Research On Fault Tolerant Control Of Underactuated Surface Vessels Based On LMI

This dissertation studied the fault tolerant control of underactuated surface vessels(USV).In the case of breaking down of USV in sailing,the control input is given through the state feedback controller, so that USV can be able to continue sailing in accordance with stable status and scheduled route. The main research method is to introduce state feedback based on the mathematical model of USV, then combining with Lyapunov stable theory and liner matrix inequality (LMI) to give the sufficient conditions of USV that have fault tolerant performance in the case of sensor failure. And get the fault-tolerant controller eventually by solving LMI equation groups.First of all, this dissertation has established mathematical model of USV in four degrees of freedom according to analyze hydrodynamic and calculate the added mass of USV. Under the restriction of actuator's mechanical structure and in the precision requirements of control inputs that near the equilibrium point approximate linearization, this paper has given the input rudder angle which is strictly limited. Simultaneously, this paper has established mathematical description containing parameter perturbation based on uncertainty of the model.Moreover, in view of USV that have input constraints and uncertain mathematical description,this article has considered the situation of the sensor failure. In order to achieve robust fault-tolerant control,this paper has reconstructed control law through calculating off line based on linear matrix inequality approach. To realize control input meeting soft constraints, this paper has proposed robust adaptive fault-tolerant control method based on model predictive control, which has took the advantages of model predictive control algorithm that is a rolling optimization process and combined with adaptive fault-tolerant control strategy based on model reference. As a result, the minimum control input is given meeting the objective function. And converting input constraints into LMI forms so as to improve the robustness of the fault-tolerant control and implement soft constraint controlling.At last,this article has combined with the kinematic description of USV under the Serrt-Frennet coordinate system and realized trajectory tracking of USV in the circumstance of sensor failure through robust adaptive fault-tolerant control method based on model predictive control.