Frequency Domain Methods for Analyzing the Stability and Maneuverability of Driver/Vehicle Systems

Abstract

Several frequency domain methods useful for describing and analyzing the directional stability and maneuverability of the closed-loop system comprised of the driver and vehicle are examined. In particular, Bode plots, Nyquist diagrams, and Nichols charts are illustrated and compared. The utility and specific features of each method for analyzing driver/vehicle responses are demonstrated through examples using experimental measurements of driver/vehicle interactions and mathematical simulation. A principal conclusion, based upon the analysis techniques and example calculations, is that preview-based steering control strategies typically employed by drivers of automobiles may produce a tradeoff of closed-loop directional stability in exchange for path maneuverability.