Research On Adaptive Dynamic Positioning Control For UUV Under Surface Observation Task

When UUV executes the observation mission near surface, the observation antenna will be used to obtain the observing data. To ensure the high quality of the observation, UUV needs to maintain staying at the desired position and heading under the external environment disturbance,that is to say UUV needs to have the dynamic positioning capability. In this paper,the adaptive dynamic positioning method of UUV is researched under the wave disturbance near surface and the UUV unbalanced force caused by the rise of the observation antenna. The main content of this paper is presented as follows:Firstly, the specific processes of the observation near surface of UUV are analyzed to identify the specific scene of UUV dynamic positioning. Then the kinematics and dynamic model of UUV is established, so is the thrust allocation of UUV. Meanwhile, the external environment disturbance and the internal imbalance disturbance are analyzed. The main function of the buoyancy balanced load system is also studied. Then a simulation case based on the researched observer UUV is presented, and its maneuverability is tested.Secondly, the high and low frequency mixed motion model of UUV under the wave disturbances based on characteristics of the wave interferences is introduced. The wave filter is designed based on the theory of non-linear passive observer. Considering the uncertainty of the designed wave filter, the sliding model function is added, and the adaptive gain law is adopted to reduce the system chattering. The wave encounter frequency is estimated based on the history motion data of UUV. The wave filtering of UUV is simulated under the different wave encounter frequencies.The imbalance force when observation antenna arise is taken into consideration, and the imbalance integrated adjust systems consisted of buoyancy balanced load system and pitch controller is designed to adjust the pitch of UUV. The pitch controller is the integration separation PID controller with buoyancy compensation because the buoyancy of UUV is changed after the adjustment of buoyancy load control system. Meanwhile, the dynamic positioning controller based on the back-stepping design method is designed,and the sliding mode function is also added to increase the robustness of the system to the external disturbance. The stability of the whole system combined adaptive wave filter and the designed controller is proved.Finally, the whole control system is constructed of adaptive wave filter, imbalance force integrated adjust system and back-stepping sliding mode dynamic positioning controller. And in the simulation environment for UUV dynamic positioning control when executes the observation mission near the surface, the proposed dynamic positioning method of UUV is simulated to demonstrate the effectiveness under the wave and imbalance disturbance.