Precise Trajectory Tracking Control of Ship Towing Systems via a Dynamical Tracking Target

Ouxue Li,Yusheng Zhou

doi:10.3390/math9090974

Abstract

This paper proposes a novel control strategy to address the precise trajectory tracking control problem of a ship towing system. At first, the kinematics and dynamics models of a ship towing system are established by introducing a passive steering angle and using its structure relationship. Then, by using the motion law derived from its nonholonomic constraints, the relative curvature of the target trajectory curve is applied to design a dynamical tracking target. By applying the sliding mode control and inverse dynamic adaptive control methods, two appropriate robust torque controllers are designed via the dynamical tracking target, so that both the tugboat and the towed ship are able to track the desired path precisely. As we show, the proposed strategy has excellent agreement with the numerical simulation results.

Highlights

A ship towing system (STS) consists of a tugboat, a towline, and a towed ship [1]
The towed ship is able to move along the trajectory of the tugboat by introducing an appropriate passive steering angle
The original motion control problem is transformed into the tugboat tracking the target trajectory curve

Summary

Introduction

A ship towing system (STS) consists of a tugboat, a towline, and a towed ship [1]. Due to external environmental disturbances and inherent internal uncertainties, the motion control of the STS was mostly based on experimental works or numerical simulations, rather than theoretical analysis [2]. An improper control would cause the actual towing trajectory deviate from the target towing route. This may lead to collisions, capsizing, and other safety accidents. It is necessary to investigate the precise motion control of the STS for its safe navigation at sea

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Results

Conclusion