Polygon interval arithmetic and design of robust control systems

Robust stability analysis and the robust controller design problem of multivariable control systems are considered. To represent and treat the uncertainty of frequency response of plants and controllers, a notion of polygon interval arithmetic (PIA) is introduced. By using PIA, the robust stability problem is solved more efficiently than the method based on the mapping theorem. Moreover, by using PIA, a robust sequential return difference (RSRD) method is proposed, which is an improved version of the traditional SRD method in the sense that it can treat uncertainty contained in both plants and controllers, and that it is possible to guarantee integrity if it is desired