%0 Journal Article %T Relay Feedback Based Time Domain Modeling of Linear 3-by-3 MIMO System %J American Journal of Systems Science %@ TBD %D 2012 %I %R 10.5923/j.ajss.20120101.01 %X Relay feedback tests are carried out on multi input multi output systems. Analytical expressions for relay responses in time domain for the interactive transfer functions (off-diagonal elements) of the systems are derived and are validated. Generalized expressions are formulated based on the observation that a relay feedback test consists of a series of step inputs and a stable limit cycle implies a convergent infinite series. MIMO systems with lower-order transfer functions with different time delays are used to illustrate the derivation. These analytical expressions, in a closed form solution are useful to identify unknown system parameters, to understand interactions, to diagnosis the fault at the earlier stage, and subsequently for autotuning. %K Modelling %K Relay Feedback %K Identification %K Autotuning %K Multi Input Multi Output %U http://article.sapub.org/10.5923.j.ajss.20120101.01.html