Fault tolerant fiber optic flight control system

A fault-tolerant flight control architecture using optical transducers and transmission lines to produce a system which is relatively unaffected by electromagnetic interference and which provides significant weight savings is discussed. Emphasis is placed on two architectures of an optical flight control system designed for use in a redundant flight control system. Option one is a passive system which requires no power transmission lines to the optical components at the actuator. All of the optical signals are returned to the optical interface electronics in the flight control computer and are processed in the box. Option two is an active system in which optical data are sent from the flight control computer to the actuator along an optical bus, usually a MIL-STD-1773 1-to-2 Mb bus, and then back to the flight control computer along the same bus. In option two, the closed-loop control around the actuator is done with a microprocessor in the actuator control electronics module (ACE), which is an electronic box placed on the actuator and powdered by a 28-V line from the flight control computer power supply. This concept is considered active because 28-V power is transmitted outside the flight control computer. It is shown how active systems could be used to provide feedback to the flight control processor and how each system interfaces to the flight control computer. The merits and shortcomings of each system are discussed in detail