Optimal Open Loop and Nonlinear Feedback Control for Remote Orbital Capture.
Abstract
In this thesis optimal open loop aand nonlinear feedback control histories are presented for a problem of detumbling (passivating) a target satellite by a remotely operated robot spacecraft. Detumbling is required so that the robot spacecraft, sometimes called a teleoperator or orbital maneuvering vehicle (OMV), can return the target satellite to low-Earth orbit for servicing and repair. The dynamics of the coupled two-body system are described with equations of motion derived from an Eulerian formulation (the Hooker-Margulies equations). Two degrees of rotational freedom are allowed at the joint which connects the OMV and target spacecraft, and the joint is allowed to translate on the surface of the OMV. The initial condition of the axially symmetric target satellite is free spin and precession. Representative masses and inertias are assumed for each body. The detumbling controls, which are the external (thruster) and internal (joint) torques applied by the OMV, are found from optimal control theory yields a nonsingular two-point-boundary-value-problem which is solved numerically for the open loop controls over a specified time internal. Control constraints on the thrusters and one of the joint torques are also considered. Liapunov stability theory is used to derive a nonlinear feedback control which results in the asympototic stability of a set of equilibria for the two-body system. This control law is analyzed numerically and compared to the results of optimum open loop control.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1985
- Accession Number
- ADA151967
Entities
People
- J. W. Widhalm Jr
Organizations
- Air Force Institute of Technology