Development and Testing of a High-Precision Position and Attitude Measuring System for a Space Mechanism

摘要

This paper describes a high-precision optical metrology system – a unique ground test equipment whichrnwas designed and implemented for simultaneous precise contactless measurements of 6 degrees-offreedomrn(3 translational + 3 rotational) of a space mechanism end-effector [1] in a thermally controlledrnISO 5 clean environment.rnThe developed contactless method reconstructs both position and attitude of the specimen from threerncross-sections measured by 2D distance sensors [2]. The cleanliness is preserved by the hermetic testrnchamber filled with high purity nitrogen. The specimen’s temperature is controlled by the thermostat [7].rnThe developed method excludes errors caused by the thermal deformations and manufacturingrninaccuracies of the test jig.rnTests and simulations show that the measurement accuracy of an object absolute position is of 20 micronrnin in-plane measurement (XY) and about 50 micron out of plane (Z). The typical absolute attitude isrndetermined with an accuracy better than 3 arcmin in rotation around X and Y and better than 10 arcmin inrnZ. The metrology system is able to determine relative position and movement with an accuracy one orderrnof magnitude lower than the absolute accuracy. Typical relative displacement measurement accuraciesrnare better than 1 micron in X and Y and about 2 micron in Z. Finally, the relative rotation can bernmeasured with accuracy better than 20 arcsec in any direction.