How can I make an elastic pendulum using Simmechanics 2nd generation

How can I define a pendulum suspended on an elastic rope in 3D using blocks from SimMechanics 2nd generation? It should have the ability to swing like a pendulum in 3D (spherical joint) and oscillate like a vertical spring oscillator at the same time. Thanks for suggestions!

Answer 1

[Manuel]

Hi Jan,

You can do that by introducing a prismatic joint on your pendulum and specifying internal mechanics with some spring stiffness. You can look at the doc of the prismatic joint: http://www.mathworks.com/help/physmod/sm/ref/prismaticjoint.html

Regards Manuel

[Jan Balajka]

Thank you, that was helpful. However I didn't understand how to set correct equilibrium length in internal mechanics of the prismatic joint. If I set it to zero the two bodies coincide, if I set it to some value, the direction is undefined and the suspended body starts flying around the fixed one. Therefore I started using prismatic joint with all values set to zero and rigid transform of the desired spring length in series. In parallel to these two I put spring&damper force where I set the correct spring parameters. It is perhaps not the nicest solution but it seems to work. Thanks, Jan