Non-contact method and apparatus for determining camber and caster of a vehicle wheel
First Claim
1. In a non-contact wheel alignment machine for use in determining one or more wheel alignment characteristics of a vehicle, said wheel alignment machine having a computer and a plurality of non-contact measurement sensors electrically connected to said computer, wherein at least one of said measurement sensors includes:
- first and second toe light sources that project shaped light onto a sidewall of a tire of one of the vehicle'"'"'s wheels at respective first and second locations;
a third light source that projects shaped light onto the sidewall of the tire at a third location; and
an optical sensor system having one or more fields of view that includes said first, second, and third locations; and
wherein said computer is operable under control of a program and in response to data from said optical sensor system to determine a toe angle and a camber angle associated with the tire;
wherein the improvement comprises;
said computer being operable under control of said program to utilize said toe angle in determining said camber angle.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and apparatus for determining camber and caster of a vehicle wheel in which the camber angle is determined in a manner that accounts for the influence of any existing toe angle. This is accomplished by detecting the displacement of one or more points located fore or aft of the wheel'"'"'s vertical measurement plane and then making a correction to these displacements to account for influence of the toe angle. The apparatus includes a laser that projects shaped light onto the sidewall of the tire at a location offset from the normal upper measurement position. The shaped light illuminates an offset measurement point on the tire sidewall and an optical sensor detects the reflected image. A computer then determines the location of the measurement point within the two-dimensional image space of the optical sensor. Trigonometric equations utilizing the toe angle are then used to determine the horizontal displacement within the vertical measurement plane of this offset measurement point from the tire center or other reference point. Once this horizontal displacement is known, the camber can be determined mathematically using a known trigonometric relationship. By determining the camber angle at left and right steered toe angle, the caster angle of the wheel can the be determined.
108 Citations
45 Claims
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1. In a non-contact wheel alignment machine for use in determining one or more wheel alignment characteristics of a vehicle, said wheel alignment machine having a computer and a plurality of non-contact measurement sensors electrically connected to said computer, wherein at least one of said measurement sensors includes:
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first and second toe light sources that project shaped light onto a sidewall of a tire of one of the vehicle'"'"'s wheels at respective first and second locations; a third light source that projects shaped light onto the sidewall of the tire at a third location; and an optical sensor system having one or more fields of view that includes said first, second, and third locations; and wherein said computer is operable under control of a program and in response to data from said optical sensor system to determine a toe angle and a camber angle associated with the tire; wherein the improvement comprises; said computer being operable under control of said program to utilize said toe angle in determining said camber angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a non-contact wheel alignment machine for use in determining one or more wheel alignment characteristics of a vehicle, said wheel alignment machine having a computer and a plurality of non-contact measurement sensors electrically connected to said computer, wherein at least one of said measurement sensors includes:
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first and second toe light sources that project shaped light onto a sidewall of a tire of one of the vehicle'"'"'s wheels at respective first and second locations; a third light source that projects shaped light onto the sidewall of the tire at a third location; and an optical sensor system having one or more fields of view that includes said first, second, and third locations; and wherein said computer is operable under control of a program and in response to data from said optical sensor system to determine a toe angle and a camber angle associated with the tire; wherein the improvement comprises; said third location being offset from a vertical measurement plane that extends through the center of the wheel perpendicular to the wheel'"'"'s rotational plane, said computer being operable under control of said program to determine an offset distance relating to the distance between said third location and the center of the wheel; and said computer being operable under control of said program to utilize said offset distance in determining said camber angle. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A non-contact measurement sensor for use in determining one or more wheel alignment characteristics of a tire on a vehicle, comprising:
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first and second toe light sources that project shaped light onto a sidewall of the tire at respective fore and aft locations; a third light source that projects shaped light onto said wheel at an upper location; a fourth light source that projects shaped light onto said wheel at an offset location that is adjacent said upper location; and an optical sensor system having one or more fields of view that includes said fore, aft, upper, and offset locations. - View Dependent Claims (20, 21, 22)
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23. A method of calculating the camber angle of a wheel of a vehicle using a measurement sensor that includes an optical sensor having a field of view and one or more light sources for projecting shaped light onto the wheel, the method comprising the steps of:
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illuminating a measurement point on the wheel using shaped light projected onto the wheel at a first location that is offset to one side of a vertical measurement plane that extends through the center of the wheel and generally perpendicular to the rotational plane of the wheel, sensing a portion of the shaped light reflected from the first location and generating data representative of the location of the measurement point, obtaining a toe angle for the wheel, determining the position of a camber reference point in at least one dimension, using the toe angle to determine the horizontal displacement within the vertical measurement plane of the measurement point from the camber reference point, and calculating the camber angle of the wheel using the horizontal displacement. - View Dependent Claims (24)
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25. A method of determining one or more alignment characteristics of a wheel of a vehicle using a measurement sensor that includes an optical sensor and one or more light sources for projecting shaped light onto the wheel, the method comprising the steps of
(a) illuminating a portion of the wheel using shaped light projected onto the wheel at an upper location that is offset to one side of a vertical measurement plane which extends through the center of the wheel, (b) sensing a portion of the shaped light reflected from the upper location and generating position data that corresponds to an offset measurement point located at the upper location, (c) obtaining a toe angle for the wheel, and (d) determining a camber angle for the wheel using the position data and toe angle.
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35. A method of determining the camber angle of a wheel of a vehicle using a measurement sensor that includes an optical sensor and one or more light sources for projecting shaped light onto the wheel, the method comprising the steps of:
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projecting shaped light onto a sidewall of the wheel at an upper location along an axis that is parallel to and offset from a vertical reference plane, wherein said vertical reference plane corresponds to a measured toe angle of zero degrees when the rotational plane of the tire is perpendicular to said vertical reference plane, sensing a portion of the shaped light reflected from the upper location and generating position data for an offset measurement point located at the upper location, and determining a camber angle for the wheel using the position data. - View Dependent Claims (36, 37, 38)
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39. A non-contact wheel alignment machine for use in determining one or more wheel alignment characteristics of a vehicle, comprising:
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a circuit having a microprocessor and memory accessible by said microprocessor, said memory having an executable computer program stored therein; one or more non-contact measurement sensors electrically connected to said circuit, wherein at least one of said measurement sensors includes; one or more light sources that projects shaped light onto a sidewall of the tire at fore, aft and upper locations, with said shaped light being projected onto the sidewall at said upper location along an axis that is parallel to and offset from a vertical reference plane, wherein said vertical reference plane corresponds to a measured toe angle of zero degrees when the rotational plane of the tire is perpendicular to said vertical reference plane; and an optical sensor system having one or more fields of view that includes said fore, aft, and upper locations, said optical sensor system being operable to provide data related to images contained within said fields of view; wherein said microprocessor is operable under control of said program to determine a camber angle associated with the tire using the data received from said optical sensor system. - View Dependent Claims (40, 41, 42, 43, 44, 45)
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Specification