CONTROL OF ATTITUDE DYNAMICS OF A SATELLITE USING FLUID RINGS

Studied in this paper is the three-dimensional attitude control of a satellite using fluid rings. These rings, which act as attitude actuators, contain a special type of fluid and that is regulated to generate the torque required to stabilize the satellite attitude. Although three fluid rings are enough to stabilize satellites attitude angles about the three orthogonal directions, a set of four fluid rings in a pyramidal configuration is used to add redundancy to the system. In this paper, the mathematical model of the attitude dynamics of the system is developed. The natural dynamical behaviour of the system without applying any control torque is simulated to study the damping effect of the fluid rings on the satellite attitude. Varying the pyramidal configuration angle, the platform which produces the largest total damping torque is obtained. However, the results of natural damping are not satisfactory, and hence, designing a controller is necessary. It is concluded, as control actuator, that the fluid rings are capable of producing the sufficient torque to stabilize the disturbances. Finally, the effect of the failure of one fluid ring on the performance of the actuators and the satellite is analyzed to prove the merit of using a redundant set of actuators.