A new result on Relative Gain Array, Niederlinski Index and decentralized stability condition: 2 × 2 plant cases

Abstract This note discusses the decentralized stability condition for a 2-channel decentralized control system where each channel is a single-input-single-output (SISO) control loop. Stabilization of each individual loop (with the other loop open) is not required, which had been the case in previous work on the Relative Gain Array (RGA) and the Niederlinski Index (NI). Therefore this new result is a generalization of previous RGA and NI stabilization conditions.