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25 December 2020, Volume 40 Issue 6 Previous Issue    Next Issue

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Fault diagnosis and fault tolerant control of spacecraft attitude control system via deep neural network GENG Feilong, LI Shuang, HUANG Xuxing, YANG Bin, CHANG Jiansong, LIN Bo 2020, 40 (6):  1-12.  doi: 10.16708/j.cnki.1000-758X.2020.0066 Abstract ( 898 )   PDF (4795KB) ( 810 )   Save In order to solve the problem of low diagnosis accuracy and control allocation efficiency of traditional fault diagnosis and faulttolerant control methods, this paper proposes a new method of fault diagnosis and fault tolerance control for spacecraft attitude control system based on deep neural network. Taking the control moment gyroscopes as actuator, the method can achieve robust attitude control when the actuator fails. First, we use three heterogeneous deep neural networks to achieve the functions of fault diagnosis, attitude control and torque distribution of traditional faulttolerant controllers, and the intelligent adaptive faulttolerant controller architecture of full neural networks is established. Then, the parameters of the three neural networks such as the number of network layers, the number of neurons and activation functions are optimized and adjusted, and the influence of the parameters of the neural network on the performance of the controller is compared and analyzed. Numerical simulation is conducted to prove that the proposed new controller has good control accuracy and robustness when the control moment gyroscopes fail. The simulation results show that for the spacecraft with a redundant control moment gyroscope, the method proposed in this paper can not only achieve highprecision faulttolerant control under single gyro failure, but also ensure a certain attitude stability control when multiple gyroscope failures occur. Related Articles | Metrics

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Design and trial of extraterrestrial artificial photosynthesis device FENG Deqiang, ZHANG Ce, JIANG Wenjun, LI Long, YANG Dongsheng, LAI Xiaoming, SONG Jian, YAO Wei 2020, 40 (6):  13-22.  doi: 10.16708/j.cnki.1000-758X.2020.0067 Abstract ( 497 )   PDF (6062KB) ( 461 )   Save In-situ resource utilization (ISRU) technology is a promising process for recycling extraterrestrial resources and constructing life support system to realize survival in extraterrestrial environment. ISRU has been the core technology in human deep space exploration. Based on the microchannel technique, a flow reactor was designed to simulate artificial photosynthesis in microgravity and other special environmental conditions as well as to realize the conversion of carbon dioxide to oxygen and hydrocarbons. The microchannel based reactor can accelerate the products of the gas-liquid reaction from the electrode surface with the reaction medium by the sheer force. Theoretically, it can overcome the influence of microgravity conditions on the reaction process, which needs to be verified by microgravity experiments in future. Simultaneously, the optimized reaction conditions can be obtained in the microchannel structure by precisely controlling the pressure, flow rate and ratio of input gas to liquid. Based on the artificial photosynthesis reactor, an extraterrestrial artificial photosynthesis device was developed, which integrated the reaction module, control module, flow drive module and detection module. The feasibility of the reactor in reducing carbon dioxide to oxygen and carbonaceous compound (CO) was verified by ground experiment. With Au and Ir/C as the catalytic cathode and anode electrode respectively, the evaluation rate of O２ can reach 11.74 mL/h under 3 V applied voltage. This device possesses multifunction of in-situ physicochemical reaction, medium supply, precise control, products collection and analysis. And this device can implement effective conversion of carbon dioxide and oxygen generation. The work provides a theoretical and practical foundation for subsequent device optimization, carbon dioxide conversion to variable hydrocarbon products with high selectivity, and on-orbit test of artificial photosynthesis device. Related Articles | Metrics

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Control method for variable skew configuration control moment gyros ZHANG Kebei, GAO Jingmin, GUAN Xin, GUO Zixi 2020, 40 (6):  23-32.  doi: 10.16708/j.cnki.1000-758X.2020.006 Abstract ( 391 )   PDF (9440KB) ( 289 )   Save The momentum envelope of fixed skew configuration control moment gyroscopes (CMGs) cannot be changed flexibly to meet the different satellite attitude maneuver requirements. The control method for variable skew configuration CMGs was designed. The dynamic model of the variable skew configuration CMGs was established. Considering multiple control variables, such as gimble rate, highspeed rotor speed and skew angle rate, the steer control law of the variable skew configuration CMGs was designed. The momentum envelope of CMGs and singular state distribution were analyzed. The variable skew configuration CMGs were used to achieve the satellite threeaxis attitude agile maneuver control. The simulation results show that the control method for the variable skew configuration CMGs can realize the satellite threeaxis attitude agile maneuver control with different number of CMG faults Related Articles | Metrics

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Study on probability calculation method of derived parameters in link statistical analysis LI Zan, FAN Min 2020, 40 (6):  33-40.  doi: 10.16708/j.cnki.1000-758X.2020.0069 Abstract ( 224 )   PDF (2250KB) ( 156 )   Save In order to meet the requirements of deep space exploration, effectively utilize the TTC resource, and improve the link calculation accuracy, statistical analysis method of the link was studied and the characteristics of probability density functions of three link parameters recommended by the Consultative Committee for Space Data System (CCSDS) were analyzed. A method was put forward when the link parameters can not meet the Lyapunov condition that uses the saddle point approximation to estimate the tail probability function to determine the derived parameter probabilities. The result shows that the parameters derived of this method are similar to that of the real function. This method can further improve the statistical calculation method of the link analysis and make it more universal. Related Articles | Metrics

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Effect of pyrolysis gases combustion on surface ablation of charring material GUO Jin, HUANG Haiming 2020, 40 (6):  41-47.  doi: 10.16708/j.cnki.1000-758X.2020.0070 Abstract ( 301 )   PDF (3550KB) ( 134 )   Save Under the trend of longer flight time and higher Mach number for near space hypersonic vehicle, contradiction between thermal protection effect and lightweight is more prominent. Thus, numerical simulation of influence of pyrolysis gases combustion on surface ablation of charring material was carried out and the result was compared with that of arcjet test. Numerical results show that pyrolysis gases combustion can lead to the reduction in thickness of the ablation layer. With the increase in aerodynamic heat, protective effect of pyrolysis gases combustion on surface char is more apparent. This study can provide technical support for the optimization design of thermal protection system of the next generation near space hypersonic vehicle. Related Articles | Metrics

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Characteristics analysis of hybrid propulsion geostationary orbit DUAN Xiaowen, QI Rui, WANG Min 2020, 40 (6):  48-55.  doi: 10.16708/j.cnki.1000-758X.2020.0071 Abstract ( 440 )   PDF (6707KB) ( 385 )   Save Taking the transfer orbit design of the geosynchronous orbit satellite as mission background, the hybrid chemical electric propulsion orbit transfer was designed and analyzed to address the problems of great fuel consumption of fully chemical propulsion and long transfer time of fully electric propulsion.  Firstly, the influence of inclination and argument of perigee of switching orbit on transfer performance was analyzed. Analysis indicates that inclination should be used as one of the optimization variables. Secondly, the perigee radius, apogee radius and inclination of the switching orbit were used as optimization variables to construct the search grid. Each point in the grid corresponded to one switching orbit. For each switching orbit, a chemical propulsion orbit segment and an electric propulsion orbit segment were computed separately. The chemical propulsion segment was achieved by Lambert transfer, and the electric propulsion segment was achieved by using hybrid method for optimization. Finally, taking fuel consumption and transfer time as design index, exhaustive search for the switching orbits in the search grid was implemented, and the trend of hybrid propulsion transfers in the entire solution space was analyzed. The method proposed provides a family of solutions, filling the gap between the fully chemical transfer solution and fullyelectric transfer solution. The solutions have different combinations of fuel consumption and transfer time, and can be used in future missions. Related Articles | Metrics

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Satellite reliability analysis based on dynamic fault tree WANG Xuyu, HU Min, ZHANG Xueyang, ZHAO Yulong, LI Jiuyang 2020, 40 (6):  56-67.  doi: 10.16708/j.cnki.1000-758X.2020.0072 Abstract ( 504 )   PDF (5748KB) ( 584 )   Save Aiming at the reliability problem of satellite system, a method for satellite reliability analysis based on dynamic fault tree was proposed. The dynamic fault tree model of three subsystems of satellite power, attitude and orbit control and propulsion was established by combining Markov chain and binary decision diagram. On this basis, the random fault model of satellite was obtained, and the reliability model of satellite was established by taking the depletion fault into consideration. Monte Carlo simulation was used to evaluate and analyze the random fault model, and its performance was compared with Weibull distribution model. The simulation results show that this method can effectively analyze the random fault of satellite, has the advantages of high computational accuracy and high efficiency, and can simulate the dynamic behavior of random fault of satellite components more effectively. Related Articles | Metrics

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Research on performance evaluation of small reconnaissance satellite constellation WANG Hao, ZHANG Zhanyue, ZHANG Haitao, JIANG Ping 2020, 40 (6):  68-76.  doi: 10.16708/j.cnki.1000-758X.2020.0073 Abstract ( 511 )   PDF (1730KB) ( 549 )   Save To evaluate small reconnaissance satellite constellation′s performance, some performance indexes were studied from three aspects: coverage, cost and flexibility. The coverage capability evaluation model, cost estimation model and flexibility capability evaluation model were built. In the coverage capability evaluation model, satellite storage capacity was taken as a constraint condition, satellite working conditions were analyzed by combining with the satellite coverage geometry model, and a calculation method of coverage indexes considering satellite storage capacity was proposed. The cost of each subsystem of constellations was estimated by the small satellite cost model(SSCM). In the flexibility evaluation model, the performance loss rate was proposed, and the weight of performance loss rate was determined according to the probability function of failure states. Applying the models to the performance evaluation of SkySat and Jinlin No.1 (JL-1) constellation, the results show that SkySat constellation has stronger coverage ability, lower cost and poorer flexibility than those in JL-1. The above models proposed in this paper can be used to evaluate the advantages and disadvantages of constellations and provide references for the construction and performance evaluation of small reconnaissance satellite constellation. Related Articles | Metrics

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Real-time calibration method for groundbased TT&C systems using satellite-to-ground differential GPS PENG Zhen, JIN Xiaojun, MO Shiming, ZHANG Wei, XU Zhaobin, JIN Zhonghe 2020, 40 (6):  77-88.  doi: 10.16708/j.cnki.1000-758X.2020.0074 Abstract ( 345 )   PDF (6153KB) ( 269 )   Save Abstract： In view of the shortcomings of traditional calibration methods and the differential GPS based post-calibration method for ground-based TT&C systems, a real-time calibration method based on satellite-to-ground differential GPS was proposed. Compared with the differential GPS based post-calibration method, the real-time calibration method enables the ground-based TT&C systems to obtain the calibrated measurement data in time to carry out orbit determination and prediction in real time and to timely inject the orbit parameters to improve the operational performance of the satellite. In view of the long baseline, high dynamic and real-time satellite-to-ground calibration scenario, all kinds of errors affecting the performance of satellite-to-ground baseline estimation and the correction effectiveness of these errors were systematically analyzed, and the concept of relative position dilution precision was proposed, thus obtaining the accuracy budget of satellite-to-ground baseline estimation. A robust adaptive Kalman filter algorithm was used as the real-time satellite-to-ground baseline estimation algorithm, and a weighted least square method was employed to solve the real-time measurement error of the ground-based TT&C system, so as to obtain the calibration results. A hardware-in-the-loop simulation platform was established by using spaceborne dual frequency GPS receivers and a navigation signal simulator. The simulation results show that, after real-time calibration, the residual ranging error of the TT&C system is reduced to about 40cm, and the residual velocity measurement error is reduced to less than 1cm/s, which is consistent with the theoretical analysis, and can well meet the requirements of future space missions. Related Articles | Metrics

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Isothermal performance analysis of heat pipe on GEO longlife satellites LIU Bailin, LI Yifan, HU Guojie, WANG Lu 2020, 40 (6):  89-98.  doi: 10.16708/j.cnki.1000-758X.2020.0075 Abstract ( 327 )   PDF (8266KB) ( 168 )   Save The heat pipe is an important heat transfer element in thermal control design, which is used in a large number of GEO long-life satellites. On-orbit isothermal heat transfer performance of the heat pipe is a key factor affecting the safe and reliable operation of satellites. Aiming at studying the heat pipe of GEO longlife satellites that have long-term stable operation on orbit in China, the mathematical statistics method was used to analyze the law of the onorbit isothermal performance of the heat pipe with time, based on the temperature telemetry date on orbit. Results show that the heat pipe of GEO long-life satellites has good isothermal stability on orbit. The isothermal performance is greatly affected by the temperature level of the heat pipe. And it shows seasonal changes during the annual cycle and a downward trend in performance degradation over the entire life cycle with the flight time. The isothermal performance of the heat pipe at the end of its life is better than 1.6℃. In this paper, the isothermal improvement analysis and application suggestions are made from the aspects of heat pipe design, heat load size and distribution and its using environment. Related Articles | Metrics

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Design of dynamic-exploration maneuver test system for astronomical observation satellite CHEN Hongliang, LUO Rongzheng, TAN Zhiyun , ZHANG Ruolin, WANG Yingshuang, LIU He 2020, 40 (6):  99-105.  doi: 10.16708/j.cnki.1000-758X.2020.0076 Abstract ( 271 )   PDF (4029KB) ( 190 )   Save  Astronomical observation satellite operates dynamic-exploration attitude maneuver mode to detect the cosmos rays. To effectively achieve the ground verification of the dynamic-exploration attitude maneuver mode, a systemlevel maneuver integration test scheme was designed. The dynamic model based on inertial space was designed to simulate the scanning process. The time unification system was developed to provide a highly precise uniform time base for subsystems. Based on the interface of STK and Matlab software, the visual interpretation system driven by telemetry data was constructed to improve the real-time and accuracy of data interpretation. The system-level test results show that the designed scheme can verify the correctness of function and the validity of performance index, which provides ideas for ground test and onorbit application. Related Articles | Metrics

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A reversible data hiding scheme for remote sensing images HUI Zheng, ZHOU Quan 2020, 40 (6):  106-114.  doi: 10.16708/j.cnki.1000-758X.2020.0077 Abstract ( 383 )   PDF (8513KB) ( 157 )   Save Reversible data hiding (RDH) can be used for lossless transmission of remote sensing images′ important target region. Based on the study of existing RDH schemes, it was found that the capacity of single embedment was not sufficient and that the process of auxiliary information required additional lossless binary compression, which cannot meet the effectiveness and real-time requirement of remote sensing image process. The smoothness of non-overlapping subblocks in carrier image was detected with a given threshold. Then RDH was achieved by encoding the differences between the reference pixel and the rest pixels in a smooth block, along with bit substitution. Capacity of a single embedment of the proposed scheme can be more than 500000 bit for a 512×512 pixel gray-scale remote sensing image. Experimental results show that the proposed algorithm can achieve reversible data hiding with the efficient capacity of single embedment, and yet no additional lossless binary compression is required for auxiliary information processing. Related Articles | Metrics

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Research on CEI phase delay resolving method for BDS GEO satellite CHEN Shaowu, WANG Jingwen, HUANG Lei, XU Dezhen 2020, 40 (6):  123-130.  doi: 10.16708/j.cnki.1000-758X.2020.0079 Abstract ( 666 )   PDF (3537KB) ( 431 )   Save Connected element interferometry (CEI) is a precision angular measurement technology widely used in the orbit determination of MEO satellites, GEO satellites, lunar probes and deep space probes. A new measurement mode was proposed based on the characteristics of CEI. The carrier and ranging signals in coherent ranging mode were used in CEI. A CEI system was established and used to observe BDS (BeiDou navigation satellite system) GEO satellite. Group delay and phase delay were calculated by using all these signals. Group delay and phase delay results of the BDS GEO satellite were estimated by using the theoretical delay values calculated by precision ephemeris. The results show that the means of the residual of group delay and phase delay is 0.47ns and 0.08ns, and that the standard deviation (3σ) of the residual of group delay and phase delay is 4.2ns and 0.13ns. The feasibility of the phase delay calculation of CEI in coherent ranging mode is verified. This paper can provide reference for precision orbit determination of co-location GEO satellites, lunar probes and deep space probes. Related Articles | Metrics