Nonlinear control of chemical processes: a review

Bequette, B. Wayne

doi:10.1021/ie00055a001

Cited by 504 publications

(189 citation statements)

References 127 publications

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“…Simultaneous solution methods use collocation (more specifically, orthogonal collocation on finite elements [33,34]) to convert a DAE-constrained dynamic optimization problem to an NLP where the objective function is minimized and the constraint equations are solved simultaneously, making the algorithm much more computationally efficient. By comparison, a sequential method requires simulation through the differential constraint equations many times for every set of inputs [35].…”

Section: Simultaneous Solution Methodsmentioning

confidence: 99%

A Continuous Formulation for Logical Decisions in Differential Algebraic Systems using Mathematical Programs with Complementarity Constraints

et al. 2016

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This work presents a methodology to represent logical decisions in differential algebraic equation simulation and constrained optimization problems using a set of continuous algebraic equations. The formulations may be used when state variables trigger a change in process dynamics, and introduces a pseudo-binary decision variable, which is continuous, but should only have valid solutions at values of either zero or one within a finite time horizon. This formulation enables dynamic optimization problems with logical disjunctions to be solved by simultaneous solution methods without using methods such as mixed integer programming. Several case studies are given to illustrate the value of this methodology including nonlinear model predictive control of a chemical reactor using a surge tank with overflow to buffer disturbances in feed flow rate. Although this work contains novel methodologies for solving dynamic algebraic equation (DAE) constrained problems where the system may experience an abrupt change in dynamics that may otherwise require a conditional statement, there remain substantial limitations to this methodology, including a limited domain where problems may converge and the possibility for ill-conditioning. Although the problems presented use only continuous algebraic equations, the formulation has inherent non-smoothness. Hence, these problems must be solved with care and only in select circumstances, such as in simulation or situations when the solution is expected to be near the solver's initial point.

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Section: Simultaneous Solution Methodsmentioning

confidence: 99%

A Continuous Formulation for Logical Decisions in Differential Algebraic Systems using Mathematical Programs with Complementarity Constraints

et al. 2016

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“…For general reviews of model predictive control, see Bequette (1991a), Henson (1998), Morari and Lee (1999), Mayne et al (2000) and Qin and Badgwell (2003). A tutorial introduction to dynamic matrix control (DMC) is presented in my process control textbook (Bequette, 2003), and the paper by Shah (1995); also, the books Bitmead et al (1990), Camacho and Bordons (2004), Maciejowski (2002) and Rossiter (2003) derive various MPC algorithms, generally with a focus on linear systems.…”

Section: Non-linear Model Predictive Controlmentioning

confidence: 99%

Non‐Linear Model Predictive Control: A Personal Retrospective

Bequette

2007

Can J Chem Eng

Self Cite

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An overview of non-linear model predictive control (NMPC) is presented, with an extreme bias towards the author's experiences and published results. Challenges include multiple solutions (from non-convex optimization problems), and divergence of the model and plant outputs when the constant additive output disturbance (the approach of dynamic matrix control, DMC) is used. Experiences with the use of fundamental models, multiple linear models (MMPC), and neural networks are reviewed. Ongoing work in unmeasured disturbance estimation, prediction and rejection is also discussed.On présente un aperçu général du contrôle prédictif par modèles non linéaires (NMPC), en mettant l'accent en particulier sur les expériences des auteurs et les résultats publiés. Les défi s incluent des solutions multiples (à partir des problèmes d'optimisation non convexes), ainsi que la divergence entre les sorties de modèle et d'installation lorsque la perturbation de sortie additive constante (la méthode du contrôle de matrice dynamique, DMC) est utilisée. Les expériences avec les modèles fondamentaux, les modèles linéaires multiples (MMPC) et les réseaux neuronaux sont examinées. Le travail actuellement mené sur l'estimation, la prédiction et le rejet des perturbations non mesurées est également examiné.

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“…In this case the controller has to stop at the minimal possible (i.e. 0) ingress rate and has to wait until the appropriate concentration decreases by natural processes [10], [11]. It also worths noting that the introduction of even a pure reagent dilutes the others that corresponds to a type of input coupling [12].…”

Section: Introduction In the Field Of Model Predictive Control (Mpc)mentioning

confidence: 99%

Preliminary investigations on the applicability of the fixed point transformations-based adaptive control for time-delayed systems

Csanadi

Haidegger²,

Redjimi

et al. 2016

2016 IEEE 20th Jubilee International Conference on Intelligent Engineering Systems (INES)

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Abstract-In this paper, for the first time, a possible tackling of the problem of known time-delay by the use of a Fixed Point Transformation-based adaptive controller is investigated. This approach at first transform the control task into a fixed point problem then solves it via iteration. The preliminary results that were obtained by numerical simulations for a strongly nonlinear controlled system, a van der Pol oscillator, are promising. It is expedient to make further, systematic investigations.

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Nonlinear control of chemical processes: a review

Cited by 504 publications

References 127 publications

A Continuous Formulation for Logical Decisions in Differential Algebraic Systems using Mathematical Programs with Complementarity Constraints

A Continuous Formulation for Logical Decisions in Differential Algebraic Systems using Mathematical Programs with Complementarity Constraints

Non‐Linear Model Predictive Control: A Personal Retrospective

Preliminary investigations on the applicability of the fixed point transformations-based adaptive control for time-delayed systems

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