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Design >> Analog Design >> an interesting control problem
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Message started by manodipan on Jun 5^th, 2009, 2:57am

Title: an interesting control problem
Post by manodipan on Jun 5^th, 2009, 2:57am

Hi all,
The problem is described below:
A system has three variables related by difference equations....now all of them are to be directed towards a reference value within a finite time....right now i am using comparison of those variables with reference independently and then using binary search algorithm...it seems like that it works for a two variable problem but i am not able to implement it for three or more variables.....i greatly solicit your suggestions in this regard....thanks a lot

Title: Re: an interesting control problem
Post by vivkr on Jun 8^th, 2009, 11:58pm

Just one thing comes to my mind. Have you atleast verified that it is possible to have all 3 variables at the same value in steady-state, not that their interrelationship gives a conflict where setting 2 of the variables to a value x0 automatically constrains the third one to be within a certain range x1 to x2 which does not include x0?

In other words, are the 3 variables of interest truly independent? If they are coupled together with difference equations, then it may that only 2 of the 3 are independent.

Regards,

Vivek

Title: Re: an interesting control problem
Post by manodipan on Jun 9^th, 2009, 1:49am

Hi Vivek,
Lot of thanks for your reply......yes the variables are related by difference equations and may be they are not all independent....so now is there any way to force them to a common value,because it can be nonlinearly controlled(i.e. digital control)...and i actually want it to be generalised for multivariable system....any kind of suggestions are greatly welcome....

Title: Re: an interesting control problem
Post by raja.cedt on Jun 9^th, 2009, 9:25am

hi,
if you have equations why don't you post?

thanks,
Rajasekhar.

Title: Re: an interesting control problem
Post by vivkr on Jun 9^th, 2009, 11:45pm

manodipan wrote on Jun 9^th, 2009, 1:49am:

Hi,

I would suggest using standard state-space techniques to describe the system and then using analysis techniques to find:
(a) the number of independent variables.
(b) the solution space, so that you may see whether or not it is possible to force all the variables to a common value, and if yes, then what that common value is allowed to be.

I assume that once you have worked out the above two, you may be able to use your binary-search based method to force the variables to a common value. I could not tell you more.

btw, your question actually does not appear to be explicitly related to analog design. Perhaps posting it on another forum would be more helpful.

Regards,

Vivek