Research On Fault Tolerant Control Technology Of Underwater Vehicle Controlled By Rudders And Thrusters

With the decrease of non-renewable resources on land, marine resources have increasingly prominent status during the human survival. Underwater vehicles have an important irreplaceable role in ocean development. Underwater vehicle controlled by rudders and thrusters, whose thrusts are generated by numbers of propellers, exercises motion control and attitude adjustment combined with control of rudders and wings. Its structure and control mode are different from the streamlined single-propeller underwater vehicle, and it is concerned by many researchers in this field. The researches on self fault diagnosis and fault tolerant control of underwater vehicle controlled by rudders and thrusters have important significance and practical value in improving the intelligence level of this underwater vehicle and to speed up its process of practical.Based on the researches on carrier technology, modeling technology and motion control technology of underwater vehicle controlled by rudders and thrusters, this paper focuses on the researches of its fault diagnosis and active fault tolerant control technology.The test-bed of underwater vehicle controlled by rudders and thrusters-" Hai Yi-Ⅰ" is been developed to study the architecture, the rudder propeller coordinated control and fault diagnosis and fault-tolerant control of underwater vehicle controlled by rudders and thrusters. The design, installation and debugging of the actuator system which includes thrusters subsystem and rudders subsystem, and the control system which includes control, energy, sense subsystem provide researchful and experimental carrier to the research of the fault diagnosis and fault-tolerant technology.Combined with the study of the hydrodynamic of rudders and wings and the investigation of the representation of lift coefficient and drag coefficient of the "Hai Yi-Ⅰ" underwater vehicle, the lift and drag model are established. Based on the analysis of drive forces distribution and actuator forces, control allocation method is researched. Having established the dynamic analytical model of "Hai Yi-Ⅰ" underwater vehicle, parameters in the dynamics model of the body, the thrusters and the rudders are identified by using the least square method. Simulations and pool experiments are performed to test the proposed method.To solve the problem of control performance degradation of Generic Model Control (GMC) method for underwater vehicle caused by the accuracy of the model, it is researched that the motion control method which combines the GMC with a model disturbing term online adjusting method based on Neural Networks. To enhance the performance of controller in the condition of the actuator saturation, the anti-integral saturation control methods of underwater vehicle based on smooth varying parameter conditional integration method is studied, and an anti-integral saturation generic model controller based on Neural Networks of underwater vehicle is established. The researches of simulations and pool experiments based on the test-bed are performed to test the proposed method.To solve the problem that weighted pseudo-inverse control allocation can not give the optimal solution within the constrained domain of the control variable, pseudo-inverse quadratic programming control allocation method is proposed, which may overcome the deficiency of weighted pseudo-inverse control allocation that the optimal solution can not be obtained within the constrained domain. An optimal control allocation method based on minimum norms l2,l∞and the minimum variation of control variable is researched, and the solution method based on matrix converter is further explored. The effectiveness of the proposed method in lowering the maximum control variable and variation of control variables is verified by performing simulations and pool experiments in the case of different values of weight matrix of the maximum control variable and different values of variation weight matrix of control variables.The fault tolerant control technology of thrusters of underwater vehicle controlled by rudders and thrusters is studied. In order to adjust fault-tolerant of thrusters by the fault level, fault-tolerant control allocation strategy based on index priority factor and a method ascertaining the index priority factor are studied by analyzing traditional fault-tolerant control allocation methods of thrusters based on control allocation. Pool experiments of fault simulation are performed to test the method.The fault diagnosis and fault-tolerant control technology of the rudders of underwater vehicle controlled by rudders and thrusters are researched. And a fault isolation method based on the angular velocity residuals and it’s the trend obtained from active diagnosis is studied to determine the fault of the deformation of rudder and rudder stuck. Based on the rudder fault isolation method, the methods determining the rudder stuck angle based on residuals, threshold and surge speed are studied. According to the fault simulation experiments of" Hai Yi-Ⅰ" underwater vehicle, decision tables judging the level of fault and the stuck rudder angle are respectively established. The influence of the rudder stuck on dynamics of underwater vehicle is analyzed, and the fault tolerant control methods of rudder stuck based on parameter matrix adjustment are studied. Pool simulation experiments of rudder fault and tolerant simulations of the rudder stuck fault are performed to test the method.