Distributed Processing and Fiber-Optic Communications in Air Data Measurement

The application of distributed processing, fiber optics, and hardware redundancy to collecting airstream data in the digitally controlled variable-response research aircraft (VRA) at the Flight Research Laboratory of Princeton University is described. Microprocessor-controlled instrumentation packages in each wingtip of the aircraft collect angle-of-attack and sideslip data in digital form; after scaling, filtering, and calibrating the data, they send it to the microprocessor digital flight control system (micro-DFCS) via digital fiber-optic data links. Each wingtip package is independent of the other; therefore, the system has dual hardware redundancy. The fiver-optic link design is presented as well as a description of the calibration and communications software. Translation of the system's dual redundancy into fault tolerance is also covered. Results of preliminary flight tests are included.