Comparative study on two-constant-amplitude input shapers to maneuver flexible satellite in small structural deflection

Abstract

The satellite attitude maneuver using thrusters is studied in this paper. The satellite consists of a rigid main body and two symmetrical solar panels that are so large that their flexibility cannot be neglected. The finite element method is used to discretize the elastic motion of the solar panels. The solar panels are modeled as a set of rectangular plate elements and only out-of-plane displacement is taken into account. The satellite is controlled by a thruster in its main body, while there are no other control inputs on the solar panels. For the attitude maneuver, the roll, pitch and yaw torques generated by the on-off thruster are used and here can produce two different constant amplitudes. Then two types of fuel-efficient input shaping are formulated and applied to perform satellite attitude correction. The first type of input LHHL is preceded by the use of a small amplitude torque followed by a large amplitude one, while the sequence of torque applied to the second type of input HLLH is the opposite of the first input. The two types of inputs are applied separately to the same satellite. They managed to dampen the residual vibrations after reaching the desired attitude, but in achieving this condition the solar panels experienced considerable deflection during the transient response. Due to this, the effectiveness of the shaped inputs for maneuvering the satellites at small structural deflections of the solar panels during their transient responses is compared. The simulation results show that the use of the LHHL input shaper can minimize the structural deflection that occurs in the transient response during the satellite attitude maneuvering process.