| Autonomous Underwater Vehicle technology has been developing rapidly with the accelerating exploitation process of ocean resource. Using autonomous underwater vehicles for underwater operation attracts people’s attention gradually.Operating underwater vehicle and underwater manipulator compose a new sort called "Underwater Vehicle-Manipulater System(UVMS)",which can accomplish underwater operating task autonomously in a large area,inheriting of the Autonomous Underwater Vehicle’s original adventages.UVMS,which has played a significant role in resource exploration development and ocean resource in the past years,represents one of the most important developing trends in the future.However,the overall barycentre position of system changes with the manipulator’s motion in the process of underwater operation,which leads to attitude alteration of UVMS.As attitude alteration will directly affects success rate and the quality of underwater operation,studying attitude control for UVMS appear inportant research significance and application value.Traditional Autonomous Underwater Vehicle can take advantage of the vertical thrusters to control trimming angle and heeling angle, which may affect the depth control of system and increase the system energy consumption.The paper developes an attitude control device for UVMS on the basis of analysing all kinds of attitude control devices used in different situations at home and abroad and the device is integrated in UVMS.The paper studys UVMS attitude control method and finally carries out related experiments in a UVMS prototype.The main research content of this paper is as follows:(1)An attitude control device for UVMS is developed and intergrated in a UVMS prototype aiming at depth control performance and increasing energy consumption problems by using vertical thrusters for UVMS attitude control. This task includes demonstration to achieve the attitude control and mechanical structure design of attitude control device.According to the control requirements of attitude control,function modules are divided,function module circuits are designed; According to the attitude control requirements of control strategy and process,the lord-corresponding mode software system is designed and software program is completed in the controller.(2)The UVMS attitude control issue is studied from the perspective of the barycentre of the whole system changement.All kinds of force (torque) of UVMS are analysed during the motion process. By analysing barycentre position changement of the underwater manipulator subsystem and attitude control device,the UVMS barycentre position changing rule is concluded.In order to provide support for the subsequent simulation, the mathematical model of attitude control subsystem and pitch and roll attitude space dynamics equations of UVMS are established.(3)Aiming at the characteristics of UVMS :strong-coupling,nonlinear and parameter time-varying,a two-dimensional fuzzy PID controller was designed on the basis of classic PID controller,based on fuzzy control theory.In order to test and verify the control effect of fuzzy PID control method on the UVMS attitude control,UVMS attitude control under manipulator’s joint motion and sinusoidal motion was simulated in MATLAB/SIMULINK.(4)In order to test and verify the control effect of attitude control device intergrated in UVMS,UVMS attitude control experiments are developed by taking adventage of attitude control devices. In this paper,the UVMS attitude control experiments under manipulator on single joints motion,multiple joint motion as well as typical operation process are developed and the performance of classic PID control method and fuzzy PID control method are analyzed.The experimental results demonstrate that during UVMS operating process,fuzzy PID control method behaves better than classic PID control method in UVMS attitude control performance,Attitude control device developed in this paper is stable and reliable to achieve excellent attitude control performance in UVMS. |
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