Adaptive Control of Truss Structures for Gossamer Spacecraft

Neural network-based adaptive control is considered for active control of a highly flexible truss structure which may be used to support solar sail membranes. The objective is to suppress unwanted vibrations in SAFE (Solar Array Flight Experiment) boom, a test-bed located at NASA. Compared to previous tests that restrained truss structures in planar motion, full three dimensional motions are tested. Experimental results illustrate the potential of adaptive control in compensating for nonlinear actuation and modeling error, and in rejecting external disturbances

Adaptive Control of Truss Structures for Gossamer Spacecraft

Neural network-based adaptive control is considered for active control of a highly flexible truss structure which may be used to support solar sail membranes. The objective is to suppress unwanted vibrations in SAFE (Solar Array Flight Experiment) boom, a test-bed located at NASA. Compared to previous tests that restrained truss structures in planar motion, full three dimensional motions are tested. Experimental results illustrate the potential of adaptive control in compensating for nonlinear actuation and modeling error, and in rejecting external disturbances

Modeling and Slew-Maneuver Control of a Flexible Spacecraft

Slew-maneuver control problem is studied for a flexible spacecraft consisting of a rigid main body to which a long flexible appendage is attached. Nonlinear dynamical system models are developed using both distributed parameter modeling and discrete parameter modeling; these models are shown to be equivalent for appropriately chosen system parameters. Lyapunov-based nonlinear feedback controllers are designed for the control of rigid-body motion while suppressing the lowest frequency vibrational mode. In case of large-angle maneuvers, these nonlinear controllers are shown to outperform the linearization-based controllers including the filtered proportional-derivative (PD) controllers as well as the linear quadratic regulator (LQR) controllers. Finally, the theoretical development is applied to a benchmark flexible system and a number of computer simulations are included to illustrate the results

Large space structures and systems in the space station era: A bibliography with indexes (supplement 03)

Bibliographies and abstracts are listed for 1221 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and June 30, 1991. Topics covered include large space structures and systems, space stations, extravehicular activity, thermal environments and control, tethering, spacecraft power supplies, structural concepts and control systems, electronics, advanced materials, propulsion, policies and international cooperation, vibration and dynamic controls, robotics and remote operations, data and communication systems, electric power generation, space commercialization, orbital transfer, and human factors engineering

Benelux meeting on systems and control, 23rd, March 17-19, 2004, Helvoirt, The Netherlands

Book of abstract

Dynamical systems : control and stability

Proceedings of the 13th Conference „Dynamical Systems - Theory and Applications" summarize 164 and the Springer Proceedings summarize 60 best papers of university teachers and students, researchers and engineers from whole the world. The papers were chosen by the International Scientific Committee from 315 papers submitted to the conference. The reader thus obtains an overview of the recent developments of dynamical systems and can study the most progressive tendencies in this field of science

Desarrollo, modelado e instrumentación de estructuras flexibles para la cancelación activa de vibraciones

Uno de los aspectos clave, desde el punto de vista tecnológico, que condiciona el diseño de sistemas aeroespaciales, es el hecho de emplear materiales muy ligeros, lo cual da lugar a estructuras muy flexibles que presentan grandes vibraciones ante pequeñas perturbaciones. Este hecho impide el posicionamiento preciso de los instrumentos instalados sobre dichas estructuras e influye sustancialmente en su vida útil. Por tanto, es evidente la importancia del desarrollo de estructuras instrumentadas que cuenten con sistemas de control activo capaces de cancelar de forma eficiente las vibraciones no deseadas. En esta tesis se han abordado fundamentalmente tres aspectos relacionados con el desarrollo de estructuras instrumentadas. El primero es la construcción de plataformas experimentales que sean representativas de sistemas aeroespaciales; en este sentido, se han construido tres plataformas: un robot flexible de un grado de libertad, una placa delgada de gran tamaño y una estructura articulada. El segundo de los aspectos es la caracterización dinámica de cada una de las estructuras. Para ello, es necesario considerar el empleo de actuadores y sensores, así como el posicionamiento de los mismos. Se han utilizado galgas extensométricas, acelerometros, fibra de bragg y piezoelectricos como sensores y motores rotativos, motores lineales (excitador electromagnetico), martillos de impacto y piezoelectricos como actuadores. El tercer y último aspecto es el relacionado con el control activo de vibraciones; para ello, se han desarrollado dos esquemas de control para la cancelación activa de vibraciones en el robot flexible: uno en cadena abierta (basado en el moldeado de la trayectoria) y otro en cadena cerrada (basado en pasividad). En el diseño de ambos esquemas se evidencia la importancia que tienen las propiedades mecánicas de la estructura en el desarrollo de algoritmos de control y en la eficacia del sistema de control en su conjunto