Gas Film Stiffness Measurement Of Dynamic Air Bearing Motors

Dynamic air bearing motors is the core component of the inertial gyroscope. Thestability of its center of mass has a great influence on the accuracy of the gyroscopeinstrument. Dynamic air bearing motor’s gas film stiffness is a key indicators ofmeasurement for its centroid stability. With the wider application of inertial gyro inthe field of aerospace, aviation and defense, the need of gas film stiffnessmeasurement for dynamic air bearing motors also increased. Accurate gas filmstiffness’s measurement method can not only improve the accuracy of the inertialgyro system, but also has high academic value on the exploration for the gas filmstiffness’s impact and dynamic control of stiffness technology in dynamic air bearingmotors.This paper analyzes the various methods of dynamic pressure motor gas filmstiffness measurement. For the requirements of dynamic measurement, rapidmeasurement in the measurement. Select the method of two positions for the gas filmstiffness’s measurement, and do some appropriate improvements. There are someproblems as small working distance, prone to wear and tear accident, edge effects inthe capacitance sensor used in the existing gas film stiffness measurement. The lasertriangulation sensor is selected as the core displacement sensor to avoid theseproblems. And the measuring spot of laser triangulation sensors is big, to reduce theimpact of the motor measured surface’s roughness and processing traces, and toimprove the measurement stability.Gas film stiffness is high accuracy measurement, mechanical portion of thesystem, such as the motor support frame, measuring device’s stiffness anddeformation would have great impact on the measurement results, and lead tomeasurement errors. In order to reduce the gas film measurement error caused by themechanical design, the detailed derivation of the mechanical deformation is done. Weanalyzes the direct result of various factors of the measurement error, and validatedusing simulation and experiment. On this basis, improved the existing mechanicalstructure, to reduce the generation of mechanical structure error.Spectral composition of measurement data is complex, signal and noise aliasingserious, not conducive to signal extraction. To this end frequency response maskingtechniques is used, to design a narrow transition zone of the filter, to reach thebalance between effectiveness and speed of operation. Used the least-squares fitting the data to further improve the signal stability.Displacement measurement is the core of the system. How the laserdisplacement sensor well adapte the environment of gas film stiffness measurementmust be addressed. This article analyzed a variety of surface conditions of the motorsurface, such as roughness, surface tilt angle, how impact the measurement by lasersensor. To guide its application in the gas film stiffness measurement.Relevant measurement experiments show that, the dynamic pressure flotationgyroscope motor gas film stiffness measurement system’s hardware runs security andstability; The data processing overcomes the interference of the measurement noisewell, ensured fast and accurate dynamic pressure motor gas film stiffnessmeasurements.