Thermal Control System Design And Simulation Analysis Of Three-axis Turntable In Simulated Space Environment

The star sensor is an optical attitude control sensor,which is a key device for positioning the satellite body and plays a key role in navigation and control of the satellite attitude.With the rapid development of space technology in China,the accuracy requirements of star sensors are getting higher and higher.The space environment in which they are located is very complex,and the precision optical system has very high requirements for its performance.The ground semi-physical simulation of star sensor plays a very important role in its accuracy.The simulation test turntable is a key hardware device for real-time ground-in-the-loop simulation and testing in the aerospace field.It can reproduce the dynamic characteristics of the aircraft in the air and various flight attitudes in a laborat ory environment in real time to achieve star sensitivity.The precise calibration and performance verification of the device provide a basis for its performance improvement through ground semi-physical simulation.Its performance is directly related to the fidelity and confidence of simulation and test experiments.The accuracy of the turntable itself determines the accuracy of the test.A three-axis turntable system is a key device for the ground calibration of star sensors.It works in an ultra-low temperature vacuum environment with a temperature of 100 K and a vacuum of 1×10-3Pa.In order to ensure the highprecision,safe and stable operation of the system in a vacuum environment,the temperature of the main body of the turntable should be controlled at 20±2℃,and the temperature of the installation table should be controlled at 20±1℃.The mass of the turntable system is close to 500 kg,the heat sink is large,the structure is complicated,and the internal heat source changes with time,which makes its thermal control more difficult.This article mainly focuses on the design requirements and technical indicators of the thermal control system of the three-axis turntable in the ultra-low temperature experimental environment.The overall structure,temperature control method,temperature measurement point distribution and insulation method are designed.Multi-layer insulation materials,reserved radiation heat dissipation surface and active electric heating temperature control method to ensure that the temperature field of the turntable meets the temperature requirements.The working environment of the equipment in this article has a very h igh degree of vacuum,and the equipment only relies on radiation to excha nge heat with the environment.The surface radiation characteristic parameter of the thermal control material is an important thermal physical parameter in this study.It determines the equilibrium temperature of the turntable system and is very important for the accuracy of simulation analysis.In this paper,the emissivity of the material surface of the thermal control system is measured,and the thermal simulation analysis of the turntable is based on the test data.The parameters of the thermal control system are optimized for the parts where the thermal control is more difficult and the thermal control requirements are higher,which reduces the thermal control resources,improves t he economics of the thermal control,and reduces the temperature gradient and temperature alternating frequency.Simulation analysis of the influence of the heat source of the star sensor on the temperature field distribution of the single-axis tabletop.The results show that when the contact radius is less than 230 mm,the star sensor must be thermally connected to the tabletop to avoid overtemperature of the tabletop.Finally,it is the most critical in the turntable system.The thermal and mechanical coupling analysis of the single-axis table was carried out,and the thermal stress and thermal deformation value at the maximum temperature gradient of the single-axis table were obtained.