
Accession Number : ADA329676
Title : Reorientations of Flexible Spacecraft Using Momentum Exchange Devices
Descriptive Note : Doctoral thesis
Corporate Author : AIR FORCE INST OF TECH WRIGHTPATTERSON AFB OH SCHOOL OF ENGINEERING
Personal Author(s) : Ford, Kevin A.
PDF Url : ADA329676
Report Date : SEP 1997
Pagination or Media Count : 148
Abstract : We study resttorest reorientations of flexible spacecraft using momentum exchange devices. A new and concise form of the equations of motion for a rigid body containing a cluster of gimbaled momentum wheels is developed using the EulerNewton approach. Special restrictions of the gimbaled momentum wheel equations yield equations of motion for the momentum wheel cluster and the control moment gyroscope cluster. A mathematical model of a free spacecraft with EulerBernoulli appendages is developed. Using the assumed modes method, a complete set of equations is developed which describes the dynamics of a spacecraft with flexible appendages and gimbaled momentum wheels. Special attention is paid to singularity problems in control moment gyro clusters. A control law based on the singular value decomposition is developed which avoids torque output commands in the nearly singular direction. The stationary platform maneuver, a maneuver along the set of equilibrium solutions of a zero angular velocity spacecraft, is extended to the control moment gyro cluster. The set of equilibria for a control moment gyro cluster is a unique surface in gimbal angle space. A control law which reorients the spacecraft while remaining close to this surface is developed using a Lyapunov method.
Descriptors : *SPACECRAFT, *ATTITUDE CONTROL SYSTEMS, *EQUATIONS OF MOTION, THESES, MANEUVERS, CONTROL THEORY, GYROSCOPES, FLEXIBLE STRUCTURES, ANGULAR MOMENTUM, GIMBALS, MOMENTUM TRANSFER, LYAPUNOV FUNCTIONS.
Subject Categories : Theoretical Mathematics
Spacecraft Trajectories and Reentry
Distribution Statement : APPROVED FOR PUBLIC RELEASE