Method for determining temperature information, associated electronic device, electronic system and computer program

Abstract

A method for determining temperature information for a part of an environment comprises the following steps: - production (E2) of a matrix of temperature values ​​based on measurements taken by a thermal sensor; - identification (E4), within a predefined area of ​​the matrix, of a set of contiguous temperature values ​​within the matrix, contained within a predefined range and whose number is between a first and a second threshold; - upon identification of said set, determination (E6) of the temperature information based on the temperature values ​​of the identified set. An electronic device, an electronic system, and a computer program are also described. Figure for the abstract: Figure 4

Description

Title of the invention: Method for determining temperature information, associated electronic device, electronic system and computer program. Technical field of the invention

[0001] The present invention relates to the technical field of temperature measurement.

[0002] It relates in particular to a method for determining temperature information, as well as an electronic device, an electronic system and an associated computer program. State of the art

[0003] It is known to use a matrix thermal sensor (embedded for example in a thermal camera) to determine temperature information relating to a part of the environment facing this matrix thermal sensor.

[0004] Such solutions are used in particular in motor vehicle cabins to obtain temperature information (for example an average temperature, a minimum temperature and / or a maximum temperature) relating to a part of the environment such as a part of the body (hand or face) of an occupant of the cabin.

[0005] Such temperature information is used in particular in the context of controlling the vehicle's heating and / or air conditioning system.

[0006] When it is desired to determine temperature information relating to a moving part of the environment (such as a hand or face of a vehicle occupant in the aforementioned example), it is necessary to implement an algorithm for detecting and tracking the part of the environment concerned.

[0007] The detection and tracking algorithms generally used, based in particular on pattern recognition, are relatively complex. This implies either performing relatively heavy processing at the sensor level, which nevertheless increases the hardware complexity of the sensor, or transmitting all the measured data from the sensor to an electronic control unit where the processing can be carried out, which however requires a significant data throughput between the sensor and the electronic control unit. Presentation of the invention

[0008] In this context, the present invention proposes a method for determining temperature information relating to a part of an environment, comprising the following steps:

[0009] - production of a matrix of temperature values ​​based on measurements performed by a thermal sensor;

[0010] - identification, within a predefined area of ​​the matrix, of a set of contiguous temperature values ​​in the matrix, within a predefined range of values ​​and whose number is between a first threshold and a second threshold;

[0011] - in the event of identification of said assembly, determination of the information of temperature based on the temperature values ​​of the identified set.

[0012] The values ​​used to determine the temperature information are thus identified in a particularly simple way, without having to resort, for example, to a shape recognition algorithm of the part of the environment concerned.

[0013] The predefined zone and the predefined range of values, as well as the first threshold and the second threshold, will be chosen according to the part of the environment for which we wish to determine the temperature information.

[0014] If, on the other hand, no set of contiguous elements in the predefined area corresponds to the predefined range of values, or includes a number of values ​​between the first threshold and the second threshold, this means that no part such as the expected one (for example a hand or a face) is present in the region of the environment corresponding to the predefined area.

[0015] The range of values ​​can be delimited, for example, by a lower and an upper limit. The lower limit can be between 20 °C and 30 °C and / or the upper limit can be between 33 °C and 40 °C. This is useful, for example, when the part of the environment being studied is an exposed part of the body of a vehicle occupant.

[0016] In some cases, the range of values ​​could be limited (only) by a lower bound. This lower bound is, for example, greater than 100 °C (or even 150 °C), which is particularly useful when one wishes to monitor a possible fire in the relevant part of the environment.

[0017] In some cases (for example when the part of the environment is a face of an occupant of a vehicle interior), the first threshold may be between 5 and 10 and / or the second threshold may be between 15 and 30. The temperature value matrix may, for example, include a number of columns between 16 and 64 and / or a number of rows between 16 and 64.

[0018] In the example described below, the method includes a step of transmitting the determined temperature information to an electronic control unit.

[0019] The temperature information determined during the determination step can be the average of the temperature values ​​of the identified set, or the minimum value among the temperature values ​​of the identified set, or the maximum value among the temperature values ​​of the identified set.

[0020] It can also be provided that in the absence of identification of said assembly, the temperature information is set to a predefined value indicative of an absence of detection of said part.

[0021] The second threshold may also be strictly less than the number of values ​​in the predefined area.

[0022] The invention also proposes an electronic device comprising:

[0023] - an acquisition module configured to produce a matrix of values ​​of temperature based on measurements taken by a thermal sensor;

[0024] - a processing module configured to identify, within a predefined area of the matrix, a set of contiguous temperature values ​​in the matrix, within a predefined range of values ​​and whose number is between a first threshold and a second threshold, and to determine, in case of identification of said set, a temperature information on the basis of the temperature values ​​of the identified set.

[0025] This electronic device may include a communication unit configured to transmit temperature information to an electronic control unit.

[0026] The optional characteristics presented above in terms of method can also be applied to this electronic device.

[0027] The invention also proposes an electronic system comprising such an electronic device and the aforementioned electronic control unit.

[0028] The invention finally proposes a computer program comprising instructions executable by a processor and designed to implement a process such as that proposed above when these instructions are executed by the processor

[0029] Of course, the various features, variants, and embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0030] In addition, various other features of the invention become apparent from the attached description made with reference to the drawings which illustrate non-limiting embodiments of the invention and where:

[0031] [Fig-1] schematically represents a system in which implementation the invention;

[0032] [Fig.2] represents a part of the system of [Fig.1];

[0033] [Fig.3] represents an example of a thermal image corresponding to a matrix of temperature values ​​as used in the invention; and

[0034] [Fig.4] is a flowchart showing the main steps of an example process in accordance with the invention.

[0035] Fig. 1 schematically represents a heating and air conditioning system of a vehicle (here a motor vehicle) in which the invention can be implemented.

[0036] The system of [Fig. 1] includes an electronic device 2 forming a thermal detector and located in a passenger compartment 4 of the vehicle. The system of [Fig. 1] also includes an electronic control unit 10, a ventilation unit 12, a heating unit 14 and an air conditioning unit 16.

[0037] The electronic control unit 10 controls the operation of the heating and air conditioning system and sends instructions to the ventilation unit 12 and / or the heating unit 14 and / or the air conditioning unit 16 for this purpose.

[0038] As shown in [Fig.2], the electronic device 2 comprises an acquisition module 20, a processing module 22 and a communication unit 24.

[0039] In the example described here, the acquisition module 20 is a thermal camera equipped with a matrix thermal sensor and configured to produce a matrix of temperature values ​​based on the measurements made by this matrix thermal sensor within the environment where this matrix thermal sensor is located, here the passenger compartment 4 of the vehicle.

[0040] The aforementioned matrix elements are thus the temperature values ​​measured by the thermal sensor in a set of spatial directions relative to the thermal sensor. The temperature values ​​therefore indicate the respective temperatures of different regions located in the environment (here, the vehicle's passenger compartment) in different spatial directions relative to the thermal sensor.

[0041] In practice, the matrix includes, for example, a number of columns between 16 and 64 and / or a number of rows between 16 and 64.

[0042] For example, a Heimann HTPA32x32d thermal camera is used here, with a resolution of 32 elements x 32 elements and covering a total angular field of view of 120° x 120° so as to cover the entire passenger compartment.

[0043] Such a thermal camera practically provides a stream of matrices (for example, at a frequency between 1 Hz and 10 Hz). However, we are interested in the processing of a matrix (at a given instant), this processing being reproducible for each of the matrices in the stream.

[0044] The processing module 22 is here a processor (for example a microcontroller) which receives the matrix of temperature values ​​produced by the acquisition module 20 and processes these temperature values ​​(as explained below) in order to obtain information relating to a part of the environment

[0045] It is noted that the example described here, where the acquisition module 20 and the processing module 22 physically correspond respectively to a thermal camera and a processor, represents only one possible implementation of the invention.

[0046] Alternatively, it could be envisaged, for example, that the acquisition module 20 is implemented by the cooperation of a thermal sensor making measurements in the environment and a processor processing these measurements (due to the execution of first instructions) so as to produce the matrix of temperature values, while the processing module 22 could then be implemented either by this same processor (executing second instructions distinct from the first instructions) or by another processor.

[0047] In the case where the same processor is used to implement the acquisition module 20 and the processing module 22, a computer program (grouping the first and second instructions mentioned above) can thus include instructions executable by this processor and designed to implement a process of the type described below with reference to [Fig.4] when these instructions are executed by this processor.

[0048] For each part of the environment for which at least one temperature measurement is desired, the processing module 22 stores:

[0049] - initial data defining an area within the matrix;

[0050] - one or more given second(s) defining a range of values ​​of temperature ;

[0051] - a first threshold and a second threshold.

[0052] In the example described here, the first threshold is strictly less than the second threshold.

[0053] The area defined by the first data (or predefined area) is the area of ​​the matrix corresponding to the region of the environment (here the passenger compartment) in which the part of the environment concerned is likely to be located.

[0054] For example, if the part of the environment concerned is the driver's face, the predefined area is an area (on the matrix) corresponding to the places (in the passenger compartment) where the driver's face can be located in the driving position (taking into account the different possible sizes of the driver, the different movements he can usually make and the different possible adjustment positions of the driver's seat).

[0055] Thanks to the processing carried out in the following steps (identification of a set of values ​​meeting certain criteria), the predefined area can be chosen relatively broadly. For example, if the part of the environment concerned is the face of a rear passenger, the predefined area can extend over an area corresponding to the entire width of the rear seat.

[0056] In some embodiments, the predefined area can cover the entire matrix (the identification described below then being done within the set of temperature values ​​of the matrix).

[0057] Several ways are possible to define the predefined area using the initial data. For example, when the predefined area is rectangular, the initial data may include the coordinates (row and column in the matrix) of the upper left corner of the predefined area, the width (in number of columns) of the predefined area, and the length (in number of rows) of the predefined area. According to another embodiment, the initial data may include the list of coordinates (row and column in the matrix) of all the elements of the matrix forming the predefined area.

[0058] The range of temperature values ​​can be chosen according to the part of the environment concerned and / or the phenomenon that one wishes to take into account or detect.

[0059] If the part of the environment concerned is a part of a human body (such as a part of the human body of an occupant of the vehicle's interior) exposed (for example, a face or a hand of an occupant), the range of values ​​is, for example, delimited by a lower limit between 20 °C and 30 °C and by an upper limit between 33 °C and 40 °C. In the example described here, a lower limit of 28 °C and an upper limit of 35 °C are used, resulting in a range of values ​​extending between 28 °C and 35 °C.

[0060] If the part of the environment concerned is a part of the passenger compartment at the level of which it is desired to be able to detect a possible fire, the range of value is for example delimited by a lower limit only, this lower limit being for example greater than 100 °C (or even 150 °C).

[0061] The second data point(s) mentioned above (defining the range of values) is (are) for example representative of the lower bound and / or the upper bound.

[0062] The first and second thresholds are defined according to the expected size of the part of the environment at the matrix level (i.e., according to the physical size of this part of the environment and the distance separating this part of the environment from the thermal sensor). As will be clear from the explanation that follows, the first and second thresholds are designed to bracket the number of matrix elements that usually correspond to the part of the environment in question.

[0063] In the example described here, when the part of the environment is a face of an occupant, the first threshold is between 5 and 10 (and is 8 in the example described) and / or the second threshold is between 15 and 30 (and is 20 in the example described). When the part of the environment being studied is mobile within the predefined area, in particular, the second threshold is generally strictly less than the number of values ​​in that predefined area.

[0064] The processing module 22 is configured (i.e. programmed for example when it is a processor) to identify, within the area of ​​the matrix defined above, a set of contiguous temperature values ​​in the matrix, included in the aforementioned range of values ​​and whose number is between a first threshold and a second threshold.

[0065] Here, for example, two temperature values ​​are considered contiguous in the matrix when these two temperature values ​​are located on the same row of the matrix and in adjacent columns, or on the same column and in two adjacent rows.

[0066] When a set of temperature values ​​as defined above is identified, each temperature value in the set is contiguous to at least one other temperature value in the set.

[0067] In practice, the processing module 22 is, for example, designed to construct such an assembly by scanning the temperature values ​​of the predefined zone and, during this scanning:

[0068] - by detecting a temperature value within the range of values,

[0069] then, iteratively:

[0070] - by adding to the set any temperature value within the range of values ​​and contiguous in the matrix to a temperature value already present in the set.

[0071] When all the temperature values ​​of the predefined zone have been considered (scanned), the processing module 22 counts the number of elements (i.e., temperature values) in the constructed set:

[0072] - if this number is between the first threshold and the second threshold, this set is identified as a set of contiguous temperature values ​​in the matrix, within the range of values ​​and whose number is between the first threshold and the second threshold (we then consider that the part of the environment of interest is detected);

[0073] - if this number is not between the first threshold and the second threshold (i.e. if the number of elements in the constructed set is strictly less than the first threshold or strictly greater than the second threshold), the constructed set is not considered to be a set as defined above and we can therefore consider that the part of the environment in which we are interested has not been detected.

[0074] Fig. 3 represents an example of a thermal image corresponding to a matrix of temperature values.

[0075] Temperature values ​​below (strictly) the lower bound of the value range are represented by pixels containing dots. Temperature values ​​between the lower and upper bounds (and therefore within the temperature range) are represented by pixels containing simple hatching. Temperature values ​​above (strictly) the upper bound of the value range are represented by cross-hatching.

[0076] The RI region comprises a single pixel corresponding to a value within the range of values, and this RI region therefore does not meet the criterion relating to the number of values ​​in the set. Consequently, no set is identified for the RL region.

[0077] The R2 region comprises 9 contiguous pixels corresponding to values ​​(therefore contiguous in the matrix) included in the range of values, so that the set of values ​​corresponding to the R2 region is identified as a set of temperature values ​​contiguous in the matrix, included in the range of values ​​and whose number is between the first threshold and the second threshold.

[0078] The processing module 22 is also designed to, when such a set of contiguous temperature values ​​in the matrix, within the range of values ​​and whose number is between the first threshold and the second threshold is identified, determine the temperature information sought on the basis of the temperature values ​​of the identified set.

[0079] The processing module 22 determines, for example, the average of the temperature values ​​of the identified set (case where the temperature information sought is the average temperature of the part of the environment).

[0080] The processing module 22 can also determine the maximum value among the temperature values ​​of the identified set (case where the temperature information sought is the maximum temperature of the part of the environment).

[0081] The processing module 22 can also determine the minimum value among the temperature values ​​of the identified set (case where the temperature information sought is the minimum temperature of the part of the environment).

[0082] The processing module 22 can determine several temperature information, for example from those just indicated.

[0083] The communication unit 24 is designed to transmit the temperature information determined by the processing module 22 to the electronic control unit 10.

[0084] The communication unit 24 and the electronic control unit 10 are here connected via an automotive communication bus, for example via a CAN (Controller Area Network) bus, or via a local interconnected network (or LIN), or even via an Ethernet connection. The Specific temperature information, which is inexpensive in terms of bandwidth, can be transmitted via such a low-speed bus.

[0085] The electronic control unit 10 is designed to receive the temperature information determined by the processing module 22 and to determine, based on the temperature information received, instructions (for example, setpoints) intended respectively for the ventilation unit 12 and / or the heating unit 14 and / or the air conditioning unit 16.

[0086] The electronic control unit 10 is designed to send each determined instruction to the unit concerned (ventilation unit 12 or heating unit 14 or air conditioning unit 16).

[0087] The processing module 22 can also be designed to, when no set of contiguous temperature values ​​in the matrix, within the range of values ​​and whose number is between the first threshold and the second threshold, is identified, set the temperature information to a predefined value indicative of an absence of detection of the part of the environment concerned.

[0088] In this case also, the temperature information is transmitted to the electronic control unit 10 by the communication unit 24 in order to inform the electronic control unit 10 of the absence of detection and therefore of the unavailability of the information sought.

[0089] Figure 4 is a flowchart showing the main steps of a process which can to be implemented in the system of [Fig.1].

[0090] This describes the implementation of a method for determining temperature information (for example, an average temperature, a maximum temperature, or a minimum temperature) relating to a particular part of the environment (here, the vehicle's interior). This particular part is, for example, the face of an occupant of the vehicle's interior (possibly the face of the vehicle's driver). Other methods of the same type can be implemented, in parallel or at separate times, with respect to another part of the environment or other temperature information.

[0091] The process begins with a step E2 of producing a matrix of temperature values ​​by the acquisition module 20, based on measurements made by the thermal sensor equipping the acquisition module 20.

[0092] The process continues with a step E4 of identification, within a predefined area of ​​the matrix (area defined here by the first data stored in the processing module 22 for the part of the environment concerned), of a set of contiguous temperature values ​​in the matrix, within a predefined range of values ​​(range defined here by the second data stored in the processing module 22 for the part of the environment concerned) and of which the number is between the first threshold and the second threshold (this first threshold and this second threshold being stored here in the processing module 22 for the part of the environment concerned).

[0093] If such an assembly is identified in step E4 (i.e. in case of identification, arrow P in [Fig.4]), the process continues with a step E6 of determining the temperature information on the basis of the temperature values ​​of the identified assembly.

[0094] If the temperature information sought is the average temperature of the part of the environment concerned, the temperature information determined in step E6 is the average of the temperature values ​​of the identified set.

[0095] If the temperature information sought is the minimum temperature of the part of the environment concerned, the temperature information determined in step E6 is the minimum value among the temperature values ​​of the identified set.

[0096] If the temperature information sought is the maximum temperature of the part of the environment concerned, the temperature information determined in step E6 is the maximum value among the temperature values ​​of the identified set.

[0097] If no set as defined above is identified in step E4 (i.e. in the absence of identification of such a set, arrow N in [Fig.4]), the method includes a step E8 of setting the temperature information to a predefined value indicative of an absence of detection of the part concerned of the environment.

[0098] In both cases considered above, the process then includes a step E10 during which the processing module 22 controls the transmission (here by the communication unit 24) of the temperature information to the electronic control unit 10 (here via the automotive communication bus linking the electronic device 2 and the electronic control unit 10).

Claims

Demands

1. A method for determining temperature information relating to a part of an environment, comprising the following steps: - production (E2) of a matrix of temperature values ​​based on measurements made by a thermal sensor; - identification (E4), within a predefined area of ​​the matrix, of a set of contiguous temperature values ​​in the matrix, within a predefined range of values ​​and whose number is between a first threshold and a second threshold; - in the event of identification of said set, determination (E6) of the temperature information based on the temperature values ​​of the identified set, and characterized in that the first threshold is between 5 and 10 and in which the second threshold is between 15 and 30.

2. A method according to claim 1, wherein the range of values ​​is delimited by a lower bound and an upper bound.

3. A method according to claim 2, wherein the lower limit is between 20 °C and 30 °C and wherein the upper limit is between 33 °C and 40 °C.

4. A method according to claim 1, wherein the range of values ​​is delimited by a lower bound.

5. A method according to claim 4, wherein the lower bound is greater than 100 °C.

6. A method according to any one of claims 1 to 5, wherein the temperature value matrix comprises a number of columns from 16 to 64.

7. A method according to any one of claims 1 to 6, comprising a step of transmitting determined temperature information to an electronic control unit.

8. A method according to any one of claims 1 to 7, wherein the temperature information determined during the determination step is the average of the temperature values ​​of the identified set.

9. A method according to any one of claims 1 to 8, wherein, in the absence of identification of said assembly, the temperature information is set to a predefined value indicative of an absence of detection of said part.

10. A method according to any one of claims 1 to 9, wherein the second threshold is strictly less than the number of values ​​in the predefined area.

11. Electronic device (2) comprising: - an acquisition module (20) configured to produce a matrix of temperature values ​​on the basis of measurements made by a thermal sensor; - a processing module (22) configured to identify, within a predefined area of ​​the matrix, a set of contiguous temperature values ​​in the matrix, within a predefined range of values ​​and whose number is between a first threshold and a second threshold, and to determine, in the event of identification of said set, a temperature information on the basis of the temperature values ​​of the identified set, and characterized in that the first threshold is between 5 and 10 and in which the second threshold is between 15 and 30.

12. Electronic device according to claim 11, comprising a communication unit (24) configured to transmit temperature information to an electronic control unit (10).

13. Electronic system comprising an electronic device (2) according to claim 12 and said electronic control unit (10).

14. A computer program comprising instructions executable by a processor and designed to implement a method according to any one of claims 1 to 9 when such instructions are executed by the processor.

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