Decentralised Markov parameters fixed modes and decentralised plucker invariants

The properties of the decentralised pole placement map under constant output feedback are investigated and they are linked to known invariants of the decentralised pole assignment problem. An expression of the differential of this map leads to the definition of the Decentralised Markov Parameters (DMP) and this in turn provides simple means for selecting decentralisation schemes which guarantee the absence of fixed modes and further well condition the problem. The results which are originally presented for the decentralised constant output feedback are subsequently extended to the case of decentralised PI feedback.