1996 Volume 116 Issue 10 Pages 1010-1017
It has been said that the nominal system is realized in low frequency region when disturbance and parameter variation are compensated by feedback of estimated disturbance signal from disturbance observer. According to analysis of the realized system, however, it is found that there are some cases in which the nominal system isn't realized. The nominal system is realized by choosing the order of the disturbance observer in accordance with disturbance and transfer function of control object. This paper shows the relationship among the order of the disturbance observer, the realized system, and the stability of the system.