Research And Improvement On The Stability For A High Precision 2D Optoelectronic Angle Sensor

Precision 2D optoelectronic angle sensor is an essential part in various precision instruments,such as micro-coordinate measurement machines(CMMs),microprobes,atomic force microscopes,precision machining instruments and et al.Generally,the stability of the angle sensor should be considered when designing instruments with high accuracy.Structural deformation caused by disturbing factors in the environment(such as temperature and vibration)is the main factor that damages the stability of the angle sensor.A 2D optoelectronic angle sensor has been built and the drift caused by structural deformations has been studied in this study.Optimal design and uncertainty evaluation have then been carried out.This article is mainly completed with the following work:1?A 2D optoelectronic angle sensor based on the laser autocollimation principle has been built.This sensor is composed of three parts: optical structure,hardware circuit and software filter.The corresponding hardware circuits,including I/V conversion circuit,operational amplifier circuit and low-pass filter circuit,have been redesigned.2?The drift caused by the structural deformation of the angle sensor has been studied and a drift error model has been achieved.Key components sensitive to thermal and vibrational effects were identified by error sensitivity analysis and simulation.3?The mounts of key components have been analyzed using finite element analysis software and optimized based on the concept of symmetric structures.Then,optimal 2D optoelectronic angle sensors have been obtained.4?The SIOS three-beam laser interferometer was used as a reference for calibration and testing.The experimental results show that:(1)the measurement range of the angle sensor is ±120 arcsec,the sensitivity is-0.04 V/arcsec,and the resolution is 0.024 arcsec in X axis;(2)the measurement range is ± 120 arcsec,the sensitivity is 0.04 V/arcsec,and the resolution is 0.024 arcsec in Y axis.The stability of the optimized angle sensor has been improved by more than 63%.It is verified that the modeling and optimal design method is effective,which can also be applied to improve the stability of other sensors with much more complex principles and structures.5?Taking the optimized angle sensor as an example,the main sources of error were analyzed and the measurement uncertainty was evaluated.The main sources of error and their changing rules were analyzed firstly.Combining theoretical analysis with experimental test results,the uncertainty and propagation coefficient of each error source was obtained.Finally,the uncertainty of the angle measurement results was synthesized,which is 6.54 arcsec in horizontal direction and 9.27 arcsec in vertical direction.It provides a practical method for the uncertainty evaluation of angle sensors.