Sliding Mode And Optimal Tracking Control For Disturbed Underwater Vehicle With Delayed State

The21st century is the century of the ocean. Countries all over the world are paying more and more attention to the development and utilization of marine resources. Autonomous underwater vehicle, called AUV briefly, can execute many jobs such as underwater marine surveying, communicating, salvaging, manual work under hazardous conditions and various other tasks. Therefore, the exploitation of the underwater vehicle has become the focus of the international research. AUV is different from the robot running on land. In the undersea environment exist various uncertain factors, such as ocean current, unknown disturbances, the restricted communication distance, communication distortion and so on. As a result, using the modern control theory to study the the AUV system problems is a meaningful research topics.The paper mainly studies sliding mode and optimal tracking control for disturbed underwater vehicle with delayed state. The mainly content and innovation of this research are:1. The paper discusses the AUV applications and research status. Then, it briefly introduces the the basic idea, current research status and application of delay systems, sliding mode control and optimal control. In addition, it points out the significance of the research.2. The paper researches physical background and mathematical model of the AUV control system on the basis of reference materials. It idealizes the current six-degree AUV control model that generally be received and simplifies it as a four-degree AUV control model. Then it separates linear part and nonlinear part of the mathematical model. According to the engineering background, and considering of the disturbance, time delay and other phenomena, the disturbed underwater vehicle mathematical model with delay state is being proposed.3. The paper studies of the stability issues of the AUV system with persistent disturbances. It designs the compensation to suppress external disturbance using of the internal model principle. According to the mathematical model, it proposes a sliding mode control algorithm which makes the sliding mode control into two divided states:on one hand, using traditional landing control law to make the system trajectory trending sliding surface monotonously; on the other hand it uses the sliding mode control to let the trajectory reach the sliding surface in one step. Simulation results shows the algorithm is efficient and effective.4. This part mainly studies the optimal output tracking control problem of a kind of underwater vehicle with delayed state. First, it converses the continuous-time systems with delayed state delay model using nondelay conversion method and derives a equivalent optimal tracking control problem of a nondelayed systems. Then it converts the optimal tracking problem into an equivalent optimal regulate problem. So, it can use the obtained control law of optimal regulate conclusion directly. The simulation results show the effectiveness of this algorithm.5. The part mainly discusses the optimal disturbance rejection problem of underwater vehicle with delayed state. The coefficient of the nonlinear terms is very small, and the external disturbance is linear. It converts the optimal disturbance rejection problem with delayed state to a nondelay optimal disturbance rejection problem. Then it puts forward the optimal disturbance rejection control law. And the simulation results show that this control law is effective.