  This paper studies global regulated state synchronization of homogeneous
networks of non-introspective agents in presence of input saturation. We
identify three classes of agent models which are neutrally stable,
double-integrator, and mixed of double-integrator, single-integrator and
neutrally stable dynamics. A \textit{scale-free linear observer-based} protocol
design methodology is developed based on localized information exchange among
neighbors where the reference trajectory is given by a so-called exosystem
which is assumed to be globally reachable. Our protocols do not need any
knowledge about the communication network topology and the spectrum of
associated Laplacian matrix. Moreover, the proposed protocol is scalable and is
designed based on only knowledge of agent models and achieves synchronization
for any communication graph with arbitrary number of agents.
