ASA 124th Meeting New Orleans 1992 October

4aSA11. Causality analysis in broadband feedforward controlled systems.

R. A. Burdisso

J. E. Vipperman

C. R. Fuller

Dept. of Mech. Eng., Virginia Polytech. Inst. and State Univ., Blacksburg, VA 24061

In recent years, adaptive feedforward control algorithms have been successfully implemented to attenuate the response of systems under persistent inputs, such as single and multiple tones and random signals. System causality is not an issue when the excitation is sinusoidal because of its deterministic nature. However, causality is a very important factor in broadband control. Although significant deterioration in the performance of acausal control systems have been reported in the literature, analytical tools are virtually nonexistent to predict the behavior of broadband controllers. The main objective of this research is to develop an approach to investigate system causality. A formulation is presented to address the effectiveness of a control configuration as a function of the filter size, delay time, and dynamic properties of the structure. The technique is illustrated in a simple numerical example and the results are also corroborated experimentally. [Work supported by Office of Naval Research.]