TITLE
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`AUTOMATIC DIRECTIONAL CONTROL
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`SYSTEM FOR VEHICLE HEADLIGHTS
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`CROSS REFERENCE TO RELATED APPLICATIONS
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`This application claims the benefit of United States Provisional Application
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`Nos. 60/335,409, filed October 31, 2001; 60/356,703, filed February 13, 2002; and
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`60/369,447, filed April 2, 2002, the disclosures of which are incorporated herein by
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`reference.
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`BACKGROUND OF THE INVENTION
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`This invention relates in general to headlights that are provided on Vehicles for
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`illuminating dark road surfaces or other areas in the path of movement. In particular,
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`this invention relates to an automatic directional control system for such vehicle
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`headlights.
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`Virtually all land vehicles, and many other types of vehicles (such as boats and
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`airplanes, for example), are provided with one or more headlights that are adapted to
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`illuminate a portion of a dark road surface or other area in the path of movement of the
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`vehicle to facilitate safe travel thereon. Typically, each headlight is mounted on or
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`near the front end of the vehicle and is oriented in such a manner that a beam of light
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`is projected forwardly therefrom. The angle at which the beam of light projects from
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`the headlight can, for example, be characterized in a variety of ways, including (1) up
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`and down relative to a horizontal reference position or plane and (2) left and right
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`relative to a Vertical reference position or plane. Such directional aiming angles are
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`usually set at the time of assembly of the headlight into the vehicle so as to illuminate
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`a predetermined portion of the road surface or other area in the path of movement of
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`the vehicle.
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`In the past, these headlights have been mounted on the vehicle in fixed
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`positions relative thereto such that the beams of light are projected therefrom at
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`MBUSA LLC
`EXHIBIT 1009
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`predetermined directional aiming angles relative to the vehicle. Although such fixed
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`aiming angle headlight systems have and continue to function adequately, they cannot
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`alter the directional aiming angles of the headlights to account for changes in the
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`operating conditions of the vehicle. For example, if the speed of the vehicle is
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`increased, it would be desirable to adjust the aiming angle of the headlights upwardly
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`such that an area that is somewhat farther in front of the vehicle is more brightly
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`illuminated. On the other hand, if the speed of the vehicle is decreased, it would be
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`desirable to adjust the aiming angle of the headlights downwardly such that an area
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`that is somewhat closer in front of the vehicle is more brightly illuminated. Similarly,
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`if the vehicle turns a corner, it would be desirable to adjust the aiming angle of the
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`headlights either toward the left or toward the right (depending on the direction of the
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`turn) such that an area that is somewhat lateral to the front of the vehicle is more
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`brightly illuminated.
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`To accomplish this, it is known to provide a directional control system for
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`vehicle headlights that is capable of automatically altering the directional aiming
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`angles of the headlights to account for changes in the operating conditions of the
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`vehicle. A variety of such automatic directional control systems for vehicle headlights
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`are known in the art. However, such known automatic headlight directional control
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`systems have been found to be deficient for various reasons. Thus, it would be
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`desirable to provide an improved structure for an automatic headlight directional
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`control system that addresses such deficiencies.
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`SUMMARY OF THE INVENTION
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`This invention relates to an improved structure and method for operating a
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`directional control system for vehicle headlights that is capable of automatically
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`altering the directional aiming angles of the headlights to account for changes in the
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`operating conditions of the vehicle. One or more operating condition sensors may be
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`provided that generate signals that are representative of an operating condition of the
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`vehicle, such as road speed, steering angle, pitch, suspension height, rate of change of
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`road speed, rate of change of steering angle, rate of change of pitch, and rate of change
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`of suspension height of the vehicle. A controller is responsive to the sensor signal for
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`generating an output signal. An actuator is adapted to be connected to the headlight to
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`effect movement thereof in accordance with the output signal. The controller can
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`include a table that relates values of sensed operating condition to values of the output
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`signal. The controller is responsive to the sensor signal for looking up the output
`signal in the table.
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`Various objects and advantages of this invention will become apparent to those
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`skilled in the art from the following detailed description of the preferred embodiments,
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`when read in light of the accompanying drawings.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`Fig. 1 is a block diagram of an automatic directional control system for a
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`vehicle headlight in accordance with this invention.
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`Fig. 2 is a flow chart of an algorithm for calibrating the automatic directional
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`control system illustrated in Fig. 1 so as to define an initial reference position for the
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`headlight from which the headlight directional controller can implement directional
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`angle adjustments.
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`Fig. 3 is a flow chart of an algorithm for generating a table that relates one or
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`more sensed vehicle operating condition values to one or more headlight directional
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`angle adjustment factors and for storing such table in the headlight directional
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`controller illustrated in Fig. 1.
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`Fig. 4 is an example of a table that can be generated and stored in the headlight
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`directional controller in accordance with the table generating algorithm illustrated in
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`Fig. 3.
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`Fig. 5 is a flow chart of an algorithm for operating the headlight directional
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`controller illustrated in Fig. 1 to automatically implement directional angle
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`adjustments in accordance with sensed condition values.
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`Fig. 6 is a flow chart of an algorithm for operating the headlight directional
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`controller illustrated in Fig. l to automatically implement directional angle
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`adjustments in accordance with the rate of change of one or more of the sensed
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`condition values.
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`Fig. 7 is a flow chart of an algorithm for operating the headlight directional
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`controller illustrated in Fig. 1 to automatically implement directional angle
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`adjustments, but only when the rate of change of one or more of the sensed condition
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`values is less than (or greater than) a predetermined value.
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`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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`Referring now to the drawings, there is illustrated in Fig. 1 an automatic
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`directional control system, indicated generally at 10, for a vehicle headlight 1 1 in
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`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
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`any type of vehicle for the purpose of illuminating any area, such as an area in the path
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`of movement of the vehicle. The headlight 11 is typically mounted on or near the
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`front end of a vehicle (not shown) and is oriented in such a manner that a beam of
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`light is projected therefrom. In a manner that is well known in the art, the headlight 11
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`is adapted to illuminate a portion of a dark road surface or other area in the path of
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`movement of the vehicle to facilitate safe travel thereon.
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`The headlight 11 is adjustably mounted on the vehicle such that the directional
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`orientation at which the beam of light projects therefrom can be adjusted relative to the
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`Vehicle. Any desired mounting structure can be provided to accomplish this.
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`Typically, the headlight 11 is mounted on the vehicle such that the angle at which the
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`beam of light projects therefrom can be adjusted both (1) up and down relative to a
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`horizontal reference position or plane and (2) left and right relative to a vertical
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`reference position or plane. Although this invention will be described and illustrated
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`in the context of a headlight that is adjustable in both the up/down direction and the
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`left/right direction, it will be appreciated that this invention may be practiced with any
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`headlight 11 that is adjustable in any single direction or multiple directions of
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`movement, whether up/down, left/right, or any other direction.
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`To effect movement of the illustrated headlight 1 1 relative to the vehicle, an
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`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
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`motors, or any other electronically controlled mechanical actuators. It has been found
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`to be desirable to use microstepping motors for the actuators 12 and 13. Such
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`microstepping motors are known in the art and consist of conventional step motors
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`that have appropriate hardware (i.e., driver integrated circuits) and software that allow
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`the step motors to be operated in fractional step increments. The use of such
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`microstepping motors has been found to be desirable because they can effect
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`movements of the headlights in a somewhat faster, smoother, and quieter manner than
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`conventional step motors, and further permit more precise positioning of the
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`headlights 11. In the illustrated embodiment, the up/down actuator 12 is mechanically
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`connected to the headlight 11 such that the headlight 11 can be selectively adjusted up
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`and down relative to a horizontal reference position or plane. Similarly, the illustrated
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`left/right actuator 13 is mechanically connected to the headlight 11 such that the
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`headlight 11 can be selectively adjusted left and right relative to a vertical reference
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`position or plane.
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`A headlight directional controller 14 is provided for controlling the operations
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`of the up/down actuator 12 and the left/right actuator 13 and, therefore, the angle at
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`which the beam of light projects from the headlight 1 1 relative to the vehicle. The
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`headlight directional controller 14 can be embodied as any control system, such as a
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`microprocessor or programmable electronic controller, that is responsive to one or
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`more sensed operating conditions of the vehicle for selectively operating the up/down
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`actuator 12 and the left/right actuator 13. To accomplish this, the automatic
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`directional control system 10 can include, for example, a pair of condition sensors 15
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`and 16 that are connected to the headlight directional controller 14. The condition
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`sensors 15 and 16 are conventional in the art and are responsive to respective sensed
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`operating conditions of the vehicle for generating electrical signals to the headlight
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`directional controller 14. However, if desired, only a single one of the condition
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`sensors 15 and 16 need be provided. Alternatively, additional condition sensors (not
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`shown) may be provided if desired to generate electrical signals that are representative
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`of any other operating conditions of the vehicle. A conventional input/output device
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`17 is connected to (or can be connected to) the headlight directional controller 14 for
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`facilitating communication therewith in the manner described below.
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`If desired, a first position feedback sensor 18 may be provided for the up/down
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`actuator 12, and a second position feedback sensor 19 may be provided for the
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`left/right actuator 13. The position feedback sensors 18 and 19 are conventional in the
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`art and are adapted to generate respective electrical signals that are representative of
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`the actual up/down and left/right positions of the headlight 11. Thus, the first position
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`feedback sensor 18 is responsive to the actual up/down position of the headlight 11 (as
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`determined by a portion of the up/down actuator 12, for example) for generating an
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`electrical signal to the headlight directional controller 14 that is representative thereof.
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`Similarly, the second position feedback sensor 19 is responsive to the actual left/right
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`position of the headlight 11 (as determined by a portion of the lefi/right actuator 13,
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`for example) for generating an electrical signal to the headlight directional controller
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`14 that is representative thereof. The position feedback sensors 18 and 19 can be
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`embodied as any conventional sensor structures, such as Hall effect sensors, that are
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`responsive to movements of the headlight 11 (or to the movements of the respective
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`actuators 12 and 13 that are connected to move the headlight l l) for generating Such
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`signals.
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`Alternatively, the position feedback sensors 18 and 19 can be embodied as
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`respective devices that generate electrical signals whenever the headlight 11 has
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`achieved respective predetermined up/down or left/right positions. This can be
`accomplished, for example, using a conventional optical interrupter (not shown) for
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`each of the actuators 12 and 13. Each of the optical interrupters includes a flag or
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`other component that is mounted on or connected to the headlight l 1 for movement
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`therewith. Each of the optical interrupters further includes an optical source and
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`sensor assembly. As the headlight 1 I is moved by the actuators 12 and 13, the flag
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`moves therewith relative to the optical source and sensor assembly between a first
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`position, wherein the flag permits light emitted from the source from reaching the
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`sensor, and a second position, wherein the flag prevents light emitted from the source
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`from reaching the sensor. When the flag is in the first position relative to the optical
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`source and sensor assembly, the sensor is permitted to receive light emitted from the
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`source. As a result, a first signal is generated from the optical source and sensor
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`assembly to the headlight directional controller 14. Conversely, when the flag is in the
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`second position relative to the optical source and sensor assembly, the sensor is not
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`permitted to receive light emitted from the source. As a result, a second signal is
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`generated from the optical source and sensor assembly to the headlight directional
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`controller 14. Thus, the edge of the flag defines a transition between the first and
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`second positions of the flag relative to the optical source and sensor assembly and,
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`therefore, defines a predetermined up/down or left/right position of the headlight 1 1.
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`The nature of the signal generated from the optical source and sensor assembly to the
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`headlight directional controller 14 (i.e., the first signal or the second signal) can also
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`be used to determine on which side of the predetermined position (the left side or the
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`right side, for example) that the headlight 11 is positioned. The purpose for such
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`position feedback sensors 18 and 19 will be discussed below.
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`Fig. 2 is a flow chart of an algorithm, indicated generally at 20, for calibrating
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`the automatic directional control system illustrated in Fig. 1 so as to def111e an initial
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`reference position or positions for the headlight 11 from which the headlight
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`directional controller 14 can implement directional angle adjustments. As mentioned
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`above, the headlight 11 is mounted on the vehicle such that the angle at which the
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`beam of light projects therefrom can be adjusted both up and down relative to a
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`horizontal reference position or plane and left and right relative to a vertical reference
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`position or plane. To insure accurate positioning of the headlight 11, it is desirable
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`that a reference position or positions be initially established by the headlight
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`directional controller 14. Subsequent directional angle adjustments can be made by
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`the headlight directional controller 14 from the pre-established reference position or
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`positions established by this calibration algorithm 20.
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`To accomplish this, the calibration algorithm 20 has a first step 21 wherein the
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`headlight directional controller 14 is caused to enter a calibration mode of operation.
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`In the calibration mode of operation, the headlight directional controller 14 is
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`responsive to input signals from the input/output device 17 (or from another source, if
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`desired) for causing manual operation of the up/down actuator 12 and the left/right
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`actuator 13. Thus, while the headlight directional controller 14 is in the calibration
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`mode of operation, an operator of the input/output device 17 can manually effect either
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`up/down movement of the headlight 1 1, left/right movement of the headlight 1 1, or
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`both, as desired.
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`In a second step 22 of the calibration algorithm 20, the up/down actuator 12 and
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`the left/right actuator 13 are manually operated to aim the headlight 1 1 in a
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`predetermined reference orientation. This can be accomplished by use of the
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`input/output device 17 that, as mentioned above, is connected to (or can be connected
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`to) the headlight directional controller 14. Traditionally, the aiming of a headlight 11
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`has been accomplished by parking the vehicle on a surface near a wall or other vertical
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`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
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`that the center of the beam therefrom is projected at the reference target. In this
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`invention, the vehicle is parked on a surface near a wall or other vertical structure, and
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`a reference target is provided at a predetermined location on the wall or other
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`structure, as described above. Next, in accordance with the second step 22 of this
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`calibration algorithm 20, the input/output device 17 is operated to generate electrical
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`signals to the headlight directional controller 14. In response to such electrical signals,
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`the headlight directional controller 14 operates the up/down actuator 12 and the
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`left/right actuator 13 to move the headlight 11 such that center of the beam projecting
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`therefrom is aimed at the reference target. When the beam from the headlight 1 1 is so
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`aimed, then the headlight 11 is determined to be oriented in the initial reference
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`position from which the headlight directional controller 14 can subsequently
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`implement directional angle adjustments.
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`In a third step 23 of the calibration algorithm 20, once this initial reference
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`position for the headlight 11 has been achieved, such position is stored in the headlight
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`directional controller 14 as the predetermined initial reference position. This can be
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`accomplished by means of the position feedback sensors 18 and 19. As discussed
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`above, the position feedback sensors 18 and 19 are adapted to generate respective
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`electrical signals that are representative of the actual up/down and left/right positions
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`of the headlight 11 or of the predetermined positions for the headlight. Thus, the first
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`position feedback sensor 18 is responsive to the actual up/down position of the
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`headlight 11 (as determined by the up/down actuator 12, for example) for generating
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`an electrical signal to the headlight directional controller 14 that is representative
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`thereof. Similarly, the second position feedback sensor 19 is responsive to the actual
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`left/right position of the headlight 11 (as determined by the left/right actuator 13, for
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`example) for generating an electrical signal to the headlight directional controller 14
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`that is representative thereof. Accordingly, the third step 23 of the calibration
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`algorithm 20 can be performed by causing the headlight directional controller 14 to
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`read the signals from the position feedback sensors 18 and 19 and store the current
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`up/down and left/right positions of the headlight 11 as the initial reference positions
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`from which the headlight directional controller 14 can subsequently implement
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`directional angle adjustments.
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`The current position of the headlight 11 is preferably stored in the non-volatile
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`memory of the headlight directional controller 14 for reference during normal
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`operation of the automatic directional control system 10 described below. Thus, when
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`the automatic directional control system 10 is initially activated (such as when the
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`electrical system of the vehicle is initially turned on), the headlight directional
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`controller 14 can position the headlight 11 at or near the calibrated position utilizing
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`the signals comparing the current position of the headlight 11 (as determined by the
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`signals generated by the position feedback sensors 18 and 19) with the predetermined
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`reference position determined by the calibration algorithm 20.
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`Fig. 3 is a flow chart of an algorithm, indicated generally at 30, for generating a
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`table that relates the sensed condition values from the condition sensors 15 and 16 to
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`the headlight directional angle adjustment factors that will be implemented by the
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`headlight directional controller 14, and further for storing such table in the headlight
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`directional controller 14 illustrated in Fig. 1. As used herein, the term “table” is
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`intended to be representative of any collection or association of data that relates one or
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`more of the sensed condition values to one or more of the headlight directional angle
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`adjustment factors. The table of data can be generated, stored, and expressed in any
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`desired format. For example, this table of data can be generated, stored, and expressed
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`in a conventional spreadsheet format, such as shown in Fig. 4, which will be discussed
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`in detail below.
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`In a first step 31 of the table generating algorithm 30, an adjustment control
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`algorithm is selected. The adjustment control algorithm can be, generally speaking,
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`any desired relationship that relates one or more operating conditions of the vehicle to
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`one or more angular orientations of the headlight l 1. A variety of such relationships
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`are known in the art, and this invention is not intended to be limited to any particular
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`relationship. Typically, such relationships will be expressed in terms of a
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`mathematical equation or similar relationship that can be readily processed using a
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`microprocessor or similar electronic computing apparatus, such as the above-described
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`headlight directional controller 14. The particular adjustment control algorithm that is
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`selected may, if desired, vary from vehicle to vehicle in accordance with a variety of
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`factors, including relative size and performance characteristics of the vehicle or any
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`other desired condition.
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`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
`condition or conditions of the vehicle may be sensed and provided to the headlight I
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`directional controller 14.
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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 1 1. 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 1 1. 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 of a 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 l 1 upwardly, while a negative up/down adjustment
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`factor represents aiming the headlight 11 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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`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 1 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. 1 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 in implementing the headlight directional angle adjustment factors. The
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`generation of the table 40 and the storage ofsuch table 40 in the memory of the
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`headlight directional controller 14 allow a designer of the automatic directional control
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`system 10 to quickly and easily alter the response characteristics of the system 10 as
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`desired, without the need for direct access to the computer code or software that is
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`used to operate the headlight directional controller 14. Rather, to effect such
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`alterations, a designer can simply change some or all of the data points that are
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`contained within the table 40. As will be described in detail below, the headlight
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`directional controller 14 will use whatever data points that are contained within the
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`table 40 in determining the need for adjustments in the angular orientation of the
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`headlight 1 1. This structure also reduces the amount of processing power that is
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`necessary for the headlight directional controller 14 because it can operate on a
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`relatively simple look-up basis using the table 40, rather than having to calculate
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`relatively high order equations that may be used to determine the data points contained
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`10
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`within the table 40.
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`Fig. 5 is a flow chart of an algorithm, indicated generally at 50, for operating
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`the headlight directional controller illustrated in Fig. 1 to automatically implement
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`directional angle adjustments in accordance with one or more of the sensed condition
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`Values from the condition sensors 15 and 16. In a first step 51 of the operating
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`algorithm 50, the values of one or more of the condition sensors 15 and 16 are read by
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`the headlight directional controller 14. Then, the operating algorithm 50 enters a
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`decision point 52, wherein it is determined whether the value or Values of the
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`condition sensors 15 and 16 that have been read by the headlight directional controller
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`14 are specifically contained in the table 40. For example, using the table 40
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`illustrated in Fig. 4, if the headlight directional controller 14 has read a steering angle
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`value of -2°, then it is determined that the value of the condition sensor 15 is
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`specifically contained within the table 40. In this instance, the operating algorithm 50
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`branches from the decision point 52 to an instruction 53, wherein the adjustment
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`factors contained in the table 40 that correspond to the sensed condition value are
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`looked up and stored in the headlight directional controller 14.
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`The operating algorithm 50 next enters an instruction 54 wherein the value of ‘
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`the magnitude of the adjustment factor (i.e., the desired position for the headlight 11)
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`is compared with the current position of the headlight l 1. This step 54 of the
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`operating algorithm 50 is optional and can be performed if one or more of the position
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`feedback sensors 18 and 19 are provided in the automatic directional control system 10
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`to generate respective electrical signals that are representative of the actual up/down
`and left/right positions of thenheadlight 11, as described above. This step 54 of the
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`operating algorithm 50 can be performed to determine how much of an adjustment is
`necessary to move the headlight 11 from its current position, as determined by the
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`position feedback sensors 18 and 19, to the desired position, as defined by the
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`adjustment factor obtained from the table 40. To accomplish this, the value of the
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`adjustment factor may, for example, be subtracted from the current position of the
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`15
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`headlight 1 1 to determine the magnitude of the difference therebetween and, therefore,
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`the magnitude of the adjustment that is necessary to move the headlight 11 from its
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`current position to the desired position. However, this step 54 of the operating
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`algorithm 50 can be accomplished in any other desired manner.
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`Next, the operating algorithm 50 enters a decision point 55, wherein it is
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`determined whether the magnitude of the adjustment that is necessary to move the
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`headlight 1 1 from its current position to the desired position is greater than a
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`predetermined minimum threshold. This step in the operating algorithm 50 is also
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`optional, but may be desirable to prevent the actuators 12 and 13 from being operated
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`continuously or unduly frequently in response t