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Driven pendulum and rotary solutions

2020-03-19
2020-03-23
  • Hesam Sharghi

    Hesam Sharghi - 2020-03-19

    I wanted to use the Matcont to follow the solution for the driven pendulum (This is the example from Nonlinear Dynamics And Chaos: With Applications To Physics, Biology, Chemistry, And Engineering by Steven H. Strogatz, pp: 268, where comprehensive explanation can be found)

    phi'=y
    y'=I0-sin(phi)-alpha*y

    where coordinates are: phi and y
    parameters: I0,alpha

    The issue is that the natural phase-space for this problem is a cylinder because the phi coordinate is limited between [0, 2 pi].

    So, I am wondering how can I enforce matcont to find the rotary solution, which are limit cycle solutions in the cylindrical phase-space, and fixed solutions, which are the equilibrium points.

    Should I rewrite the equations in another format, or should I add external equations?

     
    • hilmeijer

      hilmeijer - 2020-03-20

      Dear Hesam,

      This is not supported. A little hint, but a lot of work: You may try to modify the limitcycle class yourself in order to have a different boundary value problem. Now it has x(T)=x(0) and you want x(T)-2pi=x(0). Not impossible, but on this forum I am not going to spend much time on it now.

      Best regards, Hil Meijer


      From: Hesam Sharghi hesamaero@users.sourceforge.net
      Sent: Thursday, March 19, 2020 7:11 PM
      To: [matcont:discussion]
      Subject: [matcont:discussion] Driven pendulum and rotary solutions

      I wanted to use the Matcont to follow the solution for the driven pendulum (This is the example from Nonlinear Dynamics And Chaos: With Applications To Physics, Biology, Chemistry, And Engineering by Steven H. Strogatz, pp: 268, where comprehensive explanation can be found)

      phi'=y
      y'=I0-sin(phi)-alpha*y

      where coordinates are: phi and y
      parameters: I0,alpha

      The issue is that the natural phase-space for this problem is a cylinder because the phi coordinate is limited between [0, 2 pi].

      So, I am wondering how can I enforce matcont to find the rotary solution, which are limit cycle solutions in the cylindrical phase-space, and fixed solutions, which are the equilibrium points.

      Should I rewrite the equations in another format, or should I add external equations?


      Driven pendulum and rotary solutions


      Sent from sourceforge.net because you indicated interest in https://sourceforge.net/p/matcont/discussion/762214/

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      • Hesam Sharghi

        Hesam Sharghi - 2020-03-20

        Dear Hil,

        Is it possibe to rewrite equations in the cartesian coordinates? Then, that case I do not have the polar coordinate.

         
  • Hesam Sharghi

    Hesam Sharghi - 2020-03-20

    Dear Hil,

    Thank you for your suggestion.

     

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