皮纳卫星数据存储系统设计与在轨验证

Design and in-orbit verification of data storage system for nano-pico satellites

为提高皮纳卫星数据存储系统性能和可靠性,提出了一种基于3种介质的"三级数据存储+三模容错架构"存储系统策略.首先,基于对星载存储介质的现状和故障特性分析,选择存储器件;然后对文件系统操作流程进行详细研究,提出错误来源;由此提出了采用ECC纠错、冗余备份和电流保护的方法提高系统可靠性;提前预分配文件空间,建立环形数据存储结构,以减少FS操作复杂性,降低错误率;结合RAM、FRAM、SD卡(secure digital card,SDC)三者的优点,采用三级数据存储策略来提高存储速度和故障容错能力;最后,通过地面实验测试,在1 MB总数量时,数据写入速度提高约4.7倍,任一SDC异常或者系统突然断电均不影响系统正常工作,数据丢失≤1帧,故障切换时间≤10 ms.卫星在轨运行过程中,FS、文件和介质均工作正常,且未影响其他系统工作.地面实验和在轨验证结果表明,数据存储系统方案有效可行,系统可靠性和读写性能均能满足卫星系统的任务需求.

A storage strategy based on ＂three-level data storage,three-mode fault-tolerant structure＂is proposed to improve the performance and the reliability of the data storage system for nano-pico satellites. Firstly,the storage device is selected based on the analysis of the onboard storage media and fault characteristics. After analyzing the error sources of the file system,a scheme combining the ECC error correction,the redundancy backup and the current protection is applied to improve the reliability of the system. The file space is pre-allocated and a ring data storage structure is established to reduce errors and decrease the operating complexity for the file system. Finally,taking the advantages of RAM,FRAM and SD card,a three-level data storage method is utilized to improve the storage speed and the fault tolerance. writing speed increases by about 4.7 times when the data size is 1 MB,and the SDC abnormality or abrupt power-off of the system can not affect the system; in addition,the fault switching time is less than or equal to 10 ms when the fault switching time is less than or equal to 1 frame. In orbit operation process,all the FS,files and the storage media work well. The ground test and the in-orbit operation show that the proposed data storage strategy is feasible,and the system reliability and the performance of data reading and writing can meet the mission requirements of satellite system.