Three software products are being developed to help satisfy the needs of NASA and of private industry for reconfigurable active control systems to suppress vibrations in Reusable Launch Vehicles (RLVs) and other structures. These potentially highly marketable products are the following:

  • The Integrated Structural Modeling and Intelligent Control Toolbox serves as a software environment for mathematical modeling, analysis, design, simulation, and implementation of genetic-algorithm-based "intelligent" control of vibrations in structures.
  • The Intelligent Distributed Structural Control Node is a real-time software prototype of a distributed control system that employs distributed fuzzy-logic structural controllers and a fuzzy neural reconfiguration strategy.
  • The Distributed Health Monitoring and Decision-Making Integration System is a software system for genetic-algorithm-based, decentralized, parallelized fault detection and isolation (FDI) and reconfiguration.

The need for these products arises from the following considerations: Active control for suppressing vibrations in spacecraft is a topic of considerable importance, especially lately, given the advent of Reusable Launch Vehicles (RLVs). One of the difficulties in designing capable controllers for space structures lies in the inability to obtain or to test accurate mathematical models of their dynamics, including submodels of vibration modes, prior to launching the structures into outer space. Thus, in designing a vibration controller for a space structure, it becomes a requirement to provide robustness against all possible uncertainties. Ideally, the structure vibration controller should be able to both characterize the dynamics of the structure and modify its dynamical model after launch, thereby affording both superior robustness and excellent performance.

Also, the stability of individual components on RLVs is an issue of grave concern. Stiffening these components often entails adding undesirable weight. The characterization of these components and the attenuation of their accelerations, by use of a "smart" active vibration-control system, are of the utmost importance in an effort to attain the all-consuming goal of minimizing RLV weight.

Other important issues related directly to the vibration-control issue include the need to protect expensive, fragile payloads, to release them into their orbits as accurately as possible. An accurate and efficient placement and/or pointing of a payload to be released into orbit from an RLV an application of enormous commercial value.

The three software products mentioned above take advantage of active vibration control methods and equipment, including "smart" piezoelectric sensors, actuators, and sensor/actuator units. Genetic algorithms serve as means for optimization and learning. These three products implement genetic-algorithm-based techniques of "intelligent," reconfigurable active vibration control developed by American GNC Corp.

Potential applications for the three software products include attenuation of accelerations for space-based experimentation in combustion and growth of crystals, enhancing spacecraft and aircraft ride qualities, extending the lives of aircraft and spacecraft by minimizing the damage wrought by structural vehicle vibrations, and extending the lives of airplanes by minimizing loads on wing roots. Also, these products and the associated techniques can be used for high-precision pointing and active control of vibrations of civilian and military flexible structural systems, including optomechanical systems, aerospace structures, weapon systems, positioning machines, and robotics.

This work has been and will be undertaken by the American GNC Corporation,9131 Mason Avenue, Chatsworth, CA 91311, an SBA 8(a) certified Small Disadvantaged Business concern, as part of a NASA Small Business Innovation Research (SBIR) project monitored by Marshall Space Flight Center. The NASA SBIR Contract Number is NAS8-98101; Topic: 97-1 08.01; Topic Title: Launch Vehicle Technologies. For further information, contact Dr. Ching-Fang Lin, American GNC Corporation, at tel: (818) 407-0092, fax: (818) 407-0093, or e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..SBIR0006

NASA Tech Briefs Magazine

This article first appeared in the March, 1999 issue of NASA Tech Briefs Magazine.

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