NASA SBIR 2004 Solicitation


PROPOSAL NUMBER: 04 A2.08-9486
SUBTOPIC TITLE: Modeling, Identification, and Simulation for Control of Aerospace Vehicles in Flight Test
PROPOSAL TITLE: Reduction of Flight Control System/Structural Mode Interaction

SMALL BUSINESS CONCERN (Name, E-mail, Mail Address, City/State/Zip, Phone)
Stirling Dynamics Inc
4030 Lake Washington Blvd NE, Suite 205
Kirkland, WA 98033-7870

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Robert Stirling
4030 Lake Washington Blvd NE, Suite 205
Kirkland, WA 98033-7870

A novel approach is proposed for reducing the degree of interaction of a high gain flight control system with the airframe structural vibration modes, representing a complete departure from the traditional approach of using notch filters. In principle it offers similar or better performance than notch filters, while not suffering from the attendant low frequency phase lag that has an adverse effect on pilot handling qualities. Structural mode interaction can be a significant problem in high performance aircraft and other aircraft with low frequency vibration modes. Use of notch filters requires a compromise to be reached between airframe structural stability and handling qualities. Successful application of the proposed method will relieve the flight control system designer of the need for managing this compromise and will allow the achievement of full potential system performance with better handling qualities. Basic feasibility has already been established and Phase I will broadened this to cover practical implementation issues and to define test evaluation plans. Phase II will extend the method into actual test evaluation, either by laboratory test or flight test, or both. Other possible applications such as aircraft active control systems and control of space structures will be considered during the research program.

NASA is involved in development of advanced FCS concepts for various manned and unmanned aircraft which require treatment of interaction between the FCS and aeroelastic characteristics. Structural mode interactions are exacerbated by the introduction of adaptive systems, so the proposed SBIR project is relevant to these projects. Flight test and evaluation phases will require consultancy on the implementation aspects of the method. Other NASA projects, e.g. control of space structures, are potential applications. Enhanced scope of application and functionality of the NASA STARS software represents another NASA sales opportunity. Approximately 50% of consultancy and software sales would be with NASA.

New aircraft projects, modifications and upgrades planned by military and commercial aircraft manufacturers are potential customers for future non-NASA sales of the proposed design method. Demand will arise from successful demonstration of FCS performance benefits from avoiding notch filters. Changes to an existing FCS are normally quite difficult for a range of practical considerations, including certification issues, suggesting that the avionics companies form another customer base. Applications in other industry sectors; space, robotics, civil machinery, etc., form a significant prospect for potential future revenues. Approximately 50% of future revenue from consultancy and software sales is anticipated from these non-NASA applications.