Beyond Fault Diagnosis and Failure Prognosis Fault Tolerant Control of Aerospace Systems

ABSTRACT:Global Technology Connection, Inc., in collaboration with its academic and industrial partners proposes to develop a hierarchical 3-tier fault tolerant architecture to improve aircraft reliability, safety, and availability. The hierarchical system will support autonomous decisions for aircraft mission modification, trajectory planning, and controller reconfiguration. The architecture includes a Fault-Adaptive Control Technology (FACT) that continuously monitors for faults/failures and reconfigures low-level controllers using an active model approach in order to maintain stable control over the aircraft. The diagnostic and prognostic methodology will fuse health information at the aircraft component, subsystem, and system levels in order to improve the accuracy and reliability of the health assessment. Fault and failure information is sent to all levels of the architecture to support control reconfiguration at different levels. Based on the current aircraft health state, a mission modification module determines the appropriate top-level control actions such as modifying sequence of mission tasks and switching between different objectives (extend life / maintain control). A reasoning module is used to select the appropriate mission based upon past mission modification success and failure experiences. At the mid-level, the control problem is defined and solved. Objective function parameters, constraints, estimated dynamic parameters, etc. are used to define the problem depending on the application and the solution is found using the appropriate algorithm (stored offline solutions can also be used). For example, a path planner is often used at the mid-level to generate appropriate aircraft trajectories based on selected mission, environmental conditions, and current and predicted health states. A working prototype will be implemented and tested on a relevant aircraft system using the FEATS design process developed in Phase I. The technology will be transitioned to commercial applications in Phase III to both military and civilian aircraft applications as a framework package along with design process and test tools. This technology supports the U.S. Air Forces integrity programs such as MECSIP, PSIP, AVIP, ASIP, and CSSIP for the long term sustainability of military aircraft fleets.BENEFIT:The fault tolerant system, Fault Evaluation, Adaptation, and Tolerant System (FEATS), will provide improved reliability, safety, sustainability, and availability for manned and unmanned aircraft systems. The system can handle not only a single fault/failure, but multiple aircraft faults/failures from various aircraft subsystems and components. FEATS will provide reliable autonomous decision making in the presence of aircraft fault/failures to increase the chances of mission success and prevention of vehicle loss. There is huge commercial potential for this type of system in aircraft, ship and ground autonomous systems to detect and predict failures and provide on-line compensation for failed systems. NASAs unmanned landing systems, commercial aircraft, automobiles, automated manufacturing, etc. could also benefit from this technology.