Attitude recovery of flexible spacecraft using nonlinear control

Abstract

The general objective of this Ph.D. thesis is to study the dynamics and control of rigid and flexible spacecraft supported by a high-fidelity numerical simulation environment. The attitude control system is one of the critical technology elements, a significant cost driver on most spacecraft programs and hence a key area of study and research. The thesis will focus on the different aspects of the problem including the modeling of flexible dynamics and the design and implementation of a suitable subclass of an attitude viii TABLE OF CONTENTS LIST OF ACRONYMS xi LIST OF FIGURES xiii LIST OF TABLES xvii LIST OF APPENDICES xviii 1 INTRODUCTION AND BACKGROUND 1.1 Literature Review 1.1.1 Rigid Spacecraft Dynamics and Control 4 1.

Three-axis attitude stabilization of a flexible satellite using non-linear PD controller

“…Solar appendage is considered a symmetric beam. By expanding Newton’s second law in the rotating frame, the dynamic equation of the attitude is obtained by (Tafazoli and Khorasani, 2005):…”

“…It is assumed that the rigid body’s frame and appendages’ frame have no rotation with respect to each other. Then the flexible appendage’s kinetic energy can be written as (Tafazoli and Khorasani, 2005):…”

“…In Equation (9), b and a are appendage’s width and length, respectively, ρ is appendage’s density and n denotes number of appendages. T ω χ in Equation (4) can be written by means of adding the rotational energy of the rigid body and the kinetic energy of the flexible appendage (Tafazoli and Khorasani, 2005):…”

“…Consequently, vibration amplitude of appendages may be large enough to result in considerable variation on the moment of inertia. Therefore, moment of inertia variation and even longitudinal vibration of the appendages are considered in the modelling, as in Tafazoli and Khorasani (2005). Moreover, although damping is an inherent property of flexible structures, we have not considered it in the system to depict an interesting aspect of the flexible part and rigid hub coupling.…”

“…For the stabilization case, both linear and non-linear controllers are performed. For instance, Tafazoli and Khorasani (2005) used an inverse dynamic method to recover the attitude of a flexible satellite with a complex and accurate model where appendages are modelled as plates. Although sophisticated and non-linear controllers reveal a good performance for attitude tracking but high processing requirement, knowledge of system parameters (such as moment of inertia) and/or feedback estimators are some of the main drawbacks of such controllers.…”