ROBUST GAMMA-STABILITY ANALYSIS IN A PLANT PARAMETER SPACE

Given a characteristic polynomial whose coefficients depend polynomially on l uncertain parameters, the following robustness problem arises: Determine whether all the roots of the polynomial are located in a prescribed region-GAMMA in the complex plane for all admissible parameter values. To this end, the boundary partial-GAMMA of GAMMA is mapped into the parameter space. A necessary and sufficient condition for GAMMA-stability of an operating domain in parameter space is that it contains at least one GAMMA-stable point and is not intersected by the image of partial-GAMMA. This condition may be tested graphically by gridding l-2 parameters and projecting all boundaries into a two-dimensional subspace of the parameter space. Finally the method is applied to a track-guided bus with uncertain mass and velocity.