Method for detecting a leaning-forward position of a vehicle seat occupant and associated computer program
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- FAURECIA SIEGES D AUTOMOBILE SA
- Filing Date
- 2026-01-26
- Publication Date
- 2026-08-06
Smart Images
Figure FR2026050075_06082026_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] TITLE: Method for detecting a forward-leaning position of a vehicle seat occupant and associated computer program
[0003] Technical field of the invention
[0004] This disclosure relates to a method for detecting a forward-leaning position of a vehicle seat occupant and associated computer program.
[0005] Prior art
[0006] Many people spend an average of one to two hours a day behind the wheel. Numerous drivers complain of back and neck pain. All of this pain stems from poor driving posture, combined with stress, nervous tension, and sometimes spending excessively long periods behind the wheel. We drive instinctively, almost automatically, without considering the position of our back.
[0007] It would be useful to offer drivers software that would warn them when they adopt an unsuitable driving position.
[0008] Furthermore, studies show that when a seat occupant is in an unsuitable position, the inflation of an airbag can injure the seat occupant.
[0009] It would therefore be advisable to adjust the inflation volume and pressure in the airbag according to the seat occupant's position. In particular, when the seat occupant is leaning forward,
[0010] Presentation of the invention
[0011] A primary purpose of this disclosure is to enable the recognition of a forward-leaning position of a seat occupant without the use of a camera.
[0012] Advantageously, the forward-leaning position is detected even if the seat occupant is sitting in an incorrect initial position, for example if they are sitting sideways or at an angle on the seat.
[0013] A second purpose of this disclosure is to allow the determination, in certain cases—namely, when the occupant has an appropriate initial position—of which part of the occupant's body is leaning forward. Summary of the invention
[0014] The present invention relates to a method for detecting a forward-leaning position of an occupant of a vehicle seat; the seat comprising a seat cushion and a backrest supported by the seat cushion; the seat cushion comprising a central part and two lateral support edges, the seat cushion having a receiving surface; the receiving surface of the central part comprising a front zone, a rear zone, a middle zone; the receiving surface of the lateral support edges comprising a lateral zone; the backrest comprising a support surface; the support surface comprising an upper zone, a lower zone and an intermediate zone;the method being implemented by a detection system comprising at least one capacitive sensor with interdigitated electrodes located on the front zone, at least one capacitive sensor with interdigitated electrodes located on the middle zone, at least one capacitive sensor with interdigitated electrodes located on the rear zone and at least two capacitive sensors with interdigitated electrodes located on the lateral zone of the seat; the detection system comprising at least one capacitive sensor with interdigitated electrodes located on the upper zone, at least one capacitive sensor with interdigitated electrodes located on the lower zone and at least one capacitive sensor with interdigitated electrodes located on the intermediate zone of the backrest; the method comprising an initial phase, the initial phase comprising:;
[0015] a) a measurement of initial capacitance values by capacitive sensors located on the seat areas and on the backrest areas,
[0016] b) a characterization of the seat occupant's position between an appropriate position and an inappropriate position from the initial capacitance values, c) if the seat occupant is characterized as being in an appropriate position, a storage of the initial capacitance values measured on the backrest areas, the stored initial capacitance values being associated with the identifications of the areas on which the capacitance values were measured;
[0017] the process comprising a subsequent phase following the initial phase, the subsequent phase comprising:
[0018] d) a measurement of the following capacitance values by capacitive sensors located on the areas of the backrest,
[0019] e) detection of a forward leaning position of the seat occupant; if the seat occupant was characterized as being in an appropriate position during the initial phase, the detection of a forward leaning position is implemented from the following capacitance values and the capacitance values stored during the initial phase; if the seat occupant was characterized as being in an inappropriate position during the initial phase, the detection of the forward leaning position is implemented from the following capacitance values and typical values defined according to the morphological type of the seat occupant.
[0020] The features described in the following paragraphs may optionally be implemented. They may be implemented independently or in combination: - The characterization of the seat occupant's position includes:
[0021] - a comparison of the initial capacitance values measured on the front zone, the middle zone, the rear zone, and the lateral zone of the seat at respective seat characterization thresholds,
[0022] - a comparison of the initial capacitance values measured in the upper, middle, and lower zones of the file at respective file characterization thresholds,
[0023] - A characterization of the seat occupant's position as being in an appropriate position when the initial capacitance values measured in at least three zones of the seat are greater than the respective backrest characterization thresholds. - When the seat occupant has been characterized as being in an appropriate position, the detection of a forward-leaning position includes:
[0024] f) a consideration of an area of the file,
[0025] (g) a calculation of a ratio between the next capacitance value measured in the area of the file under consideration and the initial capacitance value stored and associated with the area of the file under consideration,
[0026] (h) a comparison of the calculated ratio to a support threshold, the support threshold being defined for the area of the file considered,
[0027] i) when the calculated ratio is less than the support threshold defined for the area of the file considered, a counter is incremented by one unit,
[0028] j) consideration of another area of the file and repetition of steps b) to e) until all areas of the file have been considered,
[0029] k) a transmission of a signal detecting a forward leaning position when the counter value is equal to at least one unit, otherwise a repetition of steps d) and f) to k).
[0030] - The support threshold(s) defined for the areas of the file is or are between 0.3 and 0.5.
[0031] - When the area of the file considered is the upper area and the ratio calculated for the upper area is less than the support threshold corresponding to the upper area, the signal for detecting a forward leaning position is representative of a position in which at least one shoulder of the occupant is leaning forward.
[0032] When the area of the file considered is the lower area and the ratio calculated for the lower area is less than the support threshold corresponding to the lower area, the detection signal of a forward leaning position is representative of a position in which the occupant's pelvis is leaning forward.
[0033] - When the seat occupant has been characterized as being in an inappropriate position, the detection (74) of a forward-leaning position includes:
[0034] - a determination of the morphological type of the seat occupant,
[0035] - a selection of a typical value from among typical values defined according to the determined morphological type,
[0036] - a calculation of the sum of the following capacitance values measured on the upper, middle, and lower zones of the backrest,
[0037] - a calculation of the ratio between the calculated sum and the selected standard value, - a comparison between the calculated ratio and a defined threshold,
[0038] - transmission of a signal detecting a forward leaning position, when the ratio is greater than the defined threshold.
[0039] - The defined threshold is between 0.05 and 0.15.
[0040] - The method includes detecting the presence of an occupant in the seat. - The detection system further includes a display screen and / or a loudspeaker, and further includes displaying or transmitting a message informing the seat occupant of their forward-leaning position.
[0041] The disclosure also relates to a computer program, loadable into memory associated with a processor, and comprising portions of code for implementing a process according to the characteristics mentioned above, during the execution of said program by the processor. Brief description of the figures
[0042] [Fig. 1 A] is a schematic side view of a seat and an occupant sitting on the seat in an inappropriate position;
[0043] [Fig. 1 B] is a schematic side view of a seat and an occupant sitting on the seat in another inappropriate position;
[0044] [Fig. 1 C] is a schematic side view of a seat and an occupant sitting on the seat in a suitable position;
[0045] [Fig. 2] is a schematic top view of a seat equipped with a detection system enabling the detection process to be implemented according to this disclosure;
[0046] [Fig. 3] is a flowchart representing the steps of the detection process according to this disclosure;
[0047] [Fig. 4] is a flowchart representing the steps for characterizing the occupant's position on the seat of the detection process according to this disclosure; and
[0048] [Fig. 5] is a flowchart representing the steps for detecting a forward leaning position in the detection process according to this disclosure in the case where the occupant was in a proper position during the initial phase.
[0049] Detailed description of the invention
[0050] In the description that follows, when referring to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures or the seat in its normal position of use.
[0051] In the following, the longitudinal direction X refers to the longitudinal direction of the seat. The longitudinal direction of the seat is considered to be the same as the longitudinal direction of the motor vehicle in which the seat is mounted. This longitudinal direction corresponds to the normal direction of travel of the vehicle. The longitudinal direction X is preferably horizontal. The transverse direction Y is the transverse direction of the seat. The transverse direction Y of the seat thus corresponds to the transverse or lateral direction of the motor vehicle. This transverse direction Y is perpendicular to the normal direction of travel of the vehicle. The transverse direction Y is preferably horizontal. Finally, the vertical direction Z is a vertical direction of the seat, perpendicular to the longitudinal direction X and the transverse direction Y.
[0052] Figure 2 shows a vehicle seat 2 comprising a seat cushion 4 and a backrest 6 supported by the seat cushion 4. The seat is equipped with a detection system 8 for implementing the detection method as described in this disclosure. The vehicle is, for example, a motor vehicle.
[0053] The seat 6 comprises a central portion 10 and two projecting lateral support edges 12, 13. These lateral support edges 12, 13 are commonly referred to as "bolsters." They are integral with and contiguous to the central portion. They extend along the lateral sides of the central portion of the seat. The seat 6 includes a receiving surface 14 designed to accommodate the seat occupant. For descriptive purposes, the receiving surface 14 of the seat is said to be divided (or distributed) into four zones. The receiving surface 14 of the central portion of the seat is divided into three zones by two lines extending along the transverse direction Y. These three zones have approximately the same dimensions along the longitudinal direction X. A zone located on the side opposite the backrest is called the "front zone 16." A zone adjacent to the backrest is called the "rear zone 18."The area between the front and rear areas is called the "median zone 20".
[0054] The receiving surface 14 of the two lateral support edges includes a lateral area 21. In other words, the lateral area 21 includes both a part of the upper face of the inner side of one lateral support edge 12 and a part of the upper face of the inner side of the other lateral support edge 13.
[0055] The seat back 4 includes a support surface 22 designed to accommodate the back of the seat occupant. For descriptive purposes, the support surface 22 of the seat back is said to be divided (or distributed) into three zones by two lines extending along the transverse direction Y. These three zones have substantially the same dimensions along the vertical direction Z. The support surface 22 comprises an upper zone 24, a lower zone 26, and an intermediate zone 28 located between the upper and lower zones. The sensing system 8 comprises coplanar interdigitated electrode capacitive sensors 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 and a control device 42 electrically connected to the interdigitated electrode capacitive sensors by electrical links.
[0056] The detection system 8 may also include a display screen 44 and / or a speaker 45 connected to the control device.
[0057] For simplicity, capacitive sensors with interdigitated electrodes are referred to hereafter as capacitive sensors. These capacitive sensors comprise two comb-shaped electrodes that interpenetrate each other. One electrode is connected to a voltage source. The second electrode is connected to ground. The control device can provide the voltage source and / or ground. An example of a capacitive sensor is described in detail in French patent FR 2 109436, granted to the applicant.
[0058] In particular, the detection system 8 includes at least one capacitive sensor 30, 31 located on the front area 16 of the seat, at least one capacitive sensor 32, 33 located on the middle area 20 of the seat, at least one capacitive sensor 34, 35 located on the rear area 18 of the seat, at least one capacitive sensor 36 located on the part of the lateral area 21 located on the left lateral edge 12 of the seat and at least one capacitive sensor 37 located on the part of the lateral area 21 located on the right lateral edge 13 of the seat.
[0059] The detection system 8 further includes at least one capacitive sensor 40, 41 located on the upper area 24 of the backrest, at least one capacitive sensor 38 located on the lower area 26 of the backrest and at least one capacitive sensor 39 located on the intermediate area 28 of the backrest.
[0060] In one embodiment, two capacitive sensors in the same area are electrically connected so that a single capacitance value from both sensors is provided to the control device. This capacitance value represents the pressure across the entire area. Alternatively, two capacitive sensors in the same area are not electrically connected. In this case, the capacitance values of each sensor are added together to obtain a capacitance value representative of the area.
[0061] In the embodiment illustrated in Figure 2 by way of example only, the detection device comprises two capacitive sensors 30, 31 located on the front area 16 of the seat, two capacitive sensors 32, 33 located on the middle area 20 of the seat, two capacitive sensors 34, 35 located on the rear area 18 of the seat and a single capacitive sensor on the lateral area 21 of the left lateral edge 12 of the seat and a single capacitive sensor 37 located on the lateral area 21 of the right lateral edge 13 of the seat.
[0062] Similarly, in the embodiment illustrated in Figure 2 by way of example only, the detection system 8 comprises two capacitive sensors 40, 41 located on the upper area 24 of the backrest, a single capacitive sensor 38 located on the lower area 26 of the backrest and a single capacitive sensor 39 located on the intermediate area 28 of the backrest.
[0063] The control device 42 includes a central processing unit such as, for example, a processor or a microcontroller. The control device may be a programmable device that uses software, a specific integrated circuit (ASIC), or part of an engine control unit (ECU).
[0064] The control device includes a read-only memory (ROM) to store executable code for the detection process and a random-access memory (RAM) to store variables and parameters necessary for implementing the detection process. In particular, the read-only memory includes:
[0065] - A first standard value L1, a second standard value L2, and a third standard value L3 are defined for morphological types within the population. For example, a first standard value L1 could be defined for individuals with a height below the 5th percentile of the European population's height and / or a weight below the 5th percentile of the European population's weight. For example, a second standard value L2 could be defined for individuals with a height below the 50th percentile of the population's height and / or a weight below the 50th percentile of the population's weight. For example, a third standard value L3 could be defined for individuals with a height above the 95th percentile of the population's height and / or a weight greater than or equal to the 95th percentile of the population's weight.
[0066] - a first base characterization threshold S1, a second base characterization threshold S2, a third base characterization threshold S3, a fourth base characterization threshold S4,
[0067] - a first case characterization threshold SD1, a second case characterization threshold SD2 and a third case characterization threshold SD3,
[0068] - a first support threshold SA1, a second support threshold SA2 and a third support threshold SA3,
[0069] - a defined threshold S,
[0070] - an executable code and the values necessary to implement the method for determining the occupancy status of a seat described in the patent published under number FR 2012255.
[0071] The first type value L1, the second type value L2, and the third type value L3 are determined during a preliminary phase for each body type, each seat type, and each vehicle. This preliminary step is, for example, performed once at the factory by the seat manufacturer or the vehicle manufacturer. Then, the first type value L1, the second type value L2, and the third type value L3 are stored in memory.
[0072] The first seat characterization threshold S1, the second seat characterization threshold S2, the third seat characterization threshold S3, the fourth seat characterization threshold S4, the first backrest characterization threshold SD1, the second backrest characterization threshold SD2, and the third backrest characterization threshold SD3 are also determined and then stored in memory during the preliminary phase. This determination is performed once for each seat type and each vehicle. This preliminary step is carried out, for example, at the factory by the seat manufacturer or the vehicle manufacturer.
[0073] For example, the first seat characterization threshold S1 concerns the front area and is between 10,000 picofarads and 30,000 picofarads. For example, the second seat characterization threshold S2 concerns the middle area and is between 20,000 picofarads and 40,000 picofarads. For example, the third seat characterization threshold S3 concerns the rear area and is between 10,000 picofarads and 30,000 picofarads. For example, the fourth seat characterization threshold, S4, concerns the lateral zone and is between 5,000 picofarads and 15,000 picofarads. For example, the first backrest characterization threshold, SD1, concerns the upper zone and is between 10,000 picofarads and 30,000 picofarads. For example, the second backrest characterization threshold, SD2, concerns the lower zone and is between 10,000 picofarads and 30,000 picofarads.For example, the third SD3 case characterization threshold concerns the intermediate zone, and is between 20000 picofarads and 40000 picofarads.
[0074] The control device 42 further includes a measuring unit configured to measure capacitance values between the two electrodes of each capacitive sensor. The capacitance values are measured at a defined frequency throughout the detection process. The control device includes a first counter, a second counter, a third counter, or executable code implementing counter functions.
[0075] According to an unrepresented variant, the detection device 8 comprises two capacitive sensors 30, 31 located on the front area 16 of the seat, two capacitive sensors 32, 33 located on the middle area 20 of the seat, two capacitive sensors 34, 35 located on the rear area 18 of the seat and two capacitive sensors located on the part of the lateral area 21 located on the left lateral edge 12 of the seat and two capacitive sensors 37 located on the part of the lateral area 21 located on the right lateral edge 13 of the seat.
[0076] According to an unrepresented variant, the detection system 8 comprises two capacitive sensors 40, 41 located on the upper area 24 of the backrest, two capacitive sensors 38 located on the lower area 26 of the backrest and two capacitive sensors 39 located on the intermediate area 28 of the backrest.
[0077] Alternatively, detection system 8 includes seat 2.
[0078] The method for detecting a forward-leaning position of a vehicle seat occupant according to this disclosure can be implemented on a seat 2 by the detection system illustrated in Figure 2. In this patent application, a forward-leaning position can be a position in which the upper torso and shoulders of a seat occupant are leaning forward as illustrated in Figure 1B. Alternatively, a forward-leaning position can be a position in which the pelvis of a seat occupant is located towards the front of the seat, as illustrated in Figure 1A.
[0079] Referring to Figure 3, the detection process comprises an initial phase 46 and a subsequent phase 48. The initial phase is, for example, implemented each time a door of the motor vehicle is opened or unlocked. The subsequent phase 48 is then implemented, for example, for the entire duration that a person is seated in the seat. The initial phase of the detection process begins with a measurement step 50 of capacitance values by the capacitive sensors 30 to 41 located on the front 16, rear 18, middle 20, and side 21 areas of the seat, as well as on the upper 24, lower 26, and middle 28 areas of the backrest. Several capacitance values can be measured by each capacitive sensor at a defined frequency.In this case, these capacitance values are processed, for example by averaging, to define capacitance values representative of several capacitance values measured at different times by the same capacitive sensor. In all cases, for the sake of simplicity, a capacitance value representative of several capacitance values is referred to as a "capacitance value" in the following description. Furthermore, in this patent application, the capacitance values measured during the initial phase are referred to as initial capacitance values.
[0080] The detection method includes a step 52 for detecting the presence of an occupant on a seat based on capacitance values measured by at least some of the capacitive sensors during step 50. This detection step can, for example, be implemented by executable code that includes the steps of the method for determining the occupancy status of a seat described in patent published under number FR 2012255.
[0081] The detection method further includes a characterization step 54 of the seat occupant's position, distinguishing between a position considered appropriate and a position considered inappropriate, based on the initial capacitance values measured during step 50. At the beginning of characterization step 54, the control device 42 initializes a first counter and a second counter to a zero value. With reference to Figure 4, characterization step 54 includes a substep 56 of considering a zone of the seat, choosing from the front zone 16, the rear zone 18, the middle zone 20, and the side zone 21.
[0082] The characterization step 54 includes a sub-step 58 of comparison of the initial capacitance value measured on the area of the seat considered to a threshold, called the first seat characterization threshold S1. For example, if the area before 16 of the seat has been considered, the initial capacitance value measured in the area before 16 is compared to the first seat characterization threshold S1.
[0083] If the initial capacitance value measured on the area of the foundation under consideration is greater than the first foundation characterization threshold, the characterization step 54 includes a substep 59 for incrementing the first counter. The first counter is incremented by one unit.
[0084] If the initial capacitance value measured in the considered seat area is not above the first threshold, the value of the first counter remains unchanged. When an area has two capacitive sensors, the initial capacitance value measured in that area is, for example, the average of the capacitance values measured by the two sensors located in that area. Since the front area has two capacitive sensors, the initial capacitance value measured in the front area 16 is, for example, the average of the capacitance values measured by capacitive sensor 30 and capacitance values measured by capacitive sensor 31. The initial capacitance value of the side area 21 is, for example, obtained by calculating the average of the capacitance values measured by capacitive sensor 36 and capacitance values measured by capacitive sensor 37.
[0085] Characterization step 54 includes a substep 60 of repeating steps 56, 58, and 59 for another area of the seat until all areas of the seat have been considered. Thus, the initial capacitance value measured in the rear area 18 is compared to a second seat characterization threshold S2. The initial capacitance value measured in the middle area 20 is compared to a third seat characterization threshold S3. And, the initial capacitance value measured in the lateral area 21 is compared to a fourth seat characterization threshold S4. Characterization step 54 includes a substep 62 of comparing the value of the first counter to the third.
[0086] If the value of the first counter is less than three, the seat occupant's position is considered inappropriate. The detection process continues with step 73, described below.
[0087] If the value of the first counter is greater than or equal to the number three, the detection process continues with a sub-step of consideration 64 of an area of the file among the upper area 24, the lower area 26 and the intermediate area 28.
[0088] The characterization step 54 includes a substep 66 comparing the initial capacitance value measured on the area of the file under consideration to a threshold, called the first file characterization threshold SD1. For example, if the area under consideration is the upper area 24, the initial capacitance value is the average of the capacitance values measured by the capacitive sensor 40 and the capacitance values measured by the capacitive sensor 41. This initial capacitance value measured on the upper area is compared to the first file characterization threshold SD1.
[0089] If the initial capacitance value measured in the area of the file under consideration is greater than the first file characterization threshold SD1, the characterization step 54 includes a substep 67 for incrementing the second counter. The second counter is incremented by one unit. If the initial capacitance value measured in the area of the file under consideration is not greater than the first file characterization threshold SD1, the value of the second counter remains unchanged.
[0090] The characterization step 54 includes a sub-step 68 of repeating all steps 64, 66 and 67 for another area of the file until all areas of the file have been considered.
[0091] Thus, the initial capacitance value measured in the lower zone is compared to a second file characterization threshold SD2. The initial capacitance value measured in the middle zone is compared to a third file characterization threshold SD3. The first file characterization threshold SD1, the second file characterization threshold SD2, and the third file characterization threshold SD3 may be identical. Alternatively, the first file characterization threshold SD1, the second file characterization threshold SD2, and the third file characterization threshold SD3 may be different from each other.
[0092] The characterization step 54 includes a sub-step 69 of comparing the value of the second counter to the number three.
[0093] If the value of the second counter is less than three, the seat occupant's position is considered inappropriate. During step 73, the control device generates a signal indicating poor posture. This signal is stored in memory as evidence in case of an accident. A message is also transmitted to the occupant, for example, via the display screen 44 and / or the loudspeaker 45. This message informs the seat occupant of their poor posture and asks them to adjust to a correct position. After a delay, the process returns to step 56.
[0094] If the value of the second counter is three, the seat occupant's position is considered appropriate. An example of an appropriate position is shown in Figure 1A.
[0095] In this case, the detection process continues with a storage step 70 of the initial capacitance values measured during step 50 in each area of the folder. Each initial capacitance value is recorded in such a way as to be associated with an identification of the folder area in which that initial capacitance value was measured. Thus, in the embodiment illustrated in Figure 2 as an example, the initial capacitance value measured in the upper area 24 is recorded in memory in such a way as to be associated with an identification of the upper area 24. The initial capacitance value stored here is the average of the capacitance values measured by the capacitive sensor 40 and the capacitance values measured by the capacitive sensor 41.The initial capacitance value measured by the capacitive sensor 39 in the intermediate zone 28 is recorded in memory so as to be associated with an identification of the intermediate zone 28. The initial capacitance value measured by the capacitive sensor 38 in the lower zone 26 is recorded in memory so as to be associated with an identification of the lower zone 26.
[0096] Steps 50, 52, 54, 56, 58, 59, 60, 62, 64, 66, 67, 68, 69, and 70 are part of the initial phase. They are implemented at the beginning of the detection process. These steps are not repeated thereafter.
[0097] The detection process continues with the following phase 48. In particular, the detection process includes a measurement step 72 of capacitance values measured by the capacitive sensors 40, 41 located on the upper area 24 of the file, of capacitance values measured by the capacitive sensor 39 located on the middle area 28 of the file and of capacitance values measured by the capacitive sensor 38 located on the lower area 26 of the file.
[0098] As in the initial phase, several capacitance values can be measured by each capacitive sensor at a defined frequency. These capacitance values are processed, for example by averaging, to define representative capacitance values of several capacitance values measured at different times by the same capacitive sensor. For simplicity, a representative capacitance value of several capacitance values is referred to as a "capacitance value" in the following description. In this patent application, the capacitance values measured during the subsequent phase are referred to as subsequent capacitance values.
[0099] With reference to Figures 3 and 5, the detection process includes detecting a forward-leaning position of the seat occupant. This step begins with the initialization of a third counter. The value of the third counter is initialized to zero.
[0100] If during the comparison substep 69, the seat occupant was characterized as being in an appropriate position, the detection step 74 includes a consideration substep 76 of a backrest area among the upper area, the lower area and the intermediate area.
[0101] The detection step 74 includes a calculation substep 77 of a ratio between the next capacitance value measured in the area of the file under consideration and the initial capacitance value stored during the initial phase and associated with the area of the file under consideration. If the area of the file under consideration is the upper area 24, the next capacitance value measured in the upper area 24 is a representative value, for example an average, of the next capacitance value measured by the capacitive sensor 40 and the next capacitance value measured by the capacitive sensor 41. Similarly, the initial capacitance value stored during step 70 is a representative value, for example an average, of the initial capacitance value measured by the capacitive sensor 40 and the initial capacitance value measured by the capacitive sensor 41.
[0102] The detection step 74 includes a sub-step 78 of comparison of the ratio calculated in step 77 to a first support threshold SA1 for the area of the file under consideration.
[0103] When the calculated ratio is less than the first SA1 support threshold for the area of the file considered, the third counter is incremented by one unit.
[0104] The detection step 74 includes a substep 80 for considering another area of the file and repeating steps 77, 78, and 79 for that other area until all areas of the file have been considered. The ratio calculated for the intermediate area is then compared to a second support threshold, SA2. The ratio calculated for the lower area is then compared to a third support threshold, SA3.
[0105] The first support threshold SA1, the second support threshold SA2 and the third support threshold SA3 are, for example, between 0.3 and 0.5.
[0106] The first support threshold SA1, the second support threshold SA2, and the third support threshold SA3 may be different from each other. The first support threshold SA1, the second support threshold SA2, and the third support threshold SA3 may be identical. In this case, preferably, the first support threshold SA1, the second support threshold SA2, and the third support threshold SA3 may be equal to 0.4.
[0107] When the value of the third counter is equal to at least one unit, the detection method includes a substep 82 of transmitting a signal for detecting a forward leaning position.
[0108] When the value of the third counter is less than one unit, steps 72 and 74 are repeated in a loop. Step 74 is then implemented using the capacitance values measured during the preceding step 72.
[0109] According to a particular embodiment, when the area of the backrest considered during step 76 or 80 is the upper area 24 of the backrest and the ratio calculated for this area is less than the support threshold corresponding to this area, the detection signal for a forward leaning position is representative of a position known as "occupant's shoulder leaning forward". This position is illustrated in Figure 1B.
[0110] According to a particular embodiment, when the area of the file considered during step 76 or 80 is the lower area 26, the detection signal for a forward-leaning position is representative of a position known as "occupant's pelvis leaning forward". This position is illustrated in Figure 1C.
[0111] When, during step 54, the seat occupant is characterized as being in an inappropriate position, the detection of a forward-leaning position includes a substep 84 for determining the morphological type of the seat occupant. This determination can, for example, be implemented by executable code that incorporates the steps of the method for determining the occupancy status of a seat described in patent number FR 2012255. This determination is performed using capacitance values measured by the seat's capacitance sensors and capacitance values measured by the backrest's capacitive sensors.
[0112] The detection of a forward-leaning position includes a substep 85 for selecting a standard value from among the first standard value L1, the second standard value L2, and the third standard value L3. The standard value is selected based on the body type determined during step 84. Thus, if the seat occupant is a person whose height is below the 50th percentile of the population height and / or whose weight is below the 50th percentile of the population weight, the second standard value L2 is selected. The standard values L1, L2, and L3 are defined by the seat manufacturer during a preliminary phase. The standard values L1, L2, and L3 are stored in the memory of the control device.
[0113] The detection of a forward leaning position includes a calculation substep 86 of a sum of the following capacitance value measured by the capacitive sensors 40, 41 on the upper area 24 of the backrest, the following capacitance value measured by the capacitive sensor 39 of the middle area 28 of the backrest and the following capacitance value measured by the capacitive sensor 38 on the lower area 26 of the backrest.
[0114] The detection of a forward leaning position includes a substep 87 of calculating a ratio between the sum calculated in step 86 and the standard value defined L1, L2, L3. The detection of a forward leaning position includes a substep 88 of comparing the calculated ratio with a defined threshold S.
[0115] This defined threshold S is, for example, between 0.05 and 0.15. This defined threshold S is, for example, equal to 0.1.
[0116] The detection of a forward leaning position includes a substep of transmission 82 of a signal for detecting a forward leaning position, when the ratio is greater than the defined threshold S.
[0117] The disclosure also relates to a computer program, loadable into memory associated with a processor, and comprising portions of code for the implementation of a detection method described above, during the execution of said program by the processor.
[0118] This process allows monitoring of the person's position relative to the seat. Furthermore, the seat's position relative to the vehicle's body can be monitored using relative engine sensors and / or absolute sensors installed on the vehicle's frame.
[0119] Thus, by combining the process described above and monitoring the position of the seat relative to the vehicle's passenger compartment, the absolute position of the occupant in the passenger compartment can be known.
[0120] Advantageously, this process allows us to use seat position to better monitor the occupant's position in the car. This process allows us to use information from sensors already installed in the seat and motor sensors already used for seat adjustments to provide information to the Occupant Classification System (OCS). This information includes, for example, the occupant's distance from the B-pillar, the distance between the seat and / or occupant and the dashboard, or the distance between the seat and / or occupant and the airbag.
Claims
DEMANDS 1. Method for detecting a forward-leaning position of an occupant of a vehicle seat (2); the seat comprising a seat cushion (4) and a backrest (6) supported by the seat cushion (4); the seat cushion (4) comprising a central part (10) and two lateral support edges (12, 13), the seat cushion having a receiving surface (14); the receiving surface of the central part comprising a front zone (16), a rear zone (18), a middle zone (20); the receiving surface of the lateral support edges (12) comprising a lateral zone (21); the backrest (6) comprising a support surface (22); the support surface comprising an upper zone (24), a lower zone (26) and an intermediate zone (28);the method being implemented by a detection system (8) comprising at least one capacitive sensor with interdigitated electrodes (30, 31) located on the front zone, at least one capacitive sensor with interdigitated electrodes (32, 33) located on the middle zone, at least one capacitive sensor with interdigitated electrodes (34, 35) located on the rear zone and at least two capacitive sensors with interdigitated electrodes (36, 37) located on the lateral zone of the seat; the detection system comprising at least one capacitive sensor with interdigitated electrodes (40, 41) located on the upper zone, at least one capacitive sensor with interdigitated electrodes (38) located on the lower zone and at least one capacitive sensor with interdigitated electrodes (39) located on the intermediate zone of the backrest; the method comprising an initial phase (46), the initial phase comprising:; a) a measurement (50) of initial capacitance values by capacitive sensors located on zones (16, 18, 20, 21) of the seat and on zones (24, 26, 28) of the backrest, b) a characterization (54) of the seat occupant's position as either an appropriate or an inappropriate position based on the initial capacitance values; c) if the seat occupant is characterized as being in an appropriate position, a storage (70) of the initial capacitance values measured on the seat back areas, the stored initial capacitance values being associated with the identifications of the areas on which the capacitance values were measured; the process comprising a subsequent step (48) following the initial step (46), the subsequent step comprising: d) a measurement (72) of the following capacitance values by capacitive sensors located on the areas of the backrest, e) detection (74, 82, 84) of a forward leaning position of the seat occupant; if the seat occupant was characterized as being in an appropriate position during the initial phase, the detection of a forward leaning position is implemented from the following capacitance values and the capacitance values stored during the initial phase; if the seat occupant was characterized as being in an inappropriate position during the initial phase, the detection of the forward leaning position is implemented from the following capacitance values and typical values defined according to the morphological type of the seat occupant.
2. A method for detecting a forward-leaning position according to claim 1, wherein the characterization (54) of the position of the seat occupant comprises: - a comparison (58) of the initial capacitance values measured on the front zone, the middle zone, the rear zone, and on the lateral zone of the seat at respective seat characterization thresholds (S1, S2, S3, S4), - a comparison (66) of the initial capacitance values measured in the upper zone, the intermediate zone, the lower zone of the file at respective file characterization thresholds (SD1, SD2, SD3), - a characterization (54) of the position of the seat occupant as being in an appropriate position when the initial capacitance values measured in at least three zones of the seat are greater than the respective backrest characterization thresholds (S1, S2, S3, S4) and the initial capacitance values measured in three zones of the backrest are greater than the respective seat characterization thresholds (SD1, SD2, SD3).
3. A method for detecting a forward-leaning position according to any one of claims 1 and 2, wherein, when the seat occupant has been characterized as being in a suitable position, the detection (74, 82) of a forward-leaning position comprises: (f) a consideration (76) of an area of the file, (g) a calculation (77) of a ratio between the next capacitance value measured in the area of the file considered and the initial capacitance value stored and associated with the area of the file considered, (h) a comparison (78) of the calculated ratio to a support threshold (SA1, SA2, SA3), the support threshold being defined for the area of the file considered, (i) when the calculated ratio is less than the support threshold defined for the area of the file considered, a counter is incremented (79) by one unit, j) a consideration (80) of another area of the file and a repetition of steps b) to e) until all areas of the file have been considered, k) a transmission (82) of a signal detecting a forward leaning position when the counter value is equal to at least one unit, otherwise a repetition of steps d) and f) to k).
4. Method for detecting a forward leaning position according to claim 3, wherein the support threshold(s) defined for the backrest areas is or are between 0.3 and 0.
5.
5. Method for detecting a forward leaning position according to any one of claims 3 and 4, wherein when the area of the backrest considered is the upper area (24) and the ratio calculated for the upper area is less than the support threshold corresponding to the upper area, the signal for detecting a forward leaning position is representative of a position in which at least one shoulder of the occupant is leaning forward.
6. Method for detecting a forward leaning position according to any one of claims 3 and 4, wherein when the area of the backrest considered is the lower area (26) and the ratio calculated for the lower area is less than the support threshold corresponding to the lower area, the signal for detecting a forward leaning position is representative of a position in which the occupant's pelvis is leaning forward.
7. A method for detecting a forward-leaning position according to any one of claims 1 and 2, wherein, when the seat occupant has been characterized as being in an inappropriate position, the detection (74) of a forward-leaning position comprises: - a determination (84) of a morphological type of the seat occupant, - a selection (85) of a typical value from among typical values (L1, L2, L3) defined according to the determined morphological type, - a calculation (86) of a sum of the following capacitance values measured on the upper zone, the intermediate zone and the lower zone of the backrest, - a calculation (87) of a ratio between the calculated sum and the selected standard value (L1, L2, L3), - a comparison (88) between the calculated ratio and a defined threshold, - transmission of a signal detecting a forward leaning position, when the ratio is greater than the defined threshold.
8. Method for detecting a forward leaning position according to claim 7, wherein the defined threshold is between 0.05 and 0.
15.
9. Method for detecting a forward leaning position according to any one of claims 1 to 8, wherein the detection system (8) further comprises a display screen (44) and / or a loudspeaker (45), and wherein the method further comprises a display or emission of a message informing the seat occupant of his forward leaning position.
10. Computer program, loadable into a memory associated with a processor, and comprising portions of code for implementing a method according to any one of claims 1 to 9 during the execution of said program by the processor.