Study On The Control Method Of The Stability Of AUV

With the research and exploration on oceans going further and further all over the world,unmanned underwater vehicles have been of greater and greater significance in a wide rangeof fields, such as scientific research, detection and exploration of underwater petroleum andnatural gas, enhancement in military force, national defense and so on. The key point toguarantee the safe and reliable environment for the vehicles to work is the motion stability ofunderwater vehicles, while maintaining the initial motion state autonomously after aperturbation is the main part of the stability control. Therefore, it is essentially important toresearch on methodologies of stability control.The paper is organized as follows. First, we analyze the overall structure and theunderwater motion characteristics of underwater vehicles. By establishing the dynamic modelof underwater vehicles, which comprises of a main propeller, a double vertical propeller and adouble side propeller, we make an essentially hydrodynamic analysis on underwater vehicles,based on which dynamic equations of the vehicles are put forward.Second, we focus on the research on motion stability of underwater vehicles. After wehave a thorough discussion about several crucial problems of the system, we propose amethod to analyze the line, direction and position stability, as well as the metacentric stability,and the criterion to determine the longitudinal stability and lateral stability. Moreover,stability requirements based on characteristic values are also provided.In the next, we propose a method to design a control system for the motion of anunderwater vehicle, and then simulate the basic controller by comparative experiments. Basedon this, a passive adaptive controller is designed to make a best investigation of the passivevariable-structured adaptive controller. Relative experiments are conducted and results areanalyzed and compared. Moreover, we also come up with an adaptive compensation toaddress the problem that an underwater vehicle is likely to be affected by the ocean currentwhen hovering and moving in the water. In this way, it is possible for us to settle down theuncertain compensation of the input variables.In the end, we set up an experimental platform mainly for the investigation of theunmanned underwater vehicle. With a series of experiments on multidirectional motion stability, we adjust the relative controller parameters and testify the validation and reliabilityof the designed stability controller of underwater vehicles.