Design Of SEU-tolerant Architecture And Study On Its Reliability Of On-board Computer Based On COTS

OBC(On-Board-Computer) works in the abominable space environment. Howerver, it is different from the earth. In outer space, there are large numbers of electrification particles. The electronical devices, like computers and so on, will be eradiated by electromagnetism and struck by heavy particles. Their interaction produces SEU(single-event upsets). It can result in numerous side effects when nanosatellite works, such as erroneous calculations, instruction and data corruption, erratic software execution, device setting changes, and even abnormity or other faults. A natural solution to mitigate SEU is using special material to reinforce and shield from radiation. Whereas the thickness of shielded material is restricted to the volume and weight of nanosatellite, and the effect is limited. The radiation-hard device is dear and difficult to purchase. What's more important, at present, radiation-hard CPU and other computer devices drop many years behind the most advanced COTS (Commercial-Off-The-Shelf). Now it has been a trend to import COTS technology to design OBCs all around the word, especially in nanosatellite application. And it has also been widely applicated in military and commercial satellite fields.We have developed an on-board computer system architecture which was high performance, reliable and reconfigurable, according to international experience and advanced technology, combined with internal facts. Compatable with multiple kinds of interface, AT91RM9200 CPU of ARM was the core of the hardware and reduced Linux was the core of the software. Start with indagation and choosing of parts, we have achieved its theory project, system architecture design, prototype system testing and validation, and replantation of Linux Operating System. Moreover, we have father ameliorated this computer on the basis of the above, and made stability groundwork for the final applications of subsequent spaceflight projects.But how to guarantee system's reliability to normally work in space radiation environment, was a challenging research.On the basis of the above, we analyzed the SEU effect of COTS-based device in space radiation environment, and implemented the design of SEU-tolerant system architecture of the OBC based on COTS. The design builded OBC reliability up more and more. Firstly, in the system grade, we adopted FPGA-based dual fault-tolerant system scheme to improve the reliability of OBC, in macroscopical point of view. Secondly, in the module grade, we adopted TMR(Triple Module Redundancy) technique to memory devices, and it improved the anti-SEU ability of SRAM and FLASH. Thirdly, in the chip grade, to greatly improve reliability, we adopted SEU-tolerant design in the inner SRAM-based FPGA(Field Programmable Gate Array), and the reconfiguration of FPGA download circuit in the outer. Our research, such as design and validation, were both on the basis of the implementation of OBC prototype system.After being more consummated, the fruits of this project can be straightly applied to low-orbit OBC and space vehicle information platform. They will certainly reduce the cost, and improve the reliability, reconfigurability and OBSM(On-Board Software Maintenance) of OBC, which is most significant to the development of our country's space science and technology.