Input saturation in nonlinear multivariable processes resolved by nonlinear decoupling

• Published in: Modeling, identification and control Vol. 16; no. 2; pp. 95 - 106
• Main Authors: BALCHEN, J. G, SANDRIB, B
• Format: Journal Article
• Language: English
• Published: Oslo Research Council of Norway 01.04.1995; Norsk Forening for Automatisering (NFA); Norwegian Society of Automatic Control
• Subjects: Applied sciences; Computer science; control theory; systems; Control system synthesis; Control theory. Systems; Exact sciences and technology; Multivariable control; saturation; Decoupling; Multivariable control; Non linear process; Simulation; Saturation; Catalytic cracking
• ISSN: 0332-7353; 1890-1328
• DOI: 10.4173/mic.1995.2.2

A new method is presented for the resolution of the problem of input saturation in nonlinear multivariable process control by means of elementary nonlinear decoupling (END). Input saturation can have serious consequences particularly in multivariable control because it may lead to very undesirable system behaviour and quite often system instability. Many authors have searched for systematic techniques for designing multivariable control systems in which saturation may occur in any of the control variables (inputs, manipulated variables). No generally accepted method seems to have been presented so far which gives a solution in closed form. The method of elementary nonlinear decoupling (END) can be applied directly to the case of saturation control variables by deriving as many control strategies as there are combinations of saturating control variables. The method is demonstrated by the multivariable control of a simulated Fluidized Catalytic Cracker (FCC) with very convincing results.