A systematic procedure to design notch filters for structural responses with multi-axis coupling

Abstract

A novel method for designing notch filters to attenuate structural responses that show significant cross-coupling (between axes) is presented. This approach differs from the conventional methods in that it is a single-step procedure that enables notch filters of each sensor path to be designed independently of those in other sensor paths while guaranteeing the stability margin requirements. As a result, this approach can result in a less conservative design as compared to the conventional methods. This paper describes the procedure in the context of the coupled lateraldirectional axes of an aircraft the objective being to gain stabilise the structural response uniformly so as to meet the MIL 9490D specifications. An example is given to illustrate the power of this method. Symbols : Plant transfenfanction from the j input to the i output .th p r Ny : Controller transfer function from the j input to the i input : Roll rate (deg/s) : Yaw rate (deg/s) : Lateral acceleration (g's) .th # Scientist, Flight Mechanics and Simulation Group, Aeronautical Development Agency,Bangalore 17, India * Scientist, Controls Division, Centre for Artificial Intelligence and Robotics, Bangalore 1, India Copyright © 1997 by authors. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. PF '• Roll rate notch filters RF : Yaw rate notch filters Nyp : Lateral Acceleration notch filters Lt : A Multivariable Loop transfer function