Patent Publication Number: US-9834165-B2

Title: Driver knee bolster deployment control

Description:
BACKGROUND 
     Present supplemental restraints including deployable knee bolsters and air bags are used in motor vehicles to provide occupant protection by providing a reaction element that resists the motion of an occupant in a controlled manner during an impact. Airbags are inflatable and are commonly used to provide increased occupant protection for the torso and head. Knee bolsters are deployed to help resist forward movement of the knees and thighs. Knee bolsters can also be inflatable, but commonly include molded plastic bladders and when fully deployed occupy much less volumetric space than an airbag. Some present knee bolsters reposition a vehicle trim component into a knee area of a passenger compartment upon detection of a collision. Once deployed, present supplemental restraints, especially inflatable supplemental restraints, need to be replaced and associated interior trim components may also need to be replaced. Present supplemental restraints are controlled by and selectively activated by an electronic control unit that receives signals from sensors, and processes such signals using software control logic stored in the electronic control unit. The electronic control unit sends out command signals to the supplemental restraints responsive to the signals received and the control logic. 
     The availability of supplemental restraints and the deployment control command logic each vary with seating position. Present logic assumes that the driver will be in a forward facing position. 
     Possible changes in vehicle interiors, including front seats rotatable to rear facing positions as may be enabled by autonomous vehicles, are rendering current sensing systems and deployment logic inadequate for future vehicle configurations. It is desirable to provide improved occupant sensors and improved supplemental restraint deployment control command logic suited for used with future vehicle configurations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an example of an interior seat arrangement of a vehicle with pivotable front seats in a forward-facing position. 
         FIG. 2  is a perspective view of the example of the interior seat arrangement of  FIG. 1  with the pivotable front seats in a rearward-facing position. 
         FIG. 3  is a side view of an example of an infrared sensor disposed in a vehicle trim panel. 
         FIG. 4  is an exemplary logic diagram flow chart for control of a supplemental restraint. 
         FIG. 5  is an alternative exemplary logic diagram flow chart for control of a supplemental restraint. 
         FIG. 6  is a second alternative exemplary logic diagram flow chart for control of a supplemental restraint. 
         FIG. 7  is an exemplary logic diagram decision chart for control of a supplemental restraint. 
     
    
    
     DETAILED DESCRIPTION 
     Relative orientations and directions (by way of example, upper, lower, bottom, rearward, front, rear, back, outboard, inboard, inward, outward, let, right) are set forth in this description not as limitations, but for the convenience of the reader in picturing at least one embodiment of the structures described. 
       FIG. 1  shows a seat arrangement for a motor vehicle  10  with seats conventionally oriented in a forward-facing direction. The exemplary seats include a pivotable driver seat  12 , a pivotable front passenger seat  14 , and rear seats provided by a fixed rear bench seat  16 . Alternative configurations for each of the seats can be employed. For example, in the case of a larger vehicle having a third row of seats, the rear bench would be located further back, and a middle row, or first rear row of seats would be disposed between the front seats and the rear bench. Each of the first rear row of row seats could be pivotable, and the bench or second rear row could be fixed. Or the second rear row of seats could be provided by pivotable seats, enabling the rear passengers to face in the rearward direction. 
     In the illustrated embodiment, supplemental restraints are disposed in locations to protect the passengers. An exemplary driver side front air bag  18  is disposed in the steering wheel. An exemplary front passenger side front air bag  20  is disposed in a dashboard. An exemplary driver side knee bolster  22  is installed on a lower side of the dashboard in front of driver seat  12 , and a passenger side knee bolster  24  is installed on the lower side of the dashboard in front of passenger seat  14 . 
     A driver side infrared proximity sensor  26  is installed in a driver side interior trim panel  28  that is disposed on an inboard side of a driver foot well  30 . Trim panel  28  is proximate to and borders foot well  30 . The location of sensor  26 , in a line of sight to foot well  30 , enables sensor  26  to emit an unimpeded beam of infrared light from sensor  26  to foot well  30 . Infrared sensor  26  may alternatively be mounted on an outboard side of driver foot well  30  in a door trim panel. The illustrated embodiment of  FIG. 3  shows an active sensor  26  characterized by the inclusion of both an infrared emitter  32  which emits infrared light and an infrared receptor  34  which detects or senses infrared light. Trim panel  28  includes separate apertures for each of emitter  32  and receptor  34 . An exemplary embodiment of sensor  26  includes a plastic housing. Sensor  26  is mounted to panel  28  by conventional means such as heat staking or threaded fasteners to a back side of trim panel  28  opposite a passenger cabin area in which the foot wells are disposed. Active sensors are key to the function of the described embodiments as active sensors are able to detect the presence and location of object and to detect motion. Passive infrared sensors are less expensive than active infrared sensors but are disadvantageously less functional than the active sensors. Passive sensors include only an infrared receptor, are typically limited to use for detecting motion, and are more predisposed to providing false positive indications of foot motion than active sensors. 
     An infrared proximity sensor  37  for the front passenger foot well  36  may be installed in a front passenger trim panel  38 . Infrared sensor  37  may alternatively be mounted on an outboard side of passenger foot well  36  in a door trim panel (not shown). 
     Rear passenger air bags  40  are illustrated as being disposed on a rear surface of seats  12  and  14 . Rear passenger knee bolsters  42  are similarly illustrated as being disposed in a lower area of seats  12  and  14 . A left side rear passenger infrared proximity sensor  44  and a right side rear passenger infrared proximity sensor (not shown) are respectively disposed to detect objects and motion in a left side rear passenger foot well  46  and a right side rear passenger foot well  48  respectively. The exemplary rear sensors are respectively disposed in a left side rear passenger door trim panel  50  and a right hand rear passenger door trim panel (not shown). The rear sensors could alternatively be located further inboard, as in a lower part of rear seat  16  for example. As yet another alternative, rear sensors could be located on the backs of seats  12  and  14  when supplemental restraints  40 ,  42  are disposed in the backs of seats  12  and  14 . Such a location would beneficially fail to detect motion of rear seat occupants when seats  12  and  14  are in a position facing the rear seat occupants. The supplemental restraints  40  and  42 , when directed away from the rear seat occupants due to pivoting of the seats, would not deploy. Alternatively or complementarily, activation of restraints  40  and  42  can be linked to a signal from sensors indicating rotary positions of seats  12  and  14 . Restraints  40  and  42  in a seat  12  or  14  are deactivated when the rotary seat position of a seat indicates that the seat is outside of a predetermined deployment position associated with providing a safety benefit to a rear seat occupant. The predetermined deployment position can be defined as a rotational range. The restraints  40  and  42  will not deploy when the seat in which the restraints are mounted is rotated to a position in which the restraints will not provide any benefit. 
     Active infrared sensors are capable of providing signals that can be used to establish a location of an object relative to at least the sensors. The activation and deactivation of knee bolsters  42  for rear seating positions is, in one exemplary embodiment, controlled as a function of a size of a gap between occupant legs and the back of a more forward seat such as seat  12  or seat  14 . 
     For three-row arrangements having a first row of rear seats (alternatively characterized as a middle row of seats) behind seats  12  and  14  and a second row of rear seats behind the first rear row of rear seats, sensors for the first row may be installed, as described above, in door trim panels, in a lower part of the first row rear seats, or in seats  12  and  14 . Sensors for the second rear row of seat may be installed in trim panels adjacent to the second rear row foot wells, in a lower part of the second row rear seats, or in a back of first row rear seats. 
     Sensors and airbags and knee bolsters collectively comprise a supplemental restraint system. The supplemental restraint system also includes an electronic control unit (not shown), alternatively characterized as a controller or a computer. The electronic control unit is electrically connected to the infrared sensors, as well as other sensors which can include, by way of example, sensors of seat weight load, vehicle speed, accelerometers indicating changes in vehicle speed, and seat position. The sensors provide electrical signals to the electronic control unit indicative of their respective parameters. Samples of the signals are alternatively characterized herein as data or as readings or as data readings or as data values. The airbags and knee bolsters are also electrically connected to the electronic control unit. Such electronic connections may be made with wire or without wire. 
     The electronic control unit includes at least one electronic processor and associated memory. The processor&#39;s operating system software is stored in memory for access by the processor. Also, control software for executing certain predetermined tasks is maintained in memory. The memory also includes a buffer region, or more simply a buffer, facilitating the storage and manipulation of data. The exemplary buffer is provided with a predetermined number of locations to store data, limiting the number of data readings stored in the buffer. When the limited number of readings is reached, the buffer is characterized as being “full.” When the buffer is full, data readings are, in an exemplary embodiment, replaced on a first-in-first-out basis. That is, the oldest data reading in the buffer is overwritten by the most recent reading. The different memory sections can be accommodated either with a single memory device, or with multiple devices dedicated to particular memory functions. The precise structure of the electronic control unit is not critical to the present description. Representations of alternative embodiments of the software are found in  FIGS. 4, 5 and 6 . 
     The electronic control unit is programmed by control software to both activate and deactivate at least the knee bolsters. A knee bolster that has been activated is ready for deployment responsive to an indication, such as data exceeding a certain value from one or more accelerometers that a vehicle impact has occurred. A knee bolster that has been deactivated will not deploy responsive to an indication that a vehicle impact has occurred. 
       FIG. 4  will be discussed with reference to  FIGS. 1, 2 and 3 . When driver seat  12  is occupied, and in a forward facing orientation, it is desirable that the supplemental restraints and particularly the driver position knee bolster be activated in anticipation of a need for possible deployment. When seat  12  is occupied, and in a rearward facing orientation, it is preferred that airbag  18  and knee bolster  22  not deploy. It is also preferred that airbag  40  and knee bolster  42  not deploy when seat  12  is facing rearward.  FIG. 4  illustrates a logic diagram  52  for computer program software which assesses whether there is a forward-facing occupant in the driver seat  12 . More specifically, the software employing the illustrated logic is stored in the electronic control unit and is used to detect the presence of feet in driver foot well  30  by determining if there is an object in foot well  30 . The terms first buffer, first memory buffer and buffer  1  are used interchangeably throughout the following description of  FIG. 4  and in  FIG. 4 . Likewise, the terms second buffer, second memory buffer and buffer  2  are used interchangeably. Also, the buffers associated with the description of a particular seat position are unique to that seat position. So, for example, a driver seat first buffer is distinct from a front passenger seat first buffer. 
     The processor executes the steps illustrated in  FIG. 4  as described below. In a start block  60 , a computer program is initiated. A first memory buffer and a second memory buffer are emptied of stored values as part of an initialization routine in block  61 . The initialization routine of block  61  captures zeroing the registers, reading program instructions from a static memory or other storage into the controller&#39;s random access memory (“RAM”), and other low-level software steps well-known in the software art, and not critical to the present description. The buffers act as means to acquire more than one successive reading from the sensor before changing knee bolster states. The length of the buffers determines the number of data points required before the system changes the knee bolster state. Per block  62 , the driver knee bolster  22  is activated. 
     A driver seat position sensor (not shown) is read per process block  63  to determine the rotational position of seat  12 . The program then moves to decision block  64 . In decision block  64 , the readings are compared to predetermined deployment position value ranges for seat  12 . When the data value from the seat position sensor is outside of the predetermined deployment position range for the seat, the computer moves to process block  78 . The driver knee bolster is deactivated per block  78 . The program moves to decision block  74 . Decision block  74  checks for a termination event. An exemplary termination event is the loss of an ignition signal. When a termination event has been detected, then the program is terminated at end block  76 . When a termination event has not been detected, the program moves back to block  63  to make another reading. 
     Sensor  26  is read per process block  66 . The latest sensor reading of sensor  26  is compared to a predetermined and stored value characterized as an “Object Detection Threshold” per decision block  68 . In accord with decision block  68 , when the latest sensor reading is not greater than the Object Detection Threshold, then the program moves to process block  70 . The most recent reading, or data value, of block  66  is stored in to the second buffer, and the program moves to decision block  72 . 
     Decision block  72  assesses whether the second buffer is full. When the second buffer is not full, the program moves to decision block  74 . Decision block  74  checks for a termination event. An exemplary termination event is the loss of an ignition signal. When a termination event has been detected, then the program is terminated at end block  76 . When a termination event has not been detected, the program moves back to block  63  to make another reading. When decision block  72  determines that the second buffer is full, the program, moves to process block  78 . Per block  78 , driver knee bolster  22  is deactivated. After block  78 , the program cycles back to block  63  to make another reading, but only after confirming in decision block  74  that a termination event has not been detected. 
     When the latest sensor reading or data value of block  66  is greater than the Object Detection Threshold, then, per decision block  68 , the program moves from block  68  to process block  79 . Per block  79 , the second memory buffer is emptied. This step causes the second memory buffer to start counting over again from zero the next time the proximity sensor reading drops below the object detection threshold. The program then move to decision block  80 . Decision block  80  assesses whether the first memory buffer is full. When the first memory buffer is not full, the program goes to block  82  where the latest reading is stored in the first buffer. When the first memory buffer is full, the program deletes the oldest data from the memory buffer, as per block  84 , and then goes to block  82  where the latest reading is stored in the first buffer. The program then moves from block  82  to decision block  86  to assess whether the first memory buffer is full after storing the latest reading. When the first memory buffer is not full, the program cycles back to block  66  and again reads the proximity sensor. When the first memory buffer is determined to be full by block  86 , the program cycles to process block  88 . The program does not progress on to block  88  until the buffer is full. Since the first memory buffer is not emptied, the memory buffer only delays the decision to activate the driver knee bolster the first time the software routine is executed in a drive cycle. If the knee bolter is subsequently deactivated, a single subsequent reading above the object detection′ threshold will reactivate it. In an alternative embodiment, the first buffer is filled in the initialization routine of block  61  and the first buffer automatically replaces the oldest reading with the newest reading. In block  88 , the driver knee bolster is activated. 
     After block  88 , the program proceeds on to decision block  74  to assess whether a termination event has been detected. If yes, then the program ends at block  76 . If not, then the program cycles back to block  63  for a new reading. The preceding logic prevents the deployment of a driver knee bolster when the driver seat is facing rearward. 
       FIG. 5  will be discussed with reference to  FIGS. 1, 2 and 3 . The illustrated exemplary rear seat  16  is fixed in a forward facing position, and has two seating positions, a left position and a right position. While the functionality is the same for both seating positions, the following discussion will, for the sake of clarity, use the left seating position as an example. When seat  16  is occupied and the front seats  12 ,  14  are in a forward facing orientation, it is desirable that the rear seat supplemental restraints  40 ,  42  be activated in anticipation of a need for possible deployment. When seat  16  is not occupied, it is preferred that airbags  40  and knee bolsters  42  not deploy.  FIG. 5  illustrates a logic diagram  54  for computer program software which assesses whether there is an occupant in rear seat  16 . More specifically, the software employing the illustrated logic is stored in the electronic control unit and is used to detect the presence of feet in rear foot well  46  by determining if there is motion in foot well  46 . 
     The processor executes the steps illustrated in  FIG. 5  as described below. In a start block  90 , the computer program is initiated. A first memory buffer, a second memory buffer and a third memory buffer are all emptied of stored values as part of an initialization routine in block  92 . The initialization routine of block  92  captures zeroing the registers, reading the process into the controller&#39;s random access memory (“RAM”), and other low-level software steps well-known in the art of controller software, and not critical to the present description. Knee bolster  42  is activated as part of the initialization routine. The terms first buffer, first memory buffer and buffer  1  are used interchangeably throughout the following description of  FIG. 5  and in  FIG. 5 . Likewise, the terms second buffer, second memory buffer and buffer  2  are used interchangeably and third buffer, third memory buffer and buffer  3  are used interchangeably. 
     Front passenger seat position sensors (not shown) are read per process block  94  to determine the rotational positions of seats  12  and  14 . The program then moves to decision block  96 . In decision block  96 , the readings are compared to predetermined deployment position value ranges for seats  12  and  14 . When the data value from a seat&#39;s position sensor is outside of the predetermined deployment position range for the seat, the computer moves to process block  98 . The rear knee bolster is deactivated per block  98 . The program moves to decision block  100 . Decision block  100  checks for a termination event. An exemplary termination event is the loss of an ignition signal. When a termination event has been detected, then the program is terminated at end block  102 . When a termination event has not been detected, the program moves back to block  94  to make another reading. 
     When, in block  96 , the data value from a seat&#39;s position sensor is within the predetermined deployment position range for the seat, the computer moves to process block  104 . Sensor  44  is read per process block  104 . The most recent reading of sensor  44  is then stored in the first buffer per process block  106 . The first buffer is automatically updated on a first-in-first-out basis. The program moves to decision block  108  where the latest sensor reading of sensor  44  is compared to a predetermined and stored value characterized as an “Object Detection Threshold.” In accord with decision block  98 , when the latest sensor reading is not greater than the Object Detection Threshold, then the program moves to process block  110 . 
     The most recent reading, or data value, of block  104  is stored in the third buffer on a first-in-first-out basis per block  110 , and the program moves to decision block  112 . Decision block  112  assesses whether the third buffer is full. When the third buffer is not full, the program moves to decision block  100 . Decision block  100  checks for a termination event. When a termination event has been detected, then the program is terminated at end block  102 . When a termination event has not been detected, the program moves back to block  94  to make another reading. When decision block  112  determines that the third buffer is full, the program empties the first buffer in block  113 , and then moves to process block  98 . Per block  98 , knee bolster  42  is deactivated. After block  98 , the program cycles back to block  94  to make another reading, but only after confirming in decision block  100  that a termination event has not been detected. 
     When decision block  108  determines that the most recent reading made in block  104  of sensor  44  is above the Object Detention Threshold, then the program moves to process block  114  which directs the emptying of the third buffer. The program then moves to process block  116 . 
     In block  116 , a motion detection process is performed on the values in the first buffer. The exact nature of the process is unimportant, but it results in a value suited to assessing whether or not there is a trend in the values of the proximity sensor readings indicative of a change in the value of the proximity sensor readings indicative of motion. An exemplary process includes the step of calculating the variance of the latest value stored in the first buffer relative to all of the values presently in the first buffer, and storing the variance of the most recent reading in a second buffer. The second buffer stores variance values for each of the buffered proximity sensor readings. The exemplary performance motion detection process would then add up all of the values of the second buffer to derive a motion detection process output. The program then moves to decision block  118 . 
     Decision block  118  assesses whether or not the motion detection process output exceeds a pre-determined threshold. When it does not, as is characteristic of no motion being detected, block  118  directs the program to block  98  which deactivates the rear passenger knee bolster. After block  98 , the program proceeds on to decision block  100  to assess whether a termination event has been detected. If yes, then the program ends at block  102 . If not, then the program cycles back to block  94  for a new reading. When block  118  determines that the motion detection process output exceeds the pre-determined threshold, as is characteristic of motion being detected, then the program is directed to process block  119 . Block  119  activates the rear passenger knee bolster. After block  119 , the program proceeds on to decision block  100  to assess whether a termination event has been detected. If yes, then the program ends at block  102 . If not, then the program cycles back to block  94  for a new reading. Logic diagram  54  does not include a decision box expressly checking to see if the first memory buffer is full, only because the first buffer is characterized as being automatically maintained in the illustrated embodiment. Alternatively, a decision block to check whether the buffer is full, such as block  80  of logic diagram  52  or block  142  of logic diagram  56  could be employed. 
       FIG. 6  will be discussed with reference to  FIGS. 1, 2 and 3 . The illustrated exemplary seat  14  is illustrated in  FIG. 1  in a forward facing position and is pivotable, as shown in  FIG. 2 , to a rearward facing position. When seat  14  is occupied, and in a forward facing orientation, it is desirable that the supplemental restraints  20 ,  24  be activated in anticipation of a need for possible deployment. When seat  14  is occupied, and is in a rearward facing orientation, it is preferred that airbag  20  and knee bolster  24  not deploy. It is also preferred that airbag  40  and knee bolster  42  not deploy when seat  14  is facing rearward.  FIG. 6  illustrates a logic diagram  56  for computer program software which assesses whether there is a forward-facing occupant in front passenger seat  14 . More specifically, the software employing the illustrated logic is stored in the electronic control unit and is used to detect the presence of feet in front passenger foot well  36  by determining if there is motion in foot well  36 . 
     The processor executes the steps illustrated in  FIG. 6  as described below. In a start block  120 , the computer program is initiated. A first memory buffer and a second memory buffer are each emptied of stored values as part of an initialization routine in block  121 . The initialization routine of block  121  also captures zeroing the registers, reading the process into the controller&#39;s random access memory (“RAM”), and other low-level software steps well-known in the art of controller software, and not critical to the present description. The program then moves to process block  122 . Knee bolster  24  is activated in accord with process block  122 . The terms first buffer, first memory buffer and buffer  1  are used interchangeably throughout the following description of  FIG. 6  and in  FIG. 6 . Likewise, the terms second buffer, second memory buffer and buffer  2  are used interchangeably and third buffer, third memory buffer and buffer  3  are used interchangeably. 
     A front passenger seat position sensor (not shown) is read per process block  123  to determine the rotational position of seat  14 . The program then moves to decision block  124 . In decision block  124 , the readings are compared to predetermined deployment position value ranges for seat  14 . When the data value from the seat position sensor is outside of the predetermined deployment position range for the seat, the computer moves to process block  136 . The front passenger knee bolster is deactivated per block  136 . The program moves to decision block  132 . Decision block  132  checks for a termination event. An exemplary termination event is the loss of an ignition signal. When a termination event has been detected, then the program is terminated at end block  134 . When a termination event has not been detected, the program moves back to block  123  to make another reading. 
     Sensor  37  is read per process block  125 . The latest sensor reading of sensor  37  is compared to a predetermined and stored value characterized as an “Object Detection Threshold” per decision block  126 . In accord with decision block  126 , when the latest sensor reading is not greater than the Object Detection Threshold, then the program moves to process block  128 . The latest reading or data value from sensor  37  per block  125  is stored in the second memory buffer per block  128 . The second buffer is automatically updated on a first-in-first-out basis. 
     After block  128 , the program moves to decision block  130 . Decision block  130  assesses whether the second buffer is full. When the second buffer is not full, the program moves to decision block  132 . Decision block  132  checks for a termination event. An exemplary termination event is the loss of an ignition signal. When a termination event has been detected, then the program is terminated at end block  134 . When a termination event has not been detected, the program moves back to block  123  to make another reading. When decision block  130  determines that the second buffer is full, the program first empties the first memory buffer in process block  135 , and then moves to process block  136 . Per block  136 , front passenger knee bolster  24  is deactivated. After block  136 , the program cycles back to block  123  to make another reading, but only after confirming in decision block  132  that a termination event has not been detected. 
     When, per decision block  126 , the latest sensor reading of block  125  is greater than the Object Detection Threshold, then the program moves from block  126  to process block  138  where the second memory buffer is emptied. The program then moves to process block  140 . As per block  140 , the latest reading is stored in the first memory buffer. The first buffer is automatically updated on a first-in-first-out basis. The program then moves to decision block  142 . 
     Decision block  142  assesses whether the first memory buffer is full. When the first memory buffer is not full, the program goes to block  125  where another value from sensor  37  is read. When the first memory buffer is full, then the program advances to process block  144 . In block  144 , a motion detection process is performed on the values in the buffer. The exact nature of the process is unimportant, but it results in a value suited to assessing whether or not there is a trend in the values of the proximity sensor readings indicative of a change in the value of the proximity sensor readings indicative of motion. An exemplary process includes the step of calculating the variance of the latest value added to the buffer relative to all of the values presently in the buffer, and storing the variance of the most recent reading in a new third buffer. The third buffer includes variances for each of the buffered proximity sensor readings. The exemplary performance motion detection process would then add up all of the values of the third buffer to derive a motion detection process output. 
     The program moves from block  144  to decision block  146 . Decision block  146  assesses whether or not the motion detection process output exceeds a pre-determined threshold. When it does not, as is characteristic of no motion being detected, block  146  directs the program to block  136  which deactivates the front passenger knee bolster. After block  136 , the program proceeds on to block  132  to assess whether a termination event has been detected. If yes, then the program ends at block  134 . If not, then the program cycles back to block  123  for a new reading. When block  146  determines that the motion detection process output exceeds the pre-determined threshold, as is characteristic of motion being detected, then the program is directed to process block  148 . Block  148  activates the front passenger knee bolster  24  and front passenger airbag  20 . After block  148 , the program proceeds on to decision block  132  to assess whether a termination event has been detected. If yes, then the program ends at block  134 . If not, then the program cycles back to block  123  for a new reading. 
       FIG. 7  illustrates an exemplary logic diagram decision chart  58  for control of supplemental restraints that is particularly applicable to the deployment of supplemental restraints for passengers and especially front passengers. Chart  58  compares decisions made based on a variety of decision criteria. The introduction of leg motion as an available decision criteria beneficially enables knee bolster deployment. An exemplary software program executed by the electronic control unit employs the illustrated logic to activate and deactivate the knee bolster. 
     In some circumstances, particularly in the front passenger location, it is desirable to activate the air bag even when the passenger weight is less than that of a fifth percentile female. While the passenger may be lighter in weight, they may still be of sufficient height and strength to benefit from deployment of all available supplemental restraints. Because the driver of a typical vehicle is of at least a certain size to enable operation of the vehicle, the driver is presumed to be sufficiently large to sustain at least a partial air bag deployment without serious injury. No such presumption can be made regarding the front passenger. For example, the front passenger seat may be occupied by a rearward facing infant, a three year old child, a 6 year old child or an adult occupant of varying sizes as noted in chart  58 . However, as noted above, a front passenger perceived as too small to safely withstand an airbag deployment based solely on weight, as shown in the supplemental restraint activate/deactivate decisions shown for the case based on minimum base threshold related to a certain base value may be tall enough to benefit from passive restraint deployment. The size of a front passenger may be based on data values from a weight sensor installed in the seat and the motion detection sensors. Weight sensors can include commercially available pressure mats integrated into the structure of the seat. Other forms of weight sensors include strain gauge devices and bladder-type sensors. The chart  58  of  FIG. 7  illustrates conditions under which supplemental restraints, including air bags and knee bolsters would be activated when leg position and movement are sensed, and under identical conditions, but without the benefit of leg position and movement sensing, would be deactivated. As one example, an undersized adult female, lighter than a 5 th  percentile female in front passenger seat  14  would not experience a supplemental restraint deployment during an impact event in a vehicle without leg position and motion sensing. However, the ability to sense leg position and motion enables the beneficial deployment of supplemental restraints for an otherwise undersized seat occupant, thereby providing enhanced occupant protection. 
     It is to be understood that the present disclosure, including the above description and the accompanying figures and below claims, is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to claims appended hereto, along with the full scope of equivalents to which such claims are entitled. Unless otherwise stated or qualified herein, all claim terms are intended to be given their plain and ordinary meanings. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the disclosed subject matter is capable of modification and variation.