Study Of In-situ Measurement Method For Hemispherical Resonator Based On Contact Probe

The hemispherical resonator is the core component of the hemispherical resonator gyro(HRG),its profile accuracy directly determines the performance of HRG.It is necessary to measure several times in the grinding process of resonator and carry out the feedback compensation processing according to the measured data in order to meet the requirement of the surface shape accuracy of a resonator.In-situ measurement can effectively improve the measurement accuracy and efficiency while avoiding the repeat installation error of workpiece caused by off-line measurement.Therefore,the in-situ measurement of hemispherical resonator is of great significance to improve the shape machining accuracy of resonator and improve the performance of HRG.In order to meet the requirement of the surface shape detection of the hemisphere resonator,in this paper,an in-situ measurement method based on the contact probe is proposed.An in-situ measurement system for the resonator profile error is established and a fitting algorithm for the resonator profile error based on the minimum zone criterion is developed in order to realize the acquisition of the surface information of a resonator with high efficiency and high precision and profile error detection.According to the measurement requirement of the surface shape accuracy of a hemispherical resonator,an in-situ measurement method of resonator profile error based on contact probe is proposed and an experimental measurement system is built.The measurement system meets the requirements of the resonator measurement process in terms of the strength,stiffness,modal,and rationality of motion track through a theoretical calculation and a motion simulation.On this basis,an inspection path and rotation angle of the measurement axis are reasonably planned.A high frequency signal acquisition system is developed to realize the high frequency data acquisition of the resonator surface point cloud.The influence of the in-situ measurement system errors on measurement results is reduced through compensating by analyzing the main sources and influencing factors of the system errors.A processing algorithm of the measured data is developed in order to analyze and process the measured signal.On this basis,the position information of the probe is obtained by calibrating the system and transforming the coordinates.The Micro-sphere compensating algorithm is used to realize the probe radius compensation.The experimental results show that the error fluctuation of the compensation algorithm is small.The evaluation method of the profile error of resonator is researched,and the error evaluation model based on the minimum zone method is established.The surface subdivision method is taken to calculate the shortest distance between measured points and ideal surface.The subdivision parameters of the subdivision approximate algorithm are optimized to improve the algorithm efficiency.On this basis,an improved differential evolution algorithm is proposed to optimize the spatial position of the measured points and the theoretical surface so as to accurately obtain the profile error distribution of resonator.The experimental results show that the profile error evaluation method is effective and feasible.