Method for Experimental Analysis of Thermostability of Star Sensors

A star sensor is a highly accurate attitude measurement device, but it is susceptible to the thermal environment. Moreover, it is difficult to establish an optical-machine-thermo model of a high-precision star sensor by simulation. Accordingly, an experimental analysis method is proposed to simulate on-orbit thermal environment of the star sensor by heating the mounting surface and baffle in a vacuum tank and simulate the star using static star simulator. The triaxial thermostability of the star sensor can be evaluated by observing its output. A prism mounted on a mounting surface was used to remove the thermal deformation of the mounting surface by auto-collimation with an error margin of 4.5%. Results show that when the baffle is heated from 27.3 ℃ to 110.6 ℃, the drifts of the x,y, and axis are 2.9″, 1.2″, and 2.6″, respectively. When the temperature control accuracy of the mounting bracket is(20±0.3) ℃, the optical axis drift is ±0.18″, which meets the requirements of thermostability indicators of the high-precision star sensor.

Due to the difficulty in establishing an accurate optical mechanical model of the star sensor in simulation analysis, the simulation results cannot accurately reflect the performance changes of the star sensor in the complex thermal environment of orbit. Therefore, this paper designs a star sensor thermal stability test method, which uses a heating plate to heat different positions of the star sensor in a vacuum tank, simulate the thermal environment of orbit, and use a static optical star simulator to simulate the starry sky, Observe the change in attitude output of the star sensor when the thermal environment changes. At the same time, the deformation component of the mounting bracket in the attitude change is peeled off using the autocollimator measurement value of the mounting bracket prism, thereby obtaining the thermal deformation of the entire star sensor itself. Based on the designed experimental method, this article establishes a data analysis model and analyzes the model error. The analysis results indicate that the measurement error of the x and y axes is within 4.5%, and the error of the z axis is within 0.2%, which can meet the accuracy requirements of the experiment. In addition, this article also selected a certain type of high-precision star sensor for thermal stability testing, and used the established analysis model to analyze the experimental data of the star sensor. The results showed that when the temperature of the star sensor’s hood increased from 27.3 ℃ to 110.6 ℃, the optical axis of the star sensor shifted 2.9 ″ around the x-axis, 1.2 ″ around the y axis, and 2.6 ″ around the z-axis; When the temperature control accuracy of the star sensor mounting bracket is (20 ± 0.3) ℃, the offset of the star sensor optical axis is ± 0.18 ″, which meets the thermal stability index of high-precision star sensors.