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Split range and selective control

• Statistical Process Control• Feedforward and ratio

control• Cascade control• Split range and selective control

• Control of MIMO processes

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Split range and selective control

Structure of discussion:• Split range control • Selective control• Case study: air-fuel control application –

ratio control vs. selector control• Lifelong learning

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1. Split range control

Reference: Marlin, T.E (2000). Process Control, Chapter 22. 4

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2. Selective control

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To think about selective control, we consider a process example.

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• Low selector:

• High selector:

• Median selector:

The output, Z, is the median of an odd number of inputs

Selector types

Reference: Seborg, D.E. et al. (2004). Process dynamics and control, Chapter 16.

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• multiple measurements• one controller• one final control element

High selector example

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3. Case study: air-fuel control application – ratio control vs. selector control

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4. Lifelong learningBooks:1. Seborg, D.E. et al. (2004). Process dynamics and control, 2nd edition, Chapter

16.2. Marlin, T.E. (2000). Process control, Chapter 22.

Trade magazines (e.g. Control Engineering) often have web-accessible tutorial articles on aspects of variable structure control. One example of these articles is:Gerry, G. (1991). Tune loops for load upsets versus setpoint changes, Control, September. http://www.expertune.com/artcon91.html

Finally, there are many web based tutorials and discussions on the basics of variable structure control. One example:“Override control”, http://www.jashaw.com/pid/override.html