Vertical Plane Motion of High Speed Planing Vessels with Controllable Transom Flaps: Modeling and Control

Authors:	Xi Handa, University of Michigan, United States Sun Jing, University of Michigan, United States
Topic:	7.2 Marine Systems
Session:	Marine Systems II
Keywords:	High-speed planing vessels, vertical-plane motion, porpoising, modeling, LQR

Abstract

Hydrodynamics of porpoising instability in vertical-plane motions of high-speed planing vessels have been investigated for years. However, not much work has been published on dynamic control of vertical-plane motions of planing boats by controllable appendages. In this paper, effects of controllable transom flaps on heave/pitch motion characteristics of high-speed planing vessels are investigated. A control-oriented nonlinear model is derived first for the high-speed prismatic planing craft equipped with a controllable transom flap in the calm water. Then, effects of different static flap deflections on the ship's equilibriumrunning attitude and vertical-plane motion stability are analyzed. Analysis shows that porpoising cannot be avoided at high speeds by presetting static transom flap deflections through static feedforward control. An LQR feedback controller is designed to achieve local asymptotical stability.