Symbolic Posted January 9, 2008 Share Posted January 9, 2008 Hi, I am trying to re-create the "newton's cradle" example from the Gnomon RBDs DVD. Some how I got stuck... something is wrong. I have to systems. One uses "RBD Pin Constrains" the other one uses "RBD Spring Constrain"... In the system with the Pin constrains, the balls just go through each other. I do not know what is wrong? Sorry it is a very messy file. I wanted to be able to control the position of everything with nulls... ended up with a totally non-procedural system. newton_15_wrong.hipnc Quote Link to comment Share on other sites More sharing options...
Symbolic Posted January 10, 2008 Author Share Posted January 10, 2008 ...any idea about what is wrong with those constrains? Quote Link to comment Share on other sites More sharing options...
Zanozza Posted January 10, 2008 Share Posted January 10, 2008 Use the RBD Hinge Constraint and don't worry... Quote Link to comment Share on other sites More sharing options...
Symbolic Posted January 10, 2008 Author Share Posted January 10, 2008 Yeah... but when I use it then the ball keeps leveled when moving up and down... like there is a rod passing through it... I just wanted the DOPs system to be correct as possible... maybe I will use just one "RBD Pin Constrain" going through the center of the ball... Instead of trying to make like the real toy... guess cheating is the word It is not that important... I just got confused about this... I wish the example was in the DVD... i guess it is not... and the RBDContrain is not there in H9... thats what confused me. Sorry for wasting your time. Quote Link to comment Share on other sites More sharing options...
eetu Posted January 11, 2008 Share Posted January 11, 2008 I tried to get the collision in your hipnc to work but couldn't - now I'm confused too (being a relative noob might explain that, though) The other branch does work, but the one with pin constraints just refuses to collide. eetu. Quote Link to comment Share on other sites More sharing options...
Symbolic Posted January 11, 2008 Author Share Posted January 11, 2008 Yes!? What is wrong with this thing?! It makes me crazy! Quote Link to comment Share on other sites More sharing options...
mtucker Posted January 14, 2008 Share Posted January 14, 2008 Jeff Lait solved this one. The Rotational Stiffness parameter on the RBD Objects was set to zero. The help for this parameter says that a lower value makes the object easier to spin. But what the help doesn't say is that a value of zero breaks the system completely. Setting this value to zero is like giving an object a zero mass - it makes the value physically meaningless. Generally when a simulation suddenly breaks, the best thing to do is hit Undo a few times until it starts working again. Then figure out what parameter is was that you changed to make it break. Fixing a simulation as soon as it breaks is always the best time to do it. Another good way to debug these problems is to rebuild the simulation from scratch, and more often than not it will work. Then you just need to start comparing parameters (opscript output can be useful here) until you find what is different. Mark Quote Link to comment Share on other sites More sharing options...
michael Posted January 14, 2008 Share Posted January 14, 2008 Fixing a simulation as soon as it breaks is always the best time to do it. Gold. Quote Link to comment Share on other sites More sharing options...
stu Posted January 15, 2008 Share Posted January 15, 2008 But what the help doesn't say... Silver. Quote Link to comment Share on other sites More sharing options...
Marc Posted January 15, 2008 Share Posted January 15, 2008 value of zero breaks the system completely Fail! Quote Link to comment Share on other sites More sharing options...
Symbolic Posted January 15, 2008 Author Share Posted January 15, 2008 Thanks! Wow! I did not know that I was on something that serious! ... I thought that it was just me being stupid Quote Link to comment Share on other sites More sharing options...
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