船舶上层建筑振动的最优控制分析

本文讨论了最优控制理论在船舶上层建筑振动控制中的应用。文中将船体和上层建筑简化为相应的船体梁和上层建筑梁模型，并将上层建筑梁的振动响应处理为支承激励下的响应。用模态分析法得到船体梁和上层建筑梁的动力特性（固有频率和固有振型），再用模态（振型）叠加法得到受控前上层建筑顶端的稳态动力响应，接着根据最优控制理论，设定目标函数，求解Riccati方程，得到主动控制力，将其作用在上层建筑梁的顶部，用模态（振型）叠加法得到受控后上层建筑梁顶部的稳态动力响应。以一条50000吨的油船为算例进行数值仿真，受控后上层建筑顶部的稳态振动位移减小了30％，可见最优控制在船舶上层建筑的振动控制中是可行的和有效的。

OPTIMAL CONTROL ANALYSIS OF SHIP SUPERSTRUCTURE VIBRATION

An investigation of vibration reduction at the top of ship superstructure by optimal control theory is presented. In this paper, the ship hull and superstructure are simplified to hull girder and superstructure beam respectively. The superstructure beam is fixed on the hull girder. The vibration of hull girder is derived from propeller exciting force. The vertical bending vibration of hull girder makes the bottom of the superstructure vibrate.So the vibration of superstructure beam is derived from the excitation of its bottom. Vibration characteristics of hull girder aqd superstructure beam are confirmed with the aid of model analysis method and vibration at the top of superstructure is got by modal superposition method. In the control part, a cost function is defined by optimal control theory and its Riccati equation is solved. The active force is offered on the top of superstructure and the vibration at the top of superstructure by active control force is got. The above method is applied to a 50000DWT tanker and reduces the vibration at the top of superstructure to 70% of its original level. This is a satisfying result and shows that active control system with optimal control theory is a powerful and feasible scheme for superstructure vibration reduction.