Abstract
When a feedback system is devised to control a mechanical member that is structurally limber, unstable (“self-excited”) vibrations may be encountered at approximately a natural frequency of the structural member. Cures are generally easy to effect once the phenomena are understood. Two interesting cases are described: ground vibrations of an airplane control system due to a limber fuselage, and vibrations of a stable platform system due to limberness in the platform structure. The investigations are carried out using the root-locus technique, which provides a plot of system characteristics as explicit functions of control strength. In the case of the stable platform, the analysis is found to be more reliable than physical intuition.
Evaluation of Linear, Inviscid, Viscous, and Reduced-Order Modeling Aeroelastic Solutions of the AGARD 445.6 Wing Using Root Locus Analysis