AN IMPROVED TECHNIQUE FOR PLOTTING ROBUST ROOT LOCUS

摘要

This paper deals with the problem of plotting the robust root loci of a feedback control system which includes affine parametric uncertainties in the coefficients of the plant transfer function. First, based on a geometrical interpretation of the value set of a family of affine parametric uncertain polynomials, an efficient algorithm is proposed for checking whether the set includes the origin of the complex plane. This /.ero-inclusion test algorithm is then applied along with a pivoting procedure to trace out the boundaries of the cross sections ol' the robust root loci, Since the proposed technique of generating a robust root locus needs not to construct all exposed edges of the value set in testing the zero inclusion condition, and needs not to use a brute-force twooodimeiisiontil gridding approach in plotting the boundary of a cross .section of the robust root loci, its advantage of saving com-putalional cost is obviously significant.