Control of nonlinearities

Jul 01, 2005 1 Replies

Hi, This may qualify as a dumb question but here goes. I'll shortly be working on a SISO loop that contains a nonlinearity that's causing the problem (real world application, process industries). The nonlinearity is likely to be definable to a degree and severe enough to invalidate linear techniques, the other characteristics of the loop are likely to be common dynamics. My normal approach would be to simulate the system and try various approaches, to reduce the amount of plant trialling. However, I'm wondering whether there exists a 'cookbook' of techniques for dealing with 'common' nonlinearities in regulatory loops. Any suggestions? TIA


Well, the possible solutions depend upon the precise nature of the non-linearity. Since there is an infinity of possible non-linearities (ranging from simple things like non-linear gain, hysteresis, backlash, etc. to exothermic chemical reactions and growth curves in biochemical processes). I'd be surprised if there is a recipe book. Maybe a description of the type of non-linearity could elicit a few suggestions?

Kelvin B. Hales Kelvin Hales Associates Limited Consulting Process Control Engineers Web:

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