Research On Fault Diagnosis And Fault Tolerant Control Of Pitch Control System Of Controllable Pitch Propeller

Controllable pitch propeller (CPP) has good operation performance, which can meet matchingfunction between engine and propeller by the maximum. Therefore, CPP and the control systemmatching that CPP have been widely used in various engineering ships. Pitch control system is animportant part of the CPP, whose control performance has a great impact on the overall efficiencyof the power device. Once the system has one failure, which not only affects the economicoperation of ships and even leads to the failure of main power device of ship and a serious impacton the normal sailing. Therefore, to ensure the safety and reliability of critical pitch control systemis important. This paper has a research on the pitch control system fault diagnosis and fault tolerantcontrol to the common faults in the pitch control system in engineering. The specific researchcontents are summarized as follows.The paper analyzes the typical fault of pitch control system and establishes a mathematicalmodel and model of fault analytical for pitch control system, and provides the basis for the faultdetection and diagnosis. Then, fault detection is gone for the fault of the typical pitch controlsystem and the effectiveness of the algorithm is verified. Finally, based on the principle of faultdetection, for the hydraulic cylinder actuator failures and pitch displacement sensor faults, effectivefault-tolerant control strategies are put forward respectively to make system in fault under normaloperation.Pitch control system has the typical faults that is multiple often in hydraulic cylinder actuatorand sensor faults. The eight groups of fault simulation test for the different fault phenomena aregoing and according to the experimental data the fault is classified into complete failure, theconstant gain failures and constant bias fault three forms and gives the corresponding analyticalmodel. On which, the pitch control system of MCP34-C/4CPP as an example, has beenestablished mathematical modeling. Through the quadratic curve fitting of experimental data, theparameters of the mathematical model are determined.Fault detection observer is given by this paper for the typical failure of the pitch controlsystem and meet the requirement of rapidity, robustness and sensitivity of fault diagnosis at thesame time. In the multi-index constraint conditions, the fault detection problem is transformed intoa feasibility problem of linear matrix inequalities. This paper analysis of the range of each performance index and gives the design method of fault detection observer. Its characteristics aresimultaneously satisfied three different requirements, which is more in line with the actual needs.Fault-tolerant control algorithm is proposed for the hydraulic cylinder actuator failures byfault diagnosis observer based on output feedback and is combining the fault diagnosis observerand output feedback fault tolerant control. This method effectively avoids the difficulties in thedesign of observer based state feedback controllers. In the process of control, the design of the faultdiagnosis observer estimates the real-time fault and fault tolerant controller is carried out tocompensate the fault signal.A design method of passive fault-tolerant controller based on observer is put forward by thepaper for the pitch displacement sensor fault. Using the equation inequality ensures the stableperformance of the system and using the function to prove the stability condition, which gets theparameters of the matrix.To sum up, the proposed fault detection method based on observer can detect actuator failureand sensor failure, online fault diagnosis based on observer output feedback fault-tolerant controland passive fault tolerant control scheme based on observer to restore the performance of controlsystem. In order to verify the practical value of fault diagnosis and fault-tolerant control method toapply the theory put forward by the pitch control system of MCP34-C/4CPP. Computer simulationresults and experimental data show that mathematical model and the fault analytical model isaccurate, fault detection and fault tolerant control methods improve the stability and reliability ofthe control system, the control system reliability and security of other system research has certaintheoretical reference value.