Research Of Smallautonomous Underwater Vehicle Motion Control

The small autonomous underwater vehicle(AUV), also known as the small unmanned underwater vehicle, has highly degree of autonomy and the ability of precisely control and track, and is able to complete some given tasks under the water by remote control or some independent operation methods. The small AUV is a strong coupling nonlinear system with multiple degree of freedom. Considering the external complex flow disturbances and its inherent modeling errors, this paper mainly focuses on the two-dimensional plane movements of the AUV, not only taking methods of sliding mode, dynamic sliding mode and Nonlinear Disturbance Observer to design the heading tracking controller, but also proposing the surge motion controller with the adaptive sliding mode, which mainly studies heading tracking control. Finally, the simulation result verifies the validity and accuracy of the two-dimensional plane movements and control method.The specific research tasks in this paper are as follows:First part: model building. It is established that a kinematics space motion coordinate system for the AUV. And a space mathematical model with six degrees of freedom for the AUV is built, according to the coordinate conversion between the ground coordinate system and the body coordinate system. Considering about the uncertainties, containing the modeling error and strong nonlinear coupling, the AUV’s mathematical model are decoupled into a yaw model and a surge motion model based on the plane motion decoupling simplified principle.Second part: heading tracking controller designing. In view of the complexity of heading motion control and variable flow disturbances from the environment, it is designed that a intelligent heading tracking controller which is able to choose a appropriate control method automatically according to different the disturbance. The simulation result has proved that the control method is useful and smart enough, and has the ability to tracking the given direction fast and precisely.Third part: surge motion controller designing. Considering the particularity of surge motion control, adaptive backstepping sliding mode is chose as the control method, and asurge motion controller is designed in this paper. The simulation result shows that the AUV has the ability to tracking the given direction reliably and precisely.