Fractional Control Basic

Home Forums FOMCON toolbox: Support forum Fractional Control Basic

Viewing 15 posts - 1 through 15 (of 36 total)
  • Author
    Posts
  • #794
    Pritesh
    Guest

    Hi,

    I have some basic understanding problem. Whenever we take fractional transfer function. Inside calculation, they use approximation method and convert to higher order control system.

    Then, if we use higher order PID (some different form), is it the same?

    sorry for asking stupid question?

    Thanking You,

    #796
    Aleksei
    Keymaster

    To an extent, yes; since approximations are used, we may consider a particular fractional-order PID controller approximation to belong to a set of all possible high-order integer-order controllers for a given control problem.

    #881
    Pritesh Shah
    Guest

    Hi Alekesi,

    One more question. What is use of Mittage Leffer function in FPID?

    or In general.

    Thanks,

    #883
    Aleksei
    Keymaster

    In general, the Mittag-Leffler function in two parameters is a powerful generalization. It may be used to compute the (roughly speaking) fractional exponential function and thus may be employed for solving fractional-order differential equations. However, direct use of this function for real-time problems is limited. Therefore, it is not used in FOMCON for FOPID related computations.

    #893
    Pritesh Shah
    Guest

    Hi Alekesi,

    I am little bit confuse between CRONE controller and fractional PID Controller.

    What is the basics difference between these?

    Thanking You,

    Pritesh

    #895
    Aleksei
    Keymaster

    The underlying principles are the same. However, different approaches are used: the fractional-order PID may be seen as a generalization of the classical PID, while the CRONE controller is based on a novel control strategy specifically developed by leveraging the flexibility of fractional-order operators. In both cases frequency domain analysis plays an important role, in case of CRONE controllers even more so.

    • This reply was modified 6 years, 7 months ago by Aleksei.
    • This reply was modified 6 years, 7 months ago by Aleksei.
    #932
    Pritesh Shah
    Guest

    Hi Alekesi,

    Once again, I am troubling you.

    I am trying to identify model of fractional order structure.

    Say I want to identify , k/(s^a+b); a is non integer.

    How can I use FOMCON for the same?

    Could you please give some small example if possible?

    Thanking You,

    Pritesh

    #935
    Aleksei
    Keymaster

    You can use the fotfid tool for this purpose.

    #958
    Pritesh Shah
    Guest

    Hi Alekesi,

    I have some basic understanding problem. We have a process control in our lab. We want to implement in real time.

    By your toolbox, we got controller in Z Transform.

    Now, we get error in time domain. How do we find out controller output? (Controller in z Transform)

    Thanking You, once again.

    #960
    Aleksei
    Keymaster

    Please elaborate. If you use Simulink then you can use the fractional PID block from the FOMCON library.

    #965
    Smita
    Guest

    Hi Aleksei,
    I am finding error while testing the stability of a FOPDT(First Order Plus Delay) plant in fotf viewer(FOMCON command).The plant is K.(e^0.2s)/20s+1.

    The error is : Cannot assess the stability of a system with internal delays.
    How can I solve it???

    Also I want to know which is the updated version of FOMCON : 0.41-beta or 0.42-beta

    Please suggest.Thanks

    Regards
    Smita

    #969
    Aleksei
    Keymaster

    At the moment, it is not possible to assess the stability of systems with delays.
    The latest version is 0.41-beta, for which a patch has been released in April. See this post: https://fomcon.net/forums/topic/preliminary-releases-and-patches/#post-914

    #1012
    Pritesh Shah
    Guest

    Hi Alekesi,

    Difference between crone and fractional order controller ?

    I know that both of them use kind of fractional calculus only. They have a different structure of controller.

    Any comparison or any paper which you can suggest.

    Thanking You, once again.

    #1014
    Aleksei
    Keymaster

    CRONE has several generations of controllers. Kindly see the book in https://fomcon.net/fo/overview-of-literature/ for details.

    For instance, the first generation CRONE controller has the following form
    \[
    C(s)=C_0 s^{\alpha}\tag{1},
    \]
    with $\alpha, C_0\in\mathbb{R}$. This can be seen as one of the dynamical components of a fractional-order PID controller, e.g., the integral component
    \[
    C_I(s)=K_i s^{-\lambda},
    \]
    where $C_0=K_i$ and $\alpha=-\lambda$ in (1).

    • This reply was modified 5 years, 11 months ago by Aleksei.
    • This reply was modified 5 years, 11 months ago by Aleksei.
    • This reply was modified 5 years, 11 months ago by Aleksei.
    • This reply was modified 5 years, 11 months ago by Aleksei.
    #1019
    Pritesh Shah
    Guest

    Thank You for your kind reply.

Viewing 15 posts - 1 through 15 (of 36 total)
  • You must be logged in to reply to this topic.