View Full Version : IK trouble...

07-08-2004, 09:31 PM
I'm animating the inside of a motorcycle engine, and I'm a bit stuck. The piston/connecting rod/flywheel assembly is driving me nuts. It's three parts, the wheel is connected to the rod and the rod is connected to the piston. When the piston moves up and down, the rod drives the wheel. My problem is I can't keep the piston from moving on the x axis. Here, a picture says a thousand words. Any ideas?

07-09-2004, 09:43 AM
Interesting :)
A few days ago I had exactly the same problem, slightly different setup. Since I was only playing around, I didn't bother to go into it deeper, but now I am interested in an answer, too.
My setup was the other way round, the flywheel as parent in an IK-chain, pulling the rod, with the Piston as goal (with the help of a few nulls, of course), and keeping goal within reach. Still the piston performs a slight x-movement, as you describe it.
So how is that one solved? Expressions?

07-09-2004, 01:19 PM
Since I'm under deadline, I'm faking it. Right now my goal object moves along the Y, with slight movement on X to try to keep the X movement close. Then I animate the piston with keyframes, hiding the sway. I can get away with it, but I wish I could come up with the real solution. I've tried everything, collision detection, nulls with size on the X set to 0... Someone somewhere has done this before. I'm suprised you cant restrain an objects movement to an axis, and that only rotation has restraints.