Development Of Bearing Gap Measurement System For Air-floating Gyroscope

Inertial navigation systems have the characteristics of autonomy,anti-interference and anti-shielding,and are widely used in aerospace,national defense and other fields.As an important part of the inertial navigation system,the gyroscope’s performance index is affected by the assembly gap between the stator and rotor of the internal component air bearing.In order to check whether the working performance of the gyroscope meets the requirements,it is necessary to accurately measure the micron-level gap inside the air bearing.At present,the gap was still measured manually-based,there was labor-intensive,low measuring efficiency,poor consistency.For this reason,an automatic measurement system for the clearance of air bearings has been developed to achieve the accuracy measurement of the internal clearance and improve the measurement efficiency and stability.Analyze the characteristics of the internal clearance of the air bearing and the measurement technical requirements,and design the overall plan for the clearance measurement.The indirect measurement method is adopted to convert the internal clearance of the bearing into external micro-displacement through external force,and the relative measurement method based multiple probes is used to obtain the clearance value indirectly.Three micro-force sensors are integrated in the system to realize closed-loop control of the force application process to ensure continuous and accurate force loading.In order to ensure the correct conversion of the internal gap,a flexible connection device is introduced in the axial clamping part,and at the same time,the rotor and stator could be aligned automatically due to the self-weight of the rotor.Based on the double feedback of contact force and displacement,the balance of parts could be adjusted automatically.According to the determined measurement plan,formulate the gap measurement process,complete the design of mechanical structure,hardware circuit and control software.In order to realize the self-alignment based on the gravity force of the rotor,the radial and axial gaps are measured separately,and a turning mechanism is designed to switch the measurement state.Based on the modularization idea,the measurement system is divided into radial force application module,axial force application module and micro-displacement measurement module.According to the measurement requirements,the performance parameters of the motion platform,force sensor,micro-displacement sensor and other components are determined to ensure the accuracy of the gap measurement.In order to realize the control of the displacement slide,pneumatic components and the acquisition of sensor data,motion control,signal acquisition and hardware protection circuits are designed.Based on Labview,control software of the measurement system was developed to realize the automatic measurement capability of the system,and a friendly human-computer interaction interface was designed to improve the ease of operation of the system.The air bearing gap measurement system is debugged and tested to verify the reliability of its measurement function and measurement accuracy.Analyzing the error source of the measurement system and conduct calibration experiments on the key hardware in the system to ensure that its parameter indicators meet the requirements.Establishing an error analysis model for the factors that may cause measurement errors,and quantitatively calculate the maximum measurement error that may be caused.After completing the calibration and adjustment of the measuring equipment,carry out the measurement experiment in a clean environment with constant temperature and humidity.Through the analysis of multiple experimental data,the results show that the maximum measurement error of the system is0.2μm.The measurement system can ensure the correct conversion of the internal gap and meet the measurement accuracy requirements.