Evaluating the Normalized Coprime Factor-Based Stability Metric for Rigid Systems

Abstract

The introduction of flexibility into rigid-body manipulator systems generally complicates the use of simple end-point feedback control. The application of force to these flexibilities induces an unmodeled oscillation that cannot be necessarily compensated through simple end-point feedback control. The normalized coprime factor based robustness metric (εmax) has been well established in the realm of optimal control and can be applied to a rigid system with flexible modes in order to determine postures that will be robust to the flexibilities. This work illustrates that for rigid (double integrator) systems there is fixed normalized coprime-factor robustness and, that for the special case of single-input, single-output flexible systems, deviation from rigidity yields a similar change in normalized coprime factor robustness.