3.1 Foreign applications The comprehensive electronic technology was first proposed and implemented by NASA to meet the mission requirements of its Mars rover. NASA first used integrated electronic technology in its Mars probe Soouner and ground principle prototype Pathfinder. In Soouner, only two boards are used to realize all the information processing of the detector and the energy distribution of the secondary power supply. Pathfinder uses an integrated electronic system to combine the attitude and rail control system and the digital tube system into one system, and integrates telemetry, remote control, Energy distribution and other functions. The application of the integrated electronic technology in Pathfinder laid a good foundation for the successful application of the integrated electronic circuit of the "Random Opportunity" and "Courage" issued by the -517-shot in 2003. The integrated electronic circuit box (REM) uses the RAD6000 as the core processor to complete tasks such as remote control, telemetry, path planning, autonomous navigation, motor control, image acquisition, and load management. NASA was greatly encouraged by the successful application of the integrated electronic technology on the "Opportunity" and "Courage" Mars rover. NASA's subsequent Mars sampling and return to the MSRP probe, and the Mars biological laboratory inspector AFL have no An exception is the use of integrated electronic technology.
In addition to deep space probes, NASA is also promoting the application of integrated electronic technology in other satellite platforms. The first star of the new millennium plan, ST5, used a centralized electronic system and was successfully launched in 2006. The lunar satellite LRO launched in 2009 also uses a high-performance, modular integrated electronic system, which is mainly responsible for the reception and processing of uplink commands, navigation control, load data collection, and telemetry data download.
Many electronic satellites launched by ESA in recent years also make extensive use of integrated electronic technology. The PROBA series of small satellites launched in 2001, the first star PR0BA1, realized the integration of the attitude and orbit control subsystem and the number management and sub-system; SpaceBUS4000, launched in 2005, uses a satellite management unit to complete attitude and orbit control, energy, payload, thermal control, remote control, Telemetry, deployment mechanism, solar windsurfing drive mechanism and other tasks and equipment management; the launch of the ESA lunar launching star SMART-1 launched in 2005, the central computer realizes star management, posture and orbit control, load management, remote control and other remote settings The unit realizes remote control reception and command, telemetry downlink and interface data collection; the atmospheric change observation satellite Aeolus launched in 2006 adopts a satellite management unit developed by SaabEricsson to centrally realize star services, attitude and orbit control, telemetry remote control, secondary power distribution, and load Data collection and management; PROBA2, the second launch star of the PROBA series of small satellites launched in 2009, based on PROBA1, the ESA next-generation space processor AT697 was adopted to further realize the electronic circuits such as digital control, control, power distribution, and load management. Overall, the quality of the electronic circuit has been reduced from 15.8kg of PROBA1 to 13.3kg, and the power consumption has also been reduced from 23.3W to 19.7W. 30% increased to 40%. 3.2 Domestic application status Domestic integrated electronic technology started late. In 2006, in order to meet the needs of the mid-lunar surface patrol of the second phase of China's lunar exploration project, the China Academy of Space Technology began to carry out preliminary research on integrated electronic technology After several years of research, the research results have been successfully applied to the lunar surface inspection detector, and various indicators meet the requirements of the model task.
Drawing on the successful experience of the lunar patrol device, China's newly developed test satellites and new platform satellites have also begun to demonstrate the feasibility of the application of integrated electronic technology, and some have begun to enter the project implementation stage.
4 Main technical difficulties of integrated electronics Integrated electronic technology has broken the interface of various subsystems in the development of traditional spacecraft, realized the optimization and rational allocation of software and hardware resources, and effectively improved the spacecraft platform load ratio. The problems that need to be solved in the process of research and application of integrated electronic technology mainly include the following parts: the development of high-performance and high-reliability space computers; the development of real-time multitasking operating systems in space; the definition and division of various functional modules within integrated electronics; synthesis Electronic structure, heat and EMC technology; comprehensive electronic integration and testing technology.
4.1 The comprehensive integration of hardware resources and software functions for the development of highly reliable and high-performance space computers requires that deep space exploration spacecraft must have extremely high operational and data processing capabilities. In the traditional spacecraft, each sub-system has its own computer, and the whole star adopts a distributed computing architecture, which does not require a high computing power of a single computer. The integrated electronic technology adopts a unified computer to centrally process the data of the spacecraft's platform or load, thus putting forward higher requirements on the computer's operation processing ability and reliability.
The technical problems that must be solved in the development of high-reliability and high-performance space computers include: high-performance space processor technology; large-capacity memory technology; high-speed bus technology; space computer architecture research.
At present, the high-performance space computers used in NASA space projects are mainly based on 6000C35MIPS) and the RAD750 embargo and technical restrictions. Relevant research has been carried out in China (such as BM3803 developed by Aerospace 772, SOC2008 developed by Aerospace 502, etc.). None of them have been put into practical use. Currently, high-performance processors and memories are mainly imported from Europe. At present, the high-performance space computer that has been developed and successfully applied in China is developed based on AT697. The highest operating frequency is 100MHz, the minimum system data memory capacity is 20MB, and the program storage includes 32KB of PROM and 2M of EEPROM. Capacity storage function.
The integration of the real-time multi-task operating system development software in space has led to the deep space exploration spacecraft software being a real-time multi-task software. The complexity of the software and the real-time requirements of the tasks will increase. To meet the task requirements, a real-time multi-task operating system must be developed to dynamically schedule hardware resources and maximize the use of limited hardware resources. A real-time multitasking operating system needs to solve the following technical difficulties: memory dynamic management technology; time slice rotation task scheduling technology based on multi-priority queues; fast interrupt response technology; dynamic synchronization technology of semaphore and message queue; Microkernel technology.
4.3 Definition and division of integrated electronic functional modules Since the boundaries of traditional spacecraft subsystems are broken, integrated electronic technology must redefine and divide the functional interface. In order to ensure the practical feasibility of the technology, the division of the modules must consider and follow the following principles: the functions of each module are independent and easy to decompose; the interface of each module is as simple and reliable as possible.
The redistribution of functional modules must take into account non-technical factors such as technical barriers and profit division in implementation, and practical product guarantee requirements must be formulated to ensure the smooth realization of technology.
4.4 Integrated electronic structure, thermal and EMC technology The integrated electronic structure design provides mechanical support and a good electromagnetic and thermal working environment for the integrated electronic modules, which is an important part of integrated electronic technology.
In order to meet the task requirements, the integrated electronic structure design must achieve maximum weight loss under the premise of meeting the mechanical strength requirements. Measures can be taken from both the structure and the material, such as the use of a new cable-free design and the use of magnesium aluminum alloy.
The integration of electronic circuits will inevitably bring about heat dissipation and EMC problems. How to ensure good heat dissipation and EMC shielding is also a major challenge for integrated electronic structure design.
4.5 Integrated Electronics Integrated Testing Technology Integrated electronics achieves the integration and integration of multiple sub-systems, the complexity of the system will increase greatly, how to ensure the comprehensiveness and effectiveness of integrated testing is another problem of integrated electronic technology. Difficulty in analyzing and locating problems in integration testing becomes more difficult. It requires testers to have a certain degree of expertise in multiple systems, and the technical requirements of testers are increased.
Brief introduction of the comprehensive electronic technology of the May surface inspector Due to the severe constraints on volume, quality and power consumption, the first comprehensive electronic technology was adopted in the first month surface inspector in China to integrate the platform and payload electronic equipment hardware to improve the degree of hardware reuse. At the same time, optimize the structure of the electronic system and reasonably divide the hardware and software functions to achieve the goal of meeting system functions and performance at a lower hardware cost. The newly designed integrated electronic unit implements 4 stand-alone devices such as the original satellite platform control computer (AOCC), number control center computer (CTU), center remote control, and center telemetry, as well as part of the functions of the power supply controller. The core processing functions of the system and the number management sub-system.
According to the principles of independent functions and clear engineering development, the integrated electronics of the lunar patrol device are functionally divided into a central computer main backup module, a fault-tolerant management module, a secondary power supply module, a mobile / mechanism control and drive module, a remote processing module, and telemetry Processing module, power supply and distribution processing module, pyrotechnics and thermal control processing module, these modules are designed and integrated in the same chassis, the entire chassis is divided into upper and lower two compartments, the two compartments are partitioned by bus board; The secondary power supply module of the device is designed to be inserted on the bus board and placed in the top cabin. The functional modules are electrically interconnected through the bus board inside the chassis, and cooperate with each other to complete the function of the integrated electronic unit.
The main technical innovations of the integrated electronic unit of the lunar patrol device include: the development of the high-performance space computer based on AT697; the development of the SpaceOS-multitask real-time operating system; and the design of the two-cabin type cableless chassis.
6 Conclusion Integrated electronic technology improves the degree of hardware reuse, optimizes the structure of electronic systems, divides hardware and software functions reasonably, reduces the quality, volume and power consumption, and improves the reliability of the system by integrating the platform and payload electronic equipment hardware , Effectively solved the difficulties faced by deep space exploration missions. The technology can be popularized and applied to other spacecrafts, which can improve the performance and reliability of the spacecraft while significantly increasing the load platform ratio and extending the service life of the spacecraft.
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