Rate weighted optimal control of flexible structures

Abstract

A new method is devised for the active control of flexible structures using output rate weighted linear optimal control. The method has an advantage over the traditional linear optimal control method in that it assigns weightage to the time rate-of-output, which may not be available for direct measurement in several important applications, such as gust and maneuver load alleviation in airplanes and ridequality augmentation in a variety of passenger vehicles. In applications to a single degree-offreedom system and a cantilevered beam, the rate-weighted optimal controller demonstrates a much better performance in terms of the smoothness of transient response, peak rate of transient response and settling time when compared to the traditional linear quadratic regulator. Introduction Generally, there are three different approaches applied to controlling flexible structures: (a) passive addition of structural damping and stiffness (b) generating specificaNy shaped input&* ,and (c) designing an optimal feedback controlle?S4. The first option is usually cumbersome and adds mass to the structure, while the second option, requiring generation of inputs that are insensitive to modeling errors and which do not excite unwanted dynamics, is di&tilt to achieve in practice. This leaves the third option of an active feedback controller as the most practical choice for controlling structural dynamics. The optimal linear *Assistant Professor, Department of Aerospace Engineering. Senior Member, AIAA. Copyright