The Investigation Of Integrated Control Technology For Vertical Plane Motion In AUV

Autonomous Underwater Vehicle (AUV) is the result of modern technological integration. The issue of the utmost importance pertaining to the AUV is the problem with motion control, especially in the vertical plane. Thus a thorough investigation in motion control development, one of the key technologies of AUV, holds significant meaning.The pitch control and depth control of AUV's motion in the vertical plane were studied in this project. Based on the characteristics of AUV, mathematical model in vertical plane by linearizing the model at a specified operating point was established. An actuator model and a disturbance model of currents and waves were also established.The dynamics of AUV motion is highly nonlinear and uncertain. Based on sliding variable structure control theory, a pitch controller and a depth controller for the established mathematical model to simulate the motion control were designed, allowing the system to achieve good performances at the operating point and non-operating points during the motion process. The simulation results show that this method is competent in the control of the nonlinear object, and has practical value in the attitude control of AUV.This dissertation discusses the pitch and depth control problems. For the complex marine environment as well as for the uncertainty of the hydrodynamic characteristics and the inherent nonlinear properties of AUV, it will be inevitable to have a big dip in the depth control process, which is a disadvantage to position and attitude control. The significance of this work lies in satisfying the pitch restriction. The pitch control is introduced to the depth control in order to make systematic analysis under different conditions. The efficacy and applicability ofthis model have been verified by computer simulation.Finally, with the changes of AUV's loads in working conditions, motion control in vertical plane is carried out by means of depth control concerning AUV's pitch state. Simulation results indicate that the system maintains strong and robust characteristics with changing system parameters using the sliding variable structure control theory. Also, it is indicated that the changed loads may improve the performance of response process.