Ship roll motion control is important for vessels engaged in oceanographic research activities and this paper focuses on the design of a controller for fin based roll motion stabilization of a Coastal Research Vessel (CRV). Based on the geometry of a pair of actuator fins installed at the midship of the vessel, the hydrodynamic coefficients are calculated for the vessel including the fin lift capacity. The wave disturbances are simulated as a sine time series. The objective is to design a Linear Quadratic Regulator (LQR), a state feedback controller and obtain the performance of the system. The larger objective is to implement the system eventually in laboratory scale physical simulations in wave environment. This paper primarily presents the design of the control system and evaluation through Simulink in Matlab environment. The global cost function of the system is minimized by precision tuning of the two control parameters (or weighting matrices), Q and R. The system analysis is done using frequency domain and state space approach. The simulation results show that the natural frequency and roll response closely match with the response of the physical model (CRV) in laboratory environment, as observed during the experimental study. The proposed control system is compared with a conventional PID controller. The simulation results demonstrate the effectiveness of the designed roll motion stabilization system with significant roll reduction over the operational range of the vessel.

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Fin based active control for ship roll motion stabilization

Captive model testing for ship motions, sea-keeping and dynamic effects has been always a challenge due to the large amount of channels of data, the need for continuous data communication for effect feedback control, and in the case of extended studies relating to fleets, the methodology for group fleet control. For the first time a solution is offered by designing a free self-propulsion, self, on-board controlled, surface ship model. The design incorporates Wi-Fi enabled robust communication and control and protocols for data storage, exchange, multiple device control and communication to fleet sister surface ships for fleet control. The design is described in this paper with details of implementation on a demonstration oceanographic research vessel. It illustrates the excellent communication between shore station computer and the on-board system on a wire-free model with robust control and exhibiting all the motion behavior and dynamic effects.

Jagadeesh Kumar

Papers

Page No. 29 - 42: Wi-Fi Enabled Autonomous Ship Model Tests For Ship Motion Dynamics And Seakeeping Assessment