Metrology device and a method for compensating for bearing runout error

• Main Author: Moy Eric J
• Format: Patent
• Language: English
• Published: 23.08.2016
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; BEARINGS; BLASTING; ELEMENTS OR CRANKSHAFT MECHANISMS; ENGINEERING ELEMENTS AND UNITS; FLEXIBLE SHAFTS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; LIGHTING; MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; MECHANICAL ENGINEERING; PHYSICS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; SHAFTS; TARIFF METERING APPARATUS; TESTING; THERMAL INSULATION IN GENERAL; WEAPONS

A system and method for determining the angular position of a bearing assembly and compensating measurements for bearing runout error in metrology devices, such as an articulated arm coordinate measurement device and a laser tracker, is provided. The system and method includes measuring the bearing runout error and defining a waveform from encoder readings for a first set of rotations. In one embodiment, a transfer function is created based on an analysis of the bearing runout error, such as with a Fourier analysis for example. In another embodiment the bearing runout error is mapped to an absolute angular position. During operation, the angular position of the bearing assembly is determined by comparing a waveform to the waveform from the first set of rotations. With the angular position determined, the bearing runout error may be used to compensate the measurements of the metrology device.