The Study Of UVMS's Coordinated Control Method

With the increasing focus on the ocean energy sources, underwater vehicles manipulator systems (UVMS),which are important parts of underwater operation equipments for marine resources development and marine reconnaissance operations,are developed by many research institutes all around the world for their unique structural composition and capability of various operation assignments. In consideration of UVMS's two subsystems which include both underwater vehicle and underwater manipulator, it's urgent to study the coordination control between these two parts, which is also a difficult aspect for the control method research of UVMS.The whole paper is organized as follow: firstly, the coordinate systems of both underwater vehicle and underwater manipulator are established separately,according to the basic principles of motion and dynamics,the kinematics and dynamics models of UVMS are obtained correspondingly, and the complete mathematical model of UVMS is established. All these work set up a mathematical model base for the following analysis of UVMS.Secondly,based on the vertical plane motion of UVMS,a few assumptions are made in order to simplify the dynamics model of underwater underactuated AUV and two-link underwater manipulator in the vertical plane. A back-stepping controller based on nonlinear disturbance observer (NDO) is proposed which makes it possible for the AUV to track desired depth under the condition of underwater manipulator system's action. According to the Lyapunov's principle, the overall stability of the controller is proved to be guaranteed.Thirdly,in the case of UVMS's horizontal motion, the dynamics model of AUV in the horizontal plane is simplified to be more practical for the construction of controller. By combining the principles of fuzzy control, sliding mode control and nonlinear disturbance observer, a fuzzy sliding mode controller based on NDO is built to achieve desired yaw motion when the underwater manipulator moves in the horizontal plane in the case of manipulator's horizontal component of moment, and the results of the simulation indicate that the designed controller shows strong robustness.Finally, the underwater manipulator system of UVMS is analyzed, a novel terminal sliding mode controller based on RBF neural network is constructed in the different conditions of underwater manipulator. Taking the two-link underwater manipulator of the vertical plane for instance, its simulation experiments in consideration of hydrodynamic interaction,uncertainties of model and external disturbance are made,and these results show the designed controller is effective in the control of underwater manipulator.