| Infrared remote sensing technology is an important technical means of collecting information about the Earth.It has many characteristics such as wide coverage area,long detection time and high mobility,and is therefore widely used in various fields such as agricultural production,land use,land resource management,atmospheric monitoring and geological disaster detection and investigation.To achieve such a high level of quantification requires not only stable and reliable infrared detection equipment,but also highly accurate on-orbit infrared radiation sources.The normal operation of infrared detection equipment requires a load that provides a stable operating temperature,while the calibration performance of the source is directly related to its temperature.Based on the major requirements above,this study designs a high-precision temperature control system of information acquisition and processing for infrared radiation reference loads.By analyzing the system components of the infrared radiation reference payload,the infrared radiation source,which has the highest temperature control requirements,is selected as the main control object of the system in this project,its basic architecture and traceability links are studied,the requirements of each key components are analyzed,and the temperature uncertainty of the source is assigned.In space applications,existing temperature measurement methods suffer from nonlinear calibration failure due to the ageing of electronic devices and their vulnerability to ambient temperature fluctuations,resulting in biased measurement results.Based on the resistance ratio method,a new multi-reference resistance ratio method is proposed,which limits the ratio of platinum resistance to reference resistance to a smaller range,reducing the effect of circuit non-linearity on the temperature measurement results when the platinum resistance is much difference from the reference resistance.The method was compared with the single reference resistance ratio circuit which is currently a high-level method in a thermostat,and the experimental results showed that the maximum measurement error of the method was approximately 0.004℃ at an ambient temperature error of the single reference resistance ratio circuit was approximately 0.03℃.Therefore,the method basically solves the problem of non-linear calibration failure without the need for the load to perform precision temperature control on it,reducing the cost of thermal control of the load,and the non-linear calibration degradation is less in the case of severe ambient temperature changes,making it more suitable for application scenarios with severe ambient temperature changes.Digital mean filters are commonly used in the measurement field to reduce measurement noise,but they can also cause distortion and introduce uncertainty in the signal,and it is difficult to quantify the effect of the filter on the measurement results with existing filter evaluation tools.To solve this problem,a digital mean filter uncertainty evaluation method is proposed.The uncertainty is calculated by modelling the distribution function of the temperature rate of change of a slowly changing object,using the model to simulate a temperature measurement sequence and input it into the filter,and finally using the uncertainty class A evaluation method.The experimental analysis is carried out on the blackbody object,and the uncertainty is plotted against the sampling period and the number of mean values.The thermodynamic model of the infrared radiation source temperature rise and fall control system is studied,and a dual feedback model based on the TEC diffuser and the driving voltage is proposed.Compared with the single feedback model based on the TEC drive voltage,the double feedback model has the advantage of considering the interference of the temperature fluctuation of the TEC diffuser to the temperature control,and can realize the advanced control of the interference.A temperature control system model identification scheme based on the longest cycle period linear shift register sequence is designed.The augmented least square method is used to identify and analyze the system model parameters.The precise mathematical model of the infrared radiation source heating and cooling control system is obtained.Aiming at the characteristics of large time delay,nonlinearity,and time-varying parameters of the infrared radiation source temperature control system model,a simplified variable universe fuzzy PID controller is researched and designed.On the basis of ensuring the advantages of the variable domain,the controller deletes the process of input variable domain transformation in the variable domain.The controller is compared with the ordinary variable universe fuzzy PID controller,fuzzy PID controller,and PID controller.The simulation experiment shows that the controller has no overshoot under different temperature control ranges,while the overshoot of other controllers ranges from 3.44% to 6.70%.The stabilization time of this controller is also shorter than other controllers.In order to simulate the space-based application environment,the performance test of the infrared radiation source temperature control system prototype was carried out in the vacuum state.The results show that the temperature control range of the system is-20℃～60℃,the temperature stability is better than 0.027 K,and the temperature uniformity is better than 0.072 K.The uncertainty of the brightness temperature of the space reference infrared radiation source at 10μm is evaluated,and its expanded uncertainty is better than 0.143K(k=2).The phase transition temperature of the micro gallium phase transition fixed point on the prototype is measured,and the platinum resistor on the infrared radiation source can be calibrated according to the phase transition temperature,which meets the definition of the ITS-90 international temperature standard.This makes the temperature of the infrared radiation source have on-orbit traceability,which is of great significance for improving the quantitative level of the infrared radiation reference load.The research results of this subject support “the key technology research and application of space infrared remote sensing temperature value traceability” project.This project won the first prize of the 2020 Chinese Society for Metrology and Testing Science and Technology Progress Application Research Category. |
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