Verification of Attitude Control Performance According to Changes in Towing Point of Towfish

In general, towfish do not have their own thrust and is moved by cable connected to the mother ship. Therefore, in order to analyze the behavioral characteristics of the towfish, the dynamic equations of the towfish and cable must be derived and analyzed. The motion of the towfish was analyzed using the 6 DOF (Degree of freedom) motion equations of the towfish [1], and the motion of the cable was formulated using the lumped mass method [2]. Although the towfish is designed to be hydrodynamically stable, it requires attitude control due to unexpected disturbances and environments. This paper aims to improve the quality of sonar data by implementing pitch and roll control of the towfish using two elevators attached to a horizontal tail fin. Meanwhile, the motion characteristics of the towfish change significantly depending on the towing point of the cable. Therefore, it is necessary to understand the motion characteristics according to the change in the towing point of the cable. In this study, by comprehensively considering the towing point, center of gravity, and speed, it was confirmed that there are regions where the attitude of towfish can controlled and regions where it cannot be controlled. To prove this, a water tank test was conducted, and it was confirmed that, as predicted through simulation, in regions where attitude control difficult to achieve, attitude control is not properly achieved even when the maximum angle of the elevator is applied and in regions where attitude control is easy, it confirmed that sufficient drag force is generated in the elevator to achieve proper attitude control.