(12) United States Patent
`Okuchi et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,193,398 B1
`Feb. 27, 2001
`
`US006193398B1
`
`(54) SYSTEM FOR AUTOMATICALLY
`ADJUSTING OPTICAL AXIS DIRECTION ()1?
`VEHICLE HEADLIGHT
`
`5,195,816 * 3/1993 Moss et al. ........................ .. 362/465
`5,877,680 * 3/1999 Okuchi et al.
`340/468
`6,010,237 * 1/2000 Gotou ........ ..
`.. 362/460
`6,049,749 * 4/2000 Kobayashi ..
`701/49
`
`
`
`Inventors: Hiroaki Okuchi, Nishimura, Gifu, both of (JP) Kenichi
`
`
`
`
`
`Tanabe 618.1. ....................... .. * FOREIGN PATENT DOCUMENTS
`
`
`
`Assigneez
`
`Corporation, Kariya
`
`
`
`9-290683 9-301055
`
`
`
`11/1997 11/1997 (JP) ............................... .. B60Q/1/12 ............................... ..
`
`
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) APPL NO; 09/333,686
`(22) Filed:
`Jun. 16, 1999
`(30)
`Foreign Application Priority Data
`
`(JP) ............................................... ..10—167626
`
`11407852
`... ......................................... ..... 11-107853
`
`Jun. 16, 1998
`[2; i?
`API' 15’ 1999
`Apr: 15’ 1999
`7
`7
`IIlt. Cl- ................................................... ..
`(52) US. Cl.
`362/466; 362/460; 362/464;
`362/465; 362/37; 362/276
`(58) Field of Search ................................... .. 362/460, 464,
`362/465, 466, 37, 276
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`*
`
`-
`-t d b
`C1 6
`y exammer
`Primary Examiner—Sandra O’Shea
`Assistant Examiner—Ali Alavi
`(74) Attorney, Agent, or Firm—Pillsbury Winthrop LLP
`(57)
`ABSTRACT
`In a vehicle headlight optical axis automatic adjusting
`system, a pitch angle in the longitudinal direction of a
`Vehicle is Calculated from a Signal of a height Sensor‘
`Filtering corresponding to a control mode according to the
`acceleration is ?xed and is not frequently sWitched unless
`the Constant Speed State of the Vehicle Continues for a
`predetermined time. The pitch angle may be calculated on
`the basis of the Vehicle rear
`Value
`using a predic
`tion expression Which is divided into a plurality of regions
`of vehicle postures according to loading conditions of an
`occupant load and a trunk load in correspondence With the
`vehicle type. The pitch angle may be updated When the
`vehicle enters a constant speed driving mode, i.e., stable
`driving mode, so that even When one trip is not ?nished the
`error is cancelled.
`
`4,973,155 * 11/1990 Masuda .............................. .. 356/121
`
`9 Claims, 18 Drawing Sheets
`
`21
`CPU
`I/O
`
`12
`/
`WHEEL SPEED
`ROM/J23 <-—SENSOR
`RAM
`/24
`B/U RAM
`
`30L
`(30R)
`
`35L 11F
`(35R)
`
`11R
`
`SL Corp. Exhibit 1006
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 1 of 18
`
`US 6,193,398 B1
`
`FIG.|
`
`12
`/
`WHEEL SPEED
`
`i
`
`30L
`(30R)
`
`35L
`(35R)
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 2 of 18
`
`US 6,193,398 B1
`
`FIG. 2
`
`30L
`Gem
`K
`
`33
`
`32
`
`31
`
`35L(35R)
`
`34
`
`9 9 9 0.9.3.9.
`Q...’ Q
`:33; B(TRC ACCELERATION) 2:42:
`9
`99
`9,9,9,9,,,999
`9999 999’9’9’9
`9999$%fl&?““‘%?9
`
`
`3@&%®fi%®%%§%%“9
`
`99999
`¢V¥%¥%
`
`9009990009900
`
`9999*“,
`999999
`
`‘Q,
`
`-
`
`/T;:;:,.(ACCELERATION) ..;.;.;.;.;.
`
`9
`’9fifififififlfi%fifififiVVN%%fiNWV
`%%%%9&%9¢¥%%94b99
`9999999999
`
`J
`
`CCCONSTANT SPEED)
`
`2 A
`’
`ACCELERATIONO STOP )%_________________,
`av/at
`MODE
`C(CONSTANT SPEED)
`VEH1CLESPEEDV[km/hJ
`999939999 999999999
`
`
`10
`
`'2
`
` ‘99¢'9"’.’:'.’:’:’
`
`9
`Qafifigfigg
`‘g?
`
`.’9’:’:’.’.’.’.
`
`qggfififif
`zaaavvt
`
`99999
`>qfifi£gggfifi%fifififififi&$&&§
`'°%%%99999999999999999
`’ '
`"29393929293620202020223930:0
`%fififi&uM?
`99o.» B (ABS DECELERATION) 3.0.:
`0
`99
`§Nb999999
`.9&%%%
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 3 of 18
`
`US 6,193,398 B1
`
`FIG.4
`
`@
`
`INITIAL SETTING A101
`
`READ VARIOUS A102
`SENSOR SIGNALS
`
`TB = o
`l
`WEAK FILTERINC A
`(STOP)
`5
`8106
`
`$109
`TB= o
`
`FLAC<-T
`I
`TB= o
`snz/
`WEAK FILTERING B
`(ACCELSEATION)
`DECELERATION
`$
`8H0
`
`m s
`
`‘——'| FLAGFO
`8H8
`S1 13
`|
`/
`TB = 0 /
`WEAK FILTERINC B
`TRC ACCELERATION
`(
`OH
`) STRONG FILTERING C
`ABS DECELERATION
`(CONSTANT SPEED)
`shs
`
`S160 ‘
`DRIVE ACTUATOR
`@@
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 4 of 18
`
`US 6,193,398 B1
`
`FIG.6
`
`TIME
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 5 of 18
`
`US 6,193,398 B1
`
`[° 1
`1.5V
`1.0
`0.5-
`O
`_0_5_
`
`-1.()
`-1.5
`
`FIG. 7
`
`PITCH ANGLE
`
`W
`M
`>
`W TIME
`
`CONTROL ANGLE
`
`FIG. 8
`
`21 r
`20
`\ /
`h'Q-EEEBP-MJ'
`CPU
`ROM /22
`
`VARIOUS SENSOR
`SIGNALS
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 6 of 18
`
`US 6,193,398 B1
`
`FIG. 9
`
`( ST A RT )
`
`8210]
`READ REAR HEIGHT HR /
`S2102
`
`NO
`
`HR 7; ha
`S2103
`'YES
`CALCULATE / CALCULATE
`PITCH ANGLE 6p
`PITCH ANGLE 6p
`FROM f1(HR)
`FROM f0(HR)
`
`S2104
`
`'. —6p
`
`DRIVE ACTUATOR
`
`( RETURN )
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 7 of 18
`
`US 6,193,398 B1
`
`F|G.|O
`
`3.
`
`gs
`3.
`
`/#
`
`?g
`
`f.
`/
`
`-60
`
`-50
`
`TRUNK LOAD
`
`FIG. ll
`
`“.-1."\\‘.Ix\\T-‘U’!G
`
`\Y\_
` No\
`
`
`TRUNK LOAD
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 8 of 18
`
`US 6,193,398 B1
`
`FIG. I2
`
`5..§\\\;\‘\\.»'01CD
` .\\’V§\\\‘_._\\\"\'(§\\'o‘in'oin
`
`-90
`
`-80
`
`-70
`
`-50 -50 -40 -30 -
`
`TRUNK LOAD
`
`
`
`I
`
`e C)
`
`15 O
`
`l\)(D
`
`0.)G
`
`OCCUPANT LOAD
`
`AL.(D
`S E’.
`
`k\f}
`
`\ l\) o
`
`L11
`
`6
`
`ha
`
`_\\\‘\_3\"§k\\‘V -<
`_
`
`-90
`
`-80
`
`-70
`
`-50
`
`-50
`
`-40
`
`-(_P“:
`30 ,
`20
`-30 -20 o
`/\ HR/;mmJ
`
`OCCUPANT LOAD
`
`A
`
`
`
`V0.5
`TRUNK LOAD
`4
`
`
`VV
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 9 of 18
`
`US 6,193,398 B1
`
`FIG. l4
`
`( START )
`
`READ REAR HEIGHT HR -/8ZZ01
`
`READ SYSTEM ERROR /SZZOZ
`INFORMATION
`
`UPDATE REAR HEICHT HR /SZ203
`HR <— K- HR-Ah
`
`S2204
`
`S2206
`/
`fSZZOS
`CALCULATE
`CALCULATE
`PITCH ANCLE 9p BY
`PITCH ANGLE 6p BY
`
`6T L, ._ep fszzov
`
`DRIVE ACTUATOR F/SZZOS
`
`( RETURN )
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 10 of 18
`
`US 6,193,398 B1
`
`FIG. I5
`
`Opt']
`1 2.0
`WITHSYSTEMERROR ?/’/////////////?
`INFORMATION
`
`WITHOUT SYSTEM
`ERROR INFORMATION
`-90 O0 -7'O -OO -5O -4O
`
`Q m I
`
`52
`
`TRUNK LOAD
`
`FIG. l6
`
`~
`
`Opt']
`7 - //////////////
`WITH sYsTEM ERROR // ’
`Z
`INFORMATION
`gm
`;
`v
`2
`$0
`/
`/
`/
`I;
`4
`‘405-
`;
`/
`/
`.
`f
`I‘YI
`4,0
`[mm]
`
`WITHOUT SYSTEM
`ERROR INFORMATION
`
`-90 -OO -TO -60 -5O -4O -3O
`
`TRUNK LOAD
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 11 of 18
`
`US 6,193,398 B1
`
`FIG. I?
`
`Qpt']
`72-0 /////////// /
`WITH SYSTEM ERRoR // ’
`;
`INFORMATION
`_
`
`/ .\\\\\\\\\\\\\
`
`FIG. l8
`
`20\ [Z1
`CPU
`
`U0
`
`/
`25 25
`
`22
`
`RoM
`[~23
`RAM 24
`
`B/U RAM
`
`12
`VEHICLE
`SPEED SENSOR /
`
`RIGHT WHEEL /13
`SPEED SENSOR
`
`LEFT WHEEL /14
`SPEED SENSOR
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 12 of 18
`
`US 6,193,398 B1
`
`
`
`0 $1 \I 0 \ll
`
`DISPLACE
`MENT
`!\ (
`[mm]
`+Al IV _
`
`
`
`|||||||| lnHHlhut |||||
`
`‘.
`
`A‘
`
`1V
`
`17m‘!
`in." W 1H
`
`THI
`
`DC
`nnE
`El
`AM M EE In".
`wH ‘w
`MR MT
`
`.m
`
`MR 0
`
`
`:Tu: 11-11 1| Ann
`wTl LT
`m m C E D DH M Em
`r}: CF
`%H ?H Mmm
`AN UN
`E0 w
`
`FIG. 20
`
`M
`
`MEASURED ‘REAR HEIGHT
`AVERAGE AT cowsmm
`RUNNING 5
`
`MEASURED
`REAR HEIGHT
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 13 of 18
`
`US 6,193,398 B1
`
`FIG. 2|
`
`CEGEO
`/s3101
`READ VARIOUS
`SENSOR SICNALS
`VEHICLE SPEED V
`REARiHElCHT VALUE HR
`
`YES
`
`$3103
`\
`CALCULATE
`PITCH ANCLE 9O
`HFO=a~HRO+h
`
`N0
`CALCULATE
`PITCH ANCLE 61
`AHR=HR-HRO
`
`$3102
`
`83106 /
`
`FILTERINC
`60, HF“ HBO
`
`83104
`
`\
`.
`9T=-—90
`
`61=tan"‘{(HF—HR)/L}
`83107
`YES
`dV/dtI>1tm/s21
`S3110
`‘*No
`FILTERINC / F \LTERING
`61 . HF, HR I
`e1
`8311]
`
`S3108
`
`i
`
`ES
`$3112
`CANCEL PROCESSING [
`FOR RCALEIDE BLOCK
`HFO+HF
`HRO~HR
`I
`CALCULATE /S3“3
`PITCH ANGLE eo
`
`a?
`DRIVE ACTUATOR
`
`S3115
`
`@
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 14 of 18
`
`US 6,193,398 B1
`
`FIG.22
`
`A \r
`
` m . we . RH UH 8 Am
`
`EE
`Mnn
`
`_nln
`
`r | I I 1 i | l a 1 1 I | . || CF
`
`MCI LO
`SN IL
`ER CN
`A0 UT
`DHH a] E UT T AH
`
`|.... Ann
`
`m C \l'
`m o u? .0 L,
`
`[ A m
`( E (
`
`Hwmm
`BEE
`DM
`
`SN NN
`
`CR
`0U
`
`Em
`SE MD
`N m .N W DM
`DITI
`
`FIG.23
`
`A
`
`WITHOUT CORRECTION
`
`WITH CORRECTION
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 15 0f 18
`
`US 6,193,398 B1
`
`Fl G. 24
`
`S3201
`
`CE)
`
`READ VARIOUS
`SENSOR SICNALS
`
`CALCULATE
`PITCH ANCLE 90
`
`S3204
`
`FILTERINC
`60,HFO,HRO I
`
`I
`
`S3205 N
`
`CALCULATE
`PITCH ANGLE e1
`AHR=HR—HRO
`AHF=—P-AHR
`HF=HFO+AHF
`
`S3206
`
`S3207
`
`[ FILTQE1RINC
`
`:l/
`
`S3210
`
`(
`
`DRIVE ACTUATOR
`
`@
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 16 of 18
`
`US 6,193,398 B1
`
`FIG. 25
`
`CALCULATED
`FRONT HEIGHT
`
`,
`
`1
`
`I
`
`‘
`
`,
`E
`:
`:
`
`i
`4*_>
`TIME
`
`~
`
`‘W! I‘ \\ I
`;
`:
`i
`:
`
`A
`
`17
`[km/h]
`0
`x :
`(P
`5
`
`DISPLACE-
`MEEdT J
`mm
`
`0
`
`1
`<->
`
`’
`$3,‘
`i
`
`I
`
`{MEASURED
`I FRONT HEIGHT
`l
`MEASURED
`I
`I
`REAR HEIGHT
`I
`I
`I
`I
`
`.1
`
`TURNING
`
`A,
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 17 of 18
`
`US 6,193,398 B1
`
`FIG. 26
`
`(FIE-D fsssm
`READ VARIOUS
`SENSOR SIGNALS
`VEHICLE SPEED TT
`HR,_ITWR.VWL
`
`S3308
`/
`
`CALCULATE / CALCULATE
`PITCH ANGLE e1
`PITCH ANCLE 61
`AHR= HR-HRG
`AHR=HR—HRO
`AHF=—P-AHR
`AHF=-O-AHR
`HF=HFO+AHF
`HF=HFO+AHF
`61=tan“{(HF—HR)/L}
`61=tan“{(HF—HR)/LI
`'1
`J
`
`FILTERINC
`e1
`
`$3310
`
`83311
`
`$3333
`CALCULATE
`PITCH ANCLE e0
`HFO=a.HRO+b
`60=tan"‘{(HF0—HR0)/LI
`
`FILTERINC
`60. HFo. HRO
`
`S3304
`
`S3305
`
`NO
`
`6T‘—:-60
`
`_ CANCEL PROCESSING _
`FOR ROADSIDE BLOCK
`
`I
`CALCULATE
`PITCH ANCLE 60
`60=’£an‘1 KHFO-HROVLI
`9T -=.l-eo
`83316
`
`| DRIVE ACTUATOR V8331?
`
`

`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 18 of 18
`
`US 6,193,398 B1
`
`FIG. 27
`
`OPTICAL
`AXIS
`DIRECTION O
`ADJUST
`MENT E“ ]
`
`WITH TURNING
`DETERMINATION
`
`I
`TURNING
`DETERMINATION
`
`TIME
`WITHOUT TURNING
`DETERMINATION
`
`

`
`US 6,193,398 B1
`
`1
`SYSTEM FOR AUTOMATICALLY
`ADJUSTING OPTICAL AXIS DIRECTION OF
`VEHICLE HEADLIGHT
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application relates to and incorporates herein by
`reference Japanese Patent Applications No. 10-167626, No.
`10-244782, No. 11-107851, No. 11-107852 and 11-107853
`?led on Jun. 16, 1998, Aug. 31, 1998,Apr. 15, 1999,Apr. 15,
`1999 and Apr. 19, 1999, respectively.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to a vehicle headlight optical
`axis direction adjusting system for automatically adjusting
`the optical axis direction of irradiation of a headlight pro
`vided for a vehicle.
`2. Description of Related Art
`Conventionally, in the headlight of a vehicle, When the
`optical axis of the a headlight is directed upWard due to
`inclination of the chassis of the vehicle, glare is given to an
`on-coming vehicle or the like. When the optical axis is
`directed doWnWard, a driver of the vehicle may lose the far
`?eld of vieW. There has been, consequently, a demand for
`holding the optical axis direction of the headlight unchanges
`as much as possible.
`JP-A-9-301055 discloses a vehicle headlight optical axis
`control system, in Which a control mode is set in accordance
`With acceleration, a ?ltering process is executed When the
`acceleration is smaller than a predetermined value, the
`?ltering process is not performed so as not to delay sWitch
`ing of the control mode When the acceleration is equal to or
`larger than the predetermined value, and the optical axis
`direction of the headlight is adjusted on the basis of a change
`in the height of the vehicle on each occasion.
`In the above system, When the acceleration of the level
`Which can not be reached in a normal driving state is sensed
`in association With a knoWn traction (TRC) control or
`antilock brake (ABS) control, since the acceleration is equal
`to or larger than the predetermined value, the ?ltering
`process is not performed and the control mode is frequently
`sWitched. At the time of acceleration associated With the
`TRC control (TRC control time) or at the time of decelera
`tion associated With the ABS control (ABS control time),
`although the acceleration largely changes, the vehicle pos
`ture does not change so much. As a result, the optical axis
`is improperly controlled When the direction of the optical
`axis of the headlight is alloWed to folloW changes in the
`acceleration at such time.
`Another optical axis control system is knoWn Which uses
`an inclination angle obtained by approximating an amount
`of change in the vehicle posture caused by loading to a linear
`expression. According to this control, the optical axis direc
`tion of the headlight can be made to coincide With the
`vehicle posture under a limited loading condition such as
`“only occupant load” or “occupant load and up to 50 kg of
`trunk load”. HoWever, various loading conditions of com
`bination of the occupant load and the trunk load can not be
`dealt With.
`In a still another system, a vehicle height sensor is
`installed only on either the right or left side of a rear Wheel
`since front Wheels are Wheels to be steered and an installa
`tion space is limited. A front height value is estimated on the
`basis of a rear height value in the stop mode of the vehicle
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`2
`to calculate the inclination angle. When the vehicle is
`stopped riding on a block or the like, a rear height value
`different from that on a ?at road is sensed. In one trip (a
`driving interval betWeen stops of the vehicle) after that, there
`is consequently an inconvenience such that a computation
`error occurs in the inclination angle in the longitudinal
`direction of the vehicle and the optical axis direction of the
`headlight is deviated. Since the rear height value changes
`due to turning Which is a rotary motion around the longi
`tudinal axis of the vehicle during a turn although the vehicle
`is not inclined in the longitudinal direction, a computation
`error occurs in the inclination angle in the longitudinal
`direction of the vehicle until the turn of the vehicle is
`?nished and there is an inconvenience such that the optical
`axis direction of the headlight is accordingly deviated.
`
`SUMMARY OF THE INVENTION
`
`The present invention has an object to properly adjust the
`optical axis direction of a headlight in accordance With a
`driving state of a vehicle Without frequently sWitching the
`optical axis direction of the headlight.
`The present invention has another object to deal With
`various loading conditions in the event of automatically
`adjusting the optical axis direction of a headlight of a vehicle
`on the basis of an output of a single vehicle height sensor.
`The present invention has a further object to properly
`correct a deviation in optical axis direction of a headlight
`When the vehicle is either stopped riding on a block or the
`like or is in a turn state.
`According to one aspect of the present invention, an
`inclination angle in the optical axis direction of a headlight
`of a vehicle to the horiZontal plane is calculated on the basis
`of output values from tWo vehicle height sensors arranged
`on the front and rear sides of the vehicle, respectively. A
`?lter for changing the response of adjustment of the optical
`axis direction of the headlight is sWitched depending on a
`control mode determined in correspondence With a vehicle
`speed and acceleration. When the acceleration exceeds the
`highest determination level Which is set so as not to be
`reached in a normal driving state, the control mode corre
`sponding to the acceleration state or the deceleration state of
`the vehicle is continued unless a constant speed state of the
`vehicle continues for a predetermined period after that.
`According to another aspect of the present invention,
`inclination angle in an optical axis direction of a headlight
`to the horiZontal plane is calculated on the basis of an output
`value from a single vehicle height sensor by using a pre
`diction expression Which is divided into a plurality of
`regions of vehicle postures having different inclinations in
`accordance With loading conditions of an occupant load and
`a trunk load. The optical axis direction of the headlight is
`adjusted on the basis of the inclination angle. For example,
`by preparing the prediction expression divided into a plu
`rality of regions of vehicle postures in accordance With the
`loading conditions of the occupant load and the trunk load
`in correspondence With the vehicle type and the like.
`Preferably, the inclination angle is calculated from both of
`the output of the single vehicle height sensor and an error
`Which occurs in association With installation of the vehicle
`height sensor.
`According to a further aspect of the invention, When it is
`determined that a driving mode of a vehicle is a stable
`driving mode, a reference inclination angle in the vehicle
`stop mode is updated based on an output of a vehicle height
`sensor, the inclination angle in the driving mode is corrected
`on the basis of the reference angle, and the optical axis
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`US 6,193,398 B1
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`direction of the headlight is thereby adjusted. When the
`vehicle once enters the constant speed driving mode before
`completion of one trip,
`irrespective of the presence or
`absence of a deviation in the optical axis direction of the
`headlight of the vehicle, the reference inclination angle in
`the vehicle stop mode is updated and the inclination angle in
`the driving mode is corrected. Thus, an effect such that even
`if the optical axis direction of the headlight is deviated, it can
`be properly adjusted is obtained.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the accompanying drawings:
`FIG. 1 is a schematic diagram showing a vehicle headlight
`optical axis direction automatic adjusting system according
`to a first embodiment of the invention;
`FIG. 2 is a cross section showing a headlight used in the
`first embodiment;
`FIG. 3 is a diagram showing filter regions corresponding
`to control modes in the first embodiment;
`FIG. 4 is a flow diagram showing an optical axis control
`in the first embodiment;
`FIG. 5 is a timing diagram showing an operation of a
`comparative example of an optical axis control by the
`vehicle headlight optical axis direction automatic adjusting
`system;
`FIG. 6 is a timing diagram showing an operation of the
`first embodiment;
`FIG. 7 is a timing diagram showing a transition state of a
`control angle according to a pitch angle in the first embodi-
`ment;
`FIG. 8 is a schematic diagram showing a vehicle headlight
`optical axis direction automatic adjusting system according
`to a second embodiment of the invention;
`FIG. 9 is a flow diagram showing an optical axis control
`depending on various loading conditions in the second
`embodiment;
`FIG. 10 is a graph showing a prediction expression which
`is divided into two vehicle posture regions for calculating a
`pitch angle on the basis of a vehicle rear height value in the
`second embodiment;
`FIG. 11 is a graph showing a prediction expression which
`is divided into two vehicle posture regions for calculating
`the pitch angle on the basis of the vehicle rear height value
`in the second embodiment;
`FIG. 12 is a graph showing a prediction expression which
`is divided into two vehicle posture regions for calculating
`the pitch angle on the basis of a vehicle front height value
`in the second embodiment;
`FIG. 13 is a graph showing three prediction expressions
`each of which is divided into two vehicle posture regions
`and one of which is selected based on outputs from sensors
`except for the vehicle height sensor in the second embodi-
`ment;
`FIG. 14 is a flow diagram showing an optical axis control
`according to a third embodiment of the invention;
`FIG. 15 is a graph showing both of a prediction expres-
`sion without consideration of system error information and
`a prediction expression in which the system error informa-
`tion of an installation error of the vehicle height sensor is
`considered in the third embodiment;
`FIG. 16 is a graph showing both of a prediction expres-
`sion without consideration of the system error information
`and a prediction expression in which the system error
`information when the inclination of the prediction expres-
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`4
`sion is changed due to an error in spring constants of the
`front and rear suspensions is considered in the third embodi-
`ment;
`
`FIG. 17 is a graph showing five prediction expressions in
`which the system error information such as the installation
`error of the vehicle height sensor to the vehicle and various
`errors caused by other factors of the vehicle is considered in
`the third embodiment;
`FIG. 18 is a schematic diagram showing a whole con-
`struction of a vehicle headlight optical axis direction auto-
`matic adjusting system according to a fourth embodiment of
`the invention;
`FIG. 19 is a timing diagram for explaining an inconve-
`nience that the vehicle is stopped riding on a block or the like
`when no headlight optical axis adjustment is applied;
`FIG. 20 is a timing diagram showing a transition of a
`measured rear height according to a change in the speed of
`the vehicle, based on which the optical axis direction of the
`headlight is adjusted in the fourth embodiment;
`FIG. 21 is a flow diagram showing a procedure for dealing
`with the case where the vehicle is stopped riding on a block
`or the like, executed by the in the fourth embodiment;
`FIG. 22 is a timing diagram showing a transition of each
`displacement according to the change in the vehicle speed,
`based on the flow diagram of FIG. 21;
`FIG. 23 is a timing diagram showing an optical axis
`direction adjustment amount of the headlight of the vehicle
`which is corrected based on the flow diagram of FIG. 21 and
`an optical axis direction adjustment amount which is not
`corrected for comparison;
`FIG. 24 is a flow diagram showing a modification of the
`procedure for dealing with the case where the vehicle is
`stopped riding on a block or the like, executed by the CPU
`in a fifth embodiment of the present invention;
`FIG. 25 is a timing diagram for explaining an inconve-
`nience occurring during a turn of the vehicle without cor-
`rection;
`FIG. 26 is a flow diagram showing a procedure for dealing
`with not only the case where the vehicle is stopped riding on
`a block or the like but also a case where the vehicle is
`
`turning, by the CPU in a sixth embodiment; and
`FIG. 27 is a timing diagram showing an optical axis
`direction adjustment amounts, one when the turn state is
`determined based on the flow diagram of FIG. 26 and the
`other when the turn state is not determined.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`The present invention will be described in detail with
`reference to various embodiments,
`in which the same or
`similar reference numerals designate the same or similar
`parts and steps.
`
`First Embodiment
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`to FIG. 1, a front (front-wheel) height
`Referring first
`sensor 11F is attached to a front suspension provided
`between a front axle and a vehicle chassis on a driver’s seat
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`side or a front passenger seat side. A rear (rear-wheel) height
`sensor 11R is attached to a rear suspension provided
`between the rear axle and the vehicle chassis on the driver’s
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`seat side or the rear passenger seat side. A front height value
`(a displacement of the vehicle height on the front wheel side)
`HF and a rear height value (a displacement of the vehicle
`height on the rear wheel side) HR as relative displacements
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`(displacements of the vehicle height) between the respective
`axles on the front and rear wheel sides and the vehicle
`chassis supplied from the height sensors 11F and 11R, and
`various sensor signals of wheel speed pulses and the like
`from a wheel speed sensor 12 which is mounted as a vehicle
`speed sensor on the vehicle side and is used for known TRC
`and ABS controls and the like are supplied to an ECU
`(Electronic Control Unit) 20. For convenience, the ECU 20
`and the wheel speed sensor 12 are illustrated outside of the
`vehicle.
`
`The ECU 20 is a logical operating circuit comprising a
`CPU 21 as a known central processing unit, a ROM 22 in
`which control programs are stored, a RAM 23 for storing
`various data, a B/U (back-up) RAM 24, an input/output
`circuit 25, and a bus line 26 connecting these elements.
`Output signals from the ECU 20 are supplied to actuators
`35R and 35L of right and left headlights 30R and 30L of the
`vehicle, thereby adjusting the optical axis direction of the
`right and left headlights 30R and 30L as will be described
`hereinlater. The various sensor signals from the wheel speed
`sensor 12 and the like are used for determining the mode of
`the vehicle, such as stop mode, acceleration mode, decel-
`eration mode, and constant speed mode.
`As shown in FIG. 2, the headlight 30L (30R) includes a
`lamp 31, a reflector 32 for fixing the lamp 31, a supporting
`member 33 of a rod shape for supporting the reflector 32
`swingably in the directions shown by the arc arrow, a
`movable member 34 having also a rod shape, for supporting
`the reflector 32, and the actuator 35L (35R) such as a
`stepping motor or a DC motor for driving the movable
`member 34 in the directions shown by the double-headed
`arrow. The movable member 34 is driven in the back and
`
`the
`forth directions by the actuator 35L (35R) so that
`reflector 32 is vertically inclined about
`the end of the
`supporting member 33 as a fulcrum only by an actuator
`driving angle (target optical axis direction adjusting angle)
`0a which will be described hereinlater, thereby adjusting the
`optical axis direction of the headlight 30L (30R). The optical
`axis direction of the headlight 30L (30R) is initially set on
`the assumption that one driver is on the vehicle.
`The pitch angle 0p[°] as an inclination angle in the
`longitudinal direction of the vehicle to a preset reference
`plane is calculated by the following equation on the basis of
`the front height value HF and the rear height value HR sent
`from the height sensors 11F and 11R among the various
`sensor signals of the vehicle supplied to the ECU 20. Lw
`denotes a wheel base (distance between the axles) between
`the front and rear wheels.
`
`6p=tan’1{(HF—HR)/Lw}
`
`In FIG. 3, the filter regions A, B, and C are illustrated that
`correspond to the control modes of the vehicle (stop mode,
`acceleration mode, TRC acceleration mode, ABS decelera-
`tion mode, deceleration mode, constant speed mode) when
`the abscissa denotes vehicle speed V [km/h] and the ordinate
`indicates acceleration dV/dt [m/s2] obtained by differentiat-
`ing the vehicle speed V. The filters are realized by either
`hardware for the height sensor signal (for example, smooth-
`ing of a signal by a CR circuit) or software for the height
`sensor signal or the pitch angle (for example, smoothing of
`a signal by the ECU by using moving average or standard
`deviation). The system uses the moving average for the pitch
`angle, which is advantageous from the viewpoint of cost
`since the ECU is originally provided therein.
`In the diagram of FIG. 3, the filter Acorresponding to the
`stop mode is used when the vehicle speed V is lower than a
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`few km/h (for example, 2 [km/h]). When the vehicle is
`stopped, a large change in the pitch angle due to loading,
`unloading, or the like is expected. No filtering or very weak
`filtering is therefore performed so that
`the actuator is
`allowed to respond quickly to the change in the pitch angle.
`On the other hand, when the vehicle speed v is equal to
`or larger than a few km/h (for example, 2 [km/h]) and the
`acceleration dV/dt obtained by differentiating the vehicle
`speed V exceeds a preset threshold (such as :2 [m/s2]), the
`filter B corresponding to the acceleration mode or the
`deceleration mode is used. Since the change in the pitch
`angle is large, no filtering or very weak filtering is performed
`so that the actuator is allowed to respond quickly to the
`change in the pitch angle.
`In this embodiment, as will be described hereinlater, when
`the speed V of the vehicle is equal to or higher than a few
`km/h (such as 2 [km/h]) and the acceleration dv/dt obtained
`by differentiating the vehicle speed V exceeds a threshold
`(for example, :2 [m/s2]) for determining the acceleration
`mode or the deceleration mode and further once exceeds a
`
`preset threshold (for example :10 [m/s2]) which can not be
`reached in the normal driving state, unless the constant
`speed driving state of the vehicle continues for a predeter-
`mined period (for instance, 0.5 [sec]) after that, the TRC
`acceleration mode at the time of the TRC control or the ABS
`deceleration mode at the time of the ABS control is deter-
`
`mined and the filtering B which is also used in the accel-
`eration or deceleration mode is continuously performed.
`When the vehicle speed V is equal to or higher than a few
`km/h (such as 2 [km/h]) and the acceleration dV/dt obtained
`by differentiating the vehicle speed V is lower than the preset
`threshold (for example, :2 [m/s2]), the filter C correspond-
`ing to the constant speed mode is used. Since it is generally
`expected that the pitch angle does not largely change, strong
`filtering is performed so as to remove high frequency
`components of a vibration at the time of driving and the
`change in the pitch angle due to unevenness of the road
`surface, thereby preventing the actuator from responding.
`The optical axis control routine is repetitively executed
`every 50 ms or so by the CPU 21.
`As shown in FIG. 4, initial setting is executed at step
`S101. After that, the routine advances to step S102 where
`various sensor signals of the wheel speed pulse, front height
`value HF, rear height value HR, and the like are read. At step
`S103, whether or not the vehicle speed V calculated from the
`wheel speed pulse read at step S102 is lower than a preset
`threshold V0 is determined. The threshold V0 is set to, for
`example, 2 [km/h] as shown in FIG. 3. When the determi-
`nation condition at step S103 is satisfied, that is, when the
`vehicle speed V is lower than 2 [km/h], the routine advances
`to step S104 where a flag Flag which will be described
`hereinlater is set to “0”. At step S105, a timer TB which will
`be described hereinlater is cleared to “0”. At step S106, the
`stop mode is determined and the weak filtering A shown in
`FIG. 3 is performed to the pitch angle 0p calculated by the
`equation. Apitch angle Gpf obtained by performing the weak
`filtering A to the pitch angle 0p follows a transition state of
`the actual pitch angle 0p to a certain extent.
`On the other hand, when the determination condition at
`step S103 is not satisfied, that is, when the vehicle speed V
`is higher than 2 [km/h], the routine advances to step S107
`where it is determined whether or not the absolute value of
`
`the acceleration dv/dt obtained by differentiating the vehicle
`speed V is equal to or lower than a preset threshold (XI. The
`threshold (X1 is set to, for example, :2 [m/s2] as shown in
`FIG. 3. When the determination condition at step S107 is not
`satisfied, that is, when the absolute value of the acceleration
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`7
`the routine
`dV/dt exceeds the threshold (X1 and is large,
`advances to step S108 where it is determined whether or not
`the absolute value of the acceleration dv/dt is equal to or
`smaller than a threshold 012. The threshold (X2 is set to the
`
`acceleration, for example, :10 [m/s2] as shown in FIG. 3
`which is preset so as not to be reached in the normal driving
`state. When the determination condition at step S108 is
`satisfied, that is, when the absolute value of the acceleration
`dv/dt is equal to or lower than the threshold 012, the routine
`advances to step S109 where the time TB is cleared to “O”.
`The routine progresses to step S110 where the acceleration
`or deceleration mode is determined and the weak filtering B
`shown in FIG. 3 is performed to the pitch angle Op calcu-
`lated by the equation. The pitch angle Opf obtained by
`performing the weak filtering B to the pitch angle Op follows
`the transition state of the actual pitch angle Op to a certain
`extent in a manner similar to the case of the stop mode.
`When the determination condition at step S108 is not
`satisfied, that is, when the absolute value of the acceleration
`dv/dt exceeds the threshold (X2 and is large,
`the routine
`advances to step S111 where the flag Flag indicating that the
`absolute value of the acceleration dv/dt once exceeds the
`threshold 012 is set to “1”. At step S112, the timer TB is
`cleared to “O”. At step S113, the TRC acceleration mode at
`the time of the TRC control or the ABS deceleration mode
`at the time of the ABS control is determined and the weak
`
`filtering B shown in FIG. 3 is performed to the pitch angle
`Op calculated by the above equation. The pitch angle Opf
`obtained by performing the weak filtering B to the pitch
`angle Op as described above follows the transition state of
`the actual pitch angle Op to a certain extent in a manner
`similar to the stop mode.
`Effectiveness of using the thresholds (X1 and (X2 of two
`stages for the absolute value of the acceleration dv/dt in the
`determination for the control mode switching at steps S107
`and S108 will now be described with reference to the timing
`diagrams of FIGS. 5 and 6.
`As will be understood from FIGS. 5 and 6, at the time of
`TRC or ABS control, the acceleration dV/