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`PTOISBIO5 (03-01)
`Approved for use through 10/31/2002. OMB 05510032
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`Automatic Directional Control System For Vehicle Headlights - __
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`ADDRESS TO.‘
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`Washinton, D.C. 20231
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`'”"e””°”‘ AUTOMATIC DIRECTIONAL CONTROL SYSTEM FOR VEHICLE HEADLIGHTS
`
`I hereby certify that the following correspondence:
`
`UTILITY PATENT APPLICATION
`
`(Identify rypc afcarrespomlcnce)
`
`is being deposited with the United States Postal Service "Express Mail Post Office to Addressee" service under
`
`37 CFR 1.10 in an envelope addressed to: The Assistant Commissioner for Patents, Washington, DC. 20231 on
`
`October 31, 2002
`(Date)
`
`Betty J. Borger
`(Typed or Printed Name of Person Mailing Cnrrespondence)
`
`(Sigagature o;l’e;s0n Mailing Corgonfienie)
`
`T‘A 7’
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`EL 777901929 US
`("Express Illuil" Mailing Label Number)
`
`Note: Each paper must have its own certificate of mailing.
`
`POGAIREVOZ
`
`2
`
`
`
`AUTOMATIC DIRECTIONAL CONTROL
`
`SYSTEM FOR VEHICLE HEADLIGHTS
`
`CROSS REFERENCE TO RELATED APPLICATIONS
`
`This application claims the benefit of United States Provisional Application
`
`Nos. 60/335,409, filed October 31, 2001; 60/356,703, filed February 13, 2002; and
`
`60/369,447, filed April 2, 2002, the disclosures of which are incorporated herein by
`
`reference.
`
`BACKGROUND OF THE INVENTION
`
`This invention relates in general to headlights that are provided on Vehicles for
`
`—
`
`illuminating dark road surfaces or other areas in the path of movement. In particular,
`
`this invention relates to an automatic directional control system for such vehicle
`
`headlights.
`
`Virtually all land vehicles, and many other types ofvehicles (such as boats and
`
`airplanes, for example), are provided with one or more headlights that are adapted to
`
`illuminate a portion of a dark road surface or other area in the path of movement of the
`
`vehicle to facilitate safe travel thereon. Typically, each headlight is mounted on or
`
`near the front end of the vehicle and is oriented in such a manner that a beam of light
`
`is projected forwardly therefrom. The angle at which the beam of light projects from
`
`the headlight can, for example, be characterized in a variety of Ways, including (1) up
`
`and down relative to a horizontal reference position or plane and (2) left and right
`
`relative to a vertical reference position or plane. Such directional aiming angles are
`
`usually set at the time of assembly of the headlight into the vehicle so as to illuminate
`
`a predetermined portion of the road surface or other area in the path of movement of
`
`the vehicle.
`
`In the past, these headlights have been mounted on the vehicle in fixed
`
`positions relative thereto such that the beams of light are projected therefrom at
`
`3
`
`
`
`predetermined directional aiming angles relative to the vehicle. Although such fixed
`
`aiming angle headlight systems haveiand continue to function adequately, they cannot
`
`alter the directional aiming angles of the headlights to account for changes in the
`
`operating conditions of the vehicle. For example, if the speed of the vehicle is
`
`increased, it would be desirable to adjust the aiming angle of the headlights upwardly
`
`such that an area that is somewhat farther in front of the vehicle is more brightly
`
`illuminated. On the other hand, if the speed of the vehicle is decreased, it would be
`
`desirable to adjust the aiming angle of the headlights downwardly such that an area
`
`that is somewhat closer in front of the vehicle is more brightly illuminated. Similarly,
`
`if the vehicle turns a corner, it would be desirable to adjust the aiming angle of the
`
`headlights either toward the left or toward the right (depending on the direction of the
`
`turn) such that an area that is somewhat lateral to the front of the vehicle is more
`
`brightly illuminated.
`
`To accomplish this, it is known to provide a directional control system for
`
`vehicle headlights that is capable of automatically altering the directional aiming
`
`angles of the headlights to account for changes in the operating conditions of the
`
`vehicle. A variety of such automatic directional control systems for vehicle headlights
`
`are known in the art. However, such known automatic headlight directional control
`
`systems have been found to be deficient for various reasons. Thus, it would be
`
`desirable to provide an improved structure for an automatic headlight directional
`
`control system that addresses such deficiencies.
`
`SUMMARY OF THE INVENTION
`
`This invention relates to an improved structure and method for operating a
`
`directional control system for vehicle headlights that is capable of automatically
`
`altering the directional aiming angles of the headlights to account for changes in the
`
`operating conditions of the vehicle. One or more operating condition sensors may be
`
`provided that generate signals that are representative of an operating condition of the
`
`vehicle, such as road speed, steering angle, pitch, suspension height, rate of change of
`
`road speed, rate of change of steering angle, rate of change of pitch, and rate of change
`
`4
`
`
`
`of suspension height of the vehicle. A controller is responsive to the sensor signal for
`
`generating an output signal. An actuator is adapted to be connected to the headlight to
`
`effect movement thereof in accordance with the output signal. The controller can
`
`include a table that relates values of sensed operating condition to values of the output
`
`signal. The controller is responsive to the sensor signal for looking up the output
`
`signal in the table.
`
`Various objects and advantages of this invention will become apparent to those
`
`skilled in the art from the following detailed description of the preferred embodiments,
`
`when read in light of the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Fig. 1 is a block diagram of an automatic directional control system for a
`
`vehicle headlight in accordance with this invention.
`
`Fig. 2 is a flow chart of an algorithm for calibrating the automatic directional
`
`control system illustrated in Fig. 1 so as to define an initial reference position for the
`
`headlight from which the headlight directional controller can implement directional
`
`angle adjustments.
`
`Fig. 3 is a [low chart of an algorithm for generating a table that relates one or
`
`more sensed vehicle operating condition values to one or more headlight directional
`
`angle adjustment factors and for storing such table in the headlight directional
`
`controller illustrated in Fig. 1.
`
`Fig. 4 is an example of a table that can be generated and stored in the headlight
`
`directional controller in accordance with the table generating algorithm illustrated in
`
`Fig. 3.
`
`Fig. 5 is a flow chart of an algorithm for operating the headlight directional
`
`controller illustrated in Fig. 1 to automatically implement directional angle
`
`adjustments in accordance with sensed condition values.
`
`Fig. 6 is a flow chart of an algorithm for operating the headlight directional
`
`controller illustrated in Fig. 1 to automatically implement directional angle
`
`5
`
`
`
`adjustments in accordance with the rate of change of one or more of the sensed
`
`condition values.
`
`Fig. 7 is a flow chart of an algorithm for operating the headlight directional
`
`controller illustrated in Fig. 1 to automatically implement directional angle
`
`adjustments, but only when the rate of change of one or more of the sensed condition
`
`values is less than (or greater than) a predetermined value.
`
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`Referring now to the drawings, there is illustrated in Fig. 1 an automatic
`
`directional control system, indicated generally at 10, for a vehicle headlight l l in
`
`accordance with this invention. The illustrated headlight 11 is, of itself, conventional
`
`in the art and is intended to be representative of any device that can be supported on
`
`any type of vehicle for the purpose of illuminating any area, such as an area in the path
`
`of movement of the vehicle. The headlight 11 is typically mounted on or near the
`
`front end of a vehicle (not shown) and is oriented in such a manner that a beam of
`
`light is projected therefrom. In a manner that is well known in the art, the headlight ll
`
`is adapted to illuminate a portion of a dark road surface or other area in the path of
`
`movement of the Vehicle to facilitate safe travel thereon.
`
`The headlight 11 is adjustably mounted on the vehicle such that the directional
`
`orientation at which the beam of light projects therefrom can be adjusted relative to the
`
`vehicle. Any desired mounting structure can be provided to accomplish this.
`
`Typically, the headlight 11 is mounted on the vehicle such that the angle at which the
`
`beam of light projects therefrom can be adjusted both (1) up and down relative to a
`
`horizontal reference position or plane and (2) left and right relative to a vertical
`
`reference position or plane. Although this invention will be described and illustrated
`
`in the context of a headlight that is adjustable in both the up/down direction and the
`
`left/right direction, it will be appreciated that this invention may be practiced with any
`
`headlight 11 that is adjustable in any single direction or multiple directions of
`
`movement, whether up/down, left/right, or any other direction.
`
`6
`
`
`
`To effect movement of the illustrated headlight 11 relative to the vehicle, an
`
`up/down actuator 12 and a left/right actuator 13 are provided. The actuators 12 and 13
`
`are conventional in the art and may, for example, be embodied as servo motors, step
`
`motors, or any other electronically controlled mechanical actuators. It has been found
`
`to be desirable to use microstepping motors for the actuators 12 and 13. Such
`
`microstepping motors are known in the art and consist of conventional step motors
`
`that have appropriate hardware (i.e., driver integrated circuits) and software that allow
`
`the step motors to be operated in fractional step increments. The use of such
`
`microsteppin g motors has been found to be desirable because they can effect
`
`movements of the headlights in a somewhat faster, smoother, and quieter manner than
`
`conventional step motors, and further permit more precise positioning of the
`
`headlights 11. In the illustrated embodiment, the up/down actuator 12 is mechanically
`
`connected to the headlight 11 such that the headlight 11 can be selectively adjusted up
`
`and down relative to a horizontal reference position or plane. Similarly, the illustrated
`
`left/right actuator 13 is mechanically connected to the headlight 11 such that the
`
`headlight 1 1 can be selectively adjusted left and right relative to a vertical reference
`
`position or plane.
`
`A headlight directional controller 14 is provided for controlling the operations
`
`of the up/down actuator 12 and the left/right actuator 13 and, therefore, the angle at
`
`which the beam of light projects from the headlight 11 relative to the vehicle. The
`
`headlight directional controller 14 can be embodied as any control system, such as a
`
`microprocessor or programmable electronic controller, that is responsive to one or
`
`more sensed operating conditions of the vehicle for selectively operating the up/down
`
`actuator 12 and the left/right actuator 13. To accomplish this, the automatic
`
`directional control system 10 can include, for example, a pair of condition sensors 15
`
`and 16 that are connected to the headlight directional controller 14. The condition
`
`sensors 15 and l6 are conventional in the art and are responsive to respective sensed
`
`operating conditions of the vehicle for generating electrical signals to the headlight
`
`directional controller 14. However, if desired, only a single one of the condition
`
`sensors 15 and 16 need be provided. Alternatively, additional condition sensors (not
`
`7
`
`
`
`shown) may be provided if desired to generate electrical signals that are representative
`
`of any other operating conditions of the vehicle. A conventional input/output device
`
`17 is connected to (or can be connected to) the headlight directional controller 14 for
`
`facilitating communication therewith in the manner described below.
`
`If desired, a first position feedback sensor 18 may be provided for the up/down
`
`actuator 12, and a second position feedback sensor 19 may be provided for the
`
`left/right actuator 13. The position feedback sensors 18 and 19 are conventional in the
`
`art and are adapted to generate respective electrical signals that are representative of
`
`the actual up/down and left/right positions of the headlight 11. Thus, the first position
`
`feedback sensor 18 is responsive to the actual up/down position of the headlight l l (as
`
`determined by a portion of the up/down actuator 12, for example) for generating an
`
`electrical signal to the headlight directional controller 14 that is representative thereof.
`
`Similarly, the second position feedback sensor 19 is responsive to the actual left/right
`
`position of the headlight 11 (as determined by a portion of the left/right actuator 13,
`
`for example) for generating an electrical signal to the headlight directional controller
`
`14 that is representative thereof. The position feedback sensors 18 and 19 can be
`
`embodied as any conventional sensor structures, such as Hall effect sensors, that are
`
`responsive to movements of the headlight 11 (or to the movements of the respective
`
`actuators 12 and 13 that are connected to move the headlight l l) for generating such
`
`signals.
`
`Alternatively, the position feedback sensors 18 and 19 can be embodied as
`
`respective devices that generate electrical signals whenever the headlight 1 1 has
`
`achieved respective predetermined up/down or left/right positions. This can be
`
`accomplished, for example, using a conventional optical interrupter (not shown) for
`
`each of the actuators 12 and 13. Each of the optical interrupters includes a flag or
`
`other component that is mounted on or connected to the headlight 11 for movement
`
`therewith. Each of the optical interrupters fiirther includes an optical source and
`
`sensor assembly. As the headlight ] I is moved by the actuators 12 and 13, the flag
`
`moves therewith relative to the optical source and sensor assembly between a first
`
`position, wherein the flag permits light emitted from the source from reaching the
`
`8
`
`
`
`sensor, and a second position, wherein the flag prevents light emitted from the source
`
`from reaching the sensor. When the flag is in the first position relative to the optical
`
`source and sensor assembly, the sensor is permitted to receive light emitted from the
`
`source. As a result, a first signal is generated from the optical source and sensor
`
`assembly to the headlight directional controller 14. Conversely, when the flag is in the
`
`second position relative to the optical source and sensor assembly, the sensor is not
`
`permitted to receive light emitted from the source. As a result, a second signal is
`
`generated from the optical source and sensor assembly to the headlight directional
`
`controller 14. Thus, the edge of the flag defines a transition between the first and
`
`second positions of the flag relative to the optical source and sensor assembly and,
`
`therefore, defines a predetermined up/down or left/right position of the headlight ll.
`
`The nature of the signal generated from the optical source and sensor assembly to the
`
`headlight directional controller 14 (i.e., the first signal or the second signal) can also
`
`be used to determine on which side of the predetermined position (the left side or the
`
`right side, for example) that the headlight 11 is positioned. The purpose for such
`
`position feedback sensors 18 and 19 will be discussed below.
`
`Fig. 2 is a flow chart of an algorithm, indicated generally at 20, for calibrating
`
`the automatic directional control system illustrated in Fig. 1 so as to define an initial
`
`reference position or positions for the headlight 11 from which the headlight
`
`directional controller 14 can implement directional angle adjustments. As mentioned
`
`above, the headlight 11 is mounted on the vehicle such that the angle at which the
`
`beam of light projects therefrom can be adjusted both up and down relative to a
`
`horizontal reference position or plane and left and right relative to a Vertical reference
`
`position or plane. To insure accurate positioning of the headlight 1 1, it is desirable
`
`that a reference position or positions be initially established by the headlight
`
`directional controller 14. Subsequent directional angle adjustments can be made by
`
`the headlight directional controller 14 from the pre-established reference position or
`
`positions established by this calibration algorithm 20.
`
`To accomplish this, the calibration algorithm 20 has a first step 21 wherein the
`
`headlight directional controller 14 is caused to enter a calibration mode of operation.
`
`9
`
`
`
`In the calibration mode of operation, the headlight directional controller 14 is
`
`responsive to input signals from the input/output device 17 (or from another source, if
`
`desired) for causing manual operation of the up/down actuator 12 and the left/right
`
`actuator 13. Thus, while the headlight directional controller 14 is in the calibration
`
`mode of operation, an operator of the input/output device 17 can manually effect either
`
`up/down movement of the headlight 1 1, left/right movement of the headlight 11, or
`
`both, as desired.
`
`In a second step 22 of the calibration algorithm 20, the up/down actuator 12 and
`
`the left/right actuator 13 are manually operated to aim the headlight 1 1 in a
`
`predetermined reference orientation. This can be accomplished by use of the
`
`input/output device 17 that, as mentioned above, is connected to (or can be connected
`
`to) the headlight directional controller 14. Traditionally, the aiming of a headlight 11
`
`has been accomplished by parking the vehicle on a surface near a wall or other vertical
`
`structure, providing a reference target at a predetermined location on the wall or other
`structure, and mechanically adjusting the mounting structure of the headlight 11 such
`
`that the center of the beam therefrom is projected at the reference target. In this
`
`invention, the vehicle is parked on a surface near a wall or other Vertical structure, and
`
`a reference target is provided at a predetermined location on the wall or other
`
`structure, as described above. Next, in accordance with the second step 22 of this
`
`calibration algorithm 20, the input/output device 17 is operated to generate electrical
`
`signals to the headlight directional controller 14. In response to such electrical signals,
`
`the headlight directional controller 14 operates the up/down actuator 12 and the
`
`left/right actuator 13 to move the headlight 11 such that center of the beam projecting
`
`therefrom is aimed at the reference target. When the beam from the headlight 11 is so
`
`aimed, then the headlight 11 is determined to be oriented in the initial reference
`
`position from which the headlight directional controller 14 can subsequently
`
`implement directional angle adjustments.
`
`In a third step 23 of the calibration algorithm 20, once this initial reference
`
`position for the headlight 11 has been achieved, such position is stored in the headlight
`
`directional controller 14 as the predetermined initial reference position. This can be
`
`10
`
`
`
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`
`accomplished by means of the position feedback sensors 18 and 19. As discussed
`
`above, the position feedback sensors 18 and 19 are adapted to generate respective
`
`electrical signals that are representative of the actual up/down and left/right positions
`
`of the headlight 11 or of the predetermined positions for the headlight. Thus, the first
`
`position feedback sensor 18 is responsive to the actual up/down position of the
`
`headlight 11 (as determined by the up/down actuator 12, for example) for generating
`
`an electrical signal to the headlight directional controller 14 that is representative
`
`thereof. Similarly, the second position feedback sensor 19 is responsive to the actual
`
`left/right position of the headlight 11 (as determined by the left/right actuator 13, for
`
`example) for generating an electrical signal to the headlight directional controller 14
`
`that is representative thereof. Accordingly, the third step 23 of the calibration
`
`algorithm 20 can be performed by causing the headlight directional controller 14 to
`
`read the signals from the position feedback sensors 18 and 19 and store the current
`
`up/down and left/right positions of the headlight 11 as the initial reference positions
`
`from which the headlight directional controller 14 can subsequently implement
`
`directional angle adjustments.
`
`The current position of the headlight 11 is preferably stored in the non-volatile
`
`memory of the headlight directional controller 14 for reference during normal
`
`operation of the automatic directional control system 10 described below. Thus, when
`
`the automatic directional control system 10 is initially activated (such as when the
`
`electrical system of the vehicle is initially turned on), the headlight directional
`
`controller 14 can position the headlight 11 at or near the calibrated position utilizing
`
`the signals comparing the current position of the headlight 11 (as determined by the
`
`signals generated by the position feedback sensors 18 and 19) with the predetermined
`
`reference position determined by the calibration algorithm 20.
`
`Fig. 3 is a flow chart of an algorithm, indicated generally at 30, for generating a
`
`table that relates the sensed condition values from the condition sensors 15 and 16 to
`
`the headlight directional angle adjustment factors that will be implemented by the
`
`headlight directional controller 14, and further for storing such table in the headlight
`
`directional controller 14 illustrated in Fig. 1. As used herein, the term “table” is
`
`11
`
`
`
`intended to be representative of any collection or association of data that relates one or
`
`more of the sensed condition values to one or more of the headlight directional angle
`
`adjustment factors. The table of data can be generated, stored, and expressed in any
`
`desired format. For example, this table of data can be generated, stored, and expressed
`
`in a conventional spreadsheet format, such as shown in Fig. 4, which will be discussed
`
`in detail below.
`
`In a first step 31 of the table generating algorithm 30, an adjustment control
`
`algorithm is selected. The adjustment control algorithm can be, generally speaking,
`
`any desired relationship that relates one or more operating conditions of the vehicle to
`
`one or more angular orientations of the headlight l 1. A variety of such relationships
`
`are known in the art, and this invention is not intended to be limited to any particular
`
`relationship. Typically, such relationships will be expressed in terms of a
`
`mathematical equation or similar relationship that can be readily processed using a
`
`microprocessor or similar electronic computing apparatus, such as the above-described
`
`headlight directional controller 14. The particular adjustment control algorithm that is
`
`selected may, if desired, vary from vehicle to vehicle in accordance with a variety of
`
`factors, including relative size and performance characteristics of the vehicle or any
`
`other desired condition.
`
`As mentioned above, a plurality of operating conditions may be sensed by the
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`condition sensors 15 and 16 and provided to the headlight directional controller 14 for
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`use with the adjustment control mechanism. For example, the condition sensors 15
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`and 16 may generate electrical signals to the headlight directional controller 14 that are
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`representative of the road speed, the steering angle, and the pitch of the vehicle (which
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`can, for example, be determined by sensing the front and rear suspension heights of
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`the vehicle or by a pitch or level sensor). Additionally, the time derivative of these
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`operating conditions (i.e., the rate of change of the road speed, steering angle, and
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`pitch of the vehicle) can be sensed or calculated. However, any other operating
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`condition or conditions of the vehicle may be sensed and provided to the headlight
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`directional controller 14.
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`12
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`In a second step 32 of the table generating algorithm 30, the table is generated
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`using the adjustment control algorithm selected in the first step 31. The table can be
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`generated in any desired manner. For example, let it be assumed that the selected
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`adjustment control algorithm relates a single sensed operating condition to each of the
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`angular adjustment control values for adjusting both the up/down orientation and the
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`left/right orientation of the headlight 11. The table can be generated by initially
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`selecting a first discrete sensed operating condition value that might be encountered
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`during operation of the vehicle. Then, the selected adjustment control algorithm is
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`solved using such first discrete sensed operating condition value to obtain the
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`corresponding adjustment control values for the up/down and left/right orientation of
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`the headlight 11. Then, the first discrete sensed operating condition value and the
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`corresponding adjustment control values are stored in the table. This process can be
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`repeated for any desired number of other discrete sensed operating condition values
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`that might be encountered during operation of the vehicle.
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`As mentioned above, Fig. 4 is a representative example ofa table, indicated
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`generally at 40, that can be generated in accordance with the second step 32 of the
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`table generating algorithm 30 illustrated in Fig. 3. As shown therein, a series of
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`discrete sensed operating condition values (degrees of steering angles, for example) is
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`related to the angular adjustment control values (degrees of movement from the
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`associated up/down and left/right reference positions or planes, for example) for
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`adjusting both the up/down orientation and the left/right orientation of the headlight
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`11. For the purposes of illustration only, let it be assumed that (l) a positive steering
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`angle value represents steering toward left, while a negative steering angle value
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`represents steering toward the right, (2) a positive up/down adjustment factor
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`represents aiming the headlight ll upwardly, while a negative up/down adjustment
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`factor represents aiming the headlight ll downwardly, and (3) a positive left/right
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`adjustment factor represents aiming the headlight 11 toward the left, while a negative
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`left/right adjustment factor represents aiming the headlight 11 toward the right.
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`Thus, in accordance with the selected adjustment control algorithm, a sensed
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`steering angle of +6° results in an up/down adjustment factor of -3.00° and a left/right
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`11
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`13
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`
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`adjustment factor of +4.50°. Similarly, a sensed steering angle of +5° results in an
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`up/down adjustment factor of -2.50° and a left/right adjustment factor of +3.75°, and
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`so on as shown in the table 40. The illustrated table 40 relates thirteen different sensed
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`steering angle values to their corresponding adjustment control values for both the
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`up/down and left/right orientation of the headlight l 1. However, the table 40 can
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`include a greater or lesser number of such sensed operating condition values, together
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`with their corresponding adjustment control values. Furthermore, although the
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`illustrated table 40 relates only a single sensed operating condition value (steering
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`angle) to the corresponding adjustment control values for both the up/down and
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`left/right orientation of the headlight 1 1, the selected adjustment control algorithm
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`may, as mentioned above, be responsive to a plurality of sensed operating condition
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`values for determining the corresponding adjustment control values. Alternatively, as
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`will be discussed further below, a plurality of tables 40 can be generated, one for each
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`of the plurality of sensed operating condition values. The size and extent of the table
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`40 or tables can be varied to accommodate any desired number of such sensed
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`operating conditions.
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`Referring back to Fig. 3, in a third step 33 of the table generating algorithm 30,
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`the table 40 generated in the second step 32 is stored in the memory of the headlight
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`directional controller 14 illustrated in Fig. 1. The contents of the table 40 can be
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`communicated serially to the headlight directional controller 14 by means of the
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`input/output device 17 illustrated in Fig. l or in any other desired manner. Regardless
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`of how it is communicated, the table 40 is preferably stored in a non—volatile memory
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`of the headlight directional controller 14 for subsequent use in the manner described
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`further below when the vehicle is operated.
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`As mentioned above, it may be desirable to vary the algorithm that is selected
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`for use i11 implement