Method for determining the mass of a person in a vehicle seat

Abstract

The invention relates to a method for determining the mass of a person or object positioned on a vehicle seat, the method comprising: - a transmission (28) of a first command to move the seat, - a first determination (30) of the current consumed during the movement, - a transmission (36) of a second command to move the seat, the person or object being positioned on the seat, - a second determination (38) of the current consumed, - a calculation of a ratio (42) between a first data point representing the current values ​​determined during the first determination, and a second data point representing the current values ​​determined during the second determination, - a determination (44) of the mass of the occupant or object from the calculated ratio and a mapping. Figure to be published with the abstract: Figure 3

Description

Title of the invention: Method for determining the mass of a person in a vehicle seat. Technical field of the invention

[0001] The invention relates to the technical field of vehicles. In particular, the invention can be used for pre-setting the comfort equipment of a vehicle according to the morphology of the vehicle occupant. The invention can also be used for managing safety airbags. Prior art

[0002] To pre-set certain comfort or safety features in a vehicle, resistive or capacitive sensors are mounted on the vehicle seat. These sensors determine the morphology of the seat occupant. However, these sensors can be expensive. Presentation of the invention

[0003] An object of the invention is to propose a method for determining the mass of a person sitting on the seat which is less expensive than the use of a pressure sensor. Summary of the invention

[0004] The present invention relates to a method for determining the mass of a person or object positioned on a vehicle seat, the seat comprising at least one actuator configured to move the seat in at least one direction among a vertical direction and a longitudinal direction, the method comprising: - a transmission of a command to move the seat according to a first movement to said at least one actuator, - a first determination of the current values ​​consumed by said at least one actuator during the first movement of the seat, - a transmission of a command to move the seat according to a second movement to said at least one actuator, the person or object being positioned on the seat during the second movement, - a second determination of the current values ​​consumed during the second movement of the seat.- a calculation of a ratio between a first data point representing the current values ​​determined during the first movement, and a second data point representing the current values ​​determined during the second movement, - a determination of the mass of the occupant or object based on the calculated ratio and a predefined map.

[0005] The features described in the following paragraphs may optionally be implemented. They may be implemented independently of each other or in combination with each other: - During the first movement, the seat is not occupied by a person or an object. - During the first movement, the seat is occupied by a person or an object. - The first movement is made in one direction and the second movement is made in the opposite direction to the direction followed during the first movement. - The first movement and the second movement are implemented in the same direction. - The first and second movements are directed along at least one vertical direction. - During at least one movement among the first and second movements, the seat is moved by a stroke of between 2 millimeters and 2 centimeters, said stroke being measured along a single direction among the vertical direction and the longitudinal direction. The process involves determining the duration of the first displacement, in which the first data point is obtained by integrating the intensity values ​​determined during the first displacement over the duration of the first displacement. - The process includes a determination of the duration of the second displacement and in which the second data is obtained by integrating the intensity values ​​determined during the second displacement over the duration of the second displacement. - The process includes a preliminary step of establishing the map from experimental measurements carried out on the seat. The method includes the detection of the opening of a vehicle door, and in which the transmission of a command for a first movement of the seat is triggered by the detection of this opening of a door. - The process includes the detection of a change of person seated on the seat, and in which the transmission of a command for a first movement of the seat is triggered by the detection of this change of person. Brief description of the figures

[0006] [Fig.1] is a schematic representation of a determination system and a seat used to implement the method according to the invention;

[0007] [Fig.2] is an example of mapping;

[0008] [Fig.3] is a diagram representing the steps of the determination process according to a first embodiment of the invention;

[0009] [Fig.4] is a diagram representing the steps of the determination process according to a second embodiment of the invention. Detailed description of the invention

[0010] In the following description, the indications of positioning in space such as top, bottom, upper, lower, horizontal, vertical etc. are to be interpreted according to the usual position of use of the seat.

[0011] The seat is defined with respect to an orthogonal coordinate system illustrated in [Fig. 1]. The longitudinal direction X is understood to be a horizontal direction extending from the front to the rear of the vehicle seat. The transverse direction Y is understood to be a horizontal direction extending from one side of the vehicle seat to the other side of the seat. The vertical direction Z is understood to be the direction perpendicular to the longitudinal direction X and the transverse direction Y.

[0012] The method for determining the mass of a person or object positioned on a vehicle seat can be implemented by a seat 2 and a determination system 4 such as those illustrated in [Fig.1].

[0013] The seat 2 is a vehicle seat, in particular a motor vehicle seat. The seat 2 comprises a seat 6 and a backrest 8 hinged to the seat. The seat is mounted on two slides, not shown here, extending along a longitudinal direction X.

[0014] The seat 2 includes at least actuator 10 represented schematically in [Fig.1].

[0015] According to a preferred embodiment, the actuator 10 is configured to raise or lower the seat. The actuator is coupled to a gearbox (not shown). The raising or lowering movement of the seat is performed along a vertical direction Z. It is generally, but not necessarily, accompanied by a movement along the longitudinal direction X.

[0016] The seat may also include an additional actuator 9 configured to move the seat 2 along the longitudinal direction X. When this additional actuator is used, the determination of the mass may be slightly distorted when the vehicle is located on a slope. The additional actuator 9 is shown in dashed lines in [Fig. 1].

[0017] The actuator 10 is controlled by an electronic board 11 designed to provide, at a defined frequency, the current intensity consumed by the actuator. The electronic board also provides the duration of each movement and optionally the voltage between ground and the output voltage of the actuator. Alternatively, the output voltage of the actuator is neglected for establishing the ratio as described below because it varies little. Alternatively, if the actuator is not controlled by an electronic board, the actuator includes a device for measuring the duration of each movement, the current drawn by the actuator at a defined frequency, and optionally a device for measuring the voltage between ground and the actuator output. The additional actuator 9 also includes an electronic board 11.

[0018] The determination system 4 includes a processor 12, for example a controller, a microcontroller, a programmable device, or a specific integrated circuit (ASIC). The processor 12 is connected to the electronic board 11 of the actuator 10 and to the electronic board 11 of the additional actuator 9 when present. The processor 12 includes a memory 14 that stores a pre-established map 16 and executable code 18 for implementing the determination method described below from values ​​of the current consumed by the actuator and optionally at least a voltage value at the actuator output.

[0019] Memory 14 includes random access memory, denoted RAM and read-only memory, denoted ROM.

[0020] An example of mapping 16 has been illustrated in [Fig.2]. Mapping 16 makes it possible to determine the mass of a person sitting on the seat or of an object placed on the seat according to pre-established ratios.

[0021] The object may be a child seat or any other object such as a cardboard box, bags etc.

[0022] The ratio is, for example, the ratio between the energy consumed by the actuator during a first movement of the seat, and the energy consumed by the actuator during a second movement of the seat. The detection system 4 includes a detection unit 22 for the presence of a person or object. This detection unit 22 may be a camera fixed substantially directly above the seat, for example behind the rearview mirror or on the side pillar of the vehicle, an infrared sensor, a resistive or capacitive presence sensor arranged on the seat, or any other type of sensor or device enabling the detection of greater resistance when the seat movement is triggered.

[0023] With reference to [Fig. 3], the method for determining the mass of a person or object according to a first embodiment begins with a preliminary step 24 of establishing the mapping from experimental measurements. This preliminary step is generally carried out by the seat manufacturer for each type of seat.

[0024] Seats of the same type are constructed with the same technical elements such as the same frame, the same foam or the same interlocking material, the same upholstery, the same actuator, the same reducer, the same slides and the same transmission chain of motion. When one of these elements is different, a new mapping must be established.

[0025] During this preliminary step 24, the actuator 10 commands an initial movement of the seat. This initial movement is performed over a defined first stroke. During this initial movement, the seat is not occupied by any persons or objects. Current intensity values ​​consumed by the actuator are determined at a defined frequency during this initial seat movement. The duration of the movement and, optionally, the output voltage of the actuator are also determined. This data is provided to the processor 12, for example, by the electronic board 11.

[0026] The energy consumed by the actuator during the first movement is calculated by integrating the intensities determined over the duration of the first movement.

[0027] The actuator then controls several second movements of the seat. These second movements are implemented over a defined second stroke. During each second movement, the seat is occupied by a person or object with a different and known mass. Thus, for example, second movements of the seat are performed with people (including children) having masses between 20 kilograms and 200 kilograms. Preferably, people with mass differences of approximately 5 kilograms occupy the seat during each second movement.

[0028] Current intensity values ​​consumed by the actuator are determined at the defined frequency during each second seat movement. The second seat movements are all implemented over the same defined second stroke (length and / or height).

[0029] The duration of the movement and, if applicable, the output voltage of the actuator are also determined. This data is provided to the processor 12, for example, by the electronic board 11.

[0030] For each second movement performed with a person or object of a different mass, the energy consumed by the actuator during each second movement is determined by integrating the current values ​​over the duration of each second movement. This yields a number N of energy consumed by the actuator for the N second movements performed with N people, each having a different mass.

[0031] Then, a ratio R between the energy consumed by the actuator during the first movement and the energy consumed by the actuator during a second movement is calculated for the N second movements. This yields N ratios R having the same numerator and different denominators.

[0032] The mapping 16 is established so as to represent the masses of the N occupants of the seat as a function of the N calculated ratios R. Second movements of the seat are also performed when the seat carries objects of different masses. Specifically, second movements are performed with different types of child seats, such as infant seats, child seats for children weighing less than 18 kilograms or more than 18 kilograms, and seats of different brands and masses. For each second movement performed with an object of a different mass, the energy consumed by the actuator during the second movement is determined. The ratios R between the energy consumed by the actuator during the first movement and the energy consumed by the actuator during a second movement are calculated for all second movements with different objects. According to this embodiment, the same map 16 represents the masses of occupants and objects as a function of the ratio. Alternatively, a first map is established for people, and a second map, different from the first, is established to represent the variation in the mass of the object placed on the seat as a function of the variation in the calculated ratio values. In this case, a camera determines whether an object or a person is placed on the seat. Alternatively, the energy consumed during each movement is calculated from the current values ​​determined during the movements, the duration of each movement, and the output voltage of the actuator. According to this alternative, one or more voltages between ground and the actuator output were determined during each movement, under the same conditions.

[0033] Preferably, the first and second movements are performed by the lifting actuator 10, which raises or lowers the seat. This raising or lowering movement is generally accompanied by a movement of the seat along the longitudinal direction X.

[0034] Alternatively, the first and second displacement of the seat is a displacement only along the longitudinal direction X.

[0035] During the first and / or second movement, the seat is moved by a stroke - that is to say by a height or a length in the longitudinal direction - of between 2 millimeters and 2 centimeters.

[0036] This stroke is measured along a single direction, either the vertical or the longitudinal direction. Thus, when the first actuator 10 moves the seat along a longitudinal and a vertical direction, the stroke length will only be considered in the vertical direction.

[0037] The stroke of the first displacement and the stroke of the second displacement can be of the same length or of different lengths. The first movement is made in one direction and the second movement is made in the opposite direction to the direction followed during the first movement.

[0038] Alternatively, the first and second displacements are carried out in the same direction.

[0039] When the mapping 16 has been established, it is stored in the memory 14 of the processor 12.

[0040] The following steps are performed by the seat user.

[0041] During a step 26, a command to determine the mass of a person or an object is received by the processor 12. This command can be triggered by a user.

[0042] Alternatively, this command can be triggered by the detection of the opening of a vehicle door.

[0043] Alternatively, this command can be triggered by the detection of a change of person sitting on the seat, for example using a camera.

[0044] Upon receiving this command, the processor 12 transmits a movement command to the actuator during a step 28.

[0045] During step 29, the seat is moved according to a first displacement. This first displacement is carried out while the seat is empty. In other words, the seat is not occupied by a person or an object.

[0046] The first movement of the seat is carried out with the same actuator, in the same direction and over the same stroke as the stroke of the first movement carried out during the establishment of the mapping 16.

[0047] During this first movement, in step 30, current intensity values ​​consumed by the actuator are determined at a defined frequency throughout the duration of the movement. The duration of the first movement is also determined. This data is provided to the processor 12, for example, by the electronic board 11. The voltage between ground and the output of the actuator can optionally be determined. During a step 32, the energy consumed by the actuator during the first movement is calculated by the processor 12 for example by integrating the intensity values ​​over the duration of the first movement.

[0048] During a step 34, the detection unit 22 detects the presence of a person sitting on the seat or an object placed on the seat and transmits a detection signal to the processor 12.

[0049] Upon receiving the detection signal, the processor 12 transmits a movement command to the actuator, during a step 36, in order to move the seat 2 according to a second movement. This second movement is carried out while the seat is occupied by a person sitting on the seat or while an object is placed on the seat.

[0050] The second movement is carried out with the same actuator, in the same direction and over the same stroke as the stroke of the second movement carried out during the establishment of the mapping 16.

[0051] During this second movement, in step 38, current intensity values ​​consumed by the actuator are determined at a predefined frequency and throughout the duration of the first movement. The duration of this second movement is given by the voltage between ground and the actuator output. These current intensity values, the duration of the movement, and optionally the output voltage of the actuator are transmitted to the processor 12.

[0052] During a step 40, the energy consumed by the actuator during the second movement is calculated by the processor 12 from the intensity values, the duration of the second movement and possibly the output voltage of the actuator.

[0053] During a step 42, the processor 12 calculates a ratio R between the energy calculated during step 32 and the energy calculated during step 40.

[0054] During a step 44, the mass of the occupant is determined by searching in the mapping for a ratio having a value identical or close to the value of the ratio R calculated during step 42 and determining the corresponding mass.

[0055] During a step 46, the mass value is transmitted to the airbag management device and / or to the vehicle's on-board computer (generally called "ECU" for "Electronic Control Unit" or "PCM" for "Powertrain Control Module").

[0056] In the example described above, the first and second movements are performed by the same actuator. Alternatively, the first movement could be performed by a first actuator 10, for example, an actuator configured to raise the seat, and the second movement could be performed by a second actuator, for example, an actuator configured to move the seat along the longitudinal direction. The second actuator is not shown in [Fig. 1]. The only constraint is that the mass determination be carried out under the same conditions during the mapping and during the actual determination of the mass of the occupant or object. The same conditions mean that the movements must be performed by the same actuator(s) and the movements must be carried out in the same directions.

[0057] The method for determining the mass of a person or object according to a second embodiment has been illustrated in [Fig. 4]. In this embodiment Steps identical or similar to the steps of the first embodiment are referenced by the same references and will not be described again in detail.

[0058] The preliminary step 242 of establishing the mapping 16 is similar to step 24 of the process according to the first embodiment except that: - the first movement is carried out under the same conditions as the second movement, namely that during this preliminary step a person or an object is sitting on the seat; - the second movement is implemented with a direction opposite to the first movement.

[0059] During a step 26, a command to determine the mass of a person or an object is received by the processor 12. This command can be triggered by a user.

[0060] In this embodiment, this command can be triggered by the detection of the fact that a person has sat on the seat, for example using the detection unit.

[0061] During a step 27, the detection unit 22 detects the presence of a person sitting on the seat or an object placed on the seat and transmits a detection signal to the processor 12. After receiving the mass determination command and the detection signal, the processor 12 transmits a displacement command to the actuator during a step 28.

[0062] In step 29, the seat is moved according to a first displacement. This first displacement is carried out while the seat is occupied by a person or an object. The other features of step 29 are identical to step 29 according to the process of the first embodiment.

[0063] Steps 30 and 32 are identical to the determination process according to the first embodiment.

[0064] During step 34, the detection unit 22 checks whether a person is still sitting on the seat or whether an object is still placed on the seat and transmits a detection signal to the processor 12.

[0065] Steps 36 to 46 are identical to the determination process according to the first embodiment.

[0066] In this case, the numerator of the ratio R is equal to the energy calculated during the first movement with an occupant or an object on the seat, and the denominator is equal to the energy calculated during the second movement with an occupant or an object on the seat.

Claims

Demands

1. A method for determining the mass of a person or object positioned on a vehicle seat (2), the seat (2) comprising at least one actuator (10) configured to move the seat in at least one direction among a vertical direction (Z) and a longitudinal direction (X), the method comprising: - a transmission (28) of a command to move the seat in a first movement to said at least one actuator (10), - a first determination (30) of the values ​​of the current consumed by said at least one actuator (10) during the first movement of the seat, - a transmission (36) of a command to move the seat in a second movement to said at least one actuator (10), the person or object being positioned on the seat during the second movement, - a second determination (38) of the values ​​of the current consumed during the second movement of the seat,- a calculation of a ratio (42) between a first data point representing the current values ​​determined during the first displacement, and a second data point representing the current values ​​determined during the second displacement, - a determination (44) of the mass of the occupant or object from the calculated ratio and a predefined map (16).

2. A method according to claim 1, wherein during the first movement, the seat (2) is not occupied by a person or an object.

3. Method according to claim 1, wherein during the first movement, the seat (2) is occupied by a person or an object.

4. A method according to any one of claims 1 to 3, wherein the first displacement is carried out in one direction and the second displacement is carried out in a direction opposite to the direction followed during the first displacement.

5. A method according to any one of claims 1 and 2, wherein the first displacement and the second displacement are carried out in the same direction.

6. A method according to any one of claims 1 to 5, wherein the first and second displacements are directed along at least one vertical direction (Z).

7. A method according to any one of claims 1 to 6, wherein during at least one displacement among the first displacement and the second displacement, the seat (2) is displaced by a stroke of between 2 millimeters and 2 centimeters, said stroke being measured in a single direction among the vertical direction and the longitudinal direction.

8. A method according to any one of claims 1 to 7, comprising a determination of the duration of the first displacement and wherein the first data is obtained by integrating the intensity values ​​determined during the first displacement over the duration of the first displacement.

9. A method according to any one of claims 1 to 8, comprising a determination of the duration of the second displacement and wherein the second data is obtained by integrating the intensity values ​​determined during the second displacement over the duration of the second displacement.

10. A method according to any one of claims 1 to 9, comprising a preliminary step (24, 241, 242) of establishing the map (16) from experimental measurements carried out on the seat (2).

11. A method according to any one of claims 1 to 10, comprising a detection of the opening of a vehicle door, and in which the transmission (28) of a command for a first movement of the seat is triggered by the detection of this opening of a door.

12. A method according to any one of claims 1 to 11, comprising a detection of a change of person seated on the seat, and wherein the transmission (28) of a command for a first movement of the seat is triggered by the detection of this change of person.

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