springs, torsion beams, and more generally the underbody of vehicle.

In the invention, the vehicle is provided with a contamination sensor. Such a contamination sensor is particularly useful to detect, on some parts of the vehicle, the possible presence of contaminants which may promote corrosion. For instance, such a contamination sensor could be configured to detect and/or measure the concentration of salt (NaCl). Indeed, the vehicle can be contaminated by salt coming from the road surface, especially during snow events, or coming from the sea air when the vehicle drives near the sea shore, such contaminating salt then promoting corrosion of the exposed vehicle parts. This information may therefore help to train the machine learning model to estimate salt exposure, and therefrom corrosion, on the basis of the weather conditions and of the location of the vehicle, each region/country having its own habits regarding salt usage and salt type, and being more or less exposed to saline sea air.

In the invention, at least some contamination data retrieved from the contamination sensor are recorded in the training database for at least some moments of said several moments, and preferably for each of them. This data is preferably the conductance (in µS) of a reference solution involved in the contamination sensor, such a conductance being linked to the total concentration of contaminants at the time of the recorded moment.

In some embodiments, the vehicle is provided with a humidity sensor. Indeed, humidity may influence corrosion.

In some embodiments, a data representative of the humidity measured by the humidity sensor is recorded in the training database for at least some moments of said several moments, and preferably for each of them. This data is preferably the average humidity over the last time interval. Alternatively, it could be the instantaneous humidity at the time of the recorded moment.

In some embodiments, the vehicle is provided with a temperature sensor. Indeed, temperature may influence corrosion.

In some embodiments, a data representative of the temperature measured by the temperature sensor is recorded in the training database for at least some moments of said several moments, and preferably for each of them. This data is preferably the average temperature over the last time interval. Alternatively, it could be the instantaneous temperature at the time of the recorded moment.

In some embodiments, the machine learning model comprises an artificial neural network. For instance, this artificial neural network may comprise three neuron layers.

The present invention also relates to a corrosion estimating method for a vehicle, according to claim <NUM>.

Thanks to such a corrosion estimating method, it is possible to estimate corrosion undergone by any vehicle on the basis of weather conditions actually faced by the vehicle. Particularly, it is possible to estimate the instantaneous corrosion undergone by the vehicle and, thus, to estimate the cumulative amount of corrosion undergone by the vehicle since its putting into service. As a result, it is possible to predict corrosion events and, thus, to anticipate the failure of some parts of the vehicle. Consequently, it is possible to plan a visual inspection of the vehicle in a garage only when the probability of a corrosion event is high enough: therefore, the number of inspections can be reduced.

In the invention, the machine learning model has been trained in accordance with the training method of any one of the above mentioned embodiments.

In some embodiments, the method comprises determining the moving state of the vehicle and inputting said moving state in the machine learning model.

In some embodiments, the method comprises determining the moving speed of the vehicle and inputting said moving speed in the machine learning model.

In some embodiments, the method comprises determining the moving direction of the vehicle and inputting said moving direction in the machine learning model.

In some embodiments, the weather data comprises the amount of precipitations.

In some embodiments, the weather data comprises the wind speed.

In some embodiments, the weather data comprises the wind direction.

In some embodiments, the weather data comprises the cloud cover.

In some embodiments, the weather data comprises the air humidity.

In some embodiments, the vehicle is provided with a humidity sensor and the humidity measured by the humidity sensor is inputted in the machine learning model.

In some embodiments, the vehicle is provided with a temperature sensor and the temperature measured by the temperature sensor is inputted in the machine learning model.

In some embodiments, several sets of data corresponding to different moments are inputted in the machine learning model. Therefore, the machine learning model will output estimated corrosions data for each of these moments. For instance, such an estimation can be carried out at a regular time interval, preferably at least once a day.

In some embodiments, the method comprises estimating a cumulative corrosion amount undergone by the vehicle on the basis of the estimated corrosion data outputted by the machine learning model.

In some embodiments, the method comprises triggering a warning when the estimated cumulative corrosion amount exceeds a predetermined threshold.

The advantages of a corrosion estimating unit for a vehicle derive from the advantages described above with respect to the corrosion estimating method. Besides, this corrosion estimating unit may comprise any or all of the additional optional features described above with respect to the training method and/or the corrosion estimating method.

The present invention also relates to a computer program according to claim <NUM>.

The above mentioned features and advantages, and others, will become apparent when reading the following detailed description of exemplary embodiments of the presented methods. This detailed description refers to the accompanying drawings.

The accompanying drawings are diagrammatic and seek above all to illustrate the principles of the invention.

In order to make the invention more concrete, exemplary embodiments of a training method, a corrosion estimation method and a corrosion estimation unit are described in detail below with reference to the accompanying drawings. It should be recalled that the invention is not limited to these examples.

<FIG> illustrates a test vehicle <NUM> used for acquiring and recording test data. Such a test vehicle <NUM>, like any regular vehicle, comprises a central electronic unit <NUM> which is connected to all the electronic components of the vehicle <NUM>. Particularly, the central electronic unit <NUM> is able to monitor at any time the essential parameters of the vehicle <NUM>.

First of all, the central electronic unit <NUM> monitors the state of the vehicle, that is to say whether the vehicle is locked, whether the accessories are on, whether the motor is running etc. Particularly, the central electronic unit <NUM> monitors the moving state MS of the vehicle, that is to say whether the vehicle is "moving" or "still".

The central electronic unit <NUM> also continuously monitors the moving speed V and the moving direction D of the vehicle <NUM>. The moving direction D can be determined either by a specific sensor, such as an electronic compass, or thanks to a Global Positioning System (GPS) device <NUM>.

Indeed, the test vehicle <NUM> includes such a GPS device <NUM> able to continuously determine the location L of the vehicle <NUM>, this location L being generally expressed as geographic coordinates. This GPS device <NUM> is connected to the central electronic unit <NUM> and provides it at any time with the vehicle location L.

The test vehicle <NUM> also includes a temperature sensor <NUM> and a humidity sensor <NUM> provided on the body of the vehicle <NUM> so as to measure the air temperature T and the air humidity H around the vehicle <NUM>. These sensors <NUM>, <NUM> are connected to the central electronic unit <NUM> and provide it at any time with the measured air temperature T and air humidity H.

The test vehicle <NUM> also includes a communication device <NUM> connected to the central electronic unit <NUM> and configured to communicate with a wireless network, for instance with the Internet network. Therefore, through the communication device <NUM>, the central electronic unit <NUM> is able to send and receive data to and from external servers.

The test vehicle <NUM> also includes a corrosion sensor <NUM> provided on a part of interest of the vehicle. For instance, such a corrosion sensor <NUM> can be attached to the underbody of the vehicle. Such a corrosion sensor <NUM> has a lamellar-like configuration with two different materials, separated by dielectric layers and connected to two different electrodes. However, of course, other types of corrosions sensors may be used, for instance a sensor assessing the resistance of a filament and correlating it with thickness loss caused by corrosion.

Such a corrosion sensor <NUM> is therefore able to measure the free corrosion FC, expressed in µA, using the linear polarization resistance method: a signal of 10mV is sent to the electrodes at a certain frequency and the response is recorded, said response depending on the ease to oxidize, that is to say to corrode, the electrodes.

Such a corrosion sensor <NUM> is also able to measure the galvanic corrosion GC, expressed in µA, using the zero resistance ammeter method: the actual current flowing from one material to the other, due to galvanic coupling, being thus measured.

Also, the corrosion sensor <NUM> is able to measure the total corrosion TC, as the sum of the free corrosion FC and the galvanic corrosion GC.

More generally, the test vehicle <NUM> may include several corrosion sensors <NUM> of this type, provided on different parts of the vehicle <NUM>.

The test vehicle <NUM> also includes a contamination sensor <NUM> preferably provided close to the corrosion sensor <NUM>. Such a contamination sensor <NUM> is a gold sensor configured to measure the conductance of a solution, this conductance being directly correlated with salt concentration in said solution. For example, an excitation voltage of <NUM> mV is sent to the gold electrode so as to calculate the conductance. The contamination sensor <NUM> is therefore able to measure the conductance C which is representative of the contamination of the surfaces of the vehicle <NUM>. These contaminants may include salt species, and especially NaCl, MgCl<NUM> or CaCl<NUM>, or other organic de-icing compounds, for instance glycols. This conductance may for instance be expressed in µS.

More generally, the test vehicle <NUM> may include several contamination sensors <NUM> of this type, provided on different parts of the vehicle <NUM>.

In the present example, the corrosion sensor <NUM> and the contamination sensor <NUM> are connected to the central electronic unit <NUM> which may record their measures in a centralized memory. However, alternatively, the corrosion sensor <NUM> and/or the contamination sensor <NUM> could be autonomous and record their measures in a local memory retrieved at the end of the testing phase.

During the test phase, several test vehicles <NUM> of this type are provided. They are intended to drive normally on the public road, in realistic conditions. For instance, these test vehicles <NUM> can be entrusted to volunteers who are tasked to use these test vehicles <NUM> in their everyday life or, else, the personal vehicles of these volunteers can be specially equipped to act as test vehicles <NUM> during the test phase. Preferably, the test vehicles <NUM> are distributed in several regions or countries, having different climates.

As depicted on <FIG>, these regions or countries should comprise weather stations <NUM> broadcasting weather data in a regular and updated fashion: for instance, these weather stations <NUM> should broadcast updated weather data at least on an hourly basis. The list of these weather stations <NUM> is saved in a weather station database in association with their locations, that is their geographic coordinates. This weather station database may also mention whether a given weather station is available, that is to say is currently broadcasting weather data, or rather is temporary unavailable.

Each weather station <NUM> may provide different types of weather data. However, it is preferred that they provide at least the amount of precipitations AP over the last measurement period; the average speed WS and direction WD of the wind over the last measurement period; the average cloud cover CC over the last measurement period; and the average air pressure P over the last measurement period.

The proceedings of the test phase will now be explained in reference to <FIG>. The objective of this test phase is to build a training database <NUM> enclosing a large number of sets of data associating corrosion data with usage data and weather data. <FIG> therefore presents how these sets of data are built and recorded with respect to a given test vehicle <NUM>. In the present example, it is assumed that the procedure of <FIG> is carried out by the central electronic unit <NUM> of the considered test vehicle <NUM>.

In a first step S11, the central electronic unit <NUM> wait until a predetermined amount of time has elapsed. This amount of time actually corresponds to the time interval Δt used in the training database <NUM>. In the present example, this time interval is equal to <NUM> minutes.

When this time interval Δt has elapsed, the central electronic unit <NUM> checks in a step S12 the moving state MS of the test vehicle <NUM>.

If the moving state MS is "moving", the central electronic unit <NUM> retrieves in a step S13 the vehicle location L thanks to the GPS device <NUM>. Then, in a step S14, the central electronic unit <NUM> retrieves the moving speed V and the moving direction D of the test vehicle <NUM>. More specifically, in the present example, the central electronic unit <NUM> retrieve the average moving speed V and the average moving direction D over the last time interval Δt.

However, if the moving state MS is "still", the central electronic unit <NUM> does not interrogate the GPS device <NUM> but reuses the last location L known by the central electronic unit <NUM> (step S15). Then, null values are saved as moving speed V and moving direction D (step S16).

Then, in both cases, in step S17, the central electronic unit <NUM> determines which weather station <NUM> is the closest to the test vehicle <NUM> by comparing the vehicle location L with the locations of the weather stations <NUM> as recorded in the weather station database.

Then, in step S18, the central electronic unit <NUM> retrieves the weather data currently broadcasted by the closest weather station <NUM>, and particularly the amount of precipitations AP, the speed WS and direction WD of the wind, the cloud cover CC and the air pressure P.

As this occasion, the central electronic unit <NUM> may condition the brut weather data retrieved from the closest weather station to adapt them to the formats used in the training database <NUM>. Particularly, when the measurement period of the weather station is longer than the time interval Δt of the training database <NUM>, the central electronic unit <NUM> may extrapolate the weather data in order to build intermediate values to be recorded in the training database <NUM>. Also, the amount of precipitations AM may be recalculated in order to match the time interval Δt of the training database <NUM>.

Then, in step S19, the central electronic unit <NUM> retrieves the corrosion data supplied by the corrosion sensor <NUM>, that is to say the free corrosion current FC and the galvanic corrosion current GC. In this respect, it is clarified that the corrosion sensor <NUM> may provide corrosion data at a more frequent interval, and even when the vehicle is not used; however, only the corrosion data measured at the time of the current sample will be retrieved for the purpose of building the database <NUM>.

Then, in step S20, the central electronic unit <NUM> may retrieve additional data, such as the temperature value T provided by the temperature sensor <NUM>, the humidity value H provided by the humidity sensor <NUM> and/or the conductance value C provided by the contamination sensor <NUM>.

Then, in step S21, the central electronic unit <NUM> records a new set of data in the training database <NUM>, this set of data associating the usage data (including the location L, the vehicle speed V and the moving direction D), the weather data (including the amount of precipitation AP, the speed WS and direction WD of wind, the cloud cover CC and the air pressure P) with the corrosion data (including the free corrosion FC and the galvanic corrosion GC) and possible additional data (including the temperature T, the humidity H and the contamination C).

These steps are then repeated until the test phase is ended (Step S22). Particularly, this test phase may be ended after a predetermined period or when the training database <NUM> is deemed satisfactory, that is to say is large enough and varied enough.

Of course, it should be understood that the actual training database <NUM> is formed by the sum of the sets of data recorded by each test vehicle <NUM>. In this regard, the training database <NUM> may be host by a centralized server and completed simultaneously by each test vehicle <NUM> or, else, may be formed at the end of the test phase by merging all the individual databases built by each of the test vehicles <NUM>.

In any case, as depicted on <FIG>, once the test phase is completed, a machine learning model <NUM> is trained on the training database <NUM> thus built. In the present example, this machine learning model <NUM> is an artificial neural network of the type "inputs-<NUM>-<NUM>-<NUM>-output", with "relu" as activation function, mean absolute error as loss function and back propagated error.

Once the training phase is completed, the machine learning model <NUM> can be used to carry out corrosion estimations. The machine learning model <NUM> thus trained may therefore be implemented in the central electronic unit <NUM> of commercial vehicles <NUM>: in such a case, the central electronic unit <NUM> acts as a corrosion estimating unit. Or else, the machine learning model <NUM> may be available on a centralized server which can communicate with the eligible commercial vehicles <NUM> thanks to their communication device <NUM>.

As depicted on <FIG>, a commercial vehicle <NUM> is a vehicle sold to and used by final users. Therefore, it includes the same standard components as the test vehicles <NUM>, that is to say notably a central electronic unit <NUM>, a GPS device <NUM>, a temperature sensor <NUM>, a humidity sensor <NUM> and a communication device <NUM>. Conversely, a commercial vehicle <NUM> is not supposed to comprise specific sensors such as corrosion sensors and/or contamination sensors.

Now, when a corrosion estimation is wished, the central electronic units <NUM> of these commercial vehicles <NUM> may determine which weather station <NUM> is the closest to the vehicle <NUM>, in the same as way as described above with respect to the test vehicle <NUM>, and retrieve the local weather data. The central electronic units may then input into the machine learning model <NUM> these local weather data together with the usage data (including moving speed V and direction D) and possible additional data (including temperature T and humidity H): the model <NUM> then outputs a estimation of the instantaneous corrosion undergone by the commercial vehicle <NUM>. This estimation can relate to the free corrosion and/or the galvanic corrosion, both expressed in µA, or total free corrosion and/or total galvanic corrosion, both expressed in C.

Alternatively, this corrosion estimation may be carried out externally: in such a case, the central electronic unit <NUM> may simply forward the usage data together with the vehicle location L to an external centralized server, then this server determines which is the closest weather station, retrieves the local weather data and interrogates the model <NUM> as explained above.

In both cases, corrosion estimations may be carried out for each commercial vehicle <NUM> eligible to this service, for instance on a daily basis, in order to estimate a cumulative corrosion amount undergone by the commercial vehicle <NUM> since its putting into service. This cumulative corrosion amount may be expressed in coulombs (C). Then, if a predetermined threshold is exceeded, a warning is issued to the driver to ask him or her to plan an inspection in a garage.

Even if the present invention has been described with regard to particular exemplary embodiments, it is clear that these examples may be modified without departing from the scope of the invention as defined by the claims. Particularly, individual features of different presented embodiments can be combined in additional embodiments. As a result, the description and the drawings shall be considered in an illustrative way rather than a limitative way.

Claim 1:
A computer-implemented training method for a machine learning model intended to carry out corrosion estimations about a vehicle,
wherein at least one vehicle (<NUM>) is equipped with at least one corrosion sensor (<NUM>),
wherein the vehicle (<NUM>) is provided with a contamination sensor (<NUM>) configured to measure a conductance which is representative of a contamination of at least one surface of the vehicle (<NUM>),
the method comprising:
determining the location of the vehicle (<NUM>) by means of a GPS device (<NUM>) provided in the vehicle (<NUM>),
determining, in a weather station database, which weather station (<NUM>) is the closest to the location of the vehicle (<NUM>),
retrieving at least some weather data from said closest weather station (<NUM>),
retrieving at least some corrosion data from said at least one corrosion sensor (<NUM>),
retrieving at least some contamination data from the contamination sensor (<NUM>),
building a training database (<NUM>) associating, for several moments over at least ten days, said corrosion data with said weather data,
recording at least some contamination data in the training database (<NUM>) for at least some moments of said several moments, and
training the machine learning model (<NUM>) on the training database (<NUM>) thus built, wherein the weather data and the contamination data are used as input training data, and the corrosion data are used as target output training data.