Design and experimental validation of a sliding-mode stabilizer for a ship-carried satellite antenna

This study designs a sliding-mode controller to stabilize the angular orientation of a ship-carried satellite antenna. The design process starts with calculating the pointing angle of the considered satellite antenna arm as opposed to given ship vibrations due to certain sea waves. This calculation is carried out by the method of Denavit-Hartenberg (D-H) transformation, which is followed by establishing a dynamic model of the satellite antenna system and platform using conventional kinematics modeling techniques. The resulted kinematics relationships are next used as the basis for designing a sliding-mode controller to maintain the antenna in a specified orientation as the ship pitches and rolls under the combined effects of wind and the sea's waves. The effectiveness of the designed controller is investigated both numerically and experimentally. Both sets of results confirm the feasibility of the proposed control scheme. It is shown that the antenna converges to the required azimuth and elevation angles within 2 s and maintains the specified orientation as the ship continues to pitch and roll.