Zeros of continuous-time linear periodic systems

Zeros of continuous-time linear periodic systems are defined and their prop erties investigated. Under the assumption that the system has uniform relat ive degree, the zero-dynamics of the system is characterized and a closed-f orm expression of the blocking inputs is derived. This leads to the definit ion of zeros as unobservable characteristic exponents of a suitably defined periodic pair. The zeros of periodic linear systems satisfy blocking prope rties that generalize the well-known time-invariant case. Finally, an effic ient computational scheme is provided that essentially amounts to solving a n eigenvalue problem. (C) Elsevier Science Ltd. All rights reserved.