Coordinated Control Technology Of Underwater Vehicle-Manipulator System

Ocean covers a large of the earth, which is relatively less explored. With the energy on earth is consumed up, the development of ocean is more and more important. The underwater vehicles and the robotic manipulators are effective tools to help people to see and touch this unfamiliar word. Robotic manipulator, mounted on the autonomous underwater vehicle(AUV), is usually called Underwater Vehicle-Manipulator System(UVMS). Currently, the master-slave configuration of underwater manipulation system is widely used. This kind of configuration has many disadvantages, such as, low accuracy of trajectory tracking, difficulty to realize accreted force control, high operational cost and operator's fatigue to name a few. To overcome these deficiencies, an autonomous manipulator control system that could simultaneously control the position of the end-effector and the force applied to the environment would be better solution. Thus, the UVMS has an important role to play in a number of shallow and deep sea missions for marine science, oil and gas searching, underwater inspection, drilling, mining, pipe-line, maintenance underwater cable burial and military application and so on.The character of the UVMS is nonlinear, coupled, time-varying and high-dimension. The implementation of the self-manipulation under water depends on various kinds of pivotal technology. The important one of them is the coordinated control of the AUV and manipulator. It was presented the coordinated control of UVMS in this dissertation.Firstly, the kimematic and dynamic equations of the AUV and the manipulator are discussed in this dissertation. Based on the motion in water of the AUV and the manipulator, the kinematic equation is got from the momentum theorem and the angular momentum theorem. We have developd the dynamic equation, based on the analysis of the hydrodynamic force.A dynamic model for the UVMS considering various hydrodynamic effects is derived using Quasi-Langrange method. And, the PID and sliding mode controllers are designed based on the decentralized form of the dynamics of UVMS, to implement the control of the end-effector trajectory tracking. Due to ensure the better control performance, the gains of the two controllers are tuned with the fuzzy logic.In order to validate the accuracy of the model and the effectiveness of the controllers, computer simulations using two UVMSs, a two degrees-of-freedom(DOF) manipulator and a four DOF manipulator separately mounted on an AUV, were performed in the environments of the slack flow and const laminar flow. The simulation results show that the sliding mode control, in contrast with the PID control, provides more accurate and robust performance, and the four DOF manipulator, in contrast with the two DOF manipulator, has the more coupled interaction with the AUV.An experiment system, composed of an UVMS and a computer controller, is founded to research the coordinated control. The UVMS is composed of a remotely operated underwater vehicle and a manipulator. The control of the vehicle is altered from the remotely operated control to the autonomous control. Some experiments were implemented to get the hydrodynamic coefficients of the vehicle, for the dynamic model.Based on the related projects, a series of research about the coordinated control of UVMS is performed in this dissertation. The results will give substantial support on theory and technique for control of UVMS. However this is just first step and more research work is required in future.