`Okuchi et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,193,398 B1
`Feb. 27, 2001
`
`US006193398B1
`
`........................ .. 362/465
`3/1993 Moss et al.
`5,195,816 *
`3/1999 Okuchi et al.
`.
`340/468
`5,877,680 *
`1/2000 Gotou
`..... ..
`362/460
`6,010,237 *
`4/2000 Kobayashi
`.. 701/49
`6,049,749 *
`Tanabe 618.1.
`*
`.........................
`FOREIGN PATENT DOCUMENTS
`
`
`
`9-290683
`9—301055
`
`............................... ..
`11/1997
`11/1997 (JP) ............................... .. B60Q/1/12
`
`(54) SYSTEM FOR AUTOMATICALLY
`ADJUSTING OPTICAL AXIS DIRECTION OF
`VEHICLE HEADLIGHT
`
`Kenichi
`Inventors: Hiroaki Okuchi
`Nishimura, Gifu, both of (JP)
`
`Assigneeg
`
`Corporation’ Kariya
`
`ot1ce:
`* N’
`
`1SC a1mer, t e term o t is
`u ect to an
`yd'l'
`Sbj
`h
`111'
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`* cited by examiner
`
`Primary Examiner—Sandra O’Shea
`Assistant Examiner—Ali Alavi
`
`(21) Appl. No.: 09/333,686
`
`(22)
`
`Filed:
`
`Jun. 16, 1999
`
`(30)
`
`Foreign Application Priority Data
`
`Jun. 16, 1998
`Aug. 31, 1998
`Apr. 15, 1999
`Apr. 15, 1999
`Apr. 15, 1999
`
`(JP) ............................................... .. 10—167626
`(JP) .
`.... .. 10—244782
`(JP) .
`.... .. 11—107851
`(JP) .
`.... .. 11—107852
`(JP) ............................................... .. 11—107853
`
`
`
`Int. Cl.7 ................................................... .. G01B 13/18
`(51)
`(52) U.S. 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
`
`(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 fixed 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 height value by 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 finished the
`error is cancelled.
`
`4,973,155 * 11/1990 Masuda .............................. .. 356/121
`
`9 Claims, 18 Drawing Sheets
`
`12
`
`WHEEL SPEED
`SENSOR
`
`
`
`KOITO 1017
`
`1
`
`KOITO 1017
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 1 of 18
`
`US 6,193,398 B1
`
`F|G.|
`
`12
`
`WHEEL SPEED
`SENSOR
`
`2
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 2 of 18
`
`US 6,193,398 B1
`
`FIG. 2
`
`30L
`
`Gem
`\
`
`,3
`
`32
`
`31
`
`35L (35R)
`
`34
`
`999 9
`9 99g~g5
`.‘..
`0.. O
`.3; B TRC ACCELERATION) 3.3:‘:
`.,;9gggg
`éW@W#9b¢Ub9999999
` O
`99999999999999
`9:9’9’9’9:9:9:9:9:9:9:9:9:9:99
`ggfifi
`qgggggy
`
`
`
`-
`
`999999/(ACCELERATION) .,:,:.:.:.:.
`
`1 0
`
`"9’9’9‘9’9’9’9’9’9'9’9:9:9:9:9:9’::9:9:'6'
`9,9’9
`&fiW@®fi%guuuw£
`9:3:>4:9’9
`n
`fifigfifififiyggaggggg
`0
`2,11,
`STOP 1
`“CONSTANT SPEED)
`.
`0 MODE)§
`
`ACCELERATION
`dV/dt
`
`Q
`9
`
`Q
`
`‘%99
`
`,,
`999999
`
`/3330B<neceLemmo~>
`
`-2
`
`40
`
`*
`
`..
`
`£§g§§%%%%$%&%%*%VM&é$
`999w999v99qng-yyw5.
`q&p99999999
`.
`99W B (ABS DECELERATION) 3;.
`‘%
`965999999
`.oé%%9
`
`99999
`
`9999
`
`3
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 3 of 18
`
`US 6,193,398 B1
`
`F|G.4
`
`S107
`
`WEAK FILTERINC B
`
`
`
`
`OR
`
`(ACCELERATION)
`DECELERATION
`
`<TRC ACC0ETH.ERAT|0N)
`
`
`
`
`
`WEAK FILTERINC B
`
`ABS DECELERATION
`
`
`
`
`
`
`DRIVE ACTUATOR
`
`RETURN
`
`4
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 4 of 18
`
`US 6,193,398 B1
`
`F|G.5
`
`V
`
`‘*""‘“ .1.
`
`0
`
`TRC CONTROL
`
`.llH4“‘ A.
`
`-
`
`“a""_'
`
`ABS CONTROL
`
`mo CONTROL
`
`.KlHa‘|‘ A.
`
`1
`
`‘
`
`ABS CONTROL
`
`A
`£
`
`K
`
`(W321
`
`‘jg
`10
`
`50
`
`-15
`
`2°
`
`10
`
`5O
`
`-15
`
`5
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 5 of 18
`
`US 6,193,398 B1
`
`FIG . 7
`
`PITCH ANGLE
`
`
`
`TIME
`
`CONTROL ANGLE
`
`E; g
`
`1.0
`
`0.5
`
`O
`_0_5
`
`-1.0
`
`-1.5
`
`Fl G. 8
`
`VARIOUS SENSOR
`
` Z0
`
`;;:»:e:;E@_na3
`
`SIGNALS
`
`6
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 6 of 18
`
`US 6,193,398 B1
`
`F|G.9
`
`
`
`S2104
`
`CALCULATE
`PITCH ANGLE 9p
`FROM f1(HR)
`
`
`
`CALCULATE
`PITCH ANGLE 6p
`FROM f0(HR)
`
`
`
`READ REAR HEIGHT HR
`
`S2101
`
`
`
`DRIVE ACTUATOR
`
`S2106
`
`
`
`
`
`
`
`7
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 7 of 18
`
`US 6,193,398 B1
`
`F|G.|O
`
`[°]
`
`No<I>1'5
`
`__\\‘<\'_\\'\\'0in
`\’\;\\\\K
`
`.
`
`-90
`
`-so -so
`
`'
`
`-
`
`1
`
`TRUNK LOAD
`
`
`
`FIG. ll
`
`
`
`TRUNK LOAD
`
`\Y\_
` No\
`
`“.-1."\\‘.Ix\\T-‘U’!G
`
`8
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 8 of 18
`
`US 6,193,398 B1
`
`FIG. I2
`
`5..§\\\;\‘\\.»'010CD
` .\\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}
`
`F|G.|3
`
`9p[']
`\ '2’ ‘
`
`L11
`
`6
`
`_g\\\__x\Ҥ_\\\\ P4\
`
`-<
`
`ha
`
`-90
`
`-80
`
`-70
`
`-50
`
`-50
`
`-40
`
`30 ,
`20
`-30 -20 o
`/\ HR1mm]
`
`V0.5
`
`VV
`
`OCCUPANT LOAD
`
`A
`
`4
`
`
`
`TRUNK LOAD
`
`9
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 9 of 18
`
`US 6,193,398 B1
`
`F’|(3. I41
`
`sTART
`
`READ REAR HEIGHT HR
`
`32201
`
`READ SYSTEM ERROR
`INFORMATION
`
`S2202
`
`UPDATE REAR HEIGHT HR
`HR <- K- HR-Ah
`
`S2203
`
`S2204
`
`”°
`
`
`32205
`
`
`
`CALCULATE
`HTCH ANGLE ep BY
`fyi(HR),(i=1,Z.---)
`
`CALCULATE
`PITCH ANCLE 9p BY
`fxi(HR).(i=1,Z;")
`
`822°?
`
`DRIVE ACTUATOR
`
`33203
`
`RETURN
`
`10
`
`10
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 10 of 18
`
`US 6,193,398 B1
`
`FIG.|5
`
`WITH SYSTEM ERROR
`INFORMATION
`
`40
`
`WITHOUT SYSTEM
`ERROR INFORMATION
`
`-90
`
`-80
`
`-7o
`
`-60
`
`-so
`
`‘
`
`TRUNK LOAD
`
`FIG. I6
`
`f\3'OCDV1:
`
`F\\
`WITH SYSTEM ERROR
`INFORMATION
`
`[°]
`
`WITHOUT SYSTEM
`ERROR INFORMATION
`
`t
`
`—L
`
`'\'\'\\\\\‘\\'§\
`
`
`
`-90
`
`-80
`
`-7o
`
`-60
`
`-so -40
`
`A_‘
`
`10
`
`20
`
`so
`
`TRUNK LOAD
`
`11
`
`11
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 11 of 18
`
`US 6,193,398 B1
`
`F|G.|7
`
`WITH SYSTEM ERROR
`INFORMATION
`
`12
`
`12
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 12 of 18
`
`US 6,193,398 B1
`
`FIG. I9
`
`I
`;
`MEASURED
`REAR HEIGHT ,MEA3URED
`EFRONT HEIGHT
`
`E
`
`E I
`
`V
`(km/h]
`
`0
`
`<+>
`,
`
`g,Ig,qgAcE- 0T~,Me.n.URm111m,m.4,w.u A
`fl_|\7‘E
`[mm]
`‘
`’
`I ‘.'§"'WNv"
`'
`' WW‘
`CALCULATED
`
`(f)
`
`FRONT HEIGHT
`
`FIG. 20
`
`TIME
`
`MEASURED REAR HEIGHT
`AVERAGE AT CONSTANT
`RUNNLNC
`-j-__/______-
`
`13
`
`13
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 13 of 18
`
`US 6,193,398 B1
`
`READ VARIOUS
`SENSOR SIGNALS
`
`83101
`
`VEHICLE SPEED V
`REAR_HE|CHT VALUE HR
`
`S3108
`
`I
`
`33“
`
`FILTERINC
`
`60, HFO, HRO
`
`S3104
`
`S3105
`
`
`
`dV/dt I31 Tm/s21
`NO
`FILTERINC
`
`
`
`I
`
`S3107
`
`YES
`
`
`83110
`I
`I
`FILTERINC
`
`$3111
`
`Ie0—911>0.1 1' 1
`ES
`CANCEL PROCESSING
`
`‘ FOR ROADSIDE BLOCK I
`
`HFO<-HF
`HRO‘-HR
`
`CALCULATE
`PITCH ANCLE 60
`
`90=tan" {(HFO-HRO)/L}
`
`
`
`
`DRIVE ACTUATOR
`
`83115
`
`RETURN
`
`14
`
`F|G.2|
`
`S3103
`
`CALCULATE
`PITCH ANCLE 90
`
`HFO = a - HRO +h
`eo=tan“{(HFo—HRo)/L}
`
`
`
`
`
`N0
`CALCULATE
`PITCH ANCLE 61
`
`33105
`
`
`
`AHR= HR-HRO
`AHF==-P-AHR
`HF=HFO+AHF
`61=tan“{(HF-HR)/L}
`
`
`14
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 14 of 18
`
`US 6,193,398 B1
`
`Fl G. 22
`
`V
`[km/h]
`
`O
`
`,
`
`.
`I
`
`:
`
`MEASURED
`
`I
`;
`
`; FRONT HEIGHT
`
`I
`g>,Ig§,gAcE- _....II.“.I,I.I~ItII»lI“I.IIfi.*IIII. A
`[mm]
`v.v w.u-1. I""IIIMu:-vjqfiIIIIH’W!A‘V A’,
`
`-HEE
`
`I
`CONSTANT SPEED
`RUNNING DETERMINATION
`
`CALCULATED
`FRONT HEICI-TT
`
`WITH CORRECTION
`
`15
`
`15
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 15 of 18
`
`US 6,193,398 B1
`
`FIG. 24
`
`S3201
`
`READ VARIOUS
`SENSOR SIGNALS
`
`
`
`
`S3203
`
`
`
`CALCULATE
`PITCH ANGLE 90
`
`
`
`HFO = a - HRO +h
`eo=tan"{(HFo—HRo)/L}
`
`
`S3202
`<®>
`
`
`S3206
`
`$3207
`
`
`
`CALCULATE
`PITCH ANCLE 61
`
`AHR=HR-HRO
`AHF=-P-AHR
`HF=HFO+AHF
`61=tan“{(HF-HR)/L}
`
`ld\T/dt|;1tm/$21
`‘"33
`I
`FILTERING
`I
`S3208
`33209
`
`
`
`
`FILTERINC
`in”F°' HR‘)
`
`
`33204
`
`$3205
`
`S3210
`
`DRIVE ACTUATOR
`
`RETURN
`
`
`
`16
`
`16
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 16 of 18
`
`US 6,193,398 B1
`
`FIG. 25
`
`V
`[km/h]
`
`0
`
`9;)
`
`I
`:
`
`5
`
`CALCULATED
`
`FRONT HEICHT
`
`,
`
`.
`
`i
`:
`
`:
`
`E
`
`_’
`TIME
`
`
`A,
`.
`
`~
`
`;
`;
`3
`
`:MEAsuRED
`- FRONT HEIGHT
`MEASURED
`REAR HEIGHT
`TURNING
`:
`
`
`DlSPLACE-
`5
`ME§‘nImJ %’:"‘:w1'm
`:
`2
`
`4
`<->
`
`17
`
`I E
`
`17
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 17 of 18
`
`US 6,193,398 B1
`
`FIG. 26
`
`3330
`
`1
`
`READ VARIOUS
`SENSOR SIGNALS
`
`VEHICLE SPEEDV
`HR,_\TwR.VwL
`
`YES< 83302
`
`No
`
`S3306
`
`
`
`
`
`83308
`
`CALCULATE
`PITCH ANCLE 91
`
`AHR=HR-HRO
`
`Y
`33312
`I
`
`FILTERINC
`
`33313
`
`.
`
`33310
`I
`
`33311
`
`S3303
`
`CALCULATE
`PITCH ANGLE 90
`
`HFO=a-HRO+b
`
`EILTERINC
`90- HF0- “R0
`33304
`83305
`
`IIIT/IItI;Icm/s2:
`NO
`FILTERINC
`kg-“mi
`I60-617|>0.1(" I
`
`
`
`
`
`ES
`CANCEL PROCESSING
`FOR ROADSIDE BLOCK
`
`HFO<-HF
`HRO<- HR
`
`CALCULATE
`PITCH ANCLE 90
`
`
`
`60=tan“{(HFO-HRO)/L}
`
`DRIVE ACTUATOR
`
`83317
`
`RETURN
`
`18
`
`18
`
`
`
`U.S. Patent
`
`Feb. 27, 2001
`
`Sheet 18 of 18
`
`US 6,193,398 B1
`
`FIG. 27
`
`
`
`wma TURNING
`DETERMINATION
`
`V
`[km/h]
`
`0
`
`<+>
`1
`
`
`
`OPTICAL
`AXIS
`
`2513110“ 0
`'
`MENT r 1
`
`
`
`
`
`1
`T”'‘“'”‘‘
`
`—»
`TIME
`WITHOUT TURNING
`
`
`
`19
`
`19
`
`
`
`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
`filed on Jun. 16, 1998, Aug. 31, 1998,Apr. 15, 1999,Apr. 15,
`1999 and Apr. 19, 1999, respectively.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`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 flat 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
`
`15
`
`finished 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.
`
`invention, an
`According to one aspect of the present
`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
`filter 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
`
`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
`field 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 filtering process is executed when the
`acceleration is smaller than a predetermined value,
`the
`filtering 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 filtering
`process is not performed and the control mode is frequently
`switched. At the time of acceleration associated with the
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`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.
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`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-
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`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
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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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`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
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`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
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`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.
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`6p=tan’1{(HF—HR)/Lw}
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`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
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`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-
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`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
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`the acceleration dv/dt obtained by differentiating the vehicle
`speed V is equal to or lower than a preset threshold (XI. The
`threshold 0.1 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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`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
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`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
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`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/dt [m/s2] obtained
`by differentiating the speed V [km/h] largely changes to a
`level which can not be reached in the normal driving state.
`When the threshold for the absolute value of the acceleration
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`dV/dt in the determination for the control mode switching is
`only one stage of :2 [m/s2] shown in FIG. 3, the control
`mode is frequently switched among the acceleration,
`deceleration, and constant speed modes in association with
`the large change in the acceleration dv/dt at the time of the
`TRC or ABS control as shown in FIG. 5. The filter corre-
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`sponding to the control mode is, accordingly, frequently
`switched between the filters B and C as shown in FIG. 5.
`In this embodiment,
`therefore,
`the thresholds for the
`absolute value of the acceleration dV/dt in the