I have a scene of numerous objects ("triggers") arranged on a path that are animated to ride on a twisting conveyor belt. Suspended over the belt, there is a rigid body physics lever that is supposed to rotate on it's hinge whenever a passing trigger object makes contact, which then causes a mallet to swing that is connected to the lever via a rigid body spring constraint.
The problem is that the lever rarely reacts when a trigger makes contact. I have tried changing the sensitivity margin settings of both the lever and each trigger, but this has yielded hard to reproduce results. I have checked my normals, scale, etc. I have increased the Rigid Body World steps per second. I was able to fiddle with settings on the object physics properties, but could only get one of the triggers to move the lever; but after saving and then re-opening the blend file, the previously working trigger failed to work again!
In the screen shot, you can see the triggers distributed along the spiral conveyor, with an example trigger labled "X" (that will make contact with the lever when the animation starts). The curving arrow illustrates the direction of travel of the triggers (which travel at a steady velocity). The lever/mallet contraption is suspended over the triggers.
I would very much appreciate any suggestions as to what might be the issue.
Here is my blend file: https://drive.google.com/file/d/0B8euJ49ta_XTUFRnT2xTdTlZOEk/view?usp=sharing
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I created a simplified setup to figure this out, and I think that I am zeroing in, but not there yet.
I placed a simple spinning paddle wheel object under the lever. Eight paddles, with seven that are 0.05 blender units thick, and one paddle that is about 0.15 units thick. The tips of the paddles are about 9 blender units apart. I set the sensitivity margins of all physics objects to default 0.04.
The speed of the paddles, and the thickness of the paddles seem to make a difference. If I set the rate of spin down to a 2 second interval per paddle, the lever responds consistently to each paddle. If I speed up the paddle wheel, to about one second paddle spacing, then the lever hits success become variable: completely missing one third, slightly twitching for a third, and the final third are hit solidly.
At a midway speed setting of 1.5 seconds per paddle, I see an improvement over the 1 second spacing results. What I also notice at this speed is that the thicker paddle has the best chance (but not 100%) of moving the lever. When it does move the lever, the thicker paddle also forces the lever to deflect further than the thinner paddles deflect the lever.
I hope these further clues help to find a solution.