Design of a fault-tolerant COTS-based bus architecture

摘要

This paper describes the authors' approach to usingncommercial-off-the-shelf (COTS) products in highly reliable systems. Thenmethodology calls for multilevel fault-protection. The methodologynrealizes that COTS products are often not developed with highnreliability in mind. Nevertheless, by using multi-level faultnprotection, the same level of reliability as the traditional full-customnfault tolerance approach can be achieved. This methodology allows morenfreedom for design trade-offs among the fault-protection levels, whichncan result in less complicated designs than the traditionalnstrictly-enforced fault-containment policy. This paper covers thenauthors' experiences and findings on the design of a fault-tolerantnavionics bus architecture comprised of two COTS buses, the IEEE 1394,nand the I2C, for the avionics system of X2000 program at thenJet Propulsion Laboratory. The X2000 design is judicious about ensuringnthe fault-tolerance provisions do not cause the bus design to deviatenfrom commercial standard specifications, so that the economicnattractiveness of using COTS is preserved. The hardware and softwarendesigns of the X2000 fault-tolerant bus are being implemented, andnflight hardware will be delivered to the Europa Orbiter missions. Thisnwork provides an example of how to construct a highly reliable systemnwith low-cost COTS interfaces