Incorporation of system inertia into reliability evaluation of real-time control systems

The control system inertia is characterized as the control system deadline (CSD). A computer controller may sometimes fail to produce correct and/or timely control signals due to massive component failures caused by external environmental interferences. However, the underlying control system does not necessarily crash immediately upon controller failure. The CSD is defined as the maximum time the control system can stay in its allowed state space without the computer controller´s services in producing correct and/or timely control signals. Through the analysis and simulation of the Boeing 737-a typical real-time control system-we characterized the CSD as a random variable. When evaluating the system reliability with the CSD knowledge, we need not derive the complete distribution of CSD, but need only the first and second moments, thus simplifying the necessary calculation. Finally, we applied the CSD knowledge to the system reliability evaluation, showing significant improvements in accuracy