Design Basing On Backstepping For Robust Controller To Ship Course

In this paper,the problem of ship course control is mainly studied.The ship course control is an important research topic in the field of ocean control all the time,especially in the current time when the global economy is in a flourish and material goods flow so fast,leading up to more and stricter requirements to ship course control proposed by people.Most course controllers nowadays are still based on Nomoto linear mathematical models,ignoring the nonlinearity in the actual motions of ships. Thus,the control problem in the ships'actual motion can't be well resolved by controllers of this kind.After reading many references,I found that there are possibilities for the robust control theory to resolve the course control problem.Robust control theory is an powerful tool to analysis and design uncertain systems,and it is aiming at resolving the control puzzles:control quality deteriorating,relating to the model perturbation which are raised by the errors in the target modeling and external disturbance.Thanks to its advancement and integrality in the theory,robust control is widely applied in the actual projects.Compared with that,many kinds of robust control algorithms are in a continuous development and consummate gradually. The closed-loop shaping algorithm is discussed in this paper which is more stable to control the uncertain systems.Backstepping is a nonlinear control method which constructs state feedback control laws and relevant Lyapunov functions.It is introduced systematically in this paper,and emphasizes the algorithm principle and steps of Backstepping. After compared with ordinary linearization design methods,the article concludes its advantages and disadvantage, laying a foundation for the course controller design.In the following,the paper starts from the building of ship motion mathematical models, analyzes and explains the process of ship course motion. On the base of Nomoto mathematical models and Norrbin mathematical models, considering the actual navigation environment, two ship motion mathematical models corresponding to conditions with external disturbance and without external disturbance are built. Direct at these models, improved robust control algorithm is a nonlinear ship motion mathematical model with external disturbances.Proposes a course controller design method which combines the closed-loop shaping algorithm is introduced into Backstepping to design course controller.The steps can be briefly summarized as followed: change system to strict feedback control form; assuming the subsequent state variable is the virtual control to the state variable before, and then constructs proper Lyapunov functions through variable substitution; deduce the control laws of controllers step by step and finally make the whole system be in a uniformly asymptotic stability.Afte selecting proper parameters , get the selfadaptive robust course controller anti-wind and wave jamming, then put it into the simulation experiment in Matlab's Simulink.The simulation results prove the effectiveness of the designed course controller.