A Disturbance Observer Based Path Tracking Control Method for Underactuated Ships

Abstract

A path tracking control method for an underactuated ship based on a disturbance observer, which establishes a virtual ship kinematics model, plans a target reference path, generates a position time series signal of the target reference path, and obtains the position of the tracking target at the current moment (x d ,y d ) and azimuth ψ d Information, calculate the relative position error z between the real ship and the virtual ship e , actual ship LOS course angle command signal ψ r , and its first-order derivative and second-order derivative, design a nonlinear disturbance observer, estimate the disturbance, design the control law according to the robust adaptive control strategy, and calculate the main engine propulsion control force rejection command signal τ u and the yaw control torque command signal τ r , to achieve path-following control. The present invention acquires dynamic estimation signals of unknown ocean disturbances under severe sea conditions by means of a nonlinear disturbance observer, effectively reduces the control torque of the driving propulsion and steering actuators, and can improve the robustness and performance of path tracking control of underactuated ships under severe sea conditions. economy.

Description

technical field [0001] The invention relates to the field of ship motion control, in particular to an underactuated ship path tracking control method based on a disturbance observer. Background technique [0002] The path tracking control of underactuated ships has been a hot spot in the field of ship control in recent years. At present, the guidance method of tracking control is mainly the virtual ship guidance method based on the Line of Sight (LOS) algorithm. Assuming that the tracking track is the track of the virtual ship, the real ship tracks the virtual ship by controlling the thrust and steering to realize path tracking. [0003] The linear control method based on the linear model has a good effect on the tracking control under deterministic conditions, but the path tracking control system of the underactuated ship subject to the random ocean disturbance needs to deal with the uncertainty of the ship motion model while considering the uncertainty of the disturbance. ...

AI Technical Summary

Problems solved by technology

However, when the ship is disturbed by severe sea conditions, the nonlinear hydrodynamic part has the characteristics of uncertainty and unmodeled dynamics, and the parameters do not have the characteristics of unknown constants. In comparison, the estimation of the upper bound of ocean disturbance will cause the phenomenon that the control force is too large, that is, the driving power of the actuator is too large

At this time, the control method based on this type of model cannot guarantee the robustness and economy of the path following control system.

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