On Input-Output Selection for Multi-Loop Control: from RGA to ROmA

A new tool for selecting the right pairing between inputs and outputs in a multiloop system is introduced. Similar in structure to the classical RGA the new array, called a Relative Omega Array, is based on the characteristic frequencies in open and closed loop under perfect control, as eventually detected by a classical relay test. This way the dynamic properties of the system are simply taken into account. Some examples show that the new tool is effective, giving the correct pairing also when the RGA approach fails