On the Kharitonov´s polynomials by orthogonal aspect and Routh-Hurwitz criterion

This paper places emphasis on the Kharitonov´s polynomials for robust stability while the system parameters are disturbed and vary up and down. One utilizes orthogonal property of experimental design methodology and Routh-Hurwitz stability criterion to analyze these four determinants. The regular cycle of plus-minus sign changed two by two coefficients based on Routh-Hurwitz criterion, not only on orthogonal property. The key determinants have derived to replace the four determinants and then save procedures for judging stability under four-order system. Some necessary conditions of robust stability determinants have been discussed. These precious rules will be demonstrated by examples with detailed description. The results have shown efficiency of the key valuable determinants to save much time then before.