Controllability-observability of expanded composite systems

The relation between original and expanded systems within the Inclusion Pri nciple from the point of view of controllability-observability of both subs ystems and composite systems is studied. It is proved that complementary ma trices always exist ensuring that the subsystems and the overall expanded s ystem are simultaneously controllable-observable. Two practically important large classes of complementary matrices are identified to offer results co mputationally attractive. First, the existence of complementary matrices en suring controllability-observability of decoupled subsystems is proved. The n, using this result, the same property is proved for the composite expande d system. (C) 2001 Elsevier Science Inc. All rights reserved.