Cooperative and Fractional Redundancy for Cost-Effective Mixed-Critical Flight Control Systems

The United States Air Force has a clear need for new unmanned assets that integrate with current assets in a mixed-initiative framework. The autonomy required by such assets, combined with the elevation of many mission-critical applications to flight-critical status, levies significant additional requirements for flight-critical computing and sensor hardware. Current approaches to this problem focus on integrating flight- and mission-critical software in order to avoid unnecessary replication of computer hardware. Sensors, however, remain unaddressed and require significant redundancy. Barron Associates will address this problem with two novel approaches to fault tolerance: cooperative redundancy and fractional redundancy. Cooperative redundancy allows a healthy aircraft to provide sensor data to a proximal aircraft that has experienced a sensor failure; fractional redundancy exploits analytical redundancy amongst sensors to reconstruct the value nominally supplied by a failed sensor. In the proposed research effort, Barron Associates will demonstrate cooperative redundancy by simulating an unmanned aircraft aiding another unmanned aircraft crippled by a sensor failure during the autoland flight phase. Barron Associates will also develop a general architecture for fractional redundancy and characterize the sensors to which both approaches are applicable. BENEFIT: Barron Associates anticipates a number of opportunities to apply this SBIR-developed technology to DoD programs. The DoD has a clear need for affordable unmanned assets that can integrate with current, manned assets. Hardware replication poses a challenge for affordability, yet single-string sensor suites offer insufficient reliability for flight-critical operations. Technologies like cooperative and fractional redundancy, which reduce hardware costs while maintaining suitable levels of reliability address this challenge and will help the DoD meet its need for affordable, reliable UAVs. Another evident application of the proposed fault-tolerance techniques is for manned aircraft. Fractional redundancy, in particular, has the potential to provide greatly improved failure isolation and recovery for critical sensors. Other potential uses of the proposed fault-tolerance technologies are in the areas of civilian UAVs intended to operate in the National Airspace as well as civilian manned aircraft. Last, fractional redundancy will offer the automotive sector cost reductions while maintaining overall sensor-suite reliability. There is an increasing trend in the automotive sector towards digital control systems for stability augmentation, braking, to four-wheel steering, etc., which will require reliable information from a diverse set of sensors.