Research And Application Of Underwater Vehicle Thruster Fault Diagnosis Technology

Underwater vehicle is one of the most important exploration tools in the ocean environment.The movement of unmanned remote-operation underwater vehicle(ROV)is realized by underwater thruster.The performance and normality of thruster's operation is directly related to the efficiency and safety of ROV,while the thruster is one of the main parts where the faults could occur frequently in actual operation.Therefore,it is of great practical value to study the fault detection and diagnosis technology suitable for ROV thruster and equip it in ROV.In this paper,a method of propeller fault detection and diagnosis is developed for the unmanned remote-controlled underwater vehicle "Strait" produced by a science and technology company in Shanghai.Based on the introduction of the structure and main functional modules of the "Strait" ROV,and analyzing and summarizing the fault mechanism of ROV and its thruster,a fault detection and diagnosis method is established,in which the measurable closed-loop control voltage signal is selected as the system description variable,and the global fault detection and diagnosis method for the propulsion system is established,and then the fault location of a single propeller is carried out by establishing a mathematical model Case.Firstly,in order to solve the problem that it is difficult to determine the number of components in the variational mode decomposition(VMD)method in advance,the "instantaneous average method" is proposed to determine the number of VMD components,which improves the original VMD algorithm.Combining with the sensitivity of autoregressive(AR)spectrum analysis method to the variation law of voltage signal,a new VMD is designed?Based on AR algorithm,a new fault detection method for ROV propulsion system is proposed.Then,through the establishment of the mathematical model of Strait,the mathematical model of the combined thrust of ROV propulsion system and the measured voltage of propulsion system is obtained,and the relationship between the thrust components of six thrusters and the resultant thrust is obtained.Thus,the thrust observation mechanism from the total voltage of the propulsion system to the single thruster is established.On this basis,the fault model of the thruster is established,and ? is taken as the fault Finally,the fault simulation platform of ROV thruster is built to realize the fault location of thruster.Finally,the fault test experiment is designed to verify.Considering that the "Strait" lithium battery power supply will introduce additional interference,the power carrier mode is designed to improve the power supply.Through the fault mode design and experimental data analysis,the effectiveness of the fault detection and diagnosis scheme is verified,which provides convenience for ROV maintenance.