  We investigate the coordination and control problems of distributed discrete
event systems that are composed of multiple subsystems subject to potential
actuator and/or sensor faults. We model actuator faults as local
controllability loss of certain actuator events and sensor faults as
observability failure of certain sensor readings, respectively. Starting from
automata-theoretic models that characterize behaviors of the subsystems in the
presence of faulty actuators and/or sensors, we establish necessary and
sufficient conditions for the existence of actuator and sensor fault tolerant
supervisors, respectively, and synthesize appropriate local post-fault
supervisors to prevent the post-fault subsystems from jeopardizing local safety
requirements. Furthermore, we apply an assume-guarantee coordination scheme to
the controlled subsystems for both the nominal and faulty subsystems so as to
achieve the desired specifications of the system. A multi-robot coordination
example is used to illustrate the proposed coordination and control
architecture.
