  The applications of reference governors to systems with unmeasured
set-bounded disturbances can lead to conservative solutions. This conservatism
can be reduced by estimating the disturbance from output measurements and
canceling it in the nominal control law. In this paper, a reference governor
based on such an approach is considered and time-varying, disturbance and state
estimation errors bounding sets are derived. Consequently, the traditional
implementation of a reference governor, which exploits a constraint admissible
positively-invariant set of constant commands and initial states, is replaced
by one which utilizes a time-dependent sequence of similar sets (which are not
necessary nested). Examples are reported which include two applications to
longitudinal control of aircraft that illustrate handling of elevator
uncertainty and wing icing.

Systems and Control;Systems and Control