The Measurement Method And Error Analysis For The Wording Radius Of Pricision Centrifuge

Precision centrifuge is an important kind of test equipment of inertial navigationwhich is used for testing and identitying the accelerometer. So the testing andidentifying accuracy of accelerometer mainly depends on the centrifuge’s accuracy,and the centrifuge’s accuracy mainly depends on the test accuracy of its centripetalacceleration and the test accuracy of its misalignment angle. The measurementaccuracy of its centripetal acceleration depends on the test accuracy of centrifuge’sworking radius and angular velocity. The problems on testing precision centrifuge’sworking radius have been studied in detail in this paper.Aiming at small-size radius’s measurement, a direct test method using standardmeasuring rod and high-accuracy micrometer is adopted, and the test model isestablished. Then supposing the nominal radius is1025mm, various error sources ofdirect test method are analyzed. The synthetic measurement uncertainty of theseerror sources reaches to1.67μm. And supposing the nominal radius is2500mm,various error sources of direct test method are analyzed briefly. The syntheticmeasurement uncertainty of these error sources reaches to2.12μm. Then thedisadvantages of this method used to test large-size radius are expounded. On thebasis of those analyses, an indirect test method using high-accuracy accelerometer isproposed.Dual-frequency laser interferometer is used to measure precision centrifuge’sdynamic radius, the dynamic radius test system is established according to theworking principle of dual-frequency laser interferometer, and various error sourcesof this dynamic radius test system are analyzed. Then supposing the nominal radiusis2500mm, various error sources of direct test method are analyzed. The syntheticmeasurement uncertainty of these error sources reaches to0.12μm. And supposing the nominal radius is1025mm, various error sources of direct test method areanalyzed briefly. The synthetic measurement uncertainty of these error sourcesreaches to0.06μm.As for the accelerometer’s error model identification under1g gravity, twomethods are adopted: the single accelerometer method and the two orthogonalaccelerometers method, and the error model’s identification principles anddifferences are expounded, the conclusion can be drew that the accuracy of twoorthogonal accelerometers is higher. Then the trial data are processed and theaccelerometer’s error model is recognized. The accuracy of these two methods bothcan reach to10^-6grade.The mathematics model of the indirect test method using high-accuracyaccelerometer is established; the test steps are designed; the radius is calculatedthrough computer simulation. And this test system’s various error sources, such asgravitational acceleration measurement error, coriolis acceleration, additional errormodels, angular velocity’s test accuracy, g’s test accuracy, etc. are analyzed; theinfluence of each error source are calculated through computer simulation.The research shows that it is convenient to test small-size radius using direct testmethod. However, as for large-size static radius’s measurement, the indirect testmethod is more reasonable. The method’s measurement accuracy designed in thispaper can satisfy the measurement uncertainty requirement of5×10^-6.