  In this paper, we consider the problem of constraint management in Linear
Periodic (LP) systems using Reference Governors (RG). First, we present the
periodic-invariant maximal output admissible sets for LP systems. We extend the
earlier results in the literature to Lyapunov stable LP systems with output
constraints, which arise in RG applications. We show that, while the invariant
sets for these systems may not be finitely determined, a finitely-determined
inner approximation can be obtained by constraint tightening. We further show
that these sets are related via simple transformations, implying that it
suffices to compute only one of them for real-time applications. This greatly
reduces the memory burden of RG, at the expense of an increase in processing
requirements. We present a thorough analysis of this trade-off. In the second
part of this paper, we discuss two RG formulations and discuss their
feasibility criteria and algorithms for their computation. Numerical
simulations demonstrate the efficacy of the approach.
