FLY RUN-OUT CORRECTION FOR VEHICLE WHEEL ALIGNMENT

摘要

In a wheel alignment system, the error caused by run-out of the axis of a fixture that is clamped to the wheel and mounts gravity stabilized inclination sensors is corrected by continuously providing fixture axis inclination signals during rotation of the wheel through at least 360.degree. from any random starting position. Maximum and minimum comparator devices continuously receive these signals, and the signals are also presented to associated maximum and minimum storage latch devices connected to their respective comparators. The maximum signal comparator provides a load signal to its storage device whenever the signal received by the comparator from a sensor is greater than that previously received by the maximum storage device whereby the maximum signal storage device stores the maximum fixture axis inclination signal. The minimum comparator device provides a load signal whenever the signal received from a sensor is less than that previously received by the associated minimum signal storage device whereby the minimum storage device stores the minimum inclination signal, A first adder adds the maximum and minimum signals and divides them by 2 to provide a preliminary alignment signal proportional to the actual angular inclination of the wheel axis in a selected alignment plane, and the perliminary alignment signal is subtracted from an intermediate inclination signal from the sensor that represents the inclination of the fixture axis at the wheel stopped position to provide a run-out error signal proportional to that portion of the total -1a-angular run-out of the fixture axis that is present in a selected alignment plane at the wheel stopped position. When the wheel is set down, a final inclination signal is received from the sensor means and the run-out error signal is subtracted therefrom to provide an inclination signal that represents the true wheel axis inclination in a selected aligmnent plane corrected for run-out error, and this signal is displayed for wheel alignment purposes. The sensors measure run-out errors in both the camber and toe planes and provide separate displays for the alignment in both planes. The maximum and minimum inclination signals are provided by maximum and minimum digital comparator and signal storage devices as well as by digital adding and other devices with suitable converters for supplying the digital devices with 8 bits of binary digital information. -1b-