Attitude Control Simulation of the Data Collecting Satellite - SCD2

This article describes a simulator of small satellite attitude environment and dynamics, complete with a set of realistic sensors and the most commonly used actuator in this class of satellites. The simulator described is useful in attitude estimation and control algorithm development. Some results of the simulation of the PoSAT-1 satellite are presented.

2014

This paper presents the overview of the mathematical simulator TORA-Sim (Total Orbital Real-time Attitude control Simulator) developed by Kyushu University and Mitsubishi Precision Co.,Ltd. used for the satellite attitude control and the simulation results for the typical small satellite application. The results have demonstrated the validity of this simulator in use for the study of the attitude control law. This simulator was used for the development of onboard software for the attitude control of the Kyushu University’s small satellite “QSAT-EOS” launched last autumn. INTRODUCTION The missions of small and micro-satellites which are developed by universities and organizations are becoming more demanding and diversified to acquire various information. For example, the small satellite "QSAT-EOS" developed in Kyushu University has the missions such as 3-dimensional observation of a fixed point on the earth, observation of a target star, and so on. Therefore, the pointing o...

Computational and Applied Mathematics

This paper presents the comparison between the numerical and analytical results of a spacecraft attitude propagation for a spin-stabilized satellite. Some external torques are introduced in the equations of the motion and the comparisons are done considering that these torques are acting together, which are: gravity gradient, aerodynamic, solar radiation, magnetic residual and eddy current. In the numerical approach it is used the quaternion to represent the attitude. This numerical approach can be applied for any kind of satellite. The analytical approach is applied directly for a spin-stabilized satellite and the equations of motion are described in terms of the spin velocity, spin axis right ascension and declination angles. An analytical solution of these equations is presented and valid for one orbit period. Applications are developed considering the Brazilian spin-stabilized satellites SCD1 and SCD2. The comparisons are important to validate some simplifications that are required in

Journal of Physics: Conference Series

The aim of this paper is to present an analytical solution for the spin motion equations of spin-stabilized satellite considering only the influence of solar radiation torque. The theory uses a cylindrical satellite on a circular orbit and considers that the satellite is always illuminated. The average components of this torque were determined over an orbital period. These components are substituted in the spin motion equations in order to get an analytical solution for the right ascension and declination of the satellite spin axis. The time evolution for the pointing deviation of the spin axis was also analyzed. These solutions were numerically implemented and compared with real data of the Brazilian Satellite of Data Collection-SCD1 an SCD2. The results show that the theory has consistency and can be applied to predict the spin motion of spin-stabilized artificial satellites.

Journal of Applied Research and Technology, 2014

This paper describes the integration and implementation of a satellite flight simulator based on an air bearing system, which was designed and instrumented in our laboratory to evaluate and to perform research in the field of Attitude Determination and Control Systems for satellites, using the hardware-in-the-loop technique. The satellite flight simulator considers two main blocks: an instrumented mobile platform and an external computer executing costume-made Matlab® software. The first block is an air bearing system containing an FPGA based on-board computer with capabilities to integrate digital architectures for data acquisition from inertial navigation sensors, control of actuators and communications data handling. The second block is an external personal computer, which runs in parallel Matlab® based algorithms for attitude determination and control. Both blocks are linked by means of radio modems. The paper also presents the analysis of the satellite flight simulator dynamics in order to obtain its movement equation which allows a better understanding of the satellite flight simulator behavior. In addition, the paper shows experimental results about the automated tracking of the satellite flight simulator based a virtual reality model developed in Matlab®. It also depicts two different versions of FPGA based on-board computers developed in-house to integrate embedded and polymorphic digital architectures for spacecrafts applications. Finally, the paper shows successful experimental results for an attitude control test using the satellite flight simulator based on a linear control law.

2010

As well as other subsystems, Attitude Determination and Control System (ADCS) development is a challenging process for small satellites because of design limitations, such as size, weight and the power consumption. Besides, if they are thought in a concept with military missions, then the requirement for a high attitude pointing accuracy is something certain. Works on the effective attitude determination and control methods for small satellites can be accepted as a part of this struggle. In this paper, problems that are met during ADCS development phase for future small satellites are stated and possible solutions are suggested.

Journal of Aerospace Engineering, Sciences and Applications, 2008

Placing a satellite or any other spacecraft in orbit is a risky and expensive process; years of research and a lot of money are transformed into equipments that will be beyond any possibility of maintenance in case something goes wrong. Therefore, space projects must be carried on as carefully as possible in order to guarantee that satellite equipments perform its mission properly. In that context, experimental validation of new equipment and/or control techniques through prototypes is the way to increase system confidence. The Space Mechanics and Control Division (DMC) of INPE is constructing a 1D simulator, with rotation around the vertical axis and a 3D simulator, with rotation in three axes, to implement and test satellite Attitude Control System (ACS). However, to perform experimental test it is necessary to estimate the platform inertia parameters in order to balance the platform accurately, so it behaves similar to space torque free conditions. This paper presents the equations of motion and control law design for a 3 D attitude control system simulator. This 3 D model is simplified to 1D simulator from which the inertia moment is estimated by a recursive least squares that uses experimental data. The platform data are obtained in a simple experiment where a reaction wheel is used to apply torques and a gyroscope is used to measure the platform angular velocity. The inertia moment estimated by this approach is very close to the platform inertia moment value obtained by other method.

2003

An analytical approach for spin-stabilized satellites attitude propagation is presented, considering the influence of the residual magnetic torque and eddy currents torque. It is assumed the inclined dipole model for the Earth´s magnetic field and the method of averaging such torques, over each orbital period, is applied to obtain the components of the torques in the satellite body frame reference system. The inclusion of these torques on the rotational motion differential equations of spin stabilized satellites yields the conditions to derive an analytical solution. The solution shows that the eddy currents torques causes an exponential decay of the angular velocity magnitude and the coupled effect of both torques produces a precession on the spin axis. Numerical simulations performed with data of the Brazilian satellites (SCD1 and SCD2) show the agreement between the analytical solution and the actual satellite behaviour.

The orientation of space satellites in stationary orbits gradually change with time. Their attitudes have to be controlled so as to make the deviation from the reference zero by firing on-board jets. It is an optimal control problem which has been addressed in this paper by the maximum principle of Pontryagrin. It has revealed that a relay element is required to minimize the response time, backed up by a dead zone to minimize the fuel consumption, and a limiter to minimize the energy. A controller has been designed along with a full order estimator using linear state variable feedback. This type of compensated linear controllers gives satisfactory performance for limited dynamic range and limited input. The design has been made by specially constructed programs and the results have been checked up using MATLAB tools.

International Conference on Aerospace Sciences and Aviation Technology, 2013

The problem of attitude control of remote sensing satellite using magnetic actuators is considered in this paper. Magnetic actuator was used because it is low power consumption, small mass, low cost and reliable attitude actuator. The attitude control problem of the satellite involves angular velocity suppression, attitude acquisition and finally attitude stabilization will be solved by magnetic actuator only. A comparison between the commonly used controllers for satellite attitude control is presented. The comparison parameters are the total consumed power, the time required to accomplish the angular velocity suppression and attitude acquisition, calculation time of the control algorithm and steady state error in angles and angular velocity. The simulation is done using the complete nonlinear model of satellite. Based on results, a new combined control algorithm was developed to assemble the advantages of these commonly used controllers. Simulation results showed the validity of the developed combined algorithm.