Two point hold pendulum with damping

Hi,

I wish to use simulink to simulate a 2D box which at each of its upper corners is attached to two fixed points on the 'ceiling'. I want to simulate the swing and damping of said box given an initial angle of displacement. Also the cables attaching the box are not rigid, i.e. they should be modelled as flexible, but not stretchy, ropes.

Any ideas on this problem are very welcome. Thanks.

Jasmine

Answer 1

[Ryan G]

I would use simmechanics.

http://www.mathworks.com/products/simmechanics/

I'm not sure how you can do a rope. Probably connect multiple rigid bodies together in series would be accurate enough. You could do this programatically to adjust the accuracy of the rope.

[Jasmine]

I had thought that SimMechanics might be best. Unfortunatly I can't get hold of it (can't even download the trial). So this means I must only use Simulink. I have already modelled a simple pendulum and a damped pendulum. I suppose that part of my question is: Is the motion of the box any different if I have two ropes attached to the upper corners than if I have a point mass pendulum with one rope?

[Ryan G]

There is a good blog post about modeling a pendulum and how complex the equations become as you add more components. The rop in this problem adds complexity as you would expect the tension of the rope to effect the dynamics as it swings. This will show why SimMechanics is a good tool for the job but unfortunately I don't think I could help any further developing the EOM of the system, which sounds like what you want.

SimMechanics Pendulum

[Jasmine]

OK thanks. I did happen to come across that blog post a couple of days ago and it did help me with simulating a simple pendulum. I guess I'll just keep trying.