Issues in the design of fault tolerant vehicle management systems for next generation unstable air vehicles

The author describes design issues in fault-tolerant vehicle management systems (VMS) for next-generation high-performance aircraft. Unstable aircraft require a highly reliable fault-tolerant computer to perform dynamic compensation of effector surface controls. Next-generation system requirements for system availability and performance will extend the role of flight criticality beyond the flight data sensors and actuation control functions. Additional control systems requiring a similar degree of fault tolerance include the primary and secondary electrical power systems, fuel management system, hydraulics control system, propulsion control system, and avionics cooling system. The incorporation of these additional control systems into the flight control system defines the vehicle management system of next-generation aircraft. In addition, the implementation of a VMS for the 1990s will incorporate state-of-the-art hardware technologies including fiber optics, high-speed local area networks, high-voltage application-specific integrated circuits, multiprocessing, smart sensors, liquid-cooled racks, and packaging for two-level maintenance. Software technology will include a multiprocessor ADA fault-tolerant executive, local area network distributed architecture synchronization and network management, and high coverage built-in-test to support two-level maintenance. Architectural and system technologies to be applied include channelized and self-monitored redundancy, integrated flight and propulsion control, centralized and distributed electric actuators, pooled processing centers, expert systems, and 270 V uninterruptible electrical systems. The goals and accomplishments of some VMS programs are summarized.<
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