Patent Publication Number: US-2019184853-A1

Title: Occupant sensing system for a vehicle

Description:
INTRODUCTION 
     The subject disclosure relates to the art of vehicles and, more particularly, to an occupant sensing system for a vehicle. 
     Many current vehicles include sensors for detecting a presence in a vehicle seat. Sensors may take the form of pressure sensors and detect the presence based on weight. Typically, the sensors are connected to a controller that is configured to provide an output signal when a mass having a weight exceeding a predetermined threshold is detected in the seat. The output may be employed to generate a passenger primary restraint warning signal (seat belt), generate signals to control a supplemental restraint system (airbags/seat belt pretensioners) for normally seated adult occupants, or enable entertainment system functionality. 
     The predetermined threshold is set to capture people of a certain size and exclude other seat occupants such as pets and packages. The predetermined threshold often times captures children in child safety seats. In many cases, child safety seats do not utilize existing passenger restraints but rather rely on dedicated attachment systems. Thus, often times, a passenger restraint warning may be issued unnecessarily. That is, a sensor may detect the presence of an occupied child safety seat that does not utilize the passenger restraint system. Accordingly, it is desirable to provide a system that can differentiate between an occupant sitting directly on a vehicle seat and an occupant that may occupy a child safety seat that does not use the primary passenger restraint system. 
     SUMMARY 
     Disclosed is an occupant detection system including a vehicle seat having a seat back and a seat base, and a biometric sensor arranged in at least one of the seat back and the seat base. The biometric sensor is configured to detect a physiological characteristic of a seat occupant. A controller is operatively connected to the biometric sensor. The controller is configured to provide an output signal in response to a physiological characteristic detected signal from the biometric sensor. 
     In addition to one or more of the features described herein include wherein the biometric sensor comprises at least one of an electrocardiogram (EKG) sensor, an electroencephalogram (EEG) sensor, an electromyography (EMG) sensor, a piezo electric sensor, a neural activity sensor, and a heart activity sensor. 
     In addition to one or more of the features described herein include wherein the biometric sensor is arranged in the seat base. 
     In addition to one or more of the features described herein include wherein the biometric sensor is arranged in the seat back. 
     In addition to one or more of the features described herein include wherein the biometric sensor is arranged between the seat back and the seat base. 
     In addition to one or more of the features described herein include wherein the biometric sensor establishes a physiological characteristic detection zone at the vehicle seat. 
     In addition to one or more of the features described herein include a non-biometric sensor configured to detect a mass of a seat occupant. 
     Also disclosed is a vehicle including a body defining, at least in part, an occupant compartment. At least one vehicle seat is arranged in the occupant compartment. The at least one vehicle seat includes a seat back and a seat base. A biometric sensor is arranged in at least one of the seat back and the seat base. The biometric sensor is configured to detect a physiological characteristic of a seat occupant. A controller is operatively connected to the biometric sensor. The controller is configured to provide an output signal in response to a physiological characteristic detected signal from the biometric sensor. 
     In addition to one or more of the features described herein include wherein the biometric sensor comprises at least one of a an electrocardiogram (EKG) sensor, an electroencephalogram (EEG) sensor, an electromyography (EMG) sensor, a piezo electric sensor, a neural activity sensor, and a heart activity sensor. 
     In addition to one or more of the features described herein include wherein the biometric sensor is arranged in the seat base. 
     In addition to one or more of the features described herein include wherein the biometric sensor is arranged in the seat back. 
     In addition to one or more of the features described herein include wherein the biometric sensor is arranged between the seat back and the seat base. 
     In addition to one or more of the features described herein include wherein the biometric sensor establishes a physiological characteristic detection zone at the at least one vehicle seat. 
     In addition to one or more of the features described herein include a non-biometric sensor configured to detect a mass of a seat occupant. 
     Further disclosed is a method of detecting an occupant in a vehicle including sensing a physiological characteristic at a vehicle seat. 
     In addition to one or more of the features described herein include wherein sensing the physiological characteristic includes detecting at least one of an electrical activity of a brain, electrical activity of a heart, heart movement, and breathing activity. 
     In addition to one or more of the features described herein include detecting an occupant restraint status of the vehicle seat. 
     In addition to one or more of the features described herein include providing a signal based on a presence of the physiological characteristic and occupant restraint status. 
     In addition to one or more of the features described herein include wherein providing the signal includes at least one of limiting operation status of the vehicle and warning the occupant to buckle a seatbelt, controlling an airbag, a seatbelt pretensioner, an entertainment system, and an HVAC system. 
     In addition to one or more of the features described herein include detecting at least one of a child in a child safety seat resting on the vehicle seat, an occupant on the vehicle seat, an out-of-position occupant on the vehicle seat, an animal on the vehicle seat, and an inanimate object on the vehicle seat based on the sensed physiological characteristic. 
     The above features and advantages, and other features and advantages of the disclosure are readily apparent from the following detailed description when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features, advantages and details appear, by way of example only, in the following detailed description, the detailed description referring to the drawings in which: 
         FIG. 1  depicts a vehicle including an occupant sensing system, in accordance with an aspect of an exemplary embodiment; 
         FIG. 2  depicts a vehicle seat including an occupant sensing system, in accordance with an aspect of an exemplary embodiment; 
         FIG. 3  depicts a block diagram illustrating the occupant sensing system, in accordance with an aspect of an exemplary embodiment; and 
         FIG. 4  depicts a flow chart illustrating a method of detecting vehicle occupants, in accordance with an aspect of an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module refers to processing circuitry that may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     A vehicle, in accordance with an exemplary embodiment, is indicated generally at  10  in  FIG. 1 . Vehicle  10  includes a body  11  that defines, at least in part, an occupant compartment  18 . Vehicle  10  may be powered by a variety of systems including internal combustion engines, hybrid electric engines, and electric motors (not shown). Vehicle  10  may be controlled by a driver, be remote controlled, or may be autonomous. Vehicle  10  may include one or more airbag systems  12 . Airbag systems  12  may include side impact airbags, front impact airbags, rollover airbags, knee airbags and the like. Vehicle  10  may also include one or more entertainment systems  14  that can be instrument panel mounted, roof mounted seat mounted, center console mounted, door mounted and the like. In addition, vehicle  10  may include one or more heater/ventilation system HVAC climate controls  13  or other reachable controls  15 . 
     A first vehicle seat  24  is arranged in occupant compartment  18 . A second vehicle seat  28  is arranged alongside first vehicle seat  24 , and a third vehicle seat  32  which may take the form of a bench seat  34  is arranged aft of first and second vehicle seats  24  and  28 . At this point, it should be understood that the number, arrangement, and type of vehicle seats may vary. First vehicle seat  24  includes a first portion  40  which may define a seat base  42 , a second portion  45  which may define a seat back  47  and a third portion  50  which may define a head restraint  52 . Second vehicle seat  28  includes a first portion  56  which may define a seat base  58 , a second portion  61  which may define a seat back  63  and a third portion  66  which may define a head restraint  68 . 
     Reference will now follow to  FIG. 2 , with continued reference to  FIG. 1 , in describing second vehicle seat  28  with an understanding that first vehicle seat  24  and third vehicle seat  32  may include similar structure and seatbelt system. Seat base  58  includes a seat base surface  74 , and seat back  63  includes a seat back surface  76 . Second vehicle seat  28  also includes an interface zone  78  that is defined between seat base  58  and seat back  63 . In addition second vehicle seat  28  may interface with a seatbelt system  17  that may include a pretensioner  19 . Pretensioner  19  can be attached to an outboard lower anchor (not separately labeled), a seatbelt buckle (not shown), or a retractor (also not shown). 
     In accordance with an aspect of an exemplary embodiment, second vehicle seat  28  includes an occupant detection system  84 . It should be understood that occupant detection system  84  may also be incorporated into first vehicle seat  24  and third vehicle seat  32 , or any other designated seating position within any mode of personal transportation. Occupant detection system  84  includes a first sensor  87  that may be arranged in seat base  58  at seat base surface  74 . A second sensor  90  may be arranged in seat back  63  at seat back surface  76 . Additionally, a third sensor  94  may be arranged in seat base  58  and a fourth sensor  95  may be arranged in seat back  63  at a higher location than second sensor  90 . It should be understood that first sensor  87  and/or second sensor  90  may extend into interface zone  78 . Alternatively, a fifth sensor (not shown) may be arranged in interface zone  78 . It should be understood that the number and location of sensors may vary. 
     First sensor  87  takes the form of a biometric sensor  98  that may detect a physiological characteristic of an occupant in second vehicle seat  28 . If provided, second sensor  90  may also take the form of a biometric sensor  100 . Further, fourth sensor  95  may also take the form of biometric sensor  101 . The number and location of biometric sensors may vary and could include sensors at interface zone  78 . Further, biometric sensors may take on various forms including, but not limited to, electrocardiogram (EKG) sensors, electroencephalogram (EEG) sensors such as a Freer neuro monitor based sensor, electromyography (EMG) sensors, and/or sensors that may detect other physiological characteristics including, but not limited to, piezo electric sensors that may detect micro motions associated with a heartbeat and ultra-high impedance heart activity sensors such as Plessy Epic sensors that may be configured to detect breathing, heart rate and the like. In addition, the biometric sensors may be used, in conjunction with non-biometric sensors, for detection of children left in vehicle. 
     Also, if provided, third sensor  94  may take the form of a non-biometric sensor  106  that can detect a mass in seat base  58 . Non-biometric sensor  106  may take the form of a load sensor such as a pressure based bladder system, a capacitive sensor, and/or a force resistive sensor that may detect localized pressure at one or more zones on seat base  58 . 
     Referring to  FIG. 3 , and with continued reference to  FIG. 2 , occupant detection system  84  includes a controller  118  that may include a central processing unit (CPU)  120 , a memory module  122 , a signal conditioning module  124  and an occupant detection module  126 . Controller  118  is operatively connected to first sensor  87  and, if provided, second sensor  90  and third sensor  94 . Signal conditioning module  124  conditions signals received through first, second and third sensors  87 ,  90  and  94 . 
     A conditioned signal may be passed to occupant detection module  126  to determine if an occupant is present on seat base surface  74 . Occupant detection module  126  may also obtain data from load sensor  106 . An “occupant present” output could be based in part on whether a load is detected above a predetermined level that may be stored in memory module  122 . If an “occupant present” determination is made, occupant detection system  84  may output, to an external control system (not shown), or use internally, a signal  130 . 
     Occupant detection system  84  may send a another signal (not shown) indicating that an occupant is sitting slightly out of normal seating position, or occupant detection system  84  may output signal  130  when an occupant is sitting across two seating positions. Signal  130  may be used for other vehicle systems such as seat or vehicle comfort features, primary or secondary restraint systems deployment, enabling/disabling vehicle entertainment/convenience features in general. Signal  130  may also be used to report to the primary owner that a child or other object was left behind when the primary occupant exits the vehicle. 
     Occupant detection system  84  is configured to discriminate between an occupant on seat base surface  74  and, for example, a child in a child safety seat. Thus, occupant detection system  84  establishes a physiological characteristic detection zone or sensing zone that may extend no more than about four inches (10 centimeters) above seat base surface  74 . It should be understood that the position of each sensor in a vehicle seat may vary in order to achieve one or more of a selected sensing zone, selected seat comfort and sensor durability. Sensors may be arranged between an outer covering and a foam layer, below the foam layer, or the like. Further, biometric sensor  98  and, if provided, biometric sensor  90 , are arranged with a minimal lateral dimension so as to avoid detecting an appendage such as an arm or a leg that may dangle from a child safety seat. 
     In addition biometric sensor  100  may be positioned at a lower portion of seat back  63  in order to avoid detecting a back or bottom of a child in a backless booster child safety seat. In this manner, occupant detection system  84  can provide output signal  130  when an occupant is sitting in a vehicle seat and not when the seat is occupied by a child in a child safety seat that does not utilize a seat belt for restraint. As will be discussed herein, output signal  130  may be employed to accurately generate a seat belt warning signal providing a reminder to buckle up, control a supplemental restraint system (airbags  12 , seatbelt pretensioners  19 ) based on occupant presence or when an out of position occupant is detected, affect other vehicle systems such as enabling entertainment system  14 , HVAC system controls  13  and functionality of other control  15 , or prevent operation of vehicle  10 . 
     Reference will now follow to  FIG. 4 , with continued reference to  FIGS. 1-3  in describing a method  200  of detecting occupants in a vehicle seat in accordance with an aspect of an exemplary embodiment. In block  202  first sensor  87 , second sensor  90 , and third sensor  94  are powered on by, for example, activating vehicle  10 . Activating vehicle  10  may include, for example, opening a vehicle door (not separately labeled). In block  204  a determination is made whether physiological characteristics are sensed by first sensor  87  and, if provided, second sensor  90 . Also, if provided, non-biometric sensor  106  may provide an input regarding a mass in, for example, second vehicle seat  28 . If no occupant is detected, no action is taken. If an occupant is detected, the input is processed through filtering logic (not shown) and output signal  130  is issued and action may be taken in block  206 . The action may include issuing a seat belt warning, enabling or affecting airbag  12  seatbelt pretensioner  14  deployment, control other vehicle features such as entertainment system  14 , HVAC system controls  13  enable other controls  15 , affect other vehicle features, or vehicle  10  may be prevented from being operated. 
     In block  302 , a determination may be made that vehicle  10  is moving. If vehicle  10  is moving, a determination is made, in block  304 , whether an occupant is present in, for example, second vehicle seat  28 . If no occupant is present, no action is taken. If, however an occupant is detected, an action may be taken in block  306 . The action may include stopping vehicle  10 , slowing vehicle  10 , enabling or controlling airbag  12 , seatbelt pretensioner  19  deployment and/or seat heater/ventilation system local HVAC climate control  13  limiting other controls  15  from younger occupants, (limiting power consumption) and/or issuing a seatbelt warning. In block  402 , a determination is made whether vehicle  10  has come to a stop. If vehicle  10  has come to a stop, occupant detection system  84  may again determine whether an occupant is in, for example, second vehicle seat  28  in block  406 . If no occupant is detected, no action is taken. If an occupant is detected, an action may be taken in block  408  including preventing vehicle  10  from starting, issuing a seat belt alert, or the like. In block  500 , occupant detection system  84  may power down. 
     Occupant detection system  84  in accordance with exemplary embodiments, employs biometric sensors to detect a physiological characteristic of an occupant in a vehicle seat. An occupant sitting on, for example, vehicle seat  28  presents a stronger signal to an associated one of first and second sensors  87  and  90  than would a child located in a child safety seat. Accordingly, the exemplary embodiments may employ sensed signal strength magnitude threshold to discriminate between an occupant that is directly on, for example, vehicle seat  28  and a child spaced from, for example, seat base surface  74  by a child safety seat. Exemplary embodiments may also detect, via sensed signal strength magnitude an out-of-position occupant that would be physically displaced away from one or more of first, second and fourth sensors  87 ,  90 ,  95 . In addition, an empty seat could produce either the same signal magnitude as a child on the child safety seat or a lower magnitude response. Thus, the exemplary embodiments may be configured to distinguish between up to six different states depending on sensor location and the use of distinct threshold values for each condition: a) occupant on the seat, b) child in a child safety seat, c) no occupant present, d.) out of position occupant, e) animals and/or f), objects or anything other than human objects on the seat. 
     If employed, non-biometric sensor  106  may be utilized to discriminate other living objects that may be resting on, for example, vehicle seat  28 . In an exemplary aspect, non-biometric sensor  106  may be configured to detect weight and controller  118  may determine whether the living object was below a pre-defined mass-based threshold. If below the mass-based threshold, an inference could be made that the living object may be a pet and not a human. Thus, the signal  130  may not be sent for living objects that are below a certain mass based threshold. 
     A confined sensing zone is established at each vehicle seat. The confined sensing zone allows the occupant detection system to discriminate between an occupant sitting in the seat and a child that may be in a child safety seat. The occupant is given a warning to use a primary restraint. A warning is not issued if the system determines that a child safety seat occupies the seat. Supplemental restraints such as airbags, seatbelt pretensioners, or other vehicle features such as entertainment systems, HVAC systems controls and other controls may be enabled or disabled. For instance, the child safety seat would not possess a physiological characteristic and thus not be detected by the occupant detection system. The exemplary embodiments ensure that a seat belt warning is issued, supplemental restraints are appropriately controlled and/or other vehicle features and actions are only taken when an occupant is seated on the seat surface. 
     The terms “about” and “substantially” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” and “substantially” can include a range of ±8% or 5%, or 2% of a given value. 
     While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope thereof.