
Saunder January 22, 2014 10:43 K15053˙Book
130 Disturbance Observer-Based Control: Methods and Applications
and the resultant control law (8.51) becomes u = A
−1
(x)
[
−b(x) +v
]
−
ˆ
d, which is
the same as that of the existing method [10].
Remark 8.8 In the absence of disturbances, the disturbance estimate by (8.36) satisfies
ˆ
d(t) ≡ 0 if the initial state of NDO (8.36) is set as z(0) =−λ(x(0)).Inthis case,
the control performance under the proposed control law (8.51) recovers to that under the
baseline feedback control law, which implies that the property of nominal performance
recovery is obtained by the proposed NDOBC.
8.4.2 Stability Analysis
Assumption ...