随机载荷作用下的板架结构的主动控制分析

本文应用控制论原理,以一个板架结构为例,分析、探讨了采用主动控制方法减小海洋工程结构弹性振动的新问题。 文章建立了受控板架的运动方程。求得了描述受控板架系统特性的传递函数和状态方程。证明该系统是可控的、可观测的,其稳定性是可以保证的。文章进一步分析论证了控制一部分主振形的可行性、实用性。证明一旦消除了观测溢出和控制溢出,就可消除受控振形与剩余振形之间的相互耦合作用,保证系统的稳定性、可控性和可观测性。文章指出了消除观测溢出与控制溢出的途径。分析比较了位移、速度、加速度型三种不同的传感器对系统特性的影响。论证除了控制系统电子器件的增益外,传感器和控制力的位置也是影响系统特性的十分重要的因素,通常应尽可能布置在受控振形的峰值点,剩余振形的结点上。最后通过一实例的计算,给出了一个板架受控前后的响应值,证实了主动控制所取得的良好效果。

ACTIVE CONTROL ANALYSIS FOR TWO-DIMENSIONAL GRILLAGE STRUCTURES UNDER THE ACTION OF A RANDOM EXCITATION

By applying the principle of control theory and taking a grillage structure as an example, this paper analyses and discusses how the active control method is used to reduce the elastic vibrations of ocean engineering structures.The equation of motion of a controlled grillage is established. The transfer function and space state equation describing the dynamic characteristics of the controlled grillage system are obtained. It has shown that the system is controllable, observable, and its stability may be guaranteed. This paper has further analysed and proved that to control a part of normal modes of the system is feasible and practical. It has verified that the coupling between the controlled modes and the residual modes may be eliminated, the stability, controllability and observability of the system can be guaranteed once the observation and control spillover are eliminated. The way of eliminating the observation and control spillover is given. The effects of the three different types sensors (diflection, velocity and accelera-tion)on the characteristics of the system are analysed and compared. Besides the gain of the electronic devices in the control system, it has been verified that the locations of the sensor and the control moment are a very important factor which affects the characteristics of the system. Usually, the locations are at the peak points of the controlled modes and the nodes of the residual modes as near as possible. Finally by using a practical example, the numerical values of the responses of a excited grillage before and after being controlled are given, so remarkable effects caused by applying active control are shown.