Scanning measurement of surface error and thickness variation of the hemispherical resonator

Abstract

Hemispherical resonant gyroscopes (HRGs) are solid-state vibration gyroscopes with the highest precision and are widely used in the aerospace field. The core part of the gyroscope is the resonator, which is a thin-walled hemispherical shell. Surface error and thickness variation of a hemispherical shell causes frequency splitting, which degrades the performance of the HRG. In order to guide the mass leveling of hemispherical resonator, this paper presents a new method for scanning measurement of the surface error and thickness variation of hemispherical resonators. First, a multi-axis platform is designed for noncontact sensor scanning measurements along the meridian and latitudinal lines of the hemispherical resonator. Second, the error model of the measurement system is established. The surface error of the standard sphere is measured to calibrate and compensate for the assembly errors of the measuring device. In addition, the identification accuracy of assembly errors and the influence of assembly errors on thickness measurement are simulated by a computer. Finally, the surface error and thickness variation of the hemispherical resonators are measured. The method is experimentally demonstrated and validated with a wavefront interferometry test. The results show that the method can achieve high precision and high repeatability, which is instructive for assessment of the machining error and further evaluation of the hemispherical resonator.

A normal tracking differential confocal measurement method for multiple geometric parameters of hemispherical shell resonator with a common reference

“…However, the spatial resolution of this method is insufficient, and the measured high-frequency information of the inside and outside surfaces is missing. Zhai et al [14] used a spectral confocal sensor and a short coherent interference sensor to measure the inside and outside surface profiles and shell thickness of the HSR, respectively. However, this method requires replacement of the sensor in the same measurement system and considerable time to recalibrate the system, resulting in a change in the measurement reference, which introduced additional measurement errors.…”

An Adaptive Multi-Population Approach for Sphericity Error Evaluation in the Manufacture of Hemispherical Shell Resonators

“…To strictly control the sphericity error in thin-walled spherical shells, it is necessary to use form error measurement equipment to measure and evaluate sphericity error [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Form error measurement equipment, such as a coordinate measuring machine (CMM), typically saves the sampled shell contour data as a large dataset in XYZ coordinate form [ 20 ].…”

“…To strictly control the sphericity error in thin-walled spherical shells, it is necessary to use form error measurement equipment to measure and evaluate sphericity error [13][14][15][16][17][18][19].…”