Method and system for filtering an analog electrical signal generated by a device for monitoring the presence of a driver in a motor vehicle

Abstract

The invention relates to a method for filtering, by a computer system embedded in a motor vehicle, an analog electrical signal generated by a driver presence monitoring device comprising a push button arranged in the vehicle's passenger compartment, to a system (100) implementing such a method, and to a motor vehicle comprising such a system. Figure for the abstract: 1

Description

Title of the invention: Method and system for filtering an analog electrical signal generated by a driver presence monitoring device for a motor vehicle Technical field of the invention

[0001] The present invention relates to the field of systems for filtering electrical signals generated on board motor vehicles. The invention relates in particular to a method for filtering an analog electrical signal generated by a driver presence monitoring device comprising a push button located in the passenger compartment of a motor vehicle. The invention also relates to a computer system implementing such a method and a motor vehicle comprising such a system. The invention is particularly applicable to passenger cars, trucks, buses, commercial vehicles, etc. Prior art

[0002] It is known that certain motor vehicles, particularly vehicles equipped with driver assistance systems that provide autonomous driving functionalities (e.g., parking assistance, lane keeping assist, emergency braking assistance, etc.), are equipped, in order to enable the provision of autonomous driving functionalities for which it is necessary to ensure that the driver is present in the vehicle's passenger compartment (e.g., automated parking), with driver presence monitoring devices, which generally include a push button arranged in the vehicle's passenger compartment. Thus, similarly to those used to equip train locomotives to monitor that the locomotive driver is present and alert (i.e.Automatic monitoring systems (AMS) operate by continuously generating analog electrical signals whose voltage varies depending on whether the push button is pressed or released by the driver. These signals are used by the driver assistance system when implementing certain autonomous driving features. However, in motor vehicles, it appears that the electrical signals generated by these monitoring devices are not always stable. In fact, instead of generating electrical signals that always have the same voltage regardless of the action performed on the push button (i.e., pressed or released), the monitoring devices sometimes generate electrical signals whose voltage oscillates between several voltage levels (i.e., the signals bounce between different voltage levels).However, this has the effect of impairing the ability of driver assistance systems to rely on these signals to safely implement functions. autonomous driving functionalities for which it is crucial to be able to determine with certainty whether the driver is actually in the vehicle. Furthermore, these oscillations also cause delays that impact the decision-making speed of driver assistance systems, which is effectively conditioned by their ability to acquire and process the electrical signals generated by the monitoring devices as quickly as possible (e.g., the acquisition and processing of electrical signals generated by the monitoring device must be on the order of 30ms to allow the implementation of automated parking functionalities). Summary of the invention

[0003] The invention aims to overcome these drawbacks. In particular, the invention aims to provide a method and a system for ensuring the safe implementation by a driver assistance system of a motor vehicle of autonomous driving functionalities based on electrical signals generated by a driver presence monitoring device comprising a push button located in the vehicle's passenger compartment. Furthermore, the invention aims to provide a method and a system for filtering (i.e., processing) an electrical signal generated by a driver presence monitoring device of a motor vehicle comprising a push button located in the vehicle's passenger compartment, so as to maximize the decision-making speed of the driver assistance system when implementing certain autonomous driving functionalities.

[0004] These objectives are achieved, according to a first object of the invention, by means of a filtering method, by a computer system embedded in a motor vehicle, of an analog electrical signal generated by a driver presence monitoring device comprising a push button arranged in the vehicle's passenger compartment, the method comprising the steps of:

[0005] • determine a first point value of the voltage of the electrical signal; • determine data characterizing a first state to which corresponds the first point value of the electrical signal voltage; • determine a duration of a sampling interval and a number of samples to consider based on the data characterizing a first state to which corresponds the first point value of the electrical signal voltage; • determine whether the electrical signal is stable as a function of the duration of a sampling interval and the number of samples to be considered; and, when this is the case, • determine data characterizing a stable state; and • transmit data characterizing a stable state via a communication network Vehicle information intended for an electronic vehicle control unit.

[0006] According to one variant, the step of determining whether the electrical signal is stable may include the steps of:

[0007] • determine at least a second point value of the electrical signal voltage as a function of the duration of a sampling interval and the number of samples to be considered; • determine data characterizing a second state corresponding to the second point value of the electrical signal voltage; and • compare the data characterizing a first state which corresponds to the first point value of the electrical signal voltage and the data characterizing a second state which corresponds to the second point value of the electrical signal voltage.

[0008] According to another variant, the step of determining whether the electrical signal is stable may include a step of determining whether a point value of a control parameter is less than a pre-established threshold value.

[0009] According to another variant, the step of determining at least a second point value of the electrical signal voltage may include a step of incrementing the point value of the control parameter.

[0010] According to another embodiment, the step of determining whether the electrical signal is stable may include the steps of:

[0011] • establish that the electrical signal is unstable if the point value of the control parameter is greater than or equal to the threshold value; and • transmit data characterizing the detection of an unstable electrical signal via the communication network to the electronic control unit.

[0012] According to another variant, the step of transmitting data characterizing a stable state may include a step of resetting the point value of the control parameter.

[0013] According to another variant, the data characterizing a first state corresponding to the first point value of the electrical signal voltage, the data characterizing a second state corresponding to the second point value of the electrical signal voltage and the data characterizing a stable state can identify a first case in which the push button is pressed, a second case in which the push button is released, a third case in which a short circuit is present, a fourth case in which an uncertainty exists or a fifth case in which an open circuit is present.

[0014] Furthermore, the invention also relates to a system for filtering a signal analog electrical generated by a driver presence monitoring device of a motor vehicle comprising a push button arranged in the passenger compartment of the vehicle, said system comprising at least one information processing unit, comprising at least one processor, and a data storage medium configured to implement a method as described above.

[0015] Furthermore, the invention also relates to a program comprising program code instructions for the execution of the steps of a process as described above when said program is executed on a computer and / or a processor.

[0016] Furthermore, the invention also relates to a medium usable in a computer on which a program such as described above is recorded.

[0017] Finally, the invention also relates to a motor vehicle comprising a system as described above. Brief description of the figures

[0018] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0019] [fig. 1] is a functional diagram of a system according to the invention;

[0020] [fig.2] is a flowchart illustrating the steps of a process according to the invention; and

[0021] [fig.3] is a diagram illustrating states as a function of a point value of the voltage of an electrical signal according to the invention. Detailed description of the invention

[0022] According to the invention, a system 100 for, on board a motor vehicle, filtering an analog electrical signal generated by a driver presence monitoring device, which includes a push button arranged in the vehicle's passenger compartment, is a computer system, represented in Figure 1, which includes an information processing unit 101, comprising one or more processors, a data storage medium 102, at least one input and output interface 103, allowing the reception of analog electrical signals and the transmission of data, and a measurement module 104 allowing the determination of a point value of the voltage of an electrical signal received through the input and output interface 103.

[0023] According to the preferred embodiment, the system 100 according to the invention is installed between a driver presence monitoring device, from which it receives the analog electrical signals generated by the driver, and an electronic control unit of a driver assistance system that manages the implementation of autonomous driving functionalities based on the received data. Preferably, the system 100 according to the invention is connected to the driver presence monitoring device by means of at least one electrical cable and is connected to the electronic control unit by means of a vehicle communication network. Mobile devices enabling data transmission, for example a CAN (Controller Area Network) or an Ethernet network. Thus, the system 100 according to the invention is also capable of transmitting data to an electronic control unit of a driver assistance system in a motor vehicle.

[0024] According to the invention, all the elements described above contribute to enabling the system 100 according to the invention to implement on board a motor vehicle a method of filtering an analog electrical signal generated by a driver presence monitoring device comprising a push button arranged in the passenger compartment of the vehicle, as described below in relation to figures 2 and 3.

[0025] According to a first step 201 of the method according to the invention, the system 100 according to the invention determines, by means of its measuring module 104, a first point value of the electrical signal voltage. Indeed, as indicated in the preamble, the conductor presence monitoring device continuously generates electrical signals whose voltage varies depending on whether the push button is pressed or released. The voltage of these signals varies, for example, between 0V and 5V.

[0026] Next, according to a second step 202 of the method according to the invention, the system 100 according to the invention determines data characterizing a first state to which the first point value of the electrical signal voltage corresponds. To do this, as schematically illustrated in Figure 3, the system uses a lookup table stored in its data storage medium 102, which, for each measured voltage level, associates a particular state that identifies an operating case of the conductor presence monitoring device. Thus, preferably, depending on the measured electrical signal voltage, the system 100 according to the invention determines the data characterizing a first state so that they identify a first case in which the push button is pressed (i.e., State 2), a second case in which the push button is released (i.e., State 4), a third case in which a short circuit is present (i.e., State 5).State 1), a fourth case in which uncertainty exists (i.e., State 3), or a fifth case in which an open circuit is present (i.e., State 5).

[0027] Next, according to a third step 203 of the process according to the invention, the system 100 according to the invention determines a duration of a sampling interval and a number of samples to be considered as a function of the data characterizing a first state to which corresponds the first point value of the voltage of the electrical signal.

[0028] To do this, the system 100 according to the invention uses another lookup table stored in its data storage medium 102 which maps each of the states (i.e., each voltage value) to a duration of a sampling interval and a number of samples to be considered. For example, when the first point value of the electrical signal voltage corresponds to the states 1, 3, or 5, which may be the case when the electrical signal bounces in these states and / or when the push button is not properly held down or when too much pressure is applied, the system 100 according to the invention determines that the duration of a sampling interval is equal to 5 ms and that the number of samples to be considered (i.e., to be taken) is equal to 6. Conversely, when it determines that the first point value of the electrical signal voltage corresponds to states 2 or 4, the system 100 according to the invention determines, for example, that the duration of a sampling interval is 5 ms and that the number of samples to be considered is equal to 2.

[0029] Then, according to a fourth step 204 of the method according to the invention, the system 100 according to the invention determines whether the electrical signal is stable as a function of the duration of a sampling interval and the number of samples to be considered.

[0030] To this end, as can be understood from the preceding paragraph, the system 100 according to the invention determines at least a second point value of the electrical signal voltage as a function of the duration of a sampling interval and the number of samples to be considered. Thus, according to the first example described above, i.e., when the first point value of the electrical signal voltage corresponded to states 1, 3, or 5, the system 100 according to the invention considers (i.e., it determines a point value of the electrical signal voltage) six samples separated by time intervals of 5 ms. Conversely, according to the second example described above, i.e., when the first point value of the electrical signal voltage corresponded to states 2 or 4, the system 100 according to the invention considers only two samples separated by time intervals of 5 ms.Next, the system 100 according to the invention determines data characterizing a second state corresponding to the second point value of the electrical signal voltage (and does the same for the other samples). Finally, the system 100 according to the invention compares the data characterizing a first state corresponding to the first point value of the electrical signal voltage with the data characterizing a second state corresponding to the second point value of the electrical signal voltage (and does the same for the other samples). This last step could consist, for example, of establishing that the electrical signal is stable if all states are identical, if a majority of states are identical, if only one state is not identical to the others, etc.

[0031] Then, when it establishes during the previous step that the electrical signal is stable, the system 100 according to the invention carries out the following steps of the process according to the invention described below.

[0032] According to a fifth step 205 of the process according to the invention, the system 100 according to the invention determines data characterizing a stable state, by establishing, for example, that the stable state is the one that is identical to the majority of the determined states thanks to the samples considered in the previous step, and, during a sixth step 206, the system 100 according to the invention transmits the data characterizing a stable state via the communication network to the electronic control unit of the vehicle to which it is connected, the latter using this data for the implementation of autonomous driving functionalities.

[0033] Furthermore, according to a particular embodiment, which advantageously allows for taking into account very numerous oscillations of the electrical signal, oscillations which generally originate from a malfunction of the device monitoring the presence of a conductor, the fourth step 204 of the method according to the invention described above includes a step during which the system 100 according to the invention, when it determines at least a second value of the voltage of the electrical signal, increments a point value of a control parameter (i.e. new value = old value +1) and it compares the point value of the control parameter with a pre-established threshold value which, preferably, is recorded in the data storage medium 102.Next, the system 100 according to the invention establishes that the electronic signal is unstable when the value of the control parameter is greater than the threshold value and, in this case, it transmits data characterizing the detection of an unstable electrical signal via the communication network to the electronic control unit. Conversely, when the system 100 according to the invention determines that the electrical signal is stable, it performs, during the sixth step 206 described above, an additional step in which it resets the point value of the control parameter (i.e., value of the control parameter = 0).

[0034] Therefore, according to the method and system of the invention described above, a solution is provided to enable the safe implementation by a driver assistance system of a motor vehicle of autonomous driving functionalities that rely on electrical signals generated by a driver presence monitoring device comprising a push button arranged in the vehicle's passenger compartment. Furthermore, the method and system of the invention described above provide a solution for filtering an electrical signal generated by a driver presence monitoring device of a motor vehicle comprising a push button arranged in the vehicle's passenger compartment so as to maximize the decision-making speed of the driver assistance system when implementing certain autonomous driving functionalities.

Claims

Claims

1. Method of filtering, by a computer system (100) on board a motor vehicle, an analog electrical signal generated by a device for monitoring the presence of a driver comprising a push button arranged in the passenger compartment of the vehicle, characterized in that the method comprises the steps of: • determine a first point value of the voltage of the electrical signal; • determine data characterizing a first state to which corresponds the first point value of the voltage of the electrical signal; • determine a duration of a sampling interval and a number of samples to be considered based on the data characterizing a first state to which corresponds the first point value of the voltage of the electrical signal; • determine whether the electrical signal is stable as a function of the duration of a sampling interval and the number of samples to be considered; and, when it is established that this is the case, • determine data characterizing a stable state; and • transmit data characterizing a stable state via a vehicle communications network to a vehicle electronic control unit.

2. A method according to claim 1, characterized in that the step of determining whether the electrical signal is stable comprises the steps of: • determine at least a second point value of the voltage of the electrical signal as a function of the duration of a sampling interval and the number of samples to be considered; • determine data characterizing a second state to which corresponds the second point value of the voltage of the electrical signal; and • compare the data characterizing a first state to which corresponds to the first point value of the voltage of the electrical signal and the data characterizing a second state to which corresponds the second point value of the voltage of the electrical signal.

3. A method according to claim 2, characterized in that the step of determining whether the electrical signal is stable comprises a step of determining whether a point value of a control parameter is less than a pre-established threshold value.

4. Method according to claim 3, characterized in that the step of determining at least a second point value of the voltage of the electrical signal comprises a step of incrementing the point value of the control parameter.

5. Method according to one of claims 3-4, characterized in that the step of determining whether the electrical signal is stable comprises the steps of: • establishing that the electrical signal is unstable if the value of the control parameter is greater than or equal to the threshold value; and • transmitting data characterizing a detection of an unstable electrical signal via the communication network to the electronic control unit.

6. Method according to one of claims 3-5, characterized in that the step of transmitting data characterizing a stable state comprises a step of resetting the value of the control parameter.

7. Method according to one of claims 3-5, characterized in that the data characterizing a first state to which the first point value of the voltage of the electrical signal corresponds, the data characterizing a second state to which the second point value of the voltage of the electrical signal corresponds and the data characterizing a stable state identify a first case in which the push button is pressed, a second case in which the push button is released, a third case in which a short circuit is present, a fourth case in which an uncertainty exists or a fifth case in which an open circuit is present.

8. System (100) for filtering an analog electrical signal generated by a device for monitoring the presence of a driver of a motor vehicle comprising a push button arranged in the passenger compartment of the vehicle, characterized in that the system comprises at least one information processing unit (101), comprising at least one processor, and a data storage medium (102) configured to implement a method according to any one of the preceding claims.

9. A computer program comprising program code instructions for performing the steps of a method according to any one of claims 1-7 when said program is executed on a computer.

10. Motor vehicle, characterized in that it comprises a system according to claim 8.

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