Study On The Integration Of Spacecraft High-precision Temperature Measurement And Intelligent Thermal Control

With the development of space technology,a variety of new types of spacecrafts are emerging,with more demanding performance,thus have higher requirements in the corresponding thermal control technologies.In particular,the temperature control precision of certain scientific instruments is directly related to their detection performance.As a result,temperature control of high precision has become one of the key technologies to improve the performance of spacecrafts in the coming future.Based on the requirements for high-precision thermal control of spacecraft,this study focuses on the classifying the budget systems for precise temperature measurement and control,and we have performed a systematic series of studies on high-precision measurement and processing of temperature signals,precise temperature control with high stability,and high-precision temperature gradient control.Furthermore,we have applied these technologies to the engineering design of some mission to overcome the critical challenges of precise temperature control.The reliability of the relevant techniques is successfully verified by in-orbit tests.Considering the fact that most of the traditional approaches to spacecraft thermal design are based on heat transfer theory for active and passive thermal control design,which fails to the combination with the application of modern control theory.This study has tried to combine the thermal analytical theory,control theory,numerical and experimental heat transfer theory,to establish a new precise temperature control method forμK-level temperature control of spacecraft.Based on the control theory,the signal and system of precise temperature control methods are clarified,and the time-frequency properties of temperature signals are explored.The heat transfer function of the temperature control process is constructed based on thermal analysis theory,and the heat network approach of spacecraft thermal analysis has been used to reveal the heat transfer properties of passive heat control systems such as damping protection.The characteristics of feedback and feedforward control circuits are studied.The basic principle of predictive control of models based on modern control theory is studied for difficulties such as large heat sources and disturbances.An MPC based optimization algorithm and a precise temperature control method combining feedforward and feedback control are proposed based on the requirements and conditions of the spacecraft thermal control system.Moreover,a high-precision experimental setup for temperature control is constructed to assess the accuracy and feasibility of the integrated temperature control approaches for signal,system and prevention control.Considering the lack of control precision due to various types of errors in the temperature measurement system,this study analyzes the mechanisms affecting the temperature measurement signal.Deviations due to temperature measurement methods and devices are identified,and noise mechanisms that affect the resolution of temperature measurements,such as sensor noise,current excitation noise,and bridge noise are discussed.The onboard calibration method is proposed and the Kalman filter method is introduced to address the bias of the temperature measurements and the noise of the temperature measurement system,enabling high-resolution processing of the on-orbit temperature data.The high-resolution temperature measuring instrument is developed,and the precision ofμK-level in temperature measuring test is realized.In precise temperature control of spacecraft,there are not only spatial accuracy requirements,but also temporal temperature stability requirements.Aiming at the temperature stability requirement of gravitational wave detection spacecraft(10^-5K/Hz^1/2@1m Hz～0.1Hz),we have carried out the precise temperature control design of the core payload module of gravitational wave spacecraft based on the precise temperature control method of integrated prevention and control.The precise temperature control scheme of the core module is designed through the closed-loop feedback temperature control of the complex heat source disturbance in the boundary of external environment of the core payload module,combined with the heat insulation component designed based on the thermal damping transfer function,and the feedforward control method based on the thermal field disturbance identification.The simulation analysis shows that the scheme can achieve the stability ofμK level.Based on the temperature control scheme,we have developed the core payload module and carried out vacuum thermal balance test of the core payload module.The high-resolution temperature measurement equipment developed is used to collect the test data.The analysis results of the thermal test shows that a precision of 34μK@1m HZ～0.1HZ has been reached,suggesting that by employing these key technologies mentioned above,the critical challenge of precise temperature control in the mission of gravitational wave detection spacecraft has been successfully overcome.Considering the requirements of precision control of the temperature gradient of the focusing mirrors set of X-ray telescope,a precision temperature control method based on closed-loop active heaters is proposed on the basis of detailed analysis of the thermal boundary characteristics of the mirrors set,the characteristics of the discontinuous medium of the mirrors,and the radial（<0.4℃）,axial（<1℃）and circumaxial（<1℃）temperature gradient requirements of the mirrors set.Non-uniform heaters based on differences in heat capacity and heat resistance are used to perform the differentiation and active thermal compensation of nonlinear mirrors,enabling simple control of small temperature difference between different mirrors.The temperature control scheme has been validated by thermal balance tests of the satellite.The test results show that the temperature gradients in all directions of the mirrors group satisfy the requirements,which solves the thermal control problem in the development of X-ray telescopes and enables high sensitivity detection of the telescopes.To meet the demands for high-precision prediction and intelligent control of the temperature field,we propose an intelligent control method based on space heat flux prediction.The intelligent control of the temperature field is achieved by the prediction of the external heat flux.This feedforward control method via heat flux prediction can be used to configure spacecraft resources efficiently.Based on this control method,a set of radiator cooling systems is designed.Depending on the on-orbit mission plan,the radiator can be automatically expanded or folded,which can greatly reduce the temperature fluctuations and compensate for the power of the instantaneous working instrument.The radiator developed has been validated by ground and in-orbit tests,and the thermal control of high power loads has been addressed.