Accession Number:

ADA329676

Title:

Reorientations of Flexible Spacecraft Using Momentum Exchange Devices

Descriptive Note:

Doctoral thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

Report Date:

1997-09-01

Pagination or Media Count:

148.0

Abstract:

We study rest-to-rest 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 Euler-Newton 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 Euler-Bernoulli 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.

Subject Categories:

  • Theoretical Mathematics
  • Spacecraft Trajectories and Reentry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE