Adaptive control references

Figure 3. Emission of Sulphur Dioxide in Eastern Canada by Source Sectors Total Canadian Emissions and Projections to 2000 and Eastern Canada Control Limits, adapted from reference 14.

Figure 9. Projected Benefit of Emission Controls Reducing Fish Damage in Eastern Canada, adapted from reference 14.

This is employed when the process is not well-known. The Model Reference Adaptive Controller contains a reference model to which the command signal or set point change is applied as well as to the process itself (Fig. 7.98)<4 ). The output of the reference model is postulated as the desired controlled process output and this is compared with the actual process output. The difference (or error) e , between the two outputs is used to adjust the controller parameters so as to minimise the relevant integral criterion. For example, if the ISE criterion is employed then the quantity... 

Fio. 7.98. Block diagram of model reference adaptive control system... 

The architecture of the self-tuning regulator is shown in Fig. 7.99. It is similar to that of the Model Reference Adaptive Controller in that it also consists basically of two loops. The inner loop contains the process and a normal linear feedback controller. The outer loop is used to adjust the parameters of the feedback controller and comprises a recursive parameter estimator and an adjustment mechanism. 

Coughanowr, D. R. Process Systems Analysis and Control, 2nd edn. (McGraw-Hill, New York, 1991). Kuo, B. C. Discrete Data Control Systems (Prentice-Hall, Englewood Cliffs, New Jersey, 1970). Landau, Y. D. Adaptive Control—The Model Reference Approach (Marcel Dekker, New York, 1979). Popovic, D. and Bhatkar, V. P. Distributed Computer Control for Industrial Automation (Marcel Dekker, New York, 1990). 

Landau, Y. D. Adaptive Control—The Model Reference Approach (Marcel Dekker, New York, 1979). 

When the process changes cannot be measured or predicted, the adaptive control strategy must be implemented in a feedback manner. Many such controllers are referred to as self-tuning controllers, or self-adaptive controllers, and a typical block diagram is shown in Figure 13. 

Model reference adaptive control is based on a Lyapunov stability approach, while the hyperstability method uses Popov stability analysis. All of the above methods have been tested on experimental systems, both SISO and MIMO (53), (54), (55). The selftuning regulator is now available as a commercial software package, although this method is not satisfactory for variable time delays, an important industrial problem. 

Oliver, W. K. Seborg, D. E. and Fisher, D.G., "Model Reference Adaptive Control Based on Lyapunov s Direct Method," Chem. Engr. Comm., 1973, 1, 125. 

Fig. 4.4 Effect of alcoholic fermentation and yeast strain on the concentration of glycoside-derived volatile compounds and of different classes of glycosidic precursors during the fermentation of a model grape juice containing Muscat glycosides. The control refers to a non-fermented sample kept under the same conditions utilized for fermentation, which accounts for add catalysed hydrolysis of glycosides (adapted from Ugliano 2006)...

Figure 7.5 Emission spectra of FITC for a model protein assay run (A) at room temperature for 30 minutes and (B) with microwave heating for 20 seconds. Control experiments, where one of the protein binding partners, BSA-biotin is omitted from the assay, run (C) at room temperature and (D) with microwave heating for 20 seconds Room Temp Room Temperature. Adapted from reference 1.

Figure 7.12 (A) Emission spectra of the TAMRA-Oligo as a function of concentration of B. anthracis and B. cereus exosporimn after 30 s low power microwave heating, (b) Control experiment where the anchor probe is omitted from the surface (c) Plot of the fluorescence emission intensity at 585 nm for TAMRA-Oligo as a function of target concentration. Adapted from reference 52.

Figure 3 All group II introns share a common secondary structure with six domains that radiate from a central wheel. Based on differences in some features, group II introns can be divided into subgroups IIA, MB, and IIC. Long-range tertiary interactions are indicated by greek letters. The folding control element is indicated. The catalytic triad in domain D5 is marked by a rectangle. The branch point adenosine in domain D6 is shown as a bold "A." Exons are depicted as gray boxes and intron binding sites are indicated (adapted from Reference 20).

A) An intBr e for the light-controlled bitxling of Cyt c.The cytochrome electrochem-tstry i promoted by the pyridine component, but it is repelled from I lb. (B) Cyclic vottammagrams of cytochrome c, Cyt c, I x 1monolayer electrode. (b)The pyrldlne-protonated-nitromerocyanine (I lb -mb(ed monolayer electrode. Data recorded at a scan rate of 50 mV sec . (Adapted from reference 89, Figure 1. Reproduced by permission ofThe Royal Society of Chemistry.)... 

Figure 5.15. Plot of log air saturation concentration = p°/RT versus water solubility C°ater for selected chemicals (25 °C). Chemicals of equal H lie on the same 45° diagonal. Water phase control and air phase control refer to the transfer kinetics (rate-controlling steps) in the two-film theory. (Adapted from Mackay, 1991.)...

Fig. 1. Simultaneous DSC/WAXS/SAXS design. Experimental setup of the microcalorimeter cell in the time-resolved synchrotron X-ray diffraction environment The cell is positioned with sample-containing capillary perpendicular to the beam in such a way that the diffraction patterns are recorded in the vertical plane including the beam by one or two one-dimensional proportional detectors (Position Sensitive Linear Detector 1 and LD2). Counting Electronic (Counting Elect.), Nanovoltmeter (mVter), and Temperature Controller (T Ctrl) are all monitored by the same PC Computer (PC Comp.). Temperature-Controlled Bath (TCB) is kept at constant temperature (e.g., 20°C). Figure is adapted from Reference 3.

Figure 12.30. Sensitivity enhancement using partial reflection inside a glass capillary with 1 mm inside diameter. Sample depth was controlled by N2 pressure. (Adapted from Reference 32 with permission.)...

Figure 13.7. Surface Raman spectra from nitrobenzene on flat Ni (Ml) in UFIV, following controlled deposition from the gas phase. Field enhancement is negligible in this case. (Adapted from Reference 12 with permission, including reversal of x axis.)...

Figure 9 Degree of platelet retention in unheparinized rabbits undergoing simulated extracorporeal membrane oxygenation (ECMO) whose extracorporeal blood conduits are lined with MAHMA/NO-containing PVC to inhibit platelet adhesion ( ) as compared with controls whose tubing is made of undiazeniumdiolated PVC ( ). [Adapted from Reference 13 with permission.]...

Figure 21. Model reference adaptive control scheme. 

The material of the subsequent four chapters (Chapter 19, 20, 21, and 22) should be viewed as an introduction to the analysis and design of the control systems above. The subject is quite involved, and the interested reader should consult the references at the the end of Part V. In particular, the discussion on the adaptive and inferential control is limited to a simple qualitative presentation of these control systems, since a more rigorous presentation goes beyond the scope of this text. Nevertheless, in Chapter 31, the interested reader will find a mathematical treatment of the adaptive control system design. 

If the process is not known well, we need to evaluate the objective function on-line (while the process is operating) using the values of the controlled output. Then the adaptation mechanism will change the controller parameters in such a way as to optimize (maximize or minimize) the value of the objective function (criterion). In the following two examples we examine the logic of two special self-adaptive control systems model reference adaptive control (MRAC) and self-tuning regulators (STRs). 

Example 22.3 Model-Reference Adaptive Control (MRAC)... 

We notice that the model-reference adaptive control is composed of two loops. The inner loop is an ordinary feedback control loop. The outer loop includes the adaptation mechanism and also looks like a feedback loop. The model output plays the role of the set point while the process... 

The following references on adaptive control involve mathematical analyses which employ more advanced tools than those covered so far in this text. The interested reader can return to these sources after he or she has had some exposure to multivariable systems theory (control and estimation). 

The model-reference adaptive control was originally proposed by Whitaker et al. in 1958 and was developed for servo problems ... 

Design of Model-Reference Adaptive Control Systems for Aircraft, by H. P. Whitaker, J.Yamron, and A. Kezer, Report R-164, Instrumentation Laboratory, MIT, Cambridge, Mass. (1958). 

IAE (see Internal of absolute error) Identification, process, 656 and adaptive control, 662-67 with frequency response data, 668 references, 672-73 using regression analysis, 657-62 Impulse function, 135... 

Self-adaptive control, 436-38, 662-67 Self-regulating systems, 7, 34, 180 Self-tuning regulator, 437-38, 662-67 references, 447, 673 Serial transmission, digital signals, 561 Servo problem (see Feedback control)... 

Discuss the logic of model-reference adaptive control and self-tuning regulators. Find the similarities and differences between the two configurations. 

Show qualitatively that the structure of a self-tuning regulator can be derived from that of a model-reference adaptive control if the parameter estimation is done by updating the reference model. 

In this chapter we have presented a rather simplistic view of the on-line adaptive control systems. There are a number of very important questions which have not been addressed, such as whether the parameter estimates are biased, the interplay between estimation and control, and the stability characteristics of the adaptive controller. A thorough examination of these questions is beyond the scope of this text. The interested reader can consult the relevant references at the end of Part VII. 

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