  In this paper, we design a symbolic output feedback controller of a
cyber-physical system (CPS). The physical plant is modeled by an infinite
transition system. We consider the situation that a finite abstracted system of
the physical plant, called a c-abstracted system, is given. There exists an
approximate alternating simulation relation from the c-abstracted system to the
physical plant. A desired behavior of the c-abstracted system is also given,
and we have a symbolic state feedback controller of the physical plant. We
consider the case where some states of the plant are not measured. Then, to
estimate the states with abstracted outputs measured by sensors, we introduce a
finite abstracted system of the physical plant, called an o-abstracted system,
such that there exists an approximate simulation relation. The relation
guarantees that an observer designed based on the state of the o-abstracted
system estimates the current state of the plant. We construct a symbolic output
feedback controller by composing these systems. By a relation-based approach,
we proved that the controlled system approximately exhibits the desired
behavior.
