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Heading control method for under-actuated ships based on nonlinear backstepping

A heading control and underactuation technology, applied in non-electric variable control, two-dimensional position/course control, vehicle position/route/altitude control, etc., can solve system performance degradation, increased rudder loss, closed-loop system instability, etc. question

Active Publication Date: 2019-10-08
SHANGHAI MARITIME UNIVERSITY
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Problems solved by technology

Input saturation is a common phenomenon in the actual control system. If the input of the actuator reaches a certain limit, it will enter a saturated state, resulting in a decrease in system performance, and even lead to instability of the closed-loop system, which will also increase the loss of the rudder.

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  • Heading control method for under-actuated ships based on nonlinear backstepping
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  • Heading control method for under-actuated ships based on nonlinear backstepping

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Embodiment Construction

[0054] The present invention proposes an underactuated ship heading control method based on nonlinear backstepping method, introduces hyperbolic tangent function and Nussbaum function to approximate the control input saturation constraint function, converts it into a derivable continuous function, and combines adaptive law to Approximation errors and external disturbances are estimated and processed. In addition, in order to avoid the complex derivation process of the virtual control law in the backstepping method, a filter-assisted system solution is proposed, and a complete control system is formed based on the backstepping method. Include the following steps:

[0055]Step 1. Establish a 2-DOF underactuated ship mathematical model;

[0056] Based on the assumption that the heave, roll, and pitch motions are negligible, the underactuated ship dynamics model can be simplified to two degrees of freedom motion in the direction of sway and yaw, which can be summarized as follows:...

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Abstract

The invention proposes a heading control method for under-actuated ships based on nonlinear backstepping. A hyperbolic tangent function and a Nussbaum function are introduced to approximate a controlinput saturation constraint function that is transformed into a differentiable continuous function required in the design of backstepping, and the approximation error and external disturbance are estimated combined with the adaptive law. In addition, in order to avoid the complex derivation process of the virtual control law in the backstepping, a solution to a filter auxiliary system is proposed.The proposed control method based on backstepping can make the nonlinear under-actuated ships always maintain the heading navigation with a small control input torque, thereby effectively reducing heading errors and improving the control performance.

Description

technical field [0001] The invention relates to the field of ship course control, in particular to an underactuated ship course control method based on a nonlinear backstepping method. Background technique [0002] With the development and utilization of marine resources, the field of ship control has also become a research hotspot. Most traditional ships are usually underactuated, that is, they only move in the direction of sway and yaw. How to control the course of underactuated ships more accurately has attracted the attention of many scholars at home and abroad. Input saturation is a common phenomenon in actual control systems. If the input of the actuator reaches a certain limit, it will enter a saturated state, resulting in a decrease in system performance, and even instability in the closed-loop system, which will also increase the loss of the rudder. The backstepping method introduces additional nonlinearity into the control process to eliminate the unwanted nonline...

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Application Information

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IPC IPC(8): G05D1/02
CPCG05D1/0206
Inventor 陆潇杨刘志全高迪驹褚建新
Owner SHANGHAI MARITIME UNIVERSITY
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