Two degree-of-freedom spacecraft attitude controller

Acta Astronautica, 2011

This paper extends the previous works that appeared in Acta Astronautica. An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a 50 kg small satellite. Numerical treatments are performed to validate the effectiveness of AFC. The attitude control capability of the combined energy and attitude control system (CEACS) is expected to improve. The result shows an important attitude pointing enhancement for the CEACS attitude control task.

The International Journal of Multiphysics, 2007

The hybrid subsystem design could be an attractive approach for future spacecraft to cope with their demands. The idea of combining the conventional Attitude Control System and the Electrical Power System is presented in this article. The Combined Energy and Attitude Control System (CEACS) consisting of a double counter rotating flywheel assembly is investigated for small satellites in this article. Another hybrid system incorporating the conventional Attitude Control System into the Thermal Control System forming the Combined Attitude and Thermal Control System (CATCS) consisting of a "fluid wheel" and permanent magnets is also investigated for small satellites herein. The governing equations describing both these novel hybrid subsystems are presented and their onboard architectures are numerically tested. Both the investigated novel hybrid spacecraft subsystems comply with the reference mission requirements.

2019

Based on the three-dimensional dynamics of a rigid body and Newton's laws, the simplified dynamics of a spacecraft is studied and described through the systematical representation, mathematical modeling and also by a block diagram representation, to finally simulates the spacecraft dynamics in the Matlab programming environment called Simulink. It is paramount to be able to identify and recognize the attitude (often represented with the Euler angles) and position variables like the degrees of freedom (DOF) of the system and also the linear behavior. All this to conclude up about the non-linear behavior presented by the accelerations, velocities, positions and Euler angles (attitude) when those mentioned are plotted against time. In addition to this, the linearized system is found in order to facilitate the control analysis and stability analysis, at using linear analysis tools of Simulink and concepts like controllability and observability, reaching the point of determining under the previous concepts to proceed with the control design phase. Lastly, an uncertainty and sensitivity analysis is realized, by means the Monte-Carlo and the Linear regression method (in Simulink too), to find the torque like critical model input, since it has the greatest effect on the response variables in the system; and thus finally, to implement the Linear Quadratic Regulator (LQR) controller, at using the lqr Matlab function.

Acta Astronautica, 2013

Feasibility of achieving three axis attitude stabilization using a single thruster is explored in this paper. Torques are generated using a thruster orientation mechanism with which the thrust vector can be tilted on a two axis gimbal. A robust nonlinear control scheme is developed based on the nonlinear kinematic and dynamic equations of motion of a rigid body spacecraft in the presence of gravity gradient torque and external disturbances. The spacecraft, controlled using the proposed concept, constitutes an underactuated system (a system with fewer independent control inputs than degrees of freedom) with nonlinear dynamics. Moreover, using thruster gimbal angles as control inputs make the system non-affine (control terms appear nonlinearly in the state equation). This necessitates the control algorithms to be developed based on nonlinear control theory since linear control methods are not directly applicable. The stability conditions for the spacecraft attitude motion for robustness against uncertainties and disturbances are derived to establish the regions of asymptotic 3-axis attitude stabilization. Several numerical simulations are presented to demonstrate the efficacy of the proposed controller and validate the theoretical results. The control algorithm is shown to compensate for time-varying external disturbances including solar radiation pressure, aerodynamic forces, and magnetic disturbances; and uncertainties in the spacecraft inertia parameters. The numerical results also establish the robustness of the proposed control scheme to negate disturbances caused by orbit eccentricity.

Advances in Spacecraft Attitude Control, 2020

Small satellites have begun to play an important role in space research, especially about new technology development and attitude control. The main objective of this research is the design of a robust flight software, in which the key feature is suitably designed control laws to guarantee the robustness to uncertainties and external disturbances. To accomplish the desired mission task and to design the robust software, a classical Proportional Integrative Derivative (PID) method and two robust control system technologies are provided, focusing on applications related to small satellites and on the real-time implementability. Starting from PID approach, simulations are performed to prove the effectiveness of the proposed control systems in different scenarios and in terms of pointing stability and accuracy, including uncertainties, measurement errors, and hardware constraints. Different control techniques are analyzed: (i) a tube-based robust model predictive control (MPC) and (ii) a variable gain continuous twisting (CT) sliding mode controller. Both controllers are compared with loop shaping PID controller.

Astrophysics and Space Science Library, 1978

1991

The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government 17 COSATI CODES FIELD GROUP SUBGROUP 18 SUBJECT TERMS (continue on reverse if necessary and identify by block number) Flexible Appendage, Finite Element Analysis, Mode Shapes, Equations of Motion 19 ABSTRACT (continue on reverse if necessary and identify by block number) This thesis details the design of the Naval Postgraduate School's Flexible Spacecraft Simulator and the first attempts at simulation and control of the model. The effect of flexible structures on the attitude control of spacecraft has been a topic of research for many years. Only recently has the technology to actually test models and theory on the ground been available. At the Naval Postgraduate School, an experimental testbed for research into this area has been constructed. This facility has a model of a satellite with a flexible arm floating on air pads to eliminate the effects of friction. A mathematical model of the system has been constructed and simulations of various maneuvers have been run, utilizing proportional-derivative (PD) control as well as a Linear-Quadratic-Gaussian (LQG) compensator. Results show that both PD and LQG work well for station keeping, but that the LQG compensator is better for slewing the arm.

Automatica, 1995

A novel approach is proposed for the attitude stabilization and reorientation of an axisymmetric spacecraft subject to two gas jet actuators. The approach is based on a new formulation of the attitude kinematics.

2011

The ISS Reshetnev is the Russian leader in development, manufacture and operations of navigation, geodetic and communication spacecraft, as well as Russian State programme for satellite telecommunication systems development. The research results achieved by the ISS Reshetnev in attitude control of some communication spacecraft, are presented.