2 Replies Latest reply on Apr 21, 2015 5:47 PM by Chris B.

    Simulating complex motion using collision detection

    Nicholas Meysner

      Hi.  I'm learning about collision detection in Solidworks for the first time, and I wanted to ask about using collision detection to define an assembly's motion as opposed to using mates to do so.

       

      For example, say you have a basic hinge design, with interlocking concentric rings attached to each of two parts, and a pin that goes though them.  It seems to me that, once the parts are properly assembled, instead of using mates to define the parts' motion, you could enable "Collision Detection with Physical Dynamics" between the parts, suppress all the mates (with the possible exception of restricting the pin's movement along the axis of the hinge), and the hinge would behave as intended.

       

      While it seems clear to me that you CAN do this, my question is, is it good practice?  On the one hand, it creates realistic motion (i.e. the parts are restricted primarily by their inability to overlap, which is how it works in real life), which can be useful; but on the other hand, I expect it would be more computationally intensive with dynamic motion compared to just using mates, especially with more complex assemblies.

       

      And the project I'm thinking of doing this with does indeed have a lot of moving parts.  Imagine simulating a bike chain to get an idea of the sheer quantity of individual part interactions that I would be keeping track of in this manner.  I want to do it for the realism, to verify that the mechanism's design works the way I intend it to; but it it impractical (or just considered not good practice) because of the computational intensity?  Thanks.

        • Re: Simulating complex motion using collision detection
          Jeff Mirisola

          Collision detection is only available during the Move or Rotate Component command. As you mentioned you can use physical dynamics, but it relies on the existing mates to define a part's degrees of freedom. Like them or not, mates are necessary.

          • Re: Simulating complex motion using collision detection
            Chris B.

            Hi Nicholas

             

            As a note, for collision detection to work, the parts cannot be touching in any way to begin with.  So all parts would have to be mated and designed with some space between them and the other parts.  I don't think any of them could even be flush.

             

            I did collision detection between two gears, to simulate the movement of one gear based on another gear's rotation.  When the tooth of one gear hit a tooth of another gear, that second gear was spun accordingly.

             

            Even this simple example nearly brought the computer to its knees.  I don't believe simulating an entire bike chain this way would work very well.