Abstract:
A universal, compartment-wide system identifies the presence and position of occupants of a multi-place vehicle by utilizing the occupants to conduct and radiate place-specific radio frequency signals that are received at various locations in the passenger compartment. The place-specific radio frequency signals are developed by low power transmitters disposed in the various seat/place locations, and a receiver disposed at a central location that is remote from the transmitters receives and decodes the signals radiated by the occupants to determine the number and location of the occupants. Additional receivers may be installed in specified regions to detect occupant intrusion into such regions, and in various control panels to assess driver distraction and to tailor the functional content and capability depending on whether a driver or non-driver is interacting with the control panel.

Description:
TECHNICAL FIELD 
   The present invention is directed to occupant detection and discrimination in a multi-place vehicle, and more particularly to a universal or compartment-wide system that identifies the presence and position of the vehicle occupants. 
   BACKGROUND OF THE INVENTION 
   Various technologies have been suggested for detecting and locating the position of vehicle occupants, particularly in relation to the deployment of pyrotechnic supplemental restraint devices such as frontal and side air bags. It has also been suggested to adapt the operation of various electrical accessories to the detected occupant position. For example, the capacity and airflow of an air conditioning system and the balance controls of an audio system may be adjusted based on the number of occupants and their location, electrically positioned mirrors and displays (such as head-up displays) may be adjusted for driver height, and so on; see, for example, the U.S. Pat. No. 4,625,329 to Ishikawa et al., issued on Nov. 25, 1986. Additionally, the occupant presence information can be utilized to limit the information supplied to a driver so as to minimize driver distraction while providing more detailed information to a non-driver occupant; see, for example, the U.S. Pat. No. 6,181,996 to Chou et al., issued on Jan. 30, 2001. 
   In systems of the type described above, practical considerations such as cost and packaging significantly limit the system content and capability. As a result, only the most essential of functions (such as disabling airbag deployment for a child) are actually utilized in all but the most expensive production vehicles. Nevertheless, there is a continuing and growing demand for a system that will reliably and cost-effectively deliver information regarding occupant position, location and activity, since it is thought that occupant safety could be considerably improved if such information were available. 
   SUMMARY OF THE INVENTION 
   The present invention provides a universal or compartment-wide system that identifies the presence and position of the occupants of a multi-place vehicle by utilizing the occupants to conduct and radiate place-specific radio frequency signals that are received and processed at various locations in the passenger compartment. The place-specific radio frequency signals are developed by low power transmitters disposed in the various seat/place locations, and a receiver disposed at a central location that is remote from the transmitters receives and decodes the signals radiated by the occupants to determine the number and location of the occupants. Additional receivers may be installed in specified regions to detect occupant intrusion into such regions, and in specified control panels (such as HVAC or infotainment control panels) to assess driver distraction and to tailor the functional content and capability depending on whether a driver or non-driver is interacting with the control panel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a diagram of a multi-place vehicle passenger compartment equipped with the occupant detection and discrimination system of this invention. 
       FIG. 2  is a block diagram of the occupant detection and discrimination system of  FIG. 1 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, and particularly to  FIG. 1 , the reference numeral  10  generally designates a multi-place passenger compartment of a motor vehicle, as viewed from overhead. In the illustrated embodiment, the passenger compartment  10  accommodates four occupants (driver  12 , front passenger  14 , left-rear passenger  16 , and right-rear passenger  18 ), but it will be understood that the system of this invention is equally applicable to various other seating arrangements. Each place or seat location of the passenger compartment  10  is equipped with a low-power transmitter  20 ,  22 ,  24 ,  26  that develops and radiates a place-specific radio frequency signal. Each of the transmitters  20 ,  22 ,  24 ,  26  is powered via microcontroller  30 , and is located in close proximity to the respective occupant  12 ,  14 ,  16 ,  18 , such as in the seat bottom or back cushion. The various transmitted signals can be made place-specific by their frequency or by different modulation patterns imposed on a common frequency. The compartment  10  is further equipped with a radio frequency receiver  28  disposed at a location that is preferably central and equally remote from the transmitters  20 ,  22 ,  24 ,  26 , such as in the compartment headliner or ceiling. The receiver, in turn, is coupled to the microcontroller  30  which identifies the number and location of the occupants. When a given place of the compartment  10  is vacant, the signal transmitted by the respective transmitter  20 ,  22 ,  24 ,  26  is only weakly received by the receiver  28 , but when the place is occupied by a person, the signal is coupled through the person so that the signal received by receiver  28  is increased by several orders of magnitude. Given the place-specific nature of the signals, microcontroller  30  reliably detects the number and location of the occupants by simply determining which of the place-specific signals are received by receiver  28 . 
   Once the number and location of the occupants is known, the microcontroller  30  provides such information to various other vehicle microcontrollers via the data bus  32 . In the illustration of  FIG. 1 , for example, the HVAC control module  34 , the infotainment (IT) module  36 , the supplemental restraint system (SRS) control module  38 , and the mobile multi-media (MMM) module  40  are also coupled to the data bus  32 . The modules  34 ,  36 ,  38 ,  40  can utilize the occupant information to optimize various control parameters and to tailor their response based on the number and location of the occupants. For example, the HVAC module  34  can adjust the air conditioning capacity and airflow to optimize passenger comfort, the infotainment module  36  can adjust the sound distribution in the compartment  10 , and the supplemental restraint control module  38  can enable, disable or control the deployment force of various supplemental restraint devices. Obviously, a number of other controls are also possible. Additionally, the occupant information may go beyond occupant presence, and include approximate proximity to the receiver  28 ; in this case, the occupant head height may be inferred, allowing appropriate positioning of electrically controlled mirrors, head-up displays, etc. Of course, the information deduced from the received signals may be combined with other related information such as seat position, seat belt signals, occupant weight, and so on to confirm and increase the extent of occupant information available to the various modules  34 ,  36 ,  38 ,  40 . 
   In the illustrated embodiment, an additional receiver  42  is integrated into a driver interface panel  44 , such as a HVAC control head or a mobile multi-media control panel. The receiver  40  is designed such that the signals transmitted by the driver  12  and front passenger  14  are only weakly received unless the driver  12  or front passenger  14  places his or her hand near the interface panel  44  in an attempt to adjust the settings thereof. The output of receiver  42  is coupled to microcontroller  30 , which identifies the received signal to determine which of the occupants  12 ,  14  is attempting to interact with the interface panel  44 . If the received signal is that of the driver transmitter  20 , and the vehicle is moving, microcontroller  30  can signal the relevant modules  34 ,  36 ,  38 ,  40  to enable only limited or specified functionality to avoid undue driver distraction, or to enable minimum distraction functionality such as voice recognition for hands-free operation of the various modules  34 ,  36   38 ,  40  or telecommunication devices. On the other hand, if the received signal is that of the front passenger transmitter  22 , the microcontroller  30  can signal the modules  34 ,  36 ,  38 ,  40  to enable expanded capability, communication and customization control functions, for example. Of course, the number of receivers and their effective range may be customized for any particular application; for example, receivers may be installed in several different control panels, or their range may be restricted to a certain region or button of a given control panel if desired. Additionally, the control panel may be as simple as a center-mounted or console-mounted lamp control with individual lamps for two or more passengers; in such case, a receiver can be installed in the lamp module to detect the presence of an occupant&#39;s hand in proximity to the lamp module, to determine the seat location of the occupant, and to activate (or deactivate) the lamp for that seating location. Obviously, the number of potential applications are too numerous to discuss or mention herein. 
     FIG. 2  depicts basic component interconnections of the various receivers and transmitters of  FIG. 1  for an embodiment in which each seat location of the compartment  10  is assigned a unique frequency. The transmitters  20 ,  22 ,  24 ,  26  each comprise an oscillator  20   a ,  22   a ,  24   a ,  26   a ; a bandpass filter  20   b ,  22   b ,  24   b ,  26   b ; a variable gain amplifier  20   c ,  22   c ,  24   c ,  26   c ; and an antenna  20   d ,  22   d ,  24   d ,  26   d . The oscillators  20   a ,  22   a ,  24   a ,  26   a  and associated bandpass filters  20   b ,  22   b ,  24   b ,  26   b  produce sinusoidal waveforms having different predefined frequencies, preferably in the range of 60 kHz to 100 kHz. The waveforms are amplified by the respective variable gain amplifiers  20   c ,  22   c ,  24   c ,  26   c  and coupled to the antennas  20   d ,  22   d ,  24   d ,  26   d , which may be conductive mats, threads, foil strips, etc. The gain of each amplifier  20   c ,  22   c ,  24   c ,  26   c  is regulated by microcontroller  30  based on the received signal strength in order to optimize the signal-to-noise ratio of the various signals. Similarly, the receivers  28 ,  42  each comprise an antenna  28   a ,  42   a ; a variable gain amplifier  28   b ,  42   b ; and a bandpass filter  28   c ,  42   c . The antennas  28   a ,  42   a  may be similar to the antennas  20   d ,  22   d ,  24   d ,  26   d  and the variable gain amplifiers  28   b ,  42   b  are also controlled by microcontroller  30  for signal-to-noise ratio optimization and for optimal analog-to-digital conversion. However, the bandpass filters  28   c ,  42   c  are designed to pass all of the transmitted frequencies. The outputs of bandpass filters  28   c ,  42   c  are supplied to microcontroller  30 , where they are converted to a digital format and processed to identify the transmitted frequencies and their amplitudes. As mentioned above, occupant presence in any given seat position is detected by the strength of the received signal emanating from that seat and its occupant, and microcontroller  30  places the occupant information on data bus  32  via transceiver  46 . 
   In summary, the present invention provides a compartment-wide occupant detection system that identifies the presence and position of the occupants of a multi-place vehicle by utilizing the occupants themselves to conduct and emanate place-specific radio frequency signals that are received and processed at various locations in the passenger compartment. As discussed above, the system is easily extended to other components and control functions simply by increasing the number of receivers. The control functions mentioned herein are illustrative only, and are by no means exhaustive. Accordingly, it is expected that various modifications and alternations in addition to those mentioned herein may occur to those skilled in the art, and it should be understood that systems incorporating such modifications may fall within the scope of this invention, which is defined by the appended claims.