Abstract:
An impact event countermeasure control method and system for an automotive vehicle includes management of impact countermeasures using not only variable timing responsive to impact severity, but also event control as a function of the displacement of a vehicle&#39;s occupant with respect to the passenger cabin environment, including various countermeasure devices.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a method and system for enhancing the protection of motor vehicle occupants during an impact event, through the use of adaptively controlled countermeasures.  
         [0002]     Impact event countermeasure devices used in automotive vehicles have become increasingly more complex as time has progressed. Beginning with simple seatbelts, which at one time were limited solely to lap belts, and then later, lap belts with shoulder harnesses, countermeasure devices have passed through a lengthy evolution to a point at which even basic restraints include not only lap and shoulder belts, but also seatbelt buckle pretensioners and seatbelt retractor multi-load limiters.  
         [0003]     In addition to seatbelts, supplemental restraint systems often include an airbag mounted within the steering wheel of a vehicle, as well as an airbag mounted within the dash panel adjacent a front seat passenger, as well as side airbags mounted upon vehicle seats, and side curtain inflatable devices. Other countermeasures include, for example, airbag inflators with multiple volume capability, and inflators with venting capability. An adaptive steering column is used in some vehicles to mitigate the impact load delivered to the chest area of a vehicle&#39;s driver during an impact event. In one incarnation, a multi-load level steering column controls the stroke, and hence, the load imposed by the steering column, during a frontal impact.  
         [0004]     All of the countermeasure devices described above require proper time and force management in order to properly control the interaction of a vehicle occupant with his/her surroundings during an impact event. U.S. Pat. No. 6,804,595 discloses a system in which variety of sensors such as an occupant weight sensor, an occupant proximity sensor, a crash severity sensor, and a pre-crash sensor are used to provide signals controlling an airbag and seatbelt mechanism. The system of the &#39;595 patent does not, however, provide for the unique combination of crash severity sensing, occupant position sensing, and occupant displacement prediction provided by the present system so as to manage the energy of an occupant in a unique and inventive manner.  
       SUMMARY OF THE INVENTION  
       [0005]     An impact event countermeasure control method for an automotive vehicle includes the steps of sensing deceleration of the vehicle during an impact event, setting a countermeasure deployment timer in the event that the sensed deceleration exceeds a first threshold, and integrating the sensed deceleration to calculate the time-based displacement of an occupant within the vehicle. The calculated displacement of the occupant is compared with a displacement threshold at the time the countermeasure deployment timer expires. In the event that the calculated displacement is less than the displacement threshold when the countermeasure deployment timer measure expires, the deployment of the countermeasure will be delayed until the displacement threshold is crossed. Crossing of the first deceleration threshold may be used, for example, as a factor in the decision making leading to deployment of a seatbelt pretensioner or other countermeasure device. The setting of the countermeasure deployment timer preferably lags the onset of the impact event by an amount of time corresponding to the severity of the impact event.  
         [0006]     The displacement threshold used in the present method is preferably calculated as a function of at least one physical characteristic of the occupant, which may for example be the longitudinal position at which a seated occupant places a seat, or perhaps, the weight of the occupant. A family of displacement thresholds may be calculated for plurality of occupant physical characteristics.  
         [0007]     Returning to the present method, in the event that the calculated displacement of a vehicle occupant is greater than the displacement threshold when the countermeasure timer expires, the countermeasure will be deployed when timeout has been reached. According to the present method, the countermeasure deployed in this manner may include, without limitation, a multi-load level (MLL) seatbelt retractor, or an adaptive steering column (ASC), or an adaptive airbag tether (AAT), or adaptive airbag canister vent (AACV), or yet other countermeasures known to those skilled in the art and suggested by this disclosure.  
         [0008]     According to another aspect of the present invention, an impact event countermeasure control system for an automotive vehicle includes at least one sensor for determining deceleration, if any, of the vehicle during an impact event, as well as a countermeasure deployment timer which is initialized in the event that the determined deceleration exceeds a first threshold. An integrator using the sensed deceleration as an input calculates the time-based displacement of an occupant within the vehicle. A comparator compares the calculated displacement of the occupant with a displacement threshold at the time the countermeasure deployment timer expires. Finally, a controller, which includes a countermeasure deployment timer, as well as the integrator and the comparator, deploys an impact countermeasure in the event that the calculated displacement of the occupant is greater than the displacement threshold when the countermeasure timer expires.  
         [0009]     It is an advantage of a system and method according to the present invention that the deployment of various countermeasures may be controlled as a function of not only the severity of an impact event, but also as a function of whether the occupant is properly seated with a buckled seatbelt, and further as a function of the fore-and-aft location of a vehicle seat in which an occupant is seated, and also as a function of the displacement of the vehicle&#39;s occupant with respect to a seat and/or various countermeasure systems.  
         [0010]     It is a further advantage of a method and system according to the present invention that the logic of the present method and system may be employed with a plurality of different countermeasure devices having different response characteristics and calibration requirements. This permits vehicle development engineers to apply either new or modified countermeasure devices without the necessity of re-engineering the entire countermeasure control system.  
         [0011]     Other advantages, as well as features and objects of the present invention, will become apparent to the reader of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a schematic representation of a portion of a vehicle having an impact event countermeasure control system according to the present invention.  
         [0013]      FIG. 2  is a plot showing time response characteristics of a method and system according to the present invention.  
         [0014]      FIG. 3  is a flow diagram showing operation of a countermeasure control system according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     Vehicle  10  is shown schematically in a partial plan view in  FIG. 1 . Vehicle  10  has four road wheels,  14 , and at least one occupant seat,  28 , which is equipped with a seat track location sensor system,  34 , a MLL,  38 , and a seatbelt pretensioner,  42 . The MLL is but one example of the countermeasures employed in vehicle  10 . Those skilled in the art will appreciate in view of this disclosure, that the present method and the system may be used to control any one or all of the countermeasures disclosed in this specification, or yet other types of countermeasures not disclosed in this specification but known to those skilled in the art and suggested by this disclosure.  
         [0016]     The purpose of seat track position sensor  34  is to alert system controller  18  as to the fore and aft position within vehicle  10 , at which an occupant has placed seat  28 . If seat  28  is in its rearwardmost position, it may be assumed that a person of larger stature is occupying the seat. The present inventive system may use this information to control airbag  24  and adaptive canister vent  26 , as well as adaptive steering column  30 , which is part of steering column system  29 , and which offers a controlled longitudinal collapse characteristic.  
         [0017]     Adaptive airbag tether  22  is used to control the shape of airbag  21  in response to commands of countermeasure system controller  18 . Adaptive canister vent  26  controls the amount of gas or, more precisely, the venting of the gas provided by a gas source, such as a pyrotechnic device. All of the countermeasure devices such as AAT  22 , AACV  26 , MLL  38 , and ASC  30  are all connected with system controller  18 , as is accelerometer  20 .  
         [0018]      FIG. 2  illustrates several of the time/event relationships of the present control system and method. An impact event starts at time zero (t 0 ), followed closely by sensing of an acceleration corresponding to an impact of the vehicle with an object sufficient to warrant the use of countermeasures. Thus, at time t 1 , an impact of vehicle  10  with an object has been sensed by accelerometers which are either distributed about vehicle  10 , as is accelerometer  20 , or by one or more accelerometers sited within system controller  18 . In any event, a first timer, also within controller  18 , is set at time t 1 . This first timer expires at time t 3 . A second timer which is set at time t 2 , expires at time t 4 . Thus, the present system accommodates multiple impact events.  
         [0019]     Curve A of  FIG. 2  is a displacement threshold curve which, if crossed, indicates that deployment of a countermeasure device should be considered. In general, Curve A corresponds to the displacement of an individual within the vehicle with respect to a countermeasure device such as an ASC, or an MLL. Curve A is generally calculated by performing a two-step integration of the sensed vehicle acceleration. As the value of Curve A increases, the distance between an occupant of a vehicle and a facing countermeasure device is decreasing, indicating either that deployment of the countermeasure device should be initiated, or that a performance characteristic of the countermeasure device should be modified. For example, with a MLL  38 , it may become advisable to release the load limiter if the occupant of the vehicle comes within a certain distance of the airbag. For ASC  30 , it may be necessary to allow stroking, or telescopic collapse, of steering column system  29  to a greater or lesser extent, depending upon the proximity of the vehicle&#39;s occupant to the steering column. Controller  18  may calculate a family of curves similar to curve A, employing seat usage characteristics, sometimes called Occupant Classification Sensing, such as an occupant&#39;s position, seatbelt usage, and occupant weight. These characteristics are determined by sensors such as seat track position sensor  34 .  
         [0020]     Curves B and C of  FIG. 2  illustrate the calculated displacement of a vehicle&#39;s occupants during impact events of varying severity. Curves B and C are but two examples of a family of curves evaluated by system controller  18 . Curve B corresponds to a relatively more severe impact, such as an impact with a fixed barrier. Curve C corresponds to an impact with a delayed severity, such as an impact against an offset deformable barrier. With Curve B, the displacement of the occupant crosses displacement threshold Curve A before time t 3  has been reached, and as a result, a countermeasure device will be employed at time t 3 . However, with the impact event illustrated by Curve C, the displacement of the occupant at time t 4  has not crossed threshold displacement Curve A, and such crossing does not incur until time t 5 . Accordingly, countermeasure devices will generally not be deployed until time t 5  has been reached.  
         [0021]      FIG. 3  is a flow chart according to the present invention which generally follows the logic of  FIG. 2 . Each of the family of curves within controller  18  having the purpose of occupant tracking, as explained in connection with curves B and C of  FIG. 2 , may be monitored using the logic of  FIG. 3 . The routine starts at block  300  and moves to block  302 , wherein the occupant seat usage characteristics are determined. These characteristics may include buckle status as determined by means of seatbelt buckle sensor  44  ( FIG. 1 ), or seat position, as determined by sensor  34  ( FIG. 1 ), or occupant weight. Controller  18  uses a measured seat usage characteristic at block  305  to determine whether any particular countermeasure should be deployed. If the answer at block  305  is negative, a countermeasure device such as an ACV will be disabled at block  304 .  
         [0022]     If the routine running within controller  18  reaches an affirmative conclusion at block  305 , the routine moves to block  306 , wherein deployment timer  1 , corresponding to the timer set at time t 1  of  FIG. 2 , is started. This timer may be set in response, for example, to a low severity impact. Moving to block  308 , if timer  1  has not expired, the routine moves to block  310  wherein a question is posed as to whether a high output threshold has been crossed. In other words, the inquiry deals with whether a high-rate of deceleration has been sensed, as would occur when striking a rigid barrier. If the answer is “no” at block  310 , the routine continues with block  308 . If, however, the answer is “yes” at block  310 , the routine moves to block  312 , wherein a second deployment timer, which corresponds to the timer set at time t 2  in  FIG. 2 , is started.  
         [0023]     At block  314 , if timer  2  has not expired, the timer is allowed to count down. If, however, at block  314  timer  2  has expired, the routine moves to block  316 . Block  316  is also reached via block  308 , if the answer to the question posed in block  308  is affirmative. At block  316 , a question is asked regarding whether a displacement threshold, as exemplified by Curve A of  FIG. 2 , has been applied to the countermeasure control system. If a displacement threshold has not been applied, the routine moves to block  320  wherein the countermeasure device is deployed immediately. If however, a displacement threshold has been applied, as verified at block  316 , the routine moves to block  318 , wherein a question is asked regarding whether a vehicle occupant calculation being tracked by the routine, has crossed the displacement threshold. If the vehicle occupant has not crossed the displacement threshold at block  318 , the routine continues to track the calculated occupant displacement at block  318 . If however, the occupant has crossed the displacement threshold at block  318 , the routine moves once again to block  320  wherein the countermeasure is deployed. Then, the routine ends at block  322 .  
         [0024]     Although the present invention has been described in connection with particular embodiments thereof, it is to be understood that various modifications, alterations, and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention set forth in the following claims.