Centralized PI controller design method for MIMO processes based on frequency response approximation. (April 2021)

• Record Type: Journal Article
• Authors: Ghosh, Sreya; Pan, Somnath
• Is Part Of: ISA transactions. Volume 110(2021)
• Page Start: 117
• Page End: 128
• Publication Date: 2021-04
• Subjects: Multivariable process -- Non-square system -- High-dimensional MIMO process -- PI controller -- Centralized control; Engineering instruments -- Periodicals; Engineering instruments; Periodicals; Electronic journals; 629.805
• DOI: 10.1016/j.isatra.2020.10.041
• Languages: English
• ISSNs: 0019-0578

Abstract

Abstract: A simple method of controller design for multi-input multi-output (MIMO) processes have been proposed in frequency domain. The intensive calculation for the inverse of the process transfer function matrix is simplified to a great extent by evaluating the process transfer function matrix at a low frequency point. The desired closed loop transfer functions are derived for the process using a single tuning parameter for each diagonal element of the process transfer function matrix which represents the desired closed loop time constant. Centralized PI controllers are then designed using a model matching technique by evaluating the transfer functions at a low frequency point. The PI controllers provide acceptable performances for lag dominated as well as time-delay dominated processes and is also applicable to high-dimensional processes. The proposed method is extended for the non-square MIMO processes using two approaches one of which squares up the process transfer function matrix to apply the proposed technique while the other is based on pseudo-inverse evaluation of the process transfer function matrix at a low frequency point. Highlights: Design of centralized PI controller for low and high-dimensional MIMO processes. Process matrix inverse calculation simplified by evaluating at a low frequency point. Non-square processes squared with small gain considered at missing diagonal elements. Alternatively, for non-square processes, pseudo-inverse is considered.