Saunder January 22, 2014 10:43 K15053˙Book
200 Disturbance Observer-Based Control: Methods and Applications
For system (12.18), the estimate
ˆ
d of the real disturbance d can be obtained by a dis-
turbance observer. However, if the composite control law is designed as u = K
x
x −
ˆ
d
(where K
x
is the feedback control gain) which is the formulation of the existing
DOBC methods from the literature, it can be found that the disturbance compensa-
tion design has nothing meaningful for system (12.18) because the disturbance can
neither be attenuated from the state equations nor from the output channels.
It should be pointed out that the mismatched disturbances are unlikely to be at-
tenuated from the state equations in general. This work aims to develop a