Disturbance observer-based underactuated ship path following control method

Abstract

The invention discloses a disturbance observer-based underactuated ship path following control method. A virtual ship kinematics model is built; a target reference path is planned; a position time series signal of the target reference path is generated; the position (xd, yd) and the azimuth angle psid of the tracked target at the current time are acquired; the relative position error ze between areal ship and the virtual ship, an LOS heading angle command signals psir of the real ship, and first and second-order derivatives thereof are calculated; a nonlinear disturbance observer is designed;disturbance is estimated; a control law is designed according to a robust adaptive control strategy; a host propulsion control moment command signal tauu and a yaw control moment command signal taurare calculated; and path following control is realized. Dynamic estimation signals for unknown ocean disturbances under severe sea conditions are acquired through a nonlinear disturbance observer method, the control moment of driving propulsion and a steering actuator can be effectively reduced, and the robustness and the economy of underactuated ship path following control under severe sea conditions can be improved.

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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