Problem with collision detection in 2003 with all the service packs

- P
- pete
  
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posted
20 years ago

Wed, Jun 25, 2003 8:51 PM

Hi, I have made an assembly with a box section with a two holes through it. There is a metal rod that passes through the box section. The rod has a 7mm slot with a circlip, (7.2mm inside dia and 11mm outside dia), in it, which is mated concentrically to the rod, and to one face of the slot, i.e. fixed to the rod. The holes in the box section are 8.2mm dia and the rod is 8mm dia. The rod is mated concentrically to the holes. The rod with the circlip moves through the box section holes and stops when the circlip hits the box section, which is correct, when the rod is moved slowly. But when I move the rod fast through the hole, there is no collision detection, and the rod and the circlip goes through the box section and out the other side!! Hmmm! I think a bug I have found, Says Yoda :-)

- A
- Arlin Sandbulte
  
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posted
20 years ago

Wed, Jun 25, 2003 9:19 PM

This has always been the case with collision detection in SWX. If parts are drug (drug, is that a word?) too fast, things can pass through each other because the refresh is too slow.

In effect, the part is teleported through and thus, never does really collide. Hey, look, SWX has invented the teleporter!!!!!!! I wonder how they do it, must be wormholes!

- H
- Heikki Leivo
  
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posted
20 years ago

Wed, Jun 25, 2003 9:23 PM

I.M.O this is not a bug, but a feature of collision detection. Collision detection is rather complicated and it takes some time to determine whether the bodies collide with each other. SW doesn't have infinite time to calculate collisions in all possible positions of the rod when you move it. If you move the shaft very fast, the shaft may "move" with larger steps than the thickness of the circlip and the material in the hole.

I believe that it is possible to create a such algorithm, which would calculate the total volume which the moving part creates while sweeping through the space. If this volume would then be used in collision detection, such problems should not happen. However, calculating the volume is even more complicated, but maybe in the distant future we might see this kind of solutions as the computers keep up on evolving...

-h-