1. Introduction 2. Orbital dynamics 3. Orbital maneuvers 4. Attitude dynamics and kinematics 5. Gravity gradient stabilization 6. Single and dual spin stabilization 7. Attitude maneuvers in space 8. Momentum-biased attitude stabilization 9. Reaction jet attitude 10. Structural dynamics and liquid sloshing Appendix A. Attitude transformation in space Appendix B. Attitude determination hardware Appendix C. Orbit and attitude control hardware.

Spacecraft Dynamics and Control: A Practical Engineering Approach

Space Vehicle Dynamics and Control, Second Edition

A new approach to control moment gyro (CMG) momentum management and attitude control of the space station is presented. The control algorithm utilizes both the gravity-gradient and gyroscopic torques to seek torque equilibrium attitude in the presence of secular and cyclic disturbances. It is shown that, depending on mission requirements, either pitch attitude or pitch-axis CMG momentum can be held constant. It is also shown that a combination of yaw attitude and roll-axis CMG momentum can be held constant, whereas a combination of roll attitude and yaw-axis CMG momentum cannot. As a result, the overall attitude and CMG momentum oscillations caused by cyclic aerodynamic disturbances are minimized. A state feedback controller with minimal computer storage requirements for gain scheduling is also presented. An inherent physical property of the coupled roll/yaw dynamics is discussed in terms of a transmission zero of a multivariable system.

New approach to attitude/momentum control for the Space Station

A new concept of generalized structural filtering and its application to active vibration control synthesis are presented. .The concept is a natural extension of the classical notch and phase-lead/-lag filtering, and emphasizes the use of a nonminimum-phase filter, which has zeros in the right-half s plane. Application of this concept to single-input/singleoutput systems with many oscillatory modes results in a robust feedback compensator with much physical insight. The concept also enables the control designer to understand the inherent nature of an "optimal" compensator and to modify the optimal design to be more robust and meaningful. This paper shows that, for certain cases, nonminimumphase structural filtering provides the proper phase lag to increase the closed-loop damping of the flexible modes while maintaining good performance and robustness to parameter variations.

New generalized structural filtering concept for active vibration control synthesis

This paper present s t h e a n a l y s i s and design o f r e a c t i o n j e t a t t i t u d e c o n t r o l system f o r a spacecraf t having l a r g e f l e x i b l e s a l a r a r rays . During t r a n s l a t i o n a l t h r u s t i n g maneuvers, t h e s o l a r a r r a y f l e x i b i l i t y s t r o n g l y i n t e r a c t s w i t h the Pulse-Width and Pulse-Frequency (PdPF) modulator. A simple t r a n s f e r f u n c t i o n model o f f l e x i b l e spacecra f t i s used f o r t h e p r e l im inary c o n t r o l design. The s t a t i c and dynamic charact e r i s t i c s o f the PWPF modulator a re discussed i n d e t a i l . Nonl inear s t a b i l i t y ana lys is i s performed us ing t h e descr ib ing f u n c t i o n o f the modulator. R e l a t i v e s t a b i l i t y margin w i t h respec t t o the l i m i t c y c l e c o n d i t i o n o f a s t r u c t u r a l mode i s used as a measure o f t h e non l inear c o n t r o l system robustness. The performance and s t a b i l i t y margin p r e d i c t e d by c l a s s i c a l s i n g l e a x i s design, a r e v e r i f i e d from t h e 3-ax is non l inear d i g i t a l s imulat i o n s .

Attitude stabilization of flexible spacecraft during stationkeeping maneuvers

Disclosed is a method and apparatus estimating yaw error and roll and yaw disturbance torques from measured roll error and yaw momentum on a continuous on-orbit basis in an orbiting satellite. The information thus obtained can be used to continuously correct for the yaw error by means of, for example, activating a magnetic torquer. Two control loops are used in this invention, a fast loop to damp nutations by changing momentum wheel speed, and a slow loop of the Luenberger observer variety. The latter is a yaw error correction loop which also serves to unload yaw momentum. The satellite in which the invention was first incorporated is of the type having three momentum wheels, all situated in the plane orthogonal to the roll axis. In normal operation, two wheels, each having major momentum component along the pitch axis and minor momentum component along the yaw axis, are operable. A third backup wheel aligned along the yaw axis becomes operable only in the eventuality that one of the primary wheels suffers a breakdown during the life of the satellite. The slow speed yaw loop is used to adjust a magnetic coil torquer. It can be implemented in a number of forms including a hard-wired analog form or a digital computer with certain constant scaling factors programmed into the memory of the computer.

Electronic on-orbit roll/yaw satellite control

Roll/yaw attitude control of a bias momentum stabilized flexible spacecraft is presented. The roll/yaw normal controller with a nonminimum phase control logic is shown to be very insensitive to the structural mode uncertainty. However, if this controller is switched on at the termination of a thruster-controlled stationkeeping maneuver, it cannot provide sufficient nutation damping by itself to guarantee that the initial transients will remain within specifications. Consequently, a roll/yaw transition controller has been designed to meet the pointing requirements during the transition from the stationkeeping mode to the normal mode. The new transition controller design requires consideration of the solar array flexibility because a control logic, designed to stabilize the nutation mode neglecting the solar array flexibility, could destabilize the solar array flexible mode.

John A. Lehner

Papers

Electronic on-orbit roll/yaw satellite control

Roll/yaw control of a flexible spacecraft using skewed bias momentumwheels