Self-calibrating wheel alignment apparatus and method

In combination with a vehicle wheel aligner having at least one primary sensor mountable to a wheel of a vehicle for measuring the angular orientation of the wheel with respect to a reference, the improvement comprising:

• first sensor means mountable to the wheel for generating a first signal when the wheel is oriented at a first known angle with respect to the reference;
• second sensor means mountable to the wheel for generating a second signal when the wheel is oriented at a second known angle with respect to the reference;
• and
• means responsive to the first and second signals for comparing a first difference between the first and second known angles with a second difference between the angles measured by the primary sensor when the wheel is oriented at the first and second known angles, and for determining whether the second difference is greater or less than the first difference by a certain predetermined amount.

A method of calibrating a vehicle wheel aligner having at least one primary sensor for generating outputs indicative of the angular orientations of a wheel of a vehicle with respect to a reference, comprising the steps of:

• recording a first output from the primary sensor when the wheel is oriented at a first known angle with respect to the reference;
• recording a second output from the primary sensor when the wheel is oriented at a second known angle with respect to the reference;
• calculating a relationship between the first and second outputs and the first and second known angles;
• and
• applying the relationship to subsequent outputs from the sensor;
• whereby the subsequent outputs are corrected in accordance with the relationship.

In combination with a vehicle wheel aligner having at least one angle measuring instrument mountable to a first wheel of a vehicle for measuring the angle of the wheel with respect to a reference line extending between the wheel and a second, adjacent wheel, the improvement comprising:

• a sensor comprising a reflective means mountable in a vertical plane at a first known angle relative to the rotational centerline the first wheel, a light emitting means mountable on the second wheel in alignment with the reference line, and a light detecting means mountable on the second wheel in vertical alignment with the light emitting means;
• wherein light from the light emitting means will be reflected off of the reflective means and back to the light detecting means when the first wheel is oriented at the first known angle with respect to the reference line;
• and
• controller means in electrical communication with the angle measuring instrument and the sensor for determining a difference between the first known angle and the angle measured by the angle measuring instrument when the first wheel is oriented at the first known angle and for determining whether the difference is greater than a certain predetermined amount.

In combination with a vehicle wheel aligner having at least one angle measuring instrument mountable to a first wheel of a vehicle for measuring the angle of the first wheel with respect to a reference line extending between the first wheel and a second, adjacent wheel, the improvement comprising:

• a sensor comprising a first reflective means mountable in a vertical plane at a first known angle relative to the rotational centerline the first wheel, a second reflective means mountable in a vertical plane at a second known angle relative to the rotational centerline of the first wheel, a light emitting means mountable on the second wheel in alignment with the reference line, and a light detecting means mountable on the second wheel in vertical alignment with the light emitting means;
• wherein light from the light emitting means will be reflected off of the first and second reflective means and back to the light detecting means when the first wheel is oriented respectively at the first and second known angles with respect to the reference line;
• and
• controller means in electrical communication with the angle measuring instrument and the sensor for comparing a first difference between the first and second known angles with a second difference between the angles measured by the angle measuring instrument when the first wheel is oriented at the first and second known angles, and for determining whether the second difference is greater or less than the first difference by a certain predetermined amount.

In combination with a vehicle wheel aligner having at least one angle measuring instrument mountable to a wheel of a vehicle for measuring the angle of the wheel in a vertical reference plane oriented with respect to the rotational centerline of the wheel, the improvement comprising:

• a first sensor means for measuring the angle of the wheel in the vertical reference plane;
• the first sensor means being mountable relative to the rotational centerline at a first known angle to vertical and being operable to generate a first signal when the wheel is oriented at the first known angle;
• a second sensor means for measuring the angle of the wheel in the vertical reference plane;
• the second sensor means being mountable relative to the rotational centerline at a second known angle to vertical and being operable to generate a second signal when the wheel is oriented at the second known angle;
• and
• controller means in electrical communication with the angle measuring instrument and the first and second sensors for comparing a first difference between the first and second known angles with a second difference between the angles measured by the angle measuring instrument when the wheel is oriented at the first and second known angles, as determined by the first and second sensors, and for determining whether the second difference is greater or less than the first difference by a certain predetermined amount.