An Output Feedback Approach for Regulation of 5-DOF Offshore Cranes With Ship Yaw and Roll Perturbations

Abstract

In practice, offshore cranes are effective transportation tools used on ships. Different from land-fixed cranes, offshore cranes work in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">noninertial</i> frame, which are usually affected by different disturbances. Therefore, the control problem of offshore cranes is much more <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">difficult</i> . Till now, only few control methods have been proposed for offshore cranes, which are usually designed for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">planar</i> offshore cranes, while the more practical three-dimensional (3-D) movements are <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ignored</i> . Considering these facts, in this article, we focus on the control problem of a 5 degrees of freedom (DOF) offshore crane in 3-D space with persistent ship yaw and roll perturbations and propose an effective <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">output feedback</i> control method. Specifically, we first present an elaborate coordinate transformation method to deal with ship perturbations. Then an energy-like function is constructed based on the transformed model, and then by designing some auxiliary signals, an output feedback method is designed with rigorous mathematical analysis to prove the closed-loop asymptotic stability results. As far as we know, the proposed method is the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">first</i> control method designed for 5-DOF offshore cranes <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">without</i> any linearization, which <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">only</i> uses output signals. Finally, experimental results are included to verify the performance of the proposed method.