United States Patent [19]
`Cashier
`
`lllllllllllllllllll-lllll-lllllllllllm 111111111� 11111111111
`
`
`
`
`
`US005732375A
`[11] Patent Number: 5,732,375
`Mar. 24, 1998
`[45] Date of Patent:
`
`OR ALLOWING
`[54] METHOD OF INHIBITING
`AIRBAG DEPLOYMENT
`
`[75] Inventor:
`Robert John Cashier, Kokomo, Ind.
`
`[73] Assignee:
`
`
`Delco Electronics Corp., Kokomo, Ind.
`
`12/1995 Schousek ................................ 180/268
`5,474,327
`2/1996 Blackburn et al . ..................... 280/735
`5,494,311
`10/1996 Barms ..................................... 364/559
`5,570,301
`1111996 Meister et al . .......................... 280/735
`5,570,903
`
`2/1997 Blackburn et al. . .................... 280/735
`5,605,348
`
`3/1997 Zeidler et al. . .................. 364/424.055
`5,612,876
`
`OTHER PUBLICATIONS
`
`[21] Appl. No.: 566,029
`
`Nguyen
`
`Research Disclosure-Jan. 1994 #357-"Method for Sens­
`
`
`
`
`
`
`ing Occupant Mass and Position." Disclosed Anonymously.
`[22] Filed: Dec. 1, 1995
`Primary Examiner-Tan Q.
`[51] Int CL 6 ••••••••••••••••••••••••••••• B60R 21132; G06F 17/40
`Auomey, Agent, or Finn-Mark A. Navarre
`180/273; [52] U.S. Cl • .............................. 701/45; 701/46;
`
`
`280/735
`ABSTRACT
`[57]
`[58] Field of Search .....................
`
`364/424.055, 424.056,
`An array of pressure sensors on a vehicle passenger seat
`
`
`
`
`
`364/424.057, 567, 568; 180/271, 282,268,
`
`
`
`senses the presence of an occupant including an infant seat
`
`
`273; 307/15.1; 340/436, 438; 280/735,
`
`and determines whether the infant seat faces forward or
`
`730.ol, 730.02
`
`
`rearward. A microprocessor coupled to the sensors deter­
`
`
`based on the mines whether to allow or inhibit deployment
`
`sensor load forces and the pattern of loading. The pattern can
`
`identify an infant seat and pattern and loading determine its
`Local areas are checked to detect child occu­
`orientation.
`5,010,774
`4/1991 Kiko et al . ......................... 73/862.042
`pants. Fuzzy logic is used to determine loading and to
`5,161,820
`11/1992 Vollmer ................................ 280/730.1
`
`recognize patterns.
`5,232,243
`8/1993 Blackburn et al ...................... 280/732
`5,384,716
`1/1995 Araki et al. ............................. 364/557
`10/1995 Mazur et al . ........................... 280/735
`5,454,591
`
`[56]
`
`References Cited
`
`U.S. PATENf DOCUMENI'S
`
`19 Claims, 4 Drawing Sheets
`
`IPR2016-00291 - Ex. 1001
`Toyota Motor Corp., Petitioner
`
`1
`
`

`
`U.S. Patent Mar. 24, 1998
`Sheet 1 of 4
`FIG - 1
`
`5,732,375
`
`FIG - 2
`
`5 10 15 20 25 30 35 40 45
`
`[§]
`
`[1]
`
`5
`
`10·
`
`15 IT]
`
`20
`
`�
`
`[[] []]
`25
`30 [I] 0 � 0]
`[I]
`[ill
`35
`
`40
`
`2
`
`

`
`FIG· 3 hNPUT 12\ _F36
`
`FIG- 4
`
`ADJUST DATA WITH BIAS I 38
`
`AND LOWPASS FILTER
`THE DATA
`
`FROM FILTERED DATA
`
`COMPUTE ALL DECISION
`MEASURES
`
`40
`
`42
`
`INHIBIT � �
`
`ALLOW
`
`46----. I
`
`�
`
`I ....--48
`
`TURN ON I
`
`INHIBIT LIGHT
`
`I TURN ON I
`
`ALLOW LIGHT
`
`COMPUTE DECISON MEASURES
`
`TOTAL FORCE = SUM
`OF SENSOR VALUES
`• COMPUTE FUZZY CONTR.
`
`DETERMINE EACH LOAD RATING
`
`COMPUTE
`• TOTAL LOAD R ATING
`• FUZZY CONTR.
`
`CHECK FOR LOCALIZED A REA
`I
`SET FLAG FOR
`• ALL F RONT
`• ALL LEFT
`• ALL RIGHT
`• ALL REAR
`
`�4o
`
`50
`
`r 52
`
`54
`
`56
`
`I
`
`COMPUTE FORCEAND
`FUZZY CONTR. FOR
`• FRONT PAIR
`• REAR PAIR
`I • RIGHT PAIR
`• LEFT PAIR
`• CENTER FOUR
`
`r-58
`
`I
`
`TO DECISION ALGORITHM }
`
`d
`•
`00
`•
`1-d =
`� � a
`
`�
`�
`:;
`N
`��
`
`1-" \Cl \Cl 00
`
`r.t:J ;
`(!) ......
`N
`0 �
`�
`
`Ol � "'
`w
`N � w
`"' Ol
`
`3
`
`

`
`U.S. Patent Mar. 24, 1998
`
`Sheet 3 of 4
`
`5,732,375
`
`FORCE OR LOAD
`FUZZY
`CONTRIBUTION
`FIG- 5
`
`b
`
`c
`
`FORCE
`OR LOAD
`
`4 --------,-------- -·---------
`1
`I
`
`LOAD RATING
`
`FIG- 6
`
`o�------�----------------�
`d
`
`LOAD
`
`5 1 0 15 20 25 30 35 40 45
`
`5
`
`10
`
`15
`
`FIG -7 20
`25
`
`30
`
`35
`
`40
`
`FIG- 9
`
`·'-·FRONT
`
`LEFT
`
`•• [ill :J
`• ..A
`( [[]
`[]]
`,--RIGHT
`\ ...
`' I
`---·REAR
`I I
`I
`I i[g] '
`.m
`[ITJ (":
`rn
`I '
`! \ [I}\
`[Q] j ,'
`' I
`.. -.. -----....----
`./ ,' ,
`
`\
`
`'
`..
`
`______
`
`YES
`
`FRONT PAIR LOADED
`AND TOTAL FORCE > Y
`
`4
`
`

`
`U.S. Patent Mar. 24, 1998
`
`Sheet 4 of 4
`
`5,732,375
`
`60
`
`68
`
`Hl
`
`INHIBIT
`
`INFANT SEAT TYPE
`
`62
`
`ALLOW
`
`LOCALIZED FORCE
`AND FLAG
`
`HI
`
`TOTAL LOAD RATING
`
`FRONT FORCE & ALL FRONT FLAG
`
`LEFT FORCE & ALL LEFT FLAG
`
`74
`
`76
`
`RIGHT FORCE & ALL RIGHT FLAG
`
`78
`
`REAR FORCE & ALL REAR FLAG
`
`80
`
`HI
`
`CENTER GROUP FORCE
`
`HI
`TOTAL FUZZY VALUE
`
`84
`
`FIG- 8
`
`5
`
`

`
`1
`METHOD OF INHffiiTING OR ALLOWING
`AIRBAG DEPLOYMENT
`
`5,732,375
`
`2
`
`FIELD OF THE INVENTION
`
`BACKGROUND OF THE INVENTION
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`sample each sensor, determine a total weight parameter by
`
`
`summing the pressures, and determine the pattern of pres­
`
`sure distribution by evaluating local groups of sensors.
`Total force is sufficient for proper detection of adults in
`5 the seat, but the pattern recognition provides improved
`
`
`detection of small children and infant seats. To detect infant
`This invention relates to occupant restraints for vehicles
`
`seats, all patterns of sensor loading which correspond to the
`and particularly to a method using seat sensors to determine
`imprints of various seats are stored in a table and the
`seat occupancy for control of airbag deployment.
`detected sensor pattern is compared to the table entries.
`10 Front and rear facing seats are discriminated on the basis of
`
`total force and the loading of sensors in the front of the seat.
`The expanding use of supplemental inflatable restraints
`
`
`
`The pattern recognition for detecting children is made
`
`(SIRs) or airbags for occupant protection in vehicles increas­
`possible by applying fuzzy logic concepts to the pressure
`ingly involves equipment for the front outboard passenger
`
`readings for each sensor in the array and assigning a load
`seat. The driver side airbag has been deployed whenever an 15
`rating to each sensor. Pattern recognition is also enhanced by
`imm inent crash is sensed. The position and size of the driver
`
`
`sampling several pairs of sensors, applying leveling tech­
`is fairly predictable so that such deployment can advanta­
`nique to them, and computing a measure for the area of the
`geously interact with the driver upon a crash. The passenger
`
`
`seat covered by each pair. For all measures calculated within
`seat, however, may be occupied by a large or a small
`
`the algorithm, a contribution is made to an overall fuzzy
`occupant including a baby in an infant seat. It can not be 20
`rating which is used to handle marginal cases.
`assumed that a passenger of any size is at an optimum
`position (leaning against or near the seat back). An infant
`seat is normally used in a rear facing position for small
`The above and other advantages of the invention will
`
`babies and in a forward facing position for larger babies and
`
`
`become more apparent from the following description taken
`small children. While the forward facing position approxi-25
`
`in conjunction with the accompanying drawings wherein
`
`mates the preferred position for airbag interaction, the rear
`like references refer to like parts and wherein:
`
`facing position places the top portion of the infant seat close
`FIG. 1 is a schematic diagram of an SIR system incor­
`to the vehicle dash which houses the airbag. In the latter
`porating a seat occupant detector;
`
`event, it is desirable to prevent deployment of the airbag.
`It has been proposed in U.S. Pat. No. 5,474,327
`which 30
`FIG. 2 is a position diagram of seat sensors for the system
`of FIG. 1, according
`to the invention;
`will issue Dec. 12, 1995, entitled VEHICLE OCCUPANT
`RESTRAINT WITH
`SEJIT PRESSURE SENSOR and
`
`FIG. 3 is a flow chart representing an overview of an
`assigned to the assignee of this invention, to incorporate
`
`
`algorithm for determining deployment permission according
`
`pressure sensors in the passenger seat and monitor the
`to the invention;
`35
`
`
`
`response of the sensors by a microprocessor to evaluate the
`FIG. 4 is a flow chart representing
`a method of computing
`
`weight distribution and determine the type of occupant and
`decision measures used in the algorithm of FIG. 3;
`
`the facing direction of an infant seat. The sensor arrange­
`FIG. 5 is a graphical representation
`of a function used in
`
`
`ment and the algorithm successfully cover most cases of seat
`fuzzy logic for total force and load ratings;
`occupancy. It is desirable, however,
`to encompass every case
`40
`of a function used in
`FIG. 6 is a graphical representation
`of seat occupancy.
`
`fuzzy logic for determining load rating;
`SUMM ARY OF THE INVENTION
`
`FIG. 7 is a position diagram of seat sensors illustrating
`sensor grouping;
`It is therefore an object of the invention to detect a
`FIG. 8 is a flow chart for deployment decision, according
`
`comprehensive range of vehicle seat occupants including
`45 to the invention; and
`
`infant seats for a determination of whether an airbag deploy­
`FIG. 9 is a flow chart representing the logic for deter­
`
`ment should be permitted. Another object in such a system
`
`mining the facing direction of an infant seat as required by
`
`is to determine whether an infant seat is facing the front or
`the algorithm of FIG. 8.
`
`the rear. Another object is to include sensitivity to the
`possible seating positions of small children.
`50
`DESCRIPTION OF THE INVENTION
`A SIR system, as is well known, has an acceleration
`Referring to FIG. 1, a SIR system includes
`a SIR module
`
`sensor to detect an impending crash, a microprocessor to
`13 coupled to a seat occupant sensing system 14. The SIR
`
`process the sensor signal and to decide whether to deploy an
`15 mounted on the
`
`airbag, and a deployment unit fired by the microprocessor.
`module 13 includes an accelerometer
`if an occupant 55
`An occupant detection system can determine
`vehicle body for sensing an impending crash, a micropro­
`
`cessor 16 for receiving a signal from the accelerometer and
`or infant seat is positioned in a way to not benefit from
`
`deployment, and then signaling the microprocessor whether
`
`
`for deciding whether to deploy an airbag. An airbag deploy­
`
`ment unit 18 is controlled by the microprocessor 16 and fires
`to allow or inhibit deploying the airbag.
`
`
`a pyrotechnic or compressed gas device to inflate an airbag
`
`located in the seat, can garner A dozen sensors, judicially
`
`20,
`60 when a deploy co mma
`
`nd is received. A fault indicator
`sufficient pressure and distribution information to allow
`
`
`also controlled by the microprocessor 16 will show a failure
`
`
`determination of the occupant type and infant seat position.
`of the seat occupant sensing system 14.
`This information, in turn, can be used as desired to inhibit
`14 comprises a micro­
`
`SIR deployment. The sensors are arranged symmetrically
`The seat occupant sensing system
`processor 22 having a 5 volt supply and an enabling line 24
`
`about the seat centerline and includes a front pair, a right
`provided with a 5 volt enabling pulse, and a
`pair, a rear pair, a left pair and four in the center. Each sensor
`65 periodically
`is a very thin resistive device, having lower resistance as
`
`series of voltage dividers coupled between the enabling ·line
`24 and ground. Each voltage divider has a fixed resistor
`
`pressure increases. A microprocessor is programm ed to
`26
`
`
`6
`
`

`
`3
`
`5,732,375
`
`4
`
`The next step in F1G. 4 is to determine the load rating of
`in series with a pressure sensor or variable resistor 28, and
`
`
`
`
`
`the junction point of each resistor 26 and variable resistor 28
`
`each sensor <52>. The load rating is a measure of whether
`to an ND port 30 of the microprocessor
`the. sensor is detecting some load and is used for pattern
`is connected
`22. The
`line 24 and
`
`
`recognition pwposes. Low loads present a borderline case
`
`microprocessor 22 controls the pulse on enabling
`reads each sensor 28 voltage during the pulse period. The
`5 which is rated by fuzzy logic according
`
`to a function similar
`to that of F1G. 5. As shown in F1G. 6, if a load is below a
`
`microprocessor 22 analyzes the sensor inputs and issues a
`base value d, which may be four, the rating is zero and if it
`decision whether to inhibit airbag deployment and the
`
`
`decision is coupled to the microprocessor 16 by a line 32.
`is above the base value it is the difference between the base
`
`
`
`The microprocessor 22 also monitors its decisions for con­
`and the measured load up to a limit value of, say, four. The
`and issues a fault signal on line 34 to the micro­
`sistency
`10 total load rating is calculated <54> by summing the indi­
`
`processor 16 if faults continue
`to occur over a long period.
`
`
`vidual sensor ratings and the fuzzy contribution of the total
`26 is. for example. 10 kohrns and the
`Each fixed resistor
`load rating is again determined as in HG. 5 where a total
`vary between 10 kohms at high pressure
`variable resistors
`and 100 kohrns at low pressure.
`
`load below a minimum threshold b is zero, a total load above
`Then the voltage applied to
`the minimum is the total load minus the minimum threshold
`the ports 30 will vary
`with pressure. Each sensor comprises
`15 up to a limit at maximum threshold c. The minimum
`two polyester sheets each having a film of resistive ink
`
`threshold may be four, for example, and the maximum
`may be 24.
`
`
`
`connected to a conductive electrode, the two resistive films
`threshold
`
`
`contacting one another such that the resistance between
`Next a check is made for force concentration in a local­
`
`
`
`
`electrodes decreases as pressure increases. Such pressure
`
`ized area <56>. Four overlapping localized areas are defined
`
`sensors are available as ALPS pressure sensors from Alps
`20 as shown in F1G. 7. The front four sensors 1, 6, 7 and 12 are
`Electric Co. Ltd, Tokyo. Japan.
`in the front group, the rear eight sensors 2, 3, 4, 5, 8, 9, 10
`The mounting arrangement of sensors 28 on a bottom
`and 11 are in the rear group, the left eight sensors 1, 2, 3. 4,
`bucket seat cushion is shown in F1G. 2. The sensors are
`5. 6, 8, and 9 are in the left group, and the eight sensors 4,
`numbered 1-12 according to seat location. A left pair of
`5, 7, 8, 9,10, 11, and 12 are in the right group. The algorithm
`sensors 1 and 2 are on the left side of the seat with sensor
`25 determines if the pressure
`
`is all concentrated in one group by
`
`2 to the rear and slightly inboard of sensor 1. Sensors 11 and
`
`summing the load ratings of the sensors in each group and
`
`
`12 are the corresponding right pair of sensors. A front pair
`lf the rating sum of any
`comparing to the total load rating.
`of sensors 6 and 7 are at the front of the seat and a rear pair
`group is equal to the total rating, a flag is set for that group
`of sensors 3 and 10 are at the rear. The four remaining
`(all right, all front etc.).
`sensors 4, 5, 8 and 9 are the center group of sensors. Sensors
`and are just in front of 30
`Finally the force and fuzzy contribution is computed for
`
`5 and 8 are astride the seat centerline
`each pair of sensors and for the center group <58>. The force
`
`sensors 4 and 9. The center group is positioned just to the
`rear of the seat middle.
`
`on each pair is used to detect occupants such as small
`children which can easily sit in one small area of the seat.
`The method of operation is illustrated by a series of
`
`
`These measures are looking for the pressure to be evenly
`
`flowcharts wherein the functional description of each block
`35 distributed
`over the two sensors of the pair. To accomplish
`in the chart is accompanied by a number in angle brackets
`
`
`this the algorithm looks at each pair, determines the mini­
`
`
`<nn> which corresponds to the reference number of the
`
`mum value of the two sensors, and clip the higher one to a
`shown in F1G. 3 wherein the
`
`block. The overall operation is
`calibrated "delta" from the lower. lf the force is evenly
`22 <36> and
`
`sensor values are read by the microprocessor
`distributed over the two sensors the values will be about
`
`
`the data is adjusted by bias correction and low pass filtering
`
`40 equal and the sum will be unaffected by clipping. The sum
`<38>. One sensor at a time is turned on, sampled four times
`
`of the two sensor forces, as adjusted, comprise the force
`
`
`and averaged. Then a bias calibrated for each sensor is
`
`measure of the pair. The fuzzy contribution of each pair is
`
`
`subtracted from each sensor reading, and the data is filtered
`equal to the force measure of the pair but limited to a
`on the order of 1 second. Then all
`maximum value such as 20 which is calibrated separately
`with a time constant
`for
`
`decision measures are computed <40> and decision algo­
`45 each pair. The center group measure
`is the sum of the sensor
`
`
`rithms are run <42>. illtimately a decision is made to allow
`
`forces and the fuzzy contribution is equal to the sum of the
`
`or inhibit airbag deployment <44>. Then either an inhibit
`maximum
`four sensors but limited to a calibrated
`value.
`light is turned on <46> or an allow light is turned on <48>.
`F1G. 4 shows the algorithm for computing decision
`mea­
`sures 40. Total force
`
`is calculated by summing the sensor
`SENSOR
`for the total 50
`values and a fuzzy contribution is calculated
`Pattern 1 2 3 4 5 6 7 8 9 10 11 12
`force <50>. Each sensor produces a voltage which is
`as a digital value in the range of 0-255. The
`expressed
`on the order of 0-50. however. An empty
`1
`u L L
`L L u
`u L L u
`typical range is
`0 after the bias adjustments.
`u u
`2 L
`u
`u
`L
`3 L
`u u u L u u
`seat will have a total force near
`A fully loaded seat could go up to about 3000 but 2000 is 55
`4
`L
`L L u L
`L
`L
`5
`L u u
`u u
`L
`more likely. For discrimination pwposes, the inhibit/allow
`is less then 255 and for reporting to the display
`6 u L u u L u u
`software, the value is clipped to 255. The total fuzzy
`u L u
`u u
`L u
`7
`u u L L u u
`8 L
`LX L
`9 LX L
`u
`u
`
`
`contribution is determined according to the function shown
`LX L
`u u
`10
`in F1G. 5. lf the total force is below a minimum or inhibit 60
`11 L
`L
`L
`threshold b. the fuzzy value is zero; if it is above a maximum
`12 L
`u
`u
`or allow threshold, the fuzzy value is the difference between
`and if it is between the
`
`the inhibit and allow thresholds;
`
`thresholds the fuzzy value is equal to the force value minus
`The measured values, ratings, patterns and flags are used
`for each 65
`
`
`
`the inhibit threshold. The thresholds are calibrated
`in deciding whether to allow or inhibit deployment. As
`shown in HG. 8, the decision algorithm 42 first decides if
`
`
`
`application; they may be for example, an inhibit threshold of
`<60> and if so whether the
`
`32 and an allow threshold of 128.
`rails of an infant seat are detected
`
`
`threshold
`
`L
`LX L
`L
`L
`
`7
`
`

`
`5,732,375
`
`6
`5
`
`allowing deployment for a forward facing seat; and
`seat is facing forwardly or rearwardly <62>. Deployment is
`
`allowed for a forward facing seat and inhibited for a rear
`
`inhibiting deployment for a rearward facing seat.
`facing seat. This is determined as shown in FIG. 9 wherein
`
`3. The method of airbag control as defined in claim 2
`if the total force
`
`is greater than a certain value <64> the seat
`wherein the step of determining a pattern of sensor loading
`is allowed. If not, and the
`5 comprises detecting which sensors are below a first load
`
`is forward facing and deployment
`front pair of sensors is loaded and the total force is greater
`
`threshold and which sensors are above a second load thresh­
`
`
`than another set value <66>, the seat is forward facing and
`old.
`
`deployment is allowed. Otherwise the seat is rear facing and
`4. The method of airbag control as defined in claim 2
`
`It should be noted that whenever an
`
`deployment is inhibited.
`
`wherein the step of determining from the pattern of loaded
`is controlling 10
`
`
`inhibit or allow decision is made, that decision
`sensors whether an infant seat is present comprises:
`and all other conditions
`lower on the chart are bypassed.
`
`establishing a table of loaded and unloaded sensor pat­
`If rails are not detected <60>, the total force is compared
`
`terns which result from the configuration of the bottom
`to high and low thresholds <68>. If it is above the high
`of an infant seat; and
`threshold deployment is allowed and if below the low
`deciding that an infant seat is present when the pattern of
`Otherwise, if the 15
`threshold the deployment is inhibited.
`sensor loading matches one of the table patterns.
`
`localized force for a sensor group is above a threshold and
`
`5. The method of airbag control as defined in claim 2
`the flag corresponding to that group is set <70>, deployment
`wherein the step of determining whether tlle infant seat is
`is allowed. If not, the next step is to compare the total load
`facing forward or rearward comprises:
`rating to high and low thresholds <72>. Deployment is
`and inhib-20
`allowed if the rating is above the high threshold
`deciding that the seat is facing forward when
`ited if below the low threshold.
`1) the total force is greater than a first value, or
`Each of the sensor pairs for
`2) sensors in the front of tlle seat are loaded and the
`front, left, right, and rear are compared to threshold values
`<74-80>. If any of them are above its allowed. If not, the
`total force is greater than a second value; and
`is compared to a threshold <82> to decide
`center group force
`deciding that the seat is facing rearward when both the
`conditions 1) and 2) are not true.
`to 25
`
`
`upon allowance. Finally, the total fuzzy value is compared
`a threshold <84> to allow deployment if it is sufficiently
`6. The method of airbag control as defined in claim 1
`high, and if not the deployment
`
`is inhibited. The fuzzy value
`including:
`decision manages a marginal case where several of the
`determining a pattern of sensor loading;
`previous measures came close to exceeding their thresholds
`prior to tlle step of allowing deployment if the total force
`but didn't, the fuzzy measure can still allow deployment. 30
`
`is above a total threshold force, determining from the
`It will thus be seen that airbag deployment
`can be allowed
`pattern of sensor loading whether an infant seat is on
`
`or inhibited by a pattern of resistive sensors embedded in a
`the seat;
`seat cushion and coupled to a microprocessor to detect the
`then determining from the total force and force distribu­
`force on each sensor to determine the loading pattern as well
`tion whether the infant seat is facing forward or rear­
`from which infant seat presence and 35
`as the force values
`ward;
`
`orientation are determined as well as the presence of other
`allowing deployment for a forward facing seat; and
`
`occupants.
`The embodiments of the invention in which an exclusive
`
`inhibiting deployment for a rearward facing seat.
`7. The method of airbag control as defined in claim 1
`
`property or privilege is claimed are defined as follows:
`
`1. A method of airbag control in a vehicle having an array 40
`wherein the defined seat areas overlap so that some sensors
`are included in more tllan one seat area, the seat areas
`
`of force sensors on the passenger seat coupled to a controller
`
`including a front area, a rear area, a right area and a left area
`
`for determining whether to allow airbag deployment based
`
`on sensed force and force distribution comprising the steps
`8. The method of airbag control as defined in claim 1
`wherein each of said seat areas includes a secondary group
`of:
`45 of sensors peculiar
`to that seat area and the method includes:
`measuring the force detected by each sensor;
`
`calculating the total force of the sensor array;
`
`calculating a modified local force for each secondary
`allowing deployment if the total force is above a total
`group located in a seat area in which the total force is
`
`concentrated; and
`threshold force;
`allowing deployment if tlle modified local force for
`defining a plurality of seat areas, at least one sensor
`50
`located in each seat area;
`exceeds a threshold for that secondary group.
`9. The method of airbag control as defined in claim 8
`
`determining the existence of a local pressure area when
`wherein each secondary group of sensors comprises a pair
`
`
`the calculated total force is concentrated in one of said
`
`and the step of calculating a modified local force comprises
`seat areas;
`limiting the higher sensor force to a maximum delta above
`calculating a local force as tlle sum of forces sensed by
`55 tlle lower sensor force and adding the higher sensor force, as
`each sensor located in the seat area in which the total
`
`limited, to the lower sensor force.
`
`force is concentrated; and
`10. The method of airbag control as defined in claim 1
`allowing deployment if the local force is greater than a
`including the steps of:
`
`predefined seat area threshold force.
`2. The method of airbag control as defined in claim 1 60
`defining a center seat area including a group of sensors
`
`located in the center of the passenger seat,
`including:
`determining a pattern of sensor loading;
`
`calculating a local force for the center seat area as the sum
`of the forces sensed by the sensors in the center seat
`determining from tlle pattern of sensor loading whether an
`area; and
`infant seat is on the passenger seat;
`then determining from the total force and force distribu-65
`allowing deployment if the local force for the center seat
`
`tion whether the infant seat is facing forward or rear­
`area is greater than a predefined center seat area thresh­
`ward;
`old force.
`
`8
`
`

`
`7
`
`5,732,375
`
`8
`
`11. A method of airbag control in a vehicle having
`an array
`
`setting minimum and maximum thresholds for the total
`
`of force sensors on the passenger seat coupled to a controller
`force and total load rating; and
`
`for detennining whether to allow airbag deployment based
`
`subtracting the minimum thresholds from the respective
`
`
`on sensed force and force distribution comprising the steps
`
`total force and total load rating, and limiting each
`of:
`5
`
`difference to the respective maximum threshold; and
`measuring the force sensed by each sensor;
`
`
`determining the fuzzy total and total loading contribution
`calculating the total force of the sensor array;
`values based on the respective limited differences.
`allowing deployment if the total force is above a total
`17. A method of airbag control in a vehicle having an
`array of force sensors on the passenger seat coupled to a
`
`threshold force;
`10
`controller for determining whether to allow airbag deploy­
`assigning a load rating to each sensor based on its
`
`ment based on sensed force and force distribution compris­
`measured force, said load ratings being limited to
`ing the steps of:
`maximum value;
`measuring the force sensed by each sensor;
`summing the assigned load ratings for all the sensors to
`15 calculating
`the total force of the sensor array;
`
`derive a total load rating; and
`allowing deployment if the total force is above a total
`allowing deployment if the total load rating is above a
`
`threshold force; and
`
`predefined total load threshold, whereby deployment is
`allowed if the sensed forces are distributed over the
`if the total force
`is not above the total threshold force,
`
`passenger seat. even if the total force is less than the
`
`
`detennining a fuzzy total force contribution value
`20
`
`total threshold force.
`
`based on the calculated total force;
`12. The method of airbag control as defined in claim 11
`
`defining a plurality of seat areas, at least one sensor
`
`wherein the step of assigning a load rating to each sensor
`
`located in each seat area, calculating a local force for
`comprises:
`each seat area as the sum of forces sensed by each
`
`establishing a base force; and
`
`sensor located in that seat area, and detennining a fuzzy
`25
`local force contribution value based on each of the
`
`assigning a load rating according to the measured force
`
`calculated local forces; and
`minus the base force.
`summing the fuzzy total force and fuzzy local force
`13. The method of airbag control as defined in claim 11
`contribution values, and allowing deployment if the
`
`further including the steps of:
`
`summed contribution values exceed a predefined fuzzy
`
`defining a plurality of seat areas, at least one sensor 30
`threshold.
`located in each seat area;
`18. The method of airbag control as defined in claim 17
`
`determining the existence of a local pressure area when
`wherein the steps of detennining the fuzzy total and local
`
`
`the calculated total force is concentrated in one of said
`
`force contribution values comprises:
`seat areas;
`
`calculating a local force as the sum of forces sensed by 35
`total and local force; and
`
`each sensor located in the seat area in which the total
`subtracting the minimum force thresholds from the
`
`force is concentrated; and
`respective total and local forces and limiting each
`allowing deployment if the local force is greater than a
`difference to the respective maximum
`force threshold;
`
`predefined seat area threshold force.
`and
`14. The method of airbag control as defined in claim 13 40
`determining the fuzzy total and local force contribution
`
`
`further including the steps of:
`values based on the respective limited differences.
`
`determining individual fuzzy values based on the total
`19. The method of airbag control as defined in claim 17
`
`force, the local forces for each seat area, and total load
`wherein
`rating;
`45
`a pair of sensors are located
`summing said fuzzy values; and
`in each seat area, and wherein:
`allowing deployment if the summ ed fuzzy values exceed
`
`the step of calculating the local force for each seat area
`a threshold.
`comprises the steps of:
`15. A method of airbag control as set forth in claim 11,
`limiting the higher force of the respective pair of
`50
`
`including the steps of:
`sensors to a set amount greater than the lower force
`determining a fuzzy total force contribution value based
`
`of the respective pair of sensors, and
`
`on the calculated total force;
`summing the lower force and the higher force, as
`determining a fuzzy total loading contribution value based
`
`
`limited, to derive the local force;
`
`on the total load rating; and
`
`and the step of detennining a fuzzy local force contribu­
`55
`summing the fuzzy total force and fuzzy total loading
`tion amount comprises the steps of:
`contribution values, and allowing deployment if the
`setting a maximum pair force threshold, and
`
`
`summed contribution values exceed a predefined fuzzy
`
`setting the fuzzy local force contribution amount equal
`threshold.
`to the local force limited to the maximum pair force
`16. The method of airbag control as defined in claim 15 60
`threshold.
`wherein the steps of determining the fuzzy total force and
`total loading contribution values comprises:
`
`setting a minimum and maximum force threshold for each
`
`* * * * *
`
`9