An adaptive cascade control for a class of chemical reactors

Alvarez-Ramı́rez, José; Álvarez, Jesús; Morales-Díaz, América Berenice

doi:10.1002/acs.717

Cited by 33 publications

(20 citation statements)

References 14 publications

(23 reference statements)

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“…Some comments on the comparison of the proposed batch reactor temperature controller with its previously presented continuous reactor counterpart [19] are in order. In the continuous reactor case, the closed-loop system is autonomous over an infinite-time horizon, the regulation is performed about a given (possibly open-loop unstable) critical point, the control characteristic time t c is not bounded from above, and t f is typically set two times smaller (i.e.…”

Section: Feedforward-state Feedback Controlmentioning

confidence: 99%

Linear PI control of batch exothermic reactors with temperature measurement

Alvarez-Ramı́rez

Álvarez

2005

Intl J Robust & Nonlinear

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SUMMARYA wide variety of speciality materials and fine chemicals such as plastics, pharmaceutical and microelectronics components are produced in batch reactors. The nonlinear, transient and finite-time features of the batch reactors give rise to complex process and control design problems. In particular, the safe operation of exothermic reactors depends on the adequate functioning of a temperature tracking controller, and to a good extent, the same is true for the attainment of a suitable compromise between productivity and product quality attributes. While the stabilization problem of continuous exothermic chemical reactors has been recently addressed with rigorous asymptotic-stability methods, the same kind of studies have not yet been performed for the finite-time batch reactor case. In this paper, the problem of designing a temperature tracking controller for an exothermic batch reactor, with n species and m reactions, is addressed under the following premises: (i) only the reactor temperature is measured, (ii) the (typically uncertain) reaction rate and heat exchange nonlinear functions are unknown, (iii) the controller must be linear and easy to tune, and (iv) the closed-loop reactor motion must be stable in a suitable sense. The combination of industrial-oriented inventory control concepts in conjunction with singular perturbation results yields a linear controller with a combined feedforward-PI feedback structure, antireset windup scheme, and conventional-like tuning rules. The controller: (i) tracks, arbitrarily fast and close, a prescribed temperature trajectory, with admissibly deviated concentration motions, and (ii) quickly recovers the behaviour of an exact model-based nonlinear I/O linearizing controller. The proposed design is put in perspective with the geometric and IMC nonlinear control approaches.

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Section: Feedforward-state Feedback Controlmentioning

confidence: 99%

Linear PI control of batch exothermic reactors with temperature measurement

Alvarez-Ramı́rez

Álvarez

2005

Intl J Robust & Nonlinear

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“…1 By providing an online estimate of the modeling error signal, the feedback controller is able to counteract, at least asymptotically, with its potentially unstablizing effects. Notice that in opposition to classical adaptive control where system parameters are continuously updated, in this case adaptation is based on estimation of the trajectory of the modeling error function.…”

Section: Controlling Bis Through Endtidal Concentrations: Master Contmentioning

confidence: 99%

“…To obtain a practical controller, as in the master control loop, the MEC idea is to use estimates of η S and φ obtained from measurement-driven estimators. 1 For convenience, assume that the time derivative dy S /dt is the measured output. Later in this subsection, we shall remove this assumption since y S is the actual measured output.…”

Section: Controlling Endtidal Concentration Through Isoflurane Dosagementioning

confidence: 99%

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A Cascade Feedback Control Approach for Hypnosis

Puebla

Alvarez-Ramı́rez

2005

Ann Biomed Eng

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This article studies the problem of controlling the drug administration during an anesthesia process, where muscle relaxation, analgesia, and hypnosis are regulated by means of monitored administration of specific drugs. On the basis of a seventh-order nonlinear pharmacokinetic-pharmacodynamic representation of the hypnosis process dynamics, a cascade (master/slave) feedback control structure for controlling the bispectral index (BIS) is proposed. The master controller compares the measured BIS with its reference value to provide the expired isoflurane concentration reference to the slave controller. In turn, the slave controller manipulates the anesthetic isoflurane concentration entering the anesthetic system to achieve the reference from the master controller. The advantage of the proposed cascade control structure with respect to its noncascade counterpart is that the former provides operation protection against BIS measurement failures. In fact, under a BIS measurement fault, the master control feedback is broken and the slave controller operates under a safe reference value. Extensive numerical simulations are used to illustrate the functioning of the proposed cascade control structure.

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“…Cascade control is a common control configuration in process control, which can be thought of as partial state feedback. A typical cascade control structure has two feedback controllers with the output of the primary (master) controller changing the set point of the secondary (slave) controller (Alvarez-Ramirez et al, 2002;Krishnaswamy et al, 1990). Figure 1 shows the recursive cascade control configuration for the class of mechanical systems given by (7).…”

Section: A Cascade Control Schemementioning

confidence: 99%