Saunder January 22, 2014 10:43 K15053˙Book
Nonlinear Disturbance Observer-Based Control for Systems 125
Assumption 8.3 The disturbances in (8.34) are bounded and satisfy lim
t→∞
d
˙
(t) = 0.
This assumption is made for steady-state analysis of disturbance estimation and
compensation.
Lemma 8.5 Suppose that Assumption 8.3 is satisfied. Disturbance estimation
ˆ
dof
NDO (8.36) can asymptotically estimate disturbance w in system (8.34) if observer gain
l(x) is chosen such that (8.38) is asymptotically stable.
The proof of this lemma can be easily derived by combining the result of ISS
definition in [87].
8.4.1 Control Law Design
In order to present the main result, the disturbance decoupling for MIMO nonlinear
systems with arbitrary DRDs is solved first.
Assumption ...