Satellite Attitude Control System Simulator

Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS) with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS), using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

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Generic Model of a Satellite Attitude Control System

International Journal of Aerospace Engineering ◽

10.1155/2020/5352019 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Janusz Narkiewicz ◽

Mateusz Sochacki ◽

Bartłomiej Zakrzewski

Keyword(s):

Control System ◽

Attitude Control ◽

Pid Controllers ◽

Control Algorithms ◽

Generic Model ◽

Attitude Control System ◽

Satellite Attitude ◽

Satellite Attitude Control ◽

Mode Of Operation ◽

Control System Model

A generic model of a nanosatellite attitude control and stabilization system was developed on the basis of magnetorquers and reaction wheels, which are controlled by PID controllers with selectable gains. This approach allows using the same architectures of control algorithms (and software) for several satellites and adjusting them to a particular mission by parameter variation. The approach is illustrated by controlling a satellite attitude in three modes of operation: detumbling after separation from the launcher, nominal operation when the satellite attitude is subjected to small or moderate disturbances, and momentum unloading after any reaction wheel saturation. The generic control algorithms adjusted to each mode of operation were implemented in a complete attitude control system. The control system model was embedded into a comprehensive simulation model of satellite flight. The simulation results proved the efficiency of the proposed approach.

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Design of Satellite Attitude Control System Considering the Interaction between Fuel Slosh and Flexible Dynamics during the System Parameters Estimation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.706.14 ◽

2014 ◽

Vol 706 ◽

pp. 14-24 ◽

Cited By ~ 5

Author(s):

Alain G. de Souza ◽

Luiz C.G. de Souza

Keyword(s):

Control System ◽

Attitude Control ◽

Rigid Motion ◽

Parameters Estimation ◽

System Stability ◽

Attitude Control System ◽

Linear Quadratic ◽

Satellite Attitude ◽

Satellite Attitude Control ◽

Fuel Slosh

The design of the satellite Attitude Control System (ACS) becomes more complex when the satellite structure has different type of components like, flexible solar panels, antennas, mechanical manipulators and tanks with fuel, since the ACS performance and robustness will depend if the dynamics interaction effects between these components are considered in the satellite controller design. A crucial interaction can occur between the fuel slosh motion and the satellite rigid motion during translational and/or rotational maneuver since these interactions can change the satellite center of mass position damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances affecting thus the satellite attitude acquisition. It is known that one way to minimize such problems is to design controllers with a bandwidth below the lowest slosh and/orvibration mode which can result in slow maneuvers inconsistent with the space mission requirements. As a result, the design of the satellite controller needs to explore the limits between the conflicting requirements of performance and robustness. This paper investigates the effects of the interaction between the liquid motion (slosh) and the flexible satellite dynamics in order to predict what the damage to the controller performance and robustness is. The fuel slosh dynamics is modeled using its pendulum analogs mechanical system which parameters are identified using the Kalman filter technique. This information is used to designs and to compare the satellite attitude control system by the Linear Quadratic Regulator (LQR) and the Linear Quadratic Gaussian (LQG methods. Besides, one investigates the effects of the rod length estimation in the plant of the system stability. This investigation has shown that the poles of the plant to walk to and from the imaginary axis, leaving in the end the plant more stable.

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