Decentralized multi-variable successive loop closure

The successive loop closure control approach is popular in engineering practice due to its ease of use. However, in most cases, the successive loop closure approach, for each loop closure, is in the configuration of single-input and single-output, which limits the usage of the control of multi-variable processes with coupled effects. In this paper, we extended the traditional successive loop closure control approach to multi-variable processes. To further improve the practicalness of the proposed method, in each closure, the decentralized integral controller will be designed. A sufficient condition for the existence of a controller to ensure the decentralized unconditional stability of each loop is proposed, under which the tuning of the loop gains becomes easier. Illustrative example is proposed to demonstrate the effectiveness of the proposed approach.