animate Double Pendulum with solved ODE.

Hi,

I'm trying to animate a double pendule with matlab.

I looked at this tutorial but didnt manage to make it work : https://fr.mathworks.com/help/symbolic/animation-and-solution-of-double-pendulum.html

function double_pendule(x,y,L1,L2)

    x1 = @(t) L1*sin(y(t));
    
    y1 = @(t) -L1 * cos(y(t));
    x2 = @(t) x1 + L2*sin(y(t));
    y2 = @(t) y1 - L2*cos(y(t));
    M1 = 1;
    
    fanimator(@(t) plot(x1(t),y1(t),'ro','MarkerSize',M1*10,'MarkerFaceColor','r'));
    axis equal;
    
end

y looks like this :

What did i do wrong ? Thanks !

[Guillaume Theret]

f animator starts at indice 0 when my y starts at 1. I can't manage to make the f animator starts from 1.

Answer 1

[Sulaymon Eshkabilov]

Hi,

Here is an updated and corrected code with a different animation procedure:

L2 = 20;
t = 0:.1:2*pi;
double_pendule(t, L1, L2);
function double_pendule(t, L1, L2)
    x1 = @(t) L1*sin(t);
    y1 = @(t) -L1 * cos(t);
    x2 = @(t) (x1(t) + L2*sin(t));
    y2 = @(t) (y1(t) - L2*cos(t));
    M1 = 1;
   for ii=1:numel(t)
    plot(x1(ii), y1(ii), 'd', x2(ii), y2(ii), 'o', 'markerfacecolor', 'c'), pause(.1)
    hold all
    axis equal;
   end
end

Good luck.

[Guillaume Theret]

ok thanks, this should work but what about my ODE ? I solved it with euler explicit. The angle needs to be y1(t).

Should i just change it ?