Application of Kharitonov's theorem to mechanical systems

Kharitonov's theorem is used to derive a robust stability condition for proportional-integral-derivative (PID)-controlled multi-degree-of-freedom mechanical systems. The characteristic equation of such a system is given as a determinant of a third-order polynomial with matrix coefficients from which a scalar interval polynomial is obtained. A simple procedure for designing PID controllers for these mechanical systems is described, and a new Kharitonov-like result which states roughly that a controller designed for an upper bounding inertia matrix results in stable set-point regulation for all other inertias is proved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>