| There is much water area in China including reservoirs, rivers, lakes, and ports and with a long coastline. The water area and impotant resource and installations within it are faced with some new problems such as exploration, exploitation and monitoring. The parts of rivers through cites, ports, water power stations, nuclear power plants and reservoirs are threatened by hostile forces including the three forces of terrorism, splittism and extremism. There are also many illegal activities such as contraband, drug trafficking and steal a crossing through underwater. When holding important festival celebrations and activities in political, economical and physical fields, the related water areas must be in monitoring and control. The underwater robots have now been widely used in civil and military fields such as hidden defects detection of dam and dyke, danger inspection of nuclear power stations, underwater structure examining and repairing of offshore drilling platforms, wreck archaeologizing, repairing of submarine optical cable, kelp reaping, green algae exploration, laying and sweeping of mines, underwater reconnaissance and so on.The aim of the project is to study and develop a monitoring underwater robot along with manipulators applicable to turbid water of busy water way in shallow region. The background, goal and study contents were expatiated in this article in allusion to the development actuality of Remotely Operated Vehicle(ROV), its manipulators and control technology. The problems produced in operating practise were taken into account. The function and index in collectivity were established and performance index of sensor and dectecting equipments were determined with that. The choosing and configuration are made for some apparatus.The study in this paper ranges from the structure, waterproof technology, circuits hardware of control system, collection system of position and gesture of ROV to design, manufacture and tests of photoelectricity tether. A finite element analysis was made for main body frame structure. The figure, material, manufacture and installation process were investigated. The calculating methods and results of barycenter and floating center were provided. The movement resistance, power and maxmium speed were estimated. The shape centers of cross-section along each direction were computed as the basis to determine the installation places of the thrusters.The creative Tuck Net Manipulator and Clasp Manipulator were presented, with which patents of invention have been applied. A deep study of function and structure of manipulators were carried out and finite element analyses on deformation and stress were made for the arms. The structure of net doffing of the Tuck Manipulator was analyzed. Both motion simulations verified the designs. The grasp tests of Clasp Manipulator were accomplished.The fixed and motion coordinate systems are set up for the ROV and the mutually conversion between them were studied. The gravity, buoyancy, thrust and hydrodynamical factors were analyzed. The general equations of space motion of ROV were derived. And according to the structure symmetry and use characteristics of ROV, the simplified motion equations on horizontal, vertical and cross section were also derived. A calculating method for the hydrodynamical coefficients of accelaration and velocity of ROV was presented.For the yaw control of ROV, the sliding mode control(SMC) method was introduced first on the control theory of ROV. The advantages and disadvantages of SMC and its application on ROV control were summarized. The cause of chattering formation in SMC and development of weakening methods were discussed. Then, the Radial Basic Function (RBF) neural network was paid more attention. And the emphasis of the analysis is on the nonlinear mapping and ability of approximating a function of RBF. According to the error back-propagation mechanism, the gradient descent method was adopted to train and adjust the weights and parameters of the basic function simultaneously. Since the speed of convergence is slow and the local minimum is possible in presence, additional momentum method was introduced to make a modification during the learning process. The sliding mode control method was used. The system is divided into a nominal model and an uncertainty composed by hydrodynamical force and disturbance. The state feedback gain method was used to control the certainty-- nominal model. As the compensating controller that is dynamic adjustable, the RBF network was adopted to learn and approach the upper bound of the uncertainty. The effects were verified by simulation and tests.For the control of depth and attitude of ROV, the open water tests were done first for each thruster. The nonlinear testing data of control voltage-thrust in forward and reverse was obtained respectively. The data were used to train the RBF network and the neural network approaching models for nonlinear thrust curves were set up. Then, the theory and contents of the fuzzy reasoning were studied and the approaching precision was also evaluated. A series controller with fuzzy control and RBF network was used to control the keep-depth motion of ROV. Let thrust be the input and control voltage be the output, the RBF network was trained bsed on the open tests data of control voltage-thrust. The fuzzy controller makes the reasoning and gets the desired thrust according to the error of the depth and its rate. As the input, the thrust is then introdued into the neural network and a desired control voltage is acquired to produce a precision thrust.When working, the Tuck Net Manipulator would cause the ROV pitch. A balance device was presented and designed by using a sliding mode controller to adjust the pitching. As it is inevitable for the chattering to occur in the control switch of SMC, A disturbance observer was used to estimate the disturbances to weaken the chattering. The simulation had shown the effect.In allusion to the rolling motion of ROV in wave, the analysis, modelling and numberical calculation were carried out. An adaptive fuzzy sliding mode control method was presented to disturb the rolling response process of the ROV by using the lateral thrusters to reduce the rolling amplitude. The simulation indicated some effects. It's a probe for the attitude adjusting of ROV in wave.Finally, the paper summarized the whole study and brought forward future direction and contents of the study. |
