The precision of photoelectric tracking and measuring equipment on the vehicle and vessel is deteriorated by the platform’s movement. Specifically, the platform’s movement leads to the deviation or loss of the target, it also causes the jitter of visual axis and then produces image blur. In order to improve the precision of photoelectric equipment, the attitude of photoelectric equipment fixed with the platform must be measured. Currently, laser gyroscope is widely used to measure the attitude of the platform. However, the measurement accuracy of laser gyro is affected by its zero bias, scale factor, installation error and random error. In this paper, these errors were analyzed and compensated based on the laser gyro’s error model. The static and dynamic experiments were carried out on a single axis turntable, and the error model was verified by comparing the gyro’s output with an encoder with an accuracy of 0.1 arc sec. The accuracy of the gyroscope has increased from 7000 arc sec to 5 arc sec for an hour after error compensation. The method used in this paper is suitable for decreasing the laser gyro errors in inertial measurement applications.
In order to choose enclosure for the next generation telescopes, numerical simulation method was used. Firstly, the
telescope, two general kinds of enclosures structure and the external flow field model were established, Then
CFD(Computational Fluid Dynamics) technology was used to analyze the wind speed, static pressure, turbulence kinetic
energy distribution and eddy around the telescope, when the telescope at two different pointing gestures and the external
wind speed at 10m/s. The simulation results showed that when the telescope adapt the retractable enclosure, the wind speed
of the main optical path between 6.1 m/s and 9.3 m/s, and the average static pressure (gauge pressure) on the primary
mirror between 42.9268 Pa and 37.5579 Pa, however when telescope adapt the hemispherical enclosure, the wind speed of
the main optical path between 3.4 m/s and 6.8 m/s, the average static pressure (gauge pressure) on the primary mirror
between 12.1387 Pa and 11.105 Pa. Although the wind resistance of the retractable enclosure was lower than the
hemispherical enclosure, no eddy generated near the main optical path, it provided the telescope a uniform flow field and
ensured the quality of the image of a star. So the retractable enclosure would have better performance than the
High precision pointing and tracking is an important performance indicator of the telescope, and tracking is implemented mainly by the azimuth axis and the altitude axis movement together method for alt-azimuth designed telescopes, and as a control feedback angle encoder must be installed on the azimuth axis, pitch axis. Scale tape grating encoder due to the advantages of non-contact measurement, high precision, simple assembly and adjustment, as a new generation of angle encoders has been widely used in modern telescopes’ angle measuring system. However performance of these systems can be limited by the factors of mechanical installation, machining error, random error, and other types of error, which often fail to meet arcsecond or sub-arcsecond angle measurement requirements. This paper analyzes the impacts of the mechanical installation eccentric, the roundness error, shafting sloshing on encoder angle measuring, and develops a 4 reading heads, which have 90 ° phase difference, software subdivision angle measurement program. And we make counterclockwise and clockwise angle measuring experiments on a experimental platform, which has mechanical installation eccentric 10um, roundness error 2um and shafting sloshing 0.6". Two sets of experiments measuring angle error RMS values are 0.387'' and 0.487''. The experiments prove that the program can eliminate the angular measurement error due to the mechanical installation the eccentric, machining roundness error, shafting sloshing, achieve arcsecond angle measuring.