SEAT BELT STATUS MONITORING SYSTEM

Abstract

A seat monitoring system for monitoring an occupancy related status of at least one seat inside an automotive vehicle compartment. The seat monitoring system includes a control module mounted within the compartment, and at least one sensor module integrated into the at least one seat. The sensor module has a sensing system for sensing an occupancy related status with respect to the seat. The control module is arranged in wireless communication with the sensor module. The control module has at least three transmitting RF antennas configured to transmit a request signal in at least three directions inside the vehicle compartment; and the sensor module is further configured to receive the request signals from the at least three directions, to determine reception parameters of the request signals, and to transmit an information responsive to the reception parameters to the control module.

Claims

1. Seat monitoring system for monitoring an occupancy related status of at least one seat inside an automotive vehicle compartment, the seat monitoring system comprising a control module mounted within the compartment, and at least one sensor module integrated into the at least one seat, the sensor module comprising a sensing system for sensing an occupancy related status with respect to the seat, wherein said control module is arranged in wireless communication with said sensor module; wherein the contol module comprises at least three transmitting RF antennas configured to transmit a request signal in at least three directions inside the vehicle compartment; and wherein the sensor module is further configured to receive the request signals from the at least three directions, to determine reception parameters of said request signals, and to transmit an information responsive to said reception parameters to said control module.

2. Seat monitoring system according to claim 1, wherein the reception parameters comprise intensities of the electromagnetic field transmitted by the request signal sent from each of the at least three transmitting RF antennas.

3. Seat monitoring system according to claim 1, wherein the control module is configured to determine the seat location using the information transmitted by the sensor module.

4. Seat monitoring system according to claim 1, wherein the sensor module is configured to determine the seat location using the reception parameters and to transmit said seat location in the information responsive to the reception parameters.

5. Seat monitoring system according to claim 1, wherein the occupancy related status comprises a seat belt buckle status.

6. Seat monitoring system according to claim 1, wherein the occupancy related status comprises an occupancy status.

7. Seat monitoring system according to claim 1, wherein the occupancy related status comprises a combination of a seat belt buckle status and an occupancy status.

8. Seat monitoring system according to claim 1, wherein, the sensing system determines the occupancy related status only when receiving a control request signal.

9. Seat monitoring system according to claim 1, wherein the sensor module is configured to transmit the information responsive to the reception parameters and the occupancy related status in separate parts of a transmission information.

10. Seat monitoring system according to claim 1, wherein the sensor module is configured to transmit the information responsive to the reception parameters only when the occupancy related status corresponds to an unbuckled and occupied seat.

11. Seat monitoring system according to claim 1, wherein the sensor module comprises a unique ID and the sensor module is configured to transmit the information indicative of the seat location to the control module only when receiving a control request signal comprising its unique ID.

12. Seat monitoring system according to claim 1, wherein the sensor module comprises a 3D coil antenna.

13. Seat monitoring system according to claim 1, wherein the control module is part of a passive entry passive start base control unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further details and advantages of the present invention will be apparent from the following detailed description of not limiting embodiments with reference to the attached drawing, wherein:

[0042] FIG. 1 is a schematic top view of a typical automobile interior compartment equipped with a system according to an embodiment of the invention.

[0043] FIG. 2 is a layout of an embodiment of a sensor module circuit according to the invention.

[0044] FIG. 3 is a layout of an embodiment of a control module circuit according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0045] FIG. 1 schematically illustrates an interior compartment of a vehicle 10 equipped with a seat monitoring system 11 according to an embodiment of the invention. The compartment comprises a front part 12 with two front seats 14, and a rear part 16 where six rear seats 18 are arranged. Here the rear seats 18 are arranged on two lines of three seats, but it is understood that the rear seats 18 are movable and interchangeable.

[0046] The rear seats 18 are mounted on fixing means not shown that allow them to be fixed at substantially random positions inside the compartment 10. For example the rear seats may be mounted on rails allowing them to be movable in the entire length of the compartment, resulting in arrangements that are not necessarily following straight lines relative to the width of the vehicle.

[0047] The vehicle compartment further comprises a control module 20 preferably located in the front part of the vehicle. The control module 20 is connected to a display system 22 of the vehicle that is at least visible to the driver. The display system 22 is configured to display a warning indicating the location of a seat 14, 18 with a passenger who has not buckled his/her seat belt. Communication between the display system 22 and the control module 20 can be made by any suitable means or/and method.

[0048] The control module 20 is further connected to a plurality of radio frequency (RF) antennas 24 arranged in different locations inside the compartment 10. In the embodiment of FIG. 1, three antennas 24 are installed at different locations in the vehicle compartment. Two antennas 24 are located respectively on each lateral side of the rear part 16 of the vehicle 10, and one antenna 24 is located roughly in the center of the vehicle 10 between the front seats 14 and the rear sets 18.

[0049] All three antennas 24 are configured to transmit a signal towards the inside of the compartment. Preferably, the configuration of the antennas 24 allows the signal to be received at any location in the compartment 10. As represented in FIG. 1, two transmitting antennas are facing each other, and configured to transmit a signal in opposite direction, and the third antenna is transmitting in an orientation perpendicular to the others.

[0050] The RF antennas 24 are low frequency (LF) antennas, but it is understood than the RF antennas 24 may use any suitable frequency. In the following description, the RF antennas 24 will be indifferently called LF antennas 24. The frequency range of the LF transmission is between 5 kHz and 10 MHz, and more preferably lies within the 125 kHz industrial, scientific, and medical (ISM) radio band.

[0051] The LF antennas 24 are configured to send a LF signal to sensor modules 26 integrated into each of the front and rear seats 14, 18. Integration of the sensor module 26 may be made anywhere in the seat with the constraint that the sensor is secured to the seat. The sensor module 26 is configured to sense an occupancy related status of its respective seat and transmit it to the control module 20. Components of the sensor module 26 will be explained below.

[0052] The sensor module 26 is also configured to determine reception parameters from the signals sent by the LF antennas 24, and to further transmit a signal comprising information responsive to the reception parameters to the control module 20.

[0053] The control module 20 is configured to receive the signal comprising information responsive to the reception parameters, and to determine with the received information responsive to the reception parameters, the location of a seat on which a passenger is seated without having buckled his/her seat belt.

[0054] FIG. 2 shows a preferred embodiment of the components comprised in the sensor module 26 which is integrated into each seat 14, 18, in order to monitor seat occupancy related status. The seat occupancy related status may be any useful information the vehicle uses in relation with seat occupancy. Here the seat occupancy related status is the seat occupancy status, indicating whether the seat is occupied by a passenger, in combination with the seat belt buckle state, indicating whether the seat belt is buckled.

[0055] The sensor module 26 comprises a first control and evaluation system 28, connected to a sensing system 30, a request signal receiver 32, and a response signal transmitter 34. The sensor module 26 also comprises a power supply circuit 36 for supplying power to the other elements of the module 26.

[0056] The sensing system 30 comprises a buckle sensor 38, represented on FIG. 2 as a switch that is operable between an open position when the seat belt is unbuckled and a closed position when the seat belt is buckled. The sensing system 30 further comprises a buckle determination system 40 connected to the buckle sensor 38 and configured to send a signal to the seat control and evaluation system 28 indicative of the seat buckle state.

[0057] The sensing system 30 also comprises an occupancy sensor 42. The occupancy sensor 42 may be for example a capacitive sensor, an acceleration sensor or any sensor known in art to determine the occupancy state of the seat. On FIG. 2, the occupancy sensor 42 is represented by a switch operable between an open position when the seat is unoccupied and a closed position when the seat is occupied.

[0058] Similarly to the buckle sensor 38, the sensing system 30 comprises an occupancy determination system 44 connected to the occupancy sensor 42 and configured to send a signal to the seat control and evaluation system 28 indicative of the seat occupancy state.

[0059] The request signal receiver 32 is connected to a 3D coil LF antenna 46 with three receiving coils 48 which are physically oriented perpendicular to one another so as to form a trihedron.

[0060] The receiver 32 is further configured to demodulate a message modulated in the received request signal, and to measure the respective intensities of the request signal received by each of the three coils 48. The receiver 32 then sends the message along with the measured intensities to the first control and evaluation system 28.

[0061] The first control and evaluation system 28 further comprises a first microcontroller 50, which stores a unique ID corresponding to the sensor module 26, associated to the respective seat 14, 18. The first control and evaluation system 28 is also connected to the response signal transmitter 34, and the response signal transmitter 34 is connected to an ultra-high frequency (UHF) antenna 52 configured to send a response signal comprising modulated messages to the control module 20.

[0062] The Power supply circuit 36 uses the power from a battery 54 to supply the sensor module 26 with electrical energy. As shown in FIG. 2, a rectifier 56 rectifies the signal received by the 3D LF antenna 46, and supplies a rectified DC voltage to the power supply circuit 36. The power supply circuit 36 is further configured to charge the battery 54 with the electrical power received from the rectifier 56.

[0063] In embodiments, the electrical power received from the rectifier 56 is employed to directly supply power to the rest of the circuit in addition to the power from the battery 54, thereby reducing the power drain on the battery 54.

[0064] In embodiments, battery 54 is replaced by a capacitor which is charged by the electrical power received from the rectifier 56.

[0065] In operation, when a request signal containing a message is received by the 3D coil LF antennas 46, the LF receiver 32 demodulates the message modulated in the signal, and stores the intensities of the signals received by each coil 48 of the 3D antenna 46. The LF receiver 32 sends all the received information to the first control and evaluation circuit 28. The first microcontroller 50 in the first control and evaluation circuit 28 decodes the demodulated message sent by the LF receiver 32 and checks if the received message contains a seat status request and a unique seat ID. If a request and an ID corresponding to the seat ID stored into the first microcontroller 50 are contained in the request signal, the first microcontroller 50 requests the seat buckle and seat occupancy status sent to the buckle and occupancy determination systems 40, 44 and reads the determined status sent in response from the buckle and occupancy detection systems 40, 44. If the seat is occupied and the seat belt is not buckled, the first microcontroller 50 further reads the intensities of the signals received by the three coils 48 of the LF antennas 46. Then it determines the total received intensity by, for example, calculating the geometric or arithmetic mean of the three intensities. The received intensities are finally transmitted to the control module 20 via the transmitter 34 and the UHF antenna 52.

[0066] In embodiments, the first control and evaluation system 28 starts in a stand-by state, meaning that when the LF receiver 32 detects a magnetic LF field request signal from a vehicle LF antenna 24, the LF receiver 32 sends a signal to wake up the first microcontroller 50 of the first control and evaluation system 28, the following operations are then identical as described above.

[0067] As shown in FIG. 3, the control module 20 comprises a second control and evaluation system 58, comprising a second microcontroller 60 which controls a request signal LF transmitter 62 connected to the three LF antennas 24. The second microcontroller 60 stores a list of all the IDs of the front and rear seats 14, 18, included in the vehicle 10. The control module 20 further comprises a response signal receiver 64 connected to the second control and evaluation system 58, and to a UHF antenna 66.

[0068] Preferably, the frequency range of the UHF transmission is between 50 MHz and 10 GHz, and more preferably lies within one of the ISM bands of 443 MHz, 868 MHz, 915 MHz, 2.45 GHz, or 5.08 GHz.

[0069] In operation, the LF transmitting antennas 24 sequentially transmit a request signal comprising a modulated message through each of the LF antenna 24. The modulated message comprises a seat occupancy related status request associated with a seat ID selected in the list of IDs included in the second microcontroller 60.

[0070] The transmitting sequence goes through all the antennas with one predetermined ID then switch to another ID. The sequence starts for example with a first antenna 24 transmitting a request signal comprising a message with the first ID in the list, then a second antenna 24 transmits the same request signal comprising the first ID in the list, and finally a third antenna 24 transmits the request signal comprising the first ID in list. Next, the same operations are repeated with the second ID in list and the third, and so on until the last ID in the list.

[0071] After each transmission, the second microcontroller 60 checks if a message is being received by the UHF receiver 64 through the UHF receiving antenna 66. As explained above, the sensor module 26 only transmits a message when the two following conditions are fulfilled: The received request signal comprises the unique ID corresponding to the sensor module 26 and hence to the seat into which the module 26 is integrated; and when the seat associated with the control module 26 is occupied and unbuckled.

[0072] Accordingly, all the signals received by the UHF antenna 66 from a sensor module 26 are indicative of a seat that is occupied and unbuckled. Upon receiving a message, the second microcontroller 60 reads the received intensities from the modulated message and stores them in memory. Once each of the intensities of a specific control module 26 corresponding to all the three LF transmitting antennas 24 have been received and stored, the second microcontroller 60 uses the stored intensities to determine the location of the corresponding seat inside the compartment 10. Determination of the location of the seat is done by triangulation. Triangulation is a common method used in the art to determine the source location of a transmitted signal, and it will not be explained here. It is also understood that determination of the location is not limited to triangulation methods but to any other method known in the art.

[0073] In embodiments, more than three antennas 24 are installed. In that case triangulation is applied several times, and for example the mean or median location is used as location of the seat.

[0074] In embodiments, the vehicle compartment already comprises a passive entry passive start system is used to allow a user to open a door or a trunk without hand by only approaching the vehicle carrying a fob key. Such a system is configured to detect the position of the key fob and activate one or more functionalities when the key fob is close enough to the vehicle. A skilled person will observe that most of the components from FIG. 3 are already comprised in the passive entry passive start control module as it is commonly used in certain automobile vehicle. In these embodiments, the system according to the invention uses the same sensor module as described above in communication with the passive entry passive start module already existing in the vehicle. These embodiments permit to reduce the diversity of the components of the system and thus reduce overall cost