Research On Thermal Control Design Method Of Two-Dimensional Turntable Under Ultra-low Temperature Vacuum

Two-dimensional turntable is the core actuator motion to achieve the remote sensing image with wide field in the space camera ground simulation experiments,it can drive space camera to achieve horizontal and pitching movement for different remote sensing images.Due to the space camera on-orbit working temperature below 100 K,the key components of two-dimensional turntable for thermal control design are particularly important,which can ensure the grating,motors,bearings and other key components in service.The paper research on thermal control design method of two-dimensional turntable under ultra-low temperature vacuum,which proposes a thermal control method with active and passive composite in the simulation of ultra-low temperature vacuum environment.The Smith prediction control algorithm is designed to achieved nearly plus or minus 0.2℃ temperature control precision.The research details are as follows:Firstly,based on the existing thermal control methods,a thermal control method with active and passive composite for two-dimensional turntable is proposed.Besides,The ANSYS is used to simulate the temperature field of the active and passive heat control schemes respectively.Based on the theory of heat conduction and heat radiation,the core design parameters,such as heating power,are obtained and optimized.Secondly,the circle grating is simulated by the Smith and classical PID and fuzzy PID temperature control algorithm,respectively,which has the highest temperature sensitivity for the two-dimensional turntable parts.Comparison of three algorithms for the step response and anti-jamming characteristic,it can be seen that the minimum overshoot,the shortest control time and the strongest robustness are obtained by the Smith temperature control algorithm.Therefore,the Smith method is choosing as the core temperature control algorithm for two-dimensional turntable.Thirdly,the next-bit machine programs and host computer software are designed by the STM32 MCU and C# software,respectively.The 20 temperature data real-time acquisition systems and 60 heating temperature control systems are achieved by the heating temperature acquisition unit and control unit.Finally,the effectiveness of two-dimensional turntable temperature control system is verified by the experiments with low temperature(-100℃~-130℃).It can be seen from the experimental results,the temperature control accuracy is ±0.2℃ and the temperature control resolution is 0.2℃.Under the situation of room temperature(18.5℃),the temperature control accuracy of the rotating grating,level reading head,motor,support bearings and some other key parts for two-dimensional turntable are ±0.2℃,which can satisfy the design requirements.