Wheel alignment with surface-oriented runout determination

• US 20050027473A1
• Filed: 06/10/2004
• Published: 02/03/2005
• Est. Priority Date: 06/11/2003
• Status: Active Grant

• Current Assignee: Snap-On Incorporated
• Original Assignee: Snap-On Incorporated
• Inventors: Bryan, Eric, Davidson, Niall, Dale, James L. Jr.
• Granted Patent: US 7,206,716 B2
• Time in Patent Office: Days
• US Class Current: 702/151
• CPC Class Codes: G01B 11/275 for testing wheel alignment
• CPC Class Codes: G01B 2210/20 Vehicle in a state of translatory motion
• CPC Class Codes: G01B 2210/26 Algorithms, instructions, databases, computerized methods and graphical user interfaces employed by a user in conjunction with the wheel aligner
• CPC Class Codes: G01B 2210/28 Beam projector and related sensors, camera, inclinometer or other active sensing or projecting device
• CPC Class Codes: G01B 2210/283 Beam projectors and related sensors

Abstract

Methods and systems for measuring and calculating wheel alignment angles are disclosed. The measuring methods include mitigating alignment error by compensating for wheel runout, and further include measuring wheel runout while the wheel maintains contact with an alignment surface.

Claims

1. A method for calculating a wheel alignment angle using measurement sensors mounted on a wheel, the wheel being rotatable while maintaining contact with a surface, the method comprising:

measuring at least one uncompensated alignment angle for the wheel;

measuring at least one wheel parameter at a plurality of positions of the wheel while disposed on the surface;

determining wheel runout for the wheel using the at least one wheel parameter; and

calculating at least one compensated alignment angle for the wheel as a function of the wheel runout and the uncompensated alignment angle.

2. The method of claim 1, wherein measuring at least one wheel parameter at a plurality of positions of the wheel while disposed on the surface further comprises:

performing at least three measurements of camber and toe.

3. The method of claim 2, further comprising:

determining a circle whose circumference substantially coincides with a combination of the at least three measurements of camber and toe.

4. The method of claim 3, further comprising:

calculating an error value for the circle; and

declaring an error event responsive to the error value exceeding a predetermined threshold.

5. The method of claim 1, further comprising:

iteratively solving an equation for a runout vector.

6. The method of claim 1, further comprising:

performing the wheel runout determination in real-time;

comparing the wheel runout to a set of criteria including a minimum number of points and minimum rollback angle; and

terminating the wheel runout determination responsive to the comparing.

7. The method of claim 1, further comprising:

measuring a rollback angle using sensor.

8. The method of claim 1, further comprising:

calculating a rollback angle based on the measuring of at least one wheel parameter at a plurality of positions of the wheel while disposed on the surface.

9. The method of claim 1, further comprising:

calculating a rollback angle based on an inclinometer measurement.

10. The method of claim 1, further comprising:

assigning a priority to a test for adaptively guiding a user through an alignment process.

11. A method for measuring runout of a wheel being rotatable while maintaining contact with a surface, the method comprising:

rotating the wheel to a first position;

measuring camber and toe at the first position to generate a first data point;

rotating the wheel to a second position;

measuring camber and toe at the second position to generate a second data point;

rotating the wheel to a third position;

measuring camber and toe at the third position to generate a third data point;

determining a circle whose circumference substantially coincides with a combination of the first, second and third data points; and

measuring the radius of the circle.

12. A method for calculating a wheel alignment angle using measurement sensors mounted on a wheel, the wheel being rotatable while maintaining contact with a surface, the method comprising:

measuring at least one uncompensated alignment angle for the wheel;

measuring at least one wheel parameter at a plurality of positions of the wheel while disposed on the surface;

determining wheel runout for the wheel using the at least one wheel parameter; and

determining the need for runout compensation, depending upon whether the runout is above or below a predetermined threshold.

13. A system for measuring runout of a wheel being rotatable while maintaining contact with a surface, the system comprising:

means for measuring camber and toe at a first position to generate a first data point;

means for measuring camber and toe at a second position to generate a second data point;

means for measuring camber and toe at a third position to generate a third data point;

means for determining a circle whose circumference substantially coincides with a combination of the first, second and third data points; and

means for measuring the radius of the circle.