Research On Sliding Mode Fault Tolerant Control Technology Of Autonomous Underwater Vehicle

Blue ocean, which covers 71% of the earth surface, contains amount of biological,mineral, water and metal resources. The ocean is a treasure for human beings' subsistence and development, playing a crucial role in sustainable development in twenty-first century when the resources in the land is increasingly scarce. Therefore, the development of marine resources has become more and more prominent strategic significance. Autonomous Underwater Vehicle, which highly integrates artificial intelligence, automatic control, pattern recognition and information fusion technology, works in the sea without man and cable. AUV with a wide range of activities, a deep diving depth and a good concealment, attracts the attention of ocean exploration technology departments of many countries. The research of autonomous underwater robot self diagnosis and fault tolerant control is significant and practical to improving the intelligent level and accelerate the process of practical.This paper focuses on the active fault tolerant control technology based on the vector technique, dynamic modeling and motion control technology of autonomous underwater vehicle."Beaver ?", an autonomous underwater vehicle experiment platform, which is to study the technology of architecture, motion control, fault diagnosis and fault tolerant control of autonomous underwater vehicle, is being worked out. The study, which provides the equipment of research and experiment for studying autonomous underwater vehicle fault diagnosis and fault tolerant control technology, includes the exterior structure design, and the design, installation and commissioning etc. of propeller execution system, state sensing system, energy system and the basic motion control system.The main force of underwater robot is analyzed as "Beaver ?" autonomous underwater robot is studied. Besides a 6 degrees of freedom dynamic model is built, which was simplified according to the characteristics of open frame underwater vehicle. Parameters of the model are recognized based on the Savitzky-Golay filter method and the least square method. In addition, current disturbance is a factor that cannot be ignored in underwater robot control process, based on which, the robot dynamics model is established.Aiming at the underwater robot system's strong coupling, nonlinear, and the complex environment working, the interference and other situation causing the certain problems of robot control, technology of motion control of AUVs is researched. Sliding mode control has a better tracking effect, but the presence of chattering limits the application of sliding mode control in AUVs. A parameter adaptive method was put out to eliminate the chattering of sliding mode control and a chattering free sliding mode controller is designed. Simulation and pool experiment in the platform is proceeded to validate the study.The thruster fault tolerant control technology of autonomous underwater vehicles is studied. Based on the identification of thruster fault degree,the underwater robot tolerant control method based on sliding mode control is proposed. Practically, it's a gradual process of thruster' fault, so increasing the thrust of fault thruster may cause more serious fault. A research on fault tolerant based on sliding mode control and thrust allocation combined control method, which is on the basis of analysis of traditional control allocation methods.which can not only exert the fault tolerant control effects, but also reduce the level of fault thruster using priority. Simulation and simulation fault experiment in the pool is proceeded to validate the study.