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Problems creating pendulum like object

Jul 15, 2011 at 9:34 AM

Hi all,

I'm trying to create something similar to a pendulum:

  • It has a round object in the middle
  • It has a weight hanging down from it
  • It can swing 360° in any direction
  • A force can be applied to the round object (motor) in the middle

How would you go about doing this?

So far I have two bodies, a circle (motor) and a rectangle (rod). The motor is pinned in place using a FixedRevoluteJoint (motorJoint) using it's origin. The rod is then connected using a WeldJoint with a slight offset to connect the two together in the right place.

The problem is, they seem to behave very strangely. The motorJoint is not enabled, so should just free wheel? What I am seeing though seems to be a maximum speed when the rod swings down, and then no friction at all when it is swinging back and forth. It never stops.

I have changed both the motors and rods friction and mass (both bodies) which seems to make no difference at all. I can't change any sort of friction or mass for the motorJoint (FixedRevoluteJoint).

What am I doing wrong?

Thanks for any help,