Runout compensation in vehicle wheel alignment measuring apparatus

摘要

In certain wheel alignment measuring apparatus, a fixture is clamped to the rim of a wheel and an alignment sensor is pendulously mounted upon the fixture so that as the wheel is rotated the sensor will not rotate with the fixture. However, since the plane of the fixture is not necessarily parallel to the plane of the wheel the sensor may oscillate relative to the ground surface as the wheel is rotated-a condition known as "runout" which results in sensor reading errors. This is corrected by rotating the fixture to three separate rotative positions and recording the sensor readings at each such position. Circuitry is provided for determining the true alignment of the wheel by calculating the amount of the runout error at the final rotative position of the wheel and correcting the sensor reading by this amount.