Analytical Tools for the Design and Verification of Safety Critical Control Systems 2001-01-2938

Safety critical real-time computer systems such as digital fly-by-wire aircraft are designed to be highly reliable, able to detect and recover from faults, and fail in a safe state even in harsh environments. This paper presents an analytical tool that is being developed to enhance the design and verification of safety critical systems. The tool is used to analyze the effect of standard error recovery systems on closed-loop flight control systems. In particular, this paper develops models and analyzes the stability effect of error recovery rollback, reset, and restart systems in digital control systems due to system functional upsets induced by multiple burst waveforms (MBW’s) during a lightning flash. A simple example will be used to illustrate one use for the tool: comparison of different recovery methodologies by determining the minimum interarrival spacing between MBW’s to maintain closed-loop stability.