Study Of Distributed Cooperative And The Fault Tolerant Control Method For Deep-sea Workclass Romotely Operated Vehicle

The demand for underwater vehicles has increased significantly in recent years,due to the fast growing and development of marine scientific investigation,oceanic engineering and its naval application.Under these circumstances,the self-development of deep-sea underwater vehicles is a national requirements for ocean operation tasks,and realistic marine sustainable developing strategy.The complicated underwater operating condition leads to higher standards for underwater vehicles,such as flexible operation mode,multiple communication interfaces,great data transportation ability,and reliability & maintainability of the system.Sponsored by the National High Technology Research and Development of China—‘The 4500 m Deep-sea Operating System',the key technologies of Remotely Operated Vehicle's(ROV)control system has been tackled.The basic scientific problem,distributed cooperative control,and fault-tolerant control strategy of deep-sea operated ROVs,has been extracted from practice,then studied through theories and experiments.The main research contents and innovations are as follows:1.The general design of control system is accomplished based on investigation of advanced technology of foreign ROVs and analysis of the client demand.The combination of RS485 bus and underwater distributed structure has been applied,in order to avoid the application of underwater computer,reduce the volumn of underwater dry chamber,and improve the system reliability;on the basis of general design,the structure of each component has been designed and implemented specifically;the researches of the isolated power supply of underwater equipment,insulation detection to the ground fault of the AC and DC power supply,the monitoring of the electricity parameters,and the isolated driver of the execution unit have been studied,in order to realize the fault detection and fault isolation,improve the efficiency of maintenance,and save operating time;designed the control software frame based on QNX Real-Time Operating System2.According to the hydrodynamic experiments,the linear and nonlinear hydrodynamic coefficients have been obtained.Then the nonlinear 6 degrees of freedom(DOF)mathematic model of the ROV has been established after the thorough derivation of the kinematic and dynamic equations.Finally,the 4-DOFs mathematic model which can be used to design the controller can be obtained through reasonable assumptions.3.An adaptive fuzzy controller based on the incomplete derivative ahead PID algorithm has been proposed and compared with several conventional PID control algorisms.The stability of the control algorithm in both manual and automatic mode,such as course keeping,depth keeping and height keeping,has been testified through simulative and water-tank experiments.4.Considering the characteristic of the vectored thrusters equipped on the deep-sea operated ROV,the fault-tolerant control strategy of the ROV in the absence of one thrust has been established.The horizontal and vertical thrust allocation models have been analyzed thoroughly,and then the validity of the control algorithm has been demonstrated through numerical simulation.5.The system integration has been completed.Many off-shore and water-tank experiments,along with the sea trial and application,have been performed to demonstrate the applicability and reliability during underwater operations.The control system proposed in this paper could also be extensively applied into the development of ROVs with different working depths and tasks.