Asked by Bas Siebers
on 10 Feb 2015

Hi,

I want to simulate a spherical pendulum in matlab. So far, I have found the equation of motion of the spherical pendulum:

But I haven't a clue how to simulate this. Any help whil be useful.

Kind regards, Bas

Answer by Roger Stafford
on 11 Feb 2015

Edited by Roger Stafford
on 11 Feb 2015

Accepted Answer

Bas, you have a sign error in the gravity term. It should be:

-g*sin(phi)/L

Use one of matlab's 'ode' solvers to numerically solve these equations. Read about how to use them at:

http://www.mathworks.com/help/matlab/math/ordinary-differential-equations.html

Note that you would have numerical accuracy difficulty if the angle phi approaches near zero because of the division by sin(phi) in the first equation. At that point theta would change very rapidly. That is inherent in the physical situation as measured by the two angles.

Bas Siebers
on 25 Feb 2015

Roger Stafford
on 26 Feb 2015

Yes, there is a way. If you (carefully!) transform your coordinate system to cartesian coordinates, this problem should not occur. That will require three dependent variables, x, y, and z. A third equation will express the constraint that the distance from the support point is the value 'L'.

As I mentioned, the problem is caused by the nature of the definition of the two angles - when phi is near zero, a small motion can change theta by large amounts. That is an artificial difficulty.

Bas Siebers
on 22 Apr 2015

Hi Roger,

I started again with solving this problem. Do you known how to transform my coordinates to cartesian coordinates?

Sign in to comment.

Answer by Youssef Khmou
on 11 Feb 2015

Edited by Youssef Khmou
on 11 Feb 2015

You can look for solution in this link :

Sign in to comment.

Opportunities for recent engineering grads.

Apply Today
## 0 Comments

Sign in to comment.