Research On LMI Method For Fault Diagnosis Of Underactuated Surface Vessels

With the rapid development of science and technology level in recent years,the control system has become more and more complicated,and the probability of failure within the system also greatly increased,more experts and scholars have been devoted to the research of fault diagnosis,which makes the problem become a hot topic in the control field.In this paper,the problem of fault diagnosis of underactuated surface vessels is studied,and the fault diagnosis method based on LMI(Linear Matrix Inequality)is selected.To ensure the effectiveness of the system diagnostic results,In order to ensure the validity of the system diagnosis results,the uncertain factors which involve unknown inputs and parameter perturbation in the system are fully considered,the design of the observer is solved by solving the LMI inequality group,and the robust fault diagnosis of the underactuated surface vessels based on the model is studied by using the LMI method.Firstly,the background and significance of this topic and the technology of fault diagnosis are introduced briefly,moreover,the development and research's status of underactuated surface vessels and fault diagnosis of ship are analyzed.The basic theory of LMI and Lyapunov stability theory are also introduced for the transformation of LMIs.According to the hydrodynamic analysis of the surface vessel,the model which provides the basis for the follow-up verification is constructed,Secondly,we consider the problem of fault diagnosis of unknown input such as noise in the system which is tested.The H_-/H_?performance indicators of the diagnosis system express the robustness against unknown input signal robustness and the sensitivity against the fault signal,and then the design of the observer is transformated by the optimization of performance indicators.The LMI form of the optimal solution of the fault diagnosis observer is deduced,and the gain matrix is obtained through the optimization algorithm,the fault is determined by the comparison of the threshold and residual evaluation.Furthermore,the simulation results show that the proposed method is validated by the model parameters.The parameter perturbation factors are considered based on the study of fault diagnosis of unknown input signals,and we construct a reference residual model without parameter uncertainty.Then,considering the parameter uncertainties,the model matching idea is used to solve the design of the observer,and the LMI method is used to solve the observer gain matrix.The threshold and the evaluation function are used to judge the fault accurately,and the method is validated by the parameters of the surface boat model.Finally,the fault diagnosis based on the tracking model of the underactuated surface vessels is studied through the research of fault diagnosis with unknown input signal and the uncertainty description which is brought by the multi-cell model.The validity of the proposed method is verified by simulating the vertexes of the polytopic type,that is,the design method I designed not only has high sensitivity to faults,but also has strong robustness to uncertain factors.