scispace - formally typeset

Journal ArticleDOI

Experimental investigation on the effects of froude number on manoeuvring characteristic of a research vessel

23 Sep 2020-Ships and Offshore Structures (Informa UK Limited)-pp 1-12

Abstract: Oceanographic research vessels (ORVs) are used to collect ocean data and analyse them to understand the physical, chemical and biological characteristics of seawater, seabed and other ocean-related...
Topics: Froude number (60%), Seabed (50%)
Citations
More filters


Journal ArticleDOI
10 Sep 2021-
Abstract: A dynamic positioning (DP) system is a computer-controlled system which maintains the positioning and heading of ship by means of active thrust. A DP system consist of sensors, observer, controller and thrust allocation algorithm. The purpose of this paper is to investigate the performance of proportional derivative type fuzzy controller with Mamdani interface scheme for dynamic positioning of an oceanographic research vessel (ORV) by numerical simulation. Nonlinear passive observer is used to filter the noise from the position and orientation. A nonlinear mathematical model of the ORV is subjected to the wave disturbance ranging from calm to phenomenal sea. Robustness and efficiency of the fuzzy logic controller is analysed in comparison with the multivariable proportional integral derivative (PID) and the linear quadratic regulator (LQR) controller. A simplified constrained linear quadratic algorithm is used for thrust allocation. The frequency response of the closed loop system with different controllers is analysed using the bode plot. The stability of controller is established using the Lyapunov criteria.

References
More filters

Journal ArticleDOI
28 Sep 2016-Philosophy study
TL;DR: It is argued that certain duties of patients counterbalance an otherwise unfair captivity of doctors as helpers and that vulnerability does not exclude obligation.
Abstract: There has been a shift from the general presumption that “doctor knows best” to a heightened respect for patient autonomy. Medical ethics remains one-sided, however. It tends (incorrectly) to interpret patient autonomy as mere participation in decisions, rather than a willingness to take the consequences. In this respect, medical ethics remains largely paternalistic, requiring doctors to protect patients from the consequences of their decisions. This is reflected in a one-sided account of duties in medical ethics. Medical ethics may exempt patients from obligations because they are the weaker or more vulnerable party in the doctor-patient relationship. We argue that vulnerability does not exclude obligation. We also look at others ways in which patients’ responsibilities flow from general ethics: for instance, from responsibilities to others and to the self, from duties of citizens, and from the responsibilities of those who solicit advice. Finally, we argue that certain duties of patients counterbalance an otherwise unfair captivity of doctors as helpers.

9,859 citations


01 Jan 2016-
Abstract: By searching the title, publisher, or authors of guide you in reality want, you can discover them rapidly. In the house, workplace, or perhaps in your method can be all best place within net connections. If you objective to download and install the guidance and control of ocean vehicles, it is utterly easy then, past currently we extend the colleague to buy and make bargains to download and install guidance and control of ocean vehicles therefore simple!

477 citations


"Experimental investigation on the e..." refers background in this paper

  • ...Fossen (1994) composed the same equation into standard format of mass spring damper system which made it easy to understand and analyse the complex system....

    [...]


01 May 1964-

161 citations


"Experimental investigation on the e..." refers methods in this paper

  • ...Abkowitz (1964) used Taylor series expansion to describe forces acting on ship hull....

    [...]


Journal ArticleDOI
Abstract: Complete nonlinear dynamic manoeuvering models of ships, with numerical values, are hard to find in the literature. This paper presents a modeling, identification, and control design where the objective is to manoeuver a ship along desired paths at different velocities. Material from a variety of references have been used to describe the ship model, its difficulties, limitations, and possible simplifications for the purpose of automatic control design. The numerical values of the parameters in the model is identified in towing tests and adaptive manoeuvering experiments for a small ship in a marine control laboratory.

138 citations


"Experimental investigation on the e..." refers methods in this paper

  • ...vessel was shown in Skjetne (2004). They used straight line captive test and force ring methods to estimate derivatives....

    [...]


Journal ArticleDOI
Abstract: Digital simulation of maneuvering motions and numerical calculation of directional stability indices are carried out on the basis of captive model test of a typical container ship. An emphasis is laid upon yaw-sway-roll-rudder coupled motion. The smaller metacenteric height proved to introduce the better turning performance and the poorer course-keeping characteristics.The yaw-sway-roll-rudder coupling can be a cause of anomalous rolling which is frequently observed at automatically steered, high speed operations in seaways. We introduce a perturbation stability analysis on the problem. It reveals the possibility of an unstable yaw-roll behavior due to roll-induced yaw moment, small GM and inadequate control parameters of autopilot steering system.

117 citations


"Experimental investigation on the e..." refers methods in this paper

  • ...Equation 6–9 are used to calculate the rudder and propeller forces (Son and Nomoto 1981)....

    [...]

  • ...Son and Nomoto (1981) estimated hydrodynamic derivatives for S175 container ship using PMM....

    [...]

  • ...The mathematical model presented here is a compact version of Son and Nomoto model (Son and Nomoto 1981)....

    [...]

  • ...…Coriolis and centripetal matrix C is written as, C = 0 0 Yv̇v 0 0 Xu̇u 0 0 0 ⎡ ⎣ ⎤ ⎦ (4) The propeller and rudder force matrix t is represented as, t = XP + Xd YP + Yd NP + Nd ⎡ ⎣ ⎤ ⎦ (5) The mathematical model presented here is a compact version of Son and Nomoto model (Son and Nomoto 1981)....

    [...]


Performance
Metrics
No. of citations received by the Paper in previous years
YearCitations
20211
19941