Direct closed-loop identification of magnetic suspension system

A new direct closed-loop identification method only using the plant input/output data acquired through an output inter-sampling scheme is presented. By taking the faster sampling of the system output than the control interval, we can clarify that the inter-sampled plant model can also be described by a SIMO model structure, which can provide the identifiability of the closed-loop. One of the advantages is that the proposed identification method using the inter-sampled output observations can remove the ordinary restrictive identifiability condition, and it is not required that the reference input holds the persistently exciting property. Its effectiveness is demonstrated through an experimental study using a magnetic suspension system.