Signal and Information Processing, Networking and Computers

In recent years, military equipment has been developing towards digitization, networking, and intelligence. Software, as a core component of equipment, and network systems, as the survival environment of software, their security and stability are crucial, which are related to whether equipment can fully exert combat effectiveness and operate in an orderly and stable manner. This article proposes a new intrusion graph model generation method based on the current status of equipment development. This model can make risk analysis in network systems more accurate and has important significance in reducing network security risks. At the same time, it also reduces the protection cost of network systems and provides support for equipment network security protection.

Models have been a hot topic for many years. Still, people are paying unprecedented attention to them because digital engineering (DE), which uses models as the “blood,” has become a symbol of the Fourth Industrial Revolution. Space and national defense have already become the pillar fields of technological innovation today. As the two major forces in the space field of the United States, NASA (the National Aeronautics and Space Administration) and USSF (the United States Space Force) have a strong interest in DE with models as the “blood,” and actively seek coordinated development under the digital engineering ecosystem (DEE). This paper focuses on summarizing the practices of NASA and USSF in the field of DE, refining the key points and methods of DE construction in terms of core ideas, fundamental base, cultural base, etc., and forming relevant enlightenment and thinking, to provide a reference for China to carry out the work-related DE.

With the rapid proliferation of spacecraft in orbit worldwide, there has been a surge in international incidents arising from collision intersections, re-entry and return, and space debris mitigation. Consequently, space traffic management has become a paramount concern in national strategies, aiming to ensure the safety of space assets and foster the development of a robust spacefaring nation. In order to address the practical challenges of managing space traffic, the conventional method of designing collision avoidance strategies suffers from issues such as independent planning of collision avoidance and mission, low efficiency, and high resource consumption. This study aims to comprehensively assess the impact of multidimensional factors, including the constellation's building health status, manoeuvrability, mission constraints, configuration requirements, and fuel consumption, on the generation of collision avoidance strategies. By exploring the intrinsic coupling relationships between these factors, a task-oriented collision avoidance model will be established. This model will incorporate a quantitative description of multiple influencing factors and an intelligent strategy decision-making algorithm for ground controllers, enabling swift determination of the optimal avoidance strategy.

The star identification is a prerequisite for the in-orbit calibration of some space cameras. This paper proposes an improved polygonal fast all-sky star identification method with the unstable internal and external states of the space infrared camera in the early stage of orbit. By utilizing a searching strategy based on star-number lookup table combined with sorting, the conventional triple loop is transformed into a double small loop to accelerate the matching search process. At the same time, the constraint of polygonal edge is introduced to reduce the matching candidate set until it is unique, which ensures the successful recognition under the loose threshold of star angular distance. The experiment effectively proves that the recognition speed is significantly improved compared with the conventional method, which is only 1/5 of the original search time, less than 10s for the triangle matching of the dense star catalog. Meanwhile, the success rate of this method is still very high even when the stars are densely distributed and the camera internal geometric error is large.

As tasks in the fields of aerospace and industrial automation become progressively more complex and intelligent, higher demands are placed on the computing power of computers. In order to integrate more functions or services in hardware to meet market demands, computer systems are beginning to use multiprocessors or multi-core processors. For real-time systems containing hard real-time tasks, the system must be not only timeliness but also fault tolerance. Timeliness means that tasks are completed before the deadline and fault tolerance means that the correct output is obtained within the deadline even in the event of a fault. Current research on fault-tolerant computer technology is gradually being extended to fault-tolerant scheduling of multiprocessors or multi-core processors. The implementation of fault-tolerant systems relies primarily on redundancy. One classification of fault-tolerant methods is time, spatial and information redundancy, another classification is hardware redundancy and software redundancy. This paper summarizes fault-tolerance techniques and provides an overview of fault-tolerant scheduling algorithms for multiprocessors or multi-core processors.

Facing the requirement of space gravitational wave detection mission, this paper analyzes the method and key technology of high precision inertial reference construction, and introduces the on-orbit verification of the test satellite. Firstly analyze the requirement index and technical approach of inertial reference construction, the noises which affecting the construction of inertial reference are classified and introduced according to the sources; Then, for all kinds of noise it analyze the corresponding key technologies which spacecraft platform to be solved; Finally, combined with the design and on-orbit test of tianqin-1 satellite, the current status and gap of various key technologies are analyzed. On-orbit test result show that, some technical indicators are close to meeting requirement which the space gravitational wave detection mission needed.

Being the most ideal power source for hypersonic flight, scramjet acquires advantages such as high working Mach number and high specific impulse, and has broad military and civilian prospects. In variable thrust engines, the calculation of thrust is a key part of engine control. Traditional engine thrust calculation methods are mainly measured using strain gauges [4] or accelerometers, and this paper proposes a more direct, more flexible and less expensive method. A reliable control method is vital for the normal operation of the engine. This paper proposes a fast and effective thrust calibration method using neural network. And the control system uses the predicted thrust from a neural network as the feedback to form a close-loop control. Two test examples demonstrate that the proposed control method can adapt to wide Mach number and thrust range.

With the development of satellite high precision temperature measurement and control system, the single step response of satellite temperature shrinks and the measurement precision exceeds the measurement accuracy. As a result, the temperature step response termination condition of conventional satellites cannot be applied to such satellites, which affects the test and experiment of high precision temperature measurement and control system. In this paper, according to the theoretical response equation of the unit step function of the first-order system, combined with the time constant, according to the static characteristics of the temperature response, the process of response discrimination and response termination conditions are given, and the static characteristics balance criterion of the high-precision temperature measurement and control system is given to some extent.

The data rate of high-resolution remote sensing satellites is constantly increasing, from the previous level of 100Mbps to the current level of over 100 Gbps.At present, the commonly used high-speed interfaces for satellites (such as LVDS, 2711, and CXP) cannot be tolerated in engineering, whether in terms of ground impact, cable size, or FPGA I/O pins. How to achieve high reliability and stable transmission of massive data on limited satellite platforms has become the key to the design of remote sensing satellite data transmission interfaces. Aiming at the problem that it is difficult to realize ultra-high data rate transmission in the current satellite common high-speed interface engineering, this paper proposes a design method of remote sensing satellite ultra-high speed data transmission interface based on optical fiber interface, selects the optical fiber interface suitable for the Satellite bus, and uses an efficient transceiver feedback mechanism to realize the highly reliable transmission of satellite optical fiber interface. At the same time, the advantages of optical fiber interface such as high speed, low power consumption, small size and long transmission distance are used, Compared to using commonly used high-speed interface methods, the cost is reduced by 60%, while the volume and weight are reduced by 80% and 70%, respectively. Through verification at a certain model identification level, high-speed serial data transmission of 400 Gbps on board was achieved. Engineering tests have shown the correctness and reliability of the interface design, laying the foundation for the on-orbit application of the model.

In order to meet the challenges of more and more complex requirements, shorter development cycle and lower cost, a data stream superposition test method for satellite control subsystem is proposed in this paper. This method combines the characteristics and test requirements of the product, analyzes the data flow of the sensor, controller and actuator, decouples the product performance test from the subsystem test, superposes the measured data of the sensor and simulation data in the attitude and orbit control computer, and sends down the control value for the ground dynamics simulation calculation. Using this method, the composition of test equipment is simplified, the test preparation time is shortened, the test preparation requirements are reduced, and the product performance evaluation means are enriched.

In the spacecraft high-speed data transmission system, for the VCO affected by high and low temperature environment, flickering clutters may occur during the temperature change. Based on this phenomenon, the author gives a test method, followed by the simulation analysis to give the causes. Furthermore, the optimization scheme and simulation analysis results are proposed and passed the physical test. The optimization scheme is found to be effective, which provides a reference solution and basis for the mitigation of flickering clutters.

As the commercial cargo transportation system of the International Space Station becoming increasingly mature, with the development trend of foreign commercial cargo ships and the current situation in China, the development of cost-effective, small tonnage economic cargo spacecraft, can be used as a necessary and beneficial supplement for China Space Station. The MBSE method and SysML provide system engineers with a rich means of system design and cost analysis under parameter constraints. The Model Based System Engineering (MBSE) tool is utilized to establish a demand analysis model for the low-cost cargo transportation system of the space station. The use cases, task stakeholders, functional implementation and parameter constraints of the low-cost cargo transportation system is analyzed, to obtain the cost of different equipment supporting through the cost estimation model, and confirm the advantages and disadvantages between different designs by comparing the total mass, total power and total cost. The “economical returnable cargo spaceship” scheme with the best comprehensive evaluation was obtained.

The growing demand for low-latency and high-bandwidth applications has led to the emergence of Mobile Edge Computing (MEC) as a promising paradigm. MEC leverages the computational and storage capabilities of edge devices to provide efficient and proximity-based services. However, the limited resources and mobility of mobile devices pose significant challenges in managing the caching operations within MEC environments. In this paper, we propose a Collaborative Cache Algorithm for MEC that aims to enhance performance and resource utilization. The algorithm leverages the cooperation among mobile devices and exploits communication and cache collaboration among MEC nodes. By analyzing data requests and cache states among mobile devices, the algorithm intelligently allocates data for caching on the most suitable MEC nodes. To evaluate the effectiveness of the proposed algorithm, we conduct a comprehensive set of experiments and compare it against existing cache algorithms. The experimental results demonstrate the superiority of the Collaborative Cache Algorithm in terms of cache hit ratio and delay reduction on MEC nodes.

The offloading of computational tasks from resource-constrained edge devices to more powerful cloud servers has been widely adopted to improve the performance and resource utilization in edge computing systems. However, effective task offloading decisions in edge computing environments remain a challenging problem due to the dynamic and heterogeneous nature of edge resources. In this paper, we propose a novel approach for optimizing task offloading in edge computing. The method leverages the concept of contract design, which define the requirements and constraints for task offloading, to guide the decision-making process. By considering factors such as task characteristics, network conditions, and edge device capabilities, the method dynamically adjusts the contract parameters to achieve optimal offloading decisions. Numerical results demonstrate that the proposed method outperforms existing approaches in terms of offloading efficiency, energy consumption, and latency.

With the rapid development of space technology, the demand for landing applications of space-based information in various fields is becoming stronger and stronger. The traditional processing strategy of transmitting space-based information from ground to ground, processing instructions to satellite, can no longer meet the requirements of intelligent space-based information applications. Aiming at the future intelligent information application scenarios, focusing on the requirements of space-based information intelligence applications, combined with software definitions and artificial intelligence related technologies, a space-based intelligent information system architecture is proposed, and the key technologies of information system are analyzed to provide supporting for the subsequent construction of an efficient and intelligent space-based information system architecture.

Through the analysis of satellite vulnerability characteristics and the statistics of damage accidents, this paper obtains four categories of risk factors, and further expounds the four aspects of “human error”, “environmental factors”, “satellite products’ own energy source”, “assembly test equipment, real-time, tool characteristics”, reflecting the characteristics of satellite products. Considering both universality and pertinence (according to the characteristics of satellite assembly activities), it can provide necessary basis for subsequent safety analysis and evaluation. Finally, the analytic hierarchy process and fuzzy evaluation method are used to analyze the data examples and determine the judgment criteria. The corresponding matrix is obtained through the primary and secondary parameters. According to the maximum membership principle, the risk level corresponding to the largest of the five values corresponding to the membership of the top-level parameters is the result of the comprehensive risk assessment. The results show that the method is suitable for the vulnerability analysis of satellite products, and can be used for risk assessment.

In order to achieve fast and accurate acquisition of spacecraft automatic interpretation software criteria under multiple constraints, firstly, the state set, input set, and output set models are established based on the finite state machine(FSM) principle using structured data such as remote control commands, telemetry parameters, and normal value ranges in database. Subsequently, based on the mapping relationship between the telemetry change process and the FSM, a graphical criterion model is generated, using changes in equipment operating conditions as state variables and remote control commands, injection, and other events as input signals. Then, by using test history data to drive the state transition of FSM for model solving, transforming the “criterion generation” problem into the process of solving the state transition function. Finally, a set of state transition functions will be obtained, and operational criteria will be generated based on specific syntax rules. Taking the telemetry and control subsystem of the Chinese space station as an example, the algorithm is validated, which has certain engineering guiding significance.

Real-time database technology is increasingly being used in space missions abroad. It allows space agencies to process and analyze data in real time, increasing their autonomy and responsiveness. The technology has been applied to perception enhancement, natural disaster monitoring and prediction, traffic congestion prediction, energy consumption monitoring, crop growth monitoring and navigation. It is used to improve the autonomous control capability of spacecraft operation control modes, reduce labor costs, and improve the characteristics of deep space exploration missions. The use of real-time database technology has also been validated in intelligent decision systems for generating effective satellite flight mission plans. Current limited communication links to Earth still pose challenges for the teleoperation of Mars missions, limiting the potential scientific payoffs. Real-time database technology can bring application value in improving spacecraft autonomy.

The bit rate of space communication is increasing, and the frequency bands used are also increasing. The Ka-band data transmission system, which is currently widely used, has a significant impact on its link performance due to atmospheric and rain attenuation. In order to ensure the reliability of data transmission, redundant coding measures are generally used. This paper mainly studies the application of LDPC codec algorithm in space communication, proposes a performance optimization design method, and gives the results of on-orbit verification of geostationary satellites.

This article intends to apply the information technology of data mining to solve the data analysis related to bond strength. Use Big data analysis means to further improve the analysis and processing capacity of complex data in the quality assurance process. A bond strength data identification model was established, and the original data in the database were cleaned, converted, and discretization to generate a data set that meets the requirements of the model. The model was evaluated and verified to generate decision rules and evaluation results based on the bond strength data identification model, and then the research was applied to practice to obtain a more scientific sampling inspection method for the number of bond strength.

Traditional document-based system engineering is difficult to meet the needs of complex spacecraft missions, it is necessary to adopt Model-Based System Engineering theory and method. Based on the requirements of model management and configuration control in MBSE engineering practice, the research of configuration management method for MBSE model is proposed. The method divides the model life cycle into co-design process and controlled release process. The configuration management of the collaborative design process is supported by the collaborative tool, and the release process is supported by the PDM system. After the design model meets the requirements for issuance, the process of review, approval and change management are executed through the integration with the PDM system, thus establishing the status control mode of the model life cycle. The application verification is carried out through pilot project to support the development of MBSE engineering practice in the CASC. The MBSE engineering practice is supported.

After spacecraft is launched into orbit, TT&C link serves as the only channel for control data exchange, which is the lifeline for spacecraft operation. With the increasing hard constraints on cost, spectrum, quality, volume, energy, time limits, and other factors, TT&C link margin tension caused by the increase in spacecraft information rate, attitude changes, and high orbit operations needs to be relieved. Main factors affecting TT&C links are identified and analyzed in this paper, and start from aspects of antenna gain, polarization loss, subcarrier modulation, information rate and coding gain, optimization design methods are proposed by not changing the orbital characteristics, transmitted power of the transponder or relay terminal. Theoretical analysis and comparative calculation results show that proposed method can improve link margin by more than 10 dB, which can be applied to the design and optimization of spacecraft TT&C links.

Previous work has determined that the initial center of mass at the launch of the parallel tank satellite is the initial center of mass of the orbit maneuvering process. And that did not consider the ability of the filling pressure of the tank gas cushion to adjust the propellant mass and the satellite center of mass. In this paper, a design method for non-isobaric gas cushion propellant filling capacity and satellite center of mass in parallel storage tank is proposed. Using the strategy of independently controlling the amount of propellant filling and gas cushion pressure of each tank in parallel tanks, and using the gas cushion as the driving force to adjust the distribution of propellant in different tanks, different satellite centers of mass are designed at the time of satellite launch and at the beginning of orbit maneuvering, so as to meet the requirements of the launch vehicle for the center of mass of the satellite launch state and the small orbit control interference torque during orbit maneuvering. The calculation results show that the engine interference torque can be reduced by about 60.3%. The work in this paper is helpful to improve the utilization efficiency of propellants and promote the application of parallel tank chemical propulsion system.

With the background of building digital aerospace in recent years, aerospace science and technology archives have been characterized by huge data volume, numerous service objects and complex data types, the digitalization of aerospace science and technology archives has gradually replaced the traditional archives management. In this paper, on the basis of analyzing the problems in the process of digitalization of aerospace science and technology archives, we propose to integrate the means of information security management into the business process of science and technology archives management through various ways. In this way, it is possible to achieve both to provide researchers with the maximum utilization of archives and to meet the requirements of information security, giving full play to the value of science and technology archives.

The improved Byzantine fault tolerance algorithm has been applied to the full digital simulation environment of the China Space Station, achieving a full digital simulation platform that supports multi-processor fault-tolerant for the first time. Based on special needs of China Space Station’s multi-processor architecture, 3 key technologies have been implemented: Firstly, improve the classic Byzantine fault-tolerant algorithm to achieve multi-processor fault-tolerance, even if dual-processor failures occur during the operation of 4 processors, the system can still run safely and stably; Secondly, “Process + Shared Memory” is used to realize the unified management and isolation of data, avoiding the problems of data mutual exclusion and low transmission efficiency in multi-processor simulation; Thirdly, based on the characteristics of data exchange, a new synchronization method has been designed to solve the problem of multi-processor synchronization under fault-tolerant architecture. Ultimately, Implemented a fully digital simulation platform under a multi-processor fault-tolerant architecture of China Space Station, get rid of hardware dependencies. Finally, the application effectiveness of simulation platform is introduced.

With the rapid development of Chinese orbital spacecraft, in order to ensure the stable operation of satellite measurement and control service, improve the disaster recovery and backup capacity of the central system, the ground satellite survey, control system is gradually carrying out the construction of backup system. According to the transmission characteristics and service operation scenarios of satellite measurement and control data, this paper puts forward the multi-center data synchronization strategy and design scheme, so as to realize the effective management of the measurement, control task software and data among the multi-centers, build a multi-center collaborative measurement and control system, effectively improve the flexibility of the measurement and control service operation.

In order to improve the efficiency, feasibility and safety of astronauts’ on-orbit maintenance, 6-DOF on-orbit intelligent maintenance tool was developed according to the loads of on-orbit maintenance of spacecraft, aiming at the faulty screws in the narrow space of extravehicular equipment room. A kinematic model of the maintenance tool manipulator arm was established based on D-H method, and the trajectory planning of the front actuator was simulated under the obstacle environment by an improved Rapidly-exploring Random Tree (RRT) algorithm. The results show that the motion planning algorithm of the maintenance tool can meet the requirements of on-orbit maintenance, and the simulation results of each position have little deviation from the theoretical results. At the same time, the fault screw locating under the simulated environment of the maintenance tool is carried out, and the maintenance attitude is smoothly entered. The correctness and feasibility of the maintenance tool path planning algorithm are verified.

The attitude and orbit control system of Terrestrial Ecosystem Carbon Inventory satellite proposes performance requirements of high attitude determination accuracy, high pointing accuracy and high stability. It also proposes geographic information service function, rapid inertial scanning function based on momentum wheel control and high temperature ground-target recognition and real-time prediction function. The purpose of geographic information service function is to coordinate with overall autonomous task planning. This article mainly introduces the design of geographic information service, rapid inertial scanning and high temperature ground-target recognition and real-time prediction function. Based on the satellite’s in orbit operation data, the in orbit verification of the control subsystem’s single machine and system performance indicators was provided.

This paper evaluates the performance of the new VL51ES Li-ion battery based on on-orbit telemetries of geosynchronous orbit communication satellite, including the charge-discharge characteristics, battery cell voltage difference, self-discharge characteristics at solstice season and temperature management characteristics. Under the same working conditions, the on-orbit performance of the geosynchronous communication satellite using the VES180SA Li-ion battery was compared. By analyzing the differences in long-term telemetry data of several equinox and solstice seasons, the degradation of battery capacity, variation of cell voltage difference, self-discharge characteristics, and temperature management characteristics of the two types of batteries were compared. According to comprehensive analysis, it can be seen that the new low-cost VL51ES Li-ion battery and VES180SA Li-ion battery have good on-orbit performance consistency. After evaluation and analysis, the new low-cost VL51ES Li-ion battery can satisfy the requirements of long-life geosynchronous orbit communication satellites.

Propellant refueling is of great significance for improving the lifespan and benefits of large spacecraft. The core module and the cargo spacecraft in China Space Station (CSS) adopt a propellant refueling technology based on gas recycling and pressure-fed schemes. The core module uses compressors to pump the pressurized gas in the gas chamber of its tanks back to high-pressure gas cylinders, and the cargo spacecraft utilizes the pressure difference between the tanks of both sides to transfer propellants to the tanks of the core module by the pressure-fed scheme. The propellant refueling requires close cooperation between the core module and the cargo spacecraft. The process of in-orbit propellant refueling between both sides is divided into five stages, namely, state setting, leakage detection of pipelines, fuel-tank refueling, oxidant-tank refueling, and state recovery. The ground flight control personnel control the whole refueling process step by step. The faults during the in-orbit propellant refueling are handled through autonomous or ground handling.

With the development of TT&C equipment, the large scale, complex composition, and high maintenance costs caused by the large number of analog circuits in TT&C equipment have hindered the improvement of the overall technical level of the system. Therefore, the development and application of radio frequency digitization technology in TT&C equipment has been applied. To satisfy the technology development requirement of TT&C equipment on radio digitalization and software baseband signal processing, the system scheme based on direct radio digitalization and IP packets transfer for S-band signals was designed. This paper gives the processing technique of direct radio digitalization and IP packets transfer for S-band signals, analysis their effects on TT&C functions and performances, and puts forward ways to resolve these problems. This technique, which can satisfy requirements for spacecraft tracking, range and Doppler measurement, telemetry and command, has been put into use on the new generation TT&C equipment.

The development of retrievable vehicles and mass manufacture of satellites has expedited the speed of human space exploration, and the number of satellites of all sorts has surged. SpaceX, the largest firm, started its Starlink program with an estimated 42,000 satellites in 2015. CASC's “Hong Yan” satellite constellation communication system and ASIC's “Hong Yun” project both launched their first satellites into orbit in 2018. Furthermore, China's broadband constellation proposal, which was presented to the ITU in 2020, includes 12,992 satellites. The disparity between China's TT&C methods and future need for huge constellation is becoming increasingly apparent. Based on a study of the problems and demands of vast low-orbiting satellites, this article proposes a new approach of leveraging high-throughput satellites to assist the TT&C of many satellites. Because of its multi-point beam, frequency multiplexing, high beam gain, and other advantages, high-throughput satellites offer inherent advantages for huge satellites TT&C. However, because of the high speed of low-orbiting satellites, ensuring continuous and uninterrupted data during the TT&C process is a critical difficulty that must be overcome. The design of beam switching time, implementation process, and beam resource scheduling technique shown in this work may effectively address the problem of high-throughput satellite support for low-orbit satellite TT&C, as well as innovate the method of TT&C of high-volume low-orbit satellite.

The application of nearly-circular deviation equations in far-range rendezvous between spaceship and lunar module in elliptical orbit guidance scheme for manned lunar missions is researched. A four-pulse far-range rendezvous guidance scheme is designed, in which the out-of-plane parameters of orbit are corrected by a vertical pulse and the far-range rendezvous is realized by three in-plane phasing pulses. First, the positions of the first two phasing pulses are fixed. Then, in order to obtain the optimal solution of the total velocity increment, the position of the third in-plane pulse and three velocity increments of in-plane pulses are solved by the sequential quadratic programming algorithm with the total velocity increment transformed into the objective function. The correctness of the scheme is verified by scenario simulation, and the effective solution interval of the scheme with different initial positions and orbital eccentricity of the lunar module is analyzed. The simulation shows that different initial positions and orbital eccentricity of the lunar module have significant effects on effective phase angles between spaceship and lunar module which are able to be solved successfully by nearly-circular deviation equations.

In this paper, a satellite-based clock taming scheme base on GNSS is proposed to address the demand for high precision autonomous clock synchronization technology for LEO satellites. Establish a clock phase-locked loop inside the stand-alone machine by configuring a modular clock board, so that the 1 PPS signal obtained by the GNSS receiver processing maintains a small phase difference with the navigation star 1 PPS signal for a long time; the tamed 10 MHz signal is also used as the sample clock signal for base-band processing. After testing and verification, the accuracy of the tamed 1 PPS signal is better than 10ns, the accuracy of the 10MHz clock signal is better than ≤ 7E−12, the stability of 1s is better than ≤ 7E−12, and the phase noise meets the requirements of other payloads on the satellite. This solution provides an economical and efficient solution for autonomous clock synchronization of distributed constellations.

In recent years, the complexity of spacecraft systems has been increasing, and the traditional document-based design model is increasingly changing to a model-based design model, which often encounters problems such as inefficient collaboration and insufficient support from information systems in the application process. In this paper, we propose to adopt an enterprise architecture approach and analyze the business architecture, data architecture and application architecture of the MBSE-based solution design process in spacecraft based on the TOGAF enterprise modelling method, and then build a standardized and efficient MBSE collaborative design model for spacecraft, and carry out a typical application to provide a deeper application of the MBSE collaborative design model for spacecraft. The paper provides guidance for the further application of the MBSE collaborative design model and the construction of MBSE-related information systems.

We study the multiplexing of advanced orbiting systems based on self-similarity traffic flows, and propose an adaptive queue management algorithm with joint scheduling feedback mechanism. The algorithm uses the ON/OFF model to generate self-similarity traffic flows, and discards packets purposefully before they enter the virtual channel cache. The algorithm takes into account the congestion degree of the data frame cache in the scheduling module, feeds it back to the queue management module, and combines it with the duration when the ON/OFF sources generate data packets to establish a joint discarding probability mechanism, through which lower queue delay and effective system congestion control can be achieved. The simulation results show that this algorithm can not only reduce system surplus, but also reduce the average system delay greatly. Thus, the congestion phenomenon in virtual channels is effectively solved and the overall performance of the system is improved.

Technologies such as real-time processing of onboard data, intelligent perception, and self-learning information fusion have become the main trends in the development of future satellites. This paper studies the algorithms for intelligent perception and self-learning fusion utilization of multiple information on satellites. The basic tasks involved in the research are summarized and divided. A computational framework for intelligent perception and fusion utilization of multiple information is proposed, which includes three levels: “target level perception scene level perception evaluation and decision support”. Target detection and recognition based on single remote sensing data, potential target self-learning detection, and Feature fusion target recognition algorithm for multivariate remote sensing data. Compared with other algorithms, the experimental results show that the proposed algorithm has better performance.

Aiming at the application requirements of nautical chart revision and marine surveying and mapping, the identification of beach features based on hyperspectral remote sensing images has the advantages of high spatial resolution, high spectral resolution and wide coverage, which has important application prospects in the recognition of shore and beach features. Due to the complexity of coastal features, it is difficult for traditional classification methods to find qualified uniform plots homogeneous parcel for sampling homogeneous parcel sampling on hyperspectral images of coastal zone, resulting in unsatisfactory classification results. SVM classification can reasonably control the generalization ability of the classifier according to the number of samples, but it is sensitive to noise. This paper attempts to process the images with the MNF transform improved by the spatial-spectral dimensional decorrelation method based on noise assessment to reduce the influence of noise on the subsequent classification work, and make the coastal zone shoreling linearly separable, so as to ensure the classification accuracy and improve the classification efficiency.

Terrain identification of coastal is of great significance for coastal development activities and coastal terrain survey in overseas areas. However, due to the complex characteristics of coastal features, the use of remote sensing images for automatic feature classification and recognition has become a current research hotspot. Utilizing the homogeneous and homogeneous spectral characteristics of hyperspectral remote sensing images and the characteristics of coastal zone elements, an object-oriented shoreland classification technique is proposed after performing operations such as atmospheric correction and image enhancement preprocessing on hyperspectral remote sensing data, which enables automatic identification and extraction of feature types and geomorphological information in the coastal zone. This method overcomes the limitation of the traditional hyperspectral remote sensing classification method, which takes image element as the processing unit, and synthesizes the spatial characteristics and spectral characteristics of the features, which greatly reduces the classification spots and significantly improves the classification effect.

The construction of simulation cases and the management of batch cases are the key aspects to ensure the coverage of spacecraft control system simulation verification. To address the problems of low efficiency, poor reusability, and lack of effective management of cases, which are difficult to adapt to the needs of complex functional tests, a model-based simulation case generation and management platform for spacecraft control is proposed. The architecture of the model-based simulation case generation and management platform is given in the paper, and four key links are described in detail: the itemized input, the standardized interface, the normalization of test cases, and the automatically generated configuration, etc. The specific implementation and model application of the software is also given. The method studied in this paper achieves model-based simulation case management and normalization, which is highly versatile and visualized, improves the efficiency of control system testing quality, reduces the dependence on designers, and can be extended to other industrial control systems.

The temperature level of the asymmetric translucent primary mirror in a diffraction imaging system is highly sensitive to the radiation environment of its surroundings. In order to ensure the temperature level of the primary mirror on-orbit, it is necessary to obtain its accurate infrared radiation parameters. Based on analysis of the radiometer measurement system, a mathematical model for infrared radiation parameters of asymmetric translucent materials is established in this paper. A new method for measuring infrared radiation parameters is proposed, which three different emissivity materials are used as substrate, and infrared radiation parameters of the translucent primary mirror are obtain by solving the mathematical model with the measuring results.

Monitoring and evaluating of satellite status, timely and effectively finding and handing of anomalies, and ensuring its safe and reliable operation are the key points of on-orbit management of satellites. In view of the limitations of traditional spacecraft anomaly detection methods, an anomaly detection method based on data drive is proposed, and then the method is verified, by extracting and processing real telemetry data from orbiting satellites, the image generation and feature recognition are completed, which proves that this method can not only find the satellite anomaly in time, but also can make up for the detection that the alarm threshold cannot recognize the trend of the telemetry curve, effectively guarantees the safe operation of the satellite in orbit, and provides a reference for the on-orbit management of satellites.

DSP is a typical embedded processor, usually embedded in mechanical devices or electrical systems, and its function is relatively simple, which is better to meet the real-time computing. Compared with general-purpose computers, debugging and performance analysis of parallel programs are more difficult to be developed in embedded systems. To solve this problem, this paper designs and implements a performance analysis method based on timer interrupt and abnormal interrupt for FT-X DSP platform. Interrupts are generated during the running of the program, and performance data are obtained and recorded by inserting the mixed code of C and assembly code into the interrupt function. Based on the on-chip debugging simulation unit of FT-X processor, the real-time hardware profile data of the target program is recorded, and the 2D-FFT algorithm is analyzed in detail through the developed data visualization tool, and some bottlenecks of performance optimization are found, which improves the overall performance of the program.

Using digital twins in space TT&C field, the digital transformation of space TT&C system is promoted, the efficiency of space TT&C is improved, and the intelligent development of space TT&C system is accelerated. The concept of digital twin of space TT&C system and the construction idea of space TT&C system based on digital twin technology are put forward. The application prospect of digital twin technology in space TT&C system is systematically analyzed. Based on the construction of intelligent space TT&C system, the architecture design of digital twin in space TT&C system is designed. From the realization level, the technical difficulties in realizing digital twin in space TT&C system are analyzed in detail, and the conclusion is drawn that digital twin in space TT&C system will change the operation mode, management mode and support mode of space TT&C.

The architecture framework is a set of principles and guidelines for conducting top-level design of large-scale complex systems. DoDAF, which stands for Department of Defense Architecture Framework, is a general method developed by the U.S. military for the development, description, and integration of defense system architectures. It plays a crucial role in reducing risks, shortening development cycles, and ensuring that systems meet military requirements. This paper explores, analyzes, and researches in detail and comprehensively from the concepts of architecture, the development history of DoDAF, and the current research status of DoDAF. It also provides a development example of a space-based early warning system using the DoDAF product model, illustrating the development process based on the DoDAF product model.

In order to improve maneuver performance and attitude control precision of satellite operating on orbit, Integral Sliding Mode Variable Structure Control (ISMVSC) method is proposed for satellite attitude maneuver, which is based on model characteristic and external disturbance influence of satellite dynamics. Attitude control law for roll, pitch and yaw is designed separately in this method. Firstly, sliding mode switching plane is constructed through attitude angle error and its corresponding integration error combined with attitude angular velocity error. Then, ISMVSC algorithm is derived from the Piecewise Power Approaching Law (PPAL). Finally, simulations on control algorithm based on different approaching law are conducted successively. The results show that maneuver speediness and control stability for ISMVSC algorithm based on PPAL are optimal and more suitable for satellite attitude control, moreover no chattering phenomenon occurs.

Constructing production line and promoting the batch manufacturing of satellites and their complementary products is an inevitable choice for the construction of a low-orbit constellation system. The core of batch manufacturing satellite is the balance of capacity, cost and quality. This paper firstly briefly analyzes the characteristics of satellite quality assurance work under the traditional single-satellite development mode, focusing on the reasons why this mode leads to high cost and is difficult to be directly applied to the batch manufacturing capacity promotion. Then the characteristics of satellite quality assurance work under the batch manufacturing mode is analyzed, and the strategies that should be taken under the batch manufacturing mode is proposed in response to the analyzed characteristics.

Although GPS has been widely used, it can only be used in the field of vision of GPS satellites, and can not effectively locate in the obstacle environment. In order to solve this problem, ultra wideband and ultra strong penetrability enable UWB to achieve accurate positioning indoors and on the ground. DTOA has been widely used in radar detection, remote sensing and measurement and control due to its high precision, high speed and high concealment. Because the traditional TOA location algorithm requires the whole system to use synchronous clock, DTOA is unnecessary, reducing the complexity of the system, so it is very practical to use DTOA in indoor location.

Digital twin satellite can receive data from in-orbit satellites for real-time evolution, and provide data feedback to in-orbit satellites. In response to the problems of long project cycles, hard quality control, and high implementation costs exposed by the traditional in-orbit management mode based on physical devices, this paper establishes a highly reliable digital twin satellite, which includes some typical models of subsystems. The digital twin satellite can receive telemetry data from in-orbit satellite and complete the evolution of its own parameters and structure during simulation, ensuring the consistency between the model and the satellite. On this basis, a digital twin of satellite is used as an information carrier to build an in-orbit management system. The in-orbit management system provides a digital solution for information services, data analysis, and decision support. This system is suitable for in-orbit management of single satellite or multiple satellites, and can greatly improve the efficiency and economy of satellite asset management.

One of the main payloads of Terrestrial Ecosystem Carbon Inventory Satellite is the Carbon Sinks and Aerosol Lidar, which is used to measure forest and aerosol profiles. The lidar is made up of a five-beam laser altimeter and an aerosol lidar, as well as a near nadir-pointing camera, which is used to obtain high-resolution multi-spectral images of the forest. The relative stability of laser pointing and camera imaging is essential for reconstructing 3D structures of the forest, and further calculating above ground biomass. In this paper, the overall principles to meet mission requirements and ensure high stability of laser pointing and high-resolution camera imaging is introduced, and design scheme of the laser altimeter and high-resolution camera are presented, and in-depth stability analysis is made from both structural and timing aspects. Ground verification results are listed, and show good stability. This work provides an important basis for calculating the vegetation biomass by use of horizontal distribution and vertical profile information of vegetation, especially forest, on orbit.

WiFi is the most widely used wireless communication technology in recent years, and satellite space communication has the characteristics of wide coverage. The article proposes a scheme for space-ground communication based on the application of WiFi technology, and analyzes and verifies the effect of high dynamic Doppler frequency shift on WiFi signals by using 802.11b protocol. It is believed that the high dynamic Doppler frequency shift will not affect the bit error rate based on 802.11b protocol for low orbit satellite space-ground communication. Besides, the scheme of onboard WiFi broadcasting and silent monitoring ground terminal devices can avoid the problem of frame filtering (MAC address constraints) in the WiFi protocol, and can achieve one-way communication from space to ground.

To overcome long training time and low-level precision rate of traditional satellite defect detection methods based on neural network, a novel fault diagnosis algorithm based on radial basis function neural network (RBFNN) and Dempster-Sharfer (DS) theory is put forward. Principal component analysis (PCA) algorithm is firstly adopted to decrease the high-dimension remote metering data’s quantity. Then RBFNN would be implemented offline training and adjustment. During the process of satellite fault diagnosis, RBFNN is applied to carry out preliminary detection and evaluation. And DS evidence theory is used to locate the error finally. To decrease calculation time, a matrix factorization algorithm is proposed to implement the matrix's parallel arithmetic during RBFNN’s training process, which could distribute remote metering data to different computing core. The experimental findings suggest that the proposed satellite fault diagnosis algorithm base on RBFNN and DS theory can achieve satisfactory fault prediction effects.

Real-time and robust calibration of camera intrinsic parameters is a prerequisite for visual sensors based algorithms and systems to obtain high-quality positioning results and maps. Although traditional DLT methods meet the requirements of real-time performance, they are difficult to maintain accuracy in the case of input data corruption. To better meet the needs of high-accuracy and real-time performance at the same time, an improved DLT method based on the combination of point and line features was presented. The proposed method has three main contributions. First, uniformly filtered point features are adopted to reduce the impact of point features distribution on calibration accuracy. Second, the average coordinates of several 3D points corresponding to 2D line feature are used to reduce the error. Finally, by combining point and line features to construct constraints for calculating camera intrinsic parameters, we obtain better results than traditional methods. In order to verify the proposed method, we compared the accuracy of the calibration results calculated by the proposed method and the reference methods. And the experimental results demonstrated the effectiveness of the proposed method.

Solar-induced chlorophyll fluorescence (SIF) remote sensing technology is a frontier in the fields of Ecological Environment, Carbon Cycle, and Quantitative Remote Sensing. The newly launched Terrestrial Ecosystem Carbon Inventory Satellite (TECIS) is equipped with the first in-orbit payload, Fluorescence Spectral Imager (FSI), which is dedicated to high spatial resolution imaging of SIF. FSI has improved its spatial resolution to 350 m × 800 m, with a spectral resolution of 0.24 nm. FSI adopts a dual diffuse reflection system to obtain solar radiation and Fraunhofer lines for wavelength and radiation calibration. The residual error after wavelength correction is less than 0.002nm, and no wavelength drift has been identified in 10 months of continuous operation. The SIF products of FSI data processing can effectively reflect the state of surface vegetation. FSI operates stably in orbit, obtaining high-precision calibration and observation data that can support forest ecological monitoring, vegetation photosynthesis, and stress effects research, as well as GPP inversion.

Lidar is widely used in aerospace vehicle to detect specific object. However, the open-loop lidar systems are usually hard to reach the desired control accuracy. To deal with this problem, this paper uses the position sensitive detector (PSD) to detect the laser angle of lidar system, and it is served as the feedback loop to improve the control accuracy of output laser. The realization and procession of whole closed-loop system is introduced. The measurement accuracy of the feedback loop reaches 0.06°, such result ensures the high precision control of laser angle. Then, a state feedback controller is proposed to make the output laser angle track the reference signal. The stability of closed-loop system is proved. A numerical simulation validates the proposed method.

Because the imaging conditions have a great influence on the image quality of optical maneuvring imaging satellite, it is necessary to analyze the influencing factors to ensure the image quality. In this paper, the influence of imaging geometric parameters on the quality of high resolution multi-mode images is analyzed. The main manifestation is image supersaturation; Then, the influence of atmospheric conditions on image quality is analyzed. The main performance is image blur. The atmospheric parameters of the camera observation area are obtained synchronously by atmospheric synchronous correction instrument, and the image is clear after atmospheric correction; Finally, the effect of the side-looking angle on the Ground Sample Distance of the optical satellite is analyzed. The Ground Sample Distance decreases with the increase of the side-looking angle, and some suggestions are given to meet the user's application requirements.

Rice is one of the main food crops in China, Timely and accurate acquisition of the spatial distribution of rice is of guiding significance for food security and agricultural development. In this study, a total of 40 candidate features in five categories: spectral, tasseled cap transformation, texture, terrain, and radar were constructed based on Sentinel-1, Sentinel-2, and terrain data, respectively. The Pearson-Relief_F algorithm was used for feature selection and weight evaluation, and was combined with random forest, support vector machine, and classification regression tree for comparison experiments to filter the optimal feature combination and optimal classification model according to the classification effect. The results show that, 13 optimal feature spaces such as red edge normalized vegetation index (NDVIre1) and (MTCI), combined with random forest features have obvious advantages for the identification of rice growing areas. They can accurately extract the spatial distribution information of rice in the Sanjiang Plain, with the overall accuracy of 95.71% and the Kappa coefficient of 0.95 by ten-fold cross-validation. The accuracy of the selected 13 optimal features is slightly higher than that of all 40 features, with a 67.5% reduction in feature dimensionality. The study can provide a reference for the accurate extraction of rice areas in large regions.

In order to reduce the impact of micro-vibration on the satellite’s imaging quality, this paper proposes an active vibration isolation platform (AVIP) based on distributed vibration absorption. The AVIP can constrain the relative movement between the upper and the lower platform benefiting from the six rigid connecting rods, and the inner movable assembly installed on each rod in parallel acts as the AVIP’s actuator. Based on the topology of the AVIP, the relationship between the distributed axial force of each rod and the disturbing force and torque on the upper platform was derived. On the basis of the Adaptive Notch Canceller (ANC) control method, a variable step Least Mean Square (LMS) algorithm with the step factor adjustment method is used to calculate the active force. The calculated control force is applied on each rod to counteract the distributed force, which considerably suppress the vibration transmitted from upper platform to the lower platform to a certain extent. Finally, the effectiveness of the AVIP together with the distributed vibration absorption method is significantly validated by the simulation results.

Aiming at the application features of onboard platform software with generalization requirements, standardization algorithms and model selection, as well as the difficulties of large differences in the requirements of each application model and short development cycle, this paper researches the generalized confirmation test technology of onboard platform software. For the traditional confirmation test environment framework and standards are not uniform, the test platform portability, maintainability, and scalability are not good, put forward the generalized test environment based on all-digital virtual simulation; for the existing test script based on the design of a single software configuration item in the current situation of insufficient degree of reuse between the models, analyzed the current script generalization problems, put forward the generalization of the platform software The solution of automatic test script is proposed to realize the generalization of platform software confirmation test. The verification of several models shows that the generalized confirmation test technology based on platform software proposed in this paper is effective and feasible.

This paper designs and implements a heterogeneous parallel computing framework for onboard computers. The purpose is to provide heterogeneous parallel computing management services for increasingly complex onboard computers, and to facilitate software developers to efficiently access these heterogeneous processor resources. The computing framework is based on the hybrid heterogeneous system of domestic mainstream on-board computers, referring to foreign heterogeneous computing framework models such as OpenCL, CUDA, and MIC, and completely independently realizes data, task, and timing management among multi-processors. On the basis of the computing framework, a test case using heuristic intelligence to optimize the orbital maneuvering strategy is implemented, which verifies the correctness of the computing framework, the completeness of the interface and the ease of use.

This paper studies the software platform design technology of driver system for satellite system, and proposes a platform design method for driver system software. This method extracts the key requirements in the system software design by analyzing the application fields, user tasks characteristics, main peripheral drive characteristics and other elements of the actuator drive unit system software. Through the classification and hierarchical division of the key requirements, an efficient and practical system software platform design method based on parameter configuration is designed. This paper describes the innovation of the method very sufficiently, and compares the innovation of the scheme with the existing method. This technology has been successfully applied to the software design of drive unit system of dozens of satellites, effectively shortening the software development cycle and improving the reliability of software development.

Star sensor is a high precision attitude measurement device widely used in space vehicles, and accuracy calibration is an important part to ensure high precision measurement. In this paper, the error of the split micro star sensor used by a civilian satellite is analyzed, and quantitatively evaluates by the method of polynomial fitting and optical axis angle. The on orbit test results show that the attitude determination accuracy of the single probe star sensor is better than 1.7″ in X-axis/Y-axis and 15″ in Z-axis.

The operating system is an essential basic software for spacecraft, and its reliability and safety are directly related to the success or failure of aerospace missions. Although various methods have been used to ensure the reliability and security of operating systems, there are still situations where defects cannot be completely eliminated. Therefore, it is imperative to conduct formal verification research on space operating systems. The verification of design layer is a part of formal verification of operating system. Based on the analysis of task management module of operating system, this paper proposes a formal modeling method using finite state machine at the design layer, and uses this method to model SpaceOS2 applied on a spacecraft at the design layer, and correspondingly describes the modeling in the theorem proving tool Coq; then, some local property are formally defined, and the proof that the system model satisfies these properties is given. The results show that SpaceOS2 meets the proposed local property at the design layer, which lays the foundation for further comprehensive formal verification.