System Identification and Pitch Control of a Planing Hull Ship with a Controllable Stern Intercepter

Abstract

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Planing hull type ships are often equipped with interceptor or trim tab to improve the excessive trim angle which leads to poor resistance and sea keeping performances. The purpose of this study is to design a controller to control the attitude of the ship by controllable stern interceptor and validate the effectiveness of the attitude control by the towing tank test. Embedded controller, servo motor and controllable stern interceptor system were equipped with planing hull type model ship. Prior to designing the control algorithm, a model test was performed to identify the system dynamic model of the planing hull type ship including the stern interceptor. The matrix components of model were optimized by Genetic Algorithm. Using the identified model, PID controller which is a classical controller and sliding mode controller which is a nonlinear robust controller were designed. Gain tuning of the controllers and running simulation was conducted before the towing tank test. Inserting the designed control algorithm into the embedded controller of the model ship, the effectiveness of the active control of the stern interceptor was validated by towing tank test. In still water test with small disturbance, the sliding mode controller showed better performance of canceling the disturbance and the steady-state control performance than the PID controller. Keywords : High speed planing hull(고속 활주선), Stern interceptor(선미 인터셉터), Ship attitude control(선박 자세 제어), System identification(시스템 식별), Genetic algorithm(유전 알고리즘), Towing tank test(예인수조실험) 1. 서 론 활주선형 선박은 여러 고속선형 중에서도 빠른 편에 속해 임 무수행 능력이 우수하고, 선저형상이 단순하여 설계가 용이하다 는 장점이 있다. 활주선형 선박은 고속으로 항주 시 중량의 상당 부분을 양력으로 지지하게 되며, 이때 선박의 부상량이 급격히 증가하게 되는데 이를 활주상태라고 한다. 활주상태에서는 종종 운항 중 과도한 트림각(trim)을 갖게 된다. 이럴 경우 항해사의 가시영역이 줄어들 뿐만 아니라 해상환경이 나빠질 경우 안 좋은 저항성능 및 내항성능을 보이게 된다. 이러한 문제를 개선하기 위하여 활주선형 선박에 인터셉터, 트림탭, 트린섬 웻지와 같은 부가물을 부착하여 음의 종동요 모멘트를 발생시켜 트림각을 줄

Numerical Study on the Influence of Interceptor and Stern Flap on Ship Resistance and Motion Response in Regular Waves

“…We compared the resistance reduction rates of these two energy-saving appendages in waves against variations in wavelength and wave steepness, summarised the alterations in the heave and pitch transfer functions post-stern appendage installation, and assessed the ship resistance and motion change mechanisms from a flow field perspective. The following conclusions are outlined: (1) For the BH at wave steepness ak = 0.075, the added resistance coefficient increases and then diminishes as the wavelength increases. At λ/LPP = 1.5, the green water phenomenon occurs on the BH deck, leading to an added resistance peak of 70.6%.…”

“…Here, φ denotes the predefined fluid properties of the given phases. The density and viscosity of water and air can be expressed as (1 ) (1 )…”

“…Speed performance remains crucial for ships, particularly military vessels [1]. As ships navigate through dual mediums, water and air resistance considerably affect their swiftness, and optimising ship form is vital to mitigating this resistance.…”

An Experimental Analysis of Active Pitch Control for an Assault Amphibious Vehicle Considering Waterjet-Hydrofoil Interaction Effect

“…Z h f (n) means the lift generated by the thrust and hydrofoil interaction. Considering the thrust and hydrofoil lift, the net pitch moment by the waterjet operation can be defined as Equation (7). Since two terms are function of n m , the pitch motion of the vehicle can be controlled by changing n m .…”

“…They designed control systems based on a linear quadratic regulator (LQR) controller and showed the application of a controlled stern interceptor reduced pitch and heave to have reductions of up to 25% and 20%, respectively. Choi et al [7] identified the pitch dynamics model of a planing hull that includes a stern interceptor capable of active control by performing model tests in regular waves. They designed a controller that controls the attitude of the ship and verified the effectiveness of active control through towing tank experiments.…”