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Machinery animations About Truespace Archives These pages are a copy of the official truespace forums prior to their removal somewhere around 2011. They are retained here for archive purposes only. Machinery animations // Archive: Tech Forum 1  |   Order by default Post by bill // Mar 14, 2006, 8:36am bill Total Posts: 114 I'm looking for suggestions on how to approach mechanical animations, specifically an engine design I'm working on. I have all the components modeled but I'm not sure about what is the best way to animate it all. I modeled the engine in Autodesk Inventor. Inventor is great for this because all the parts are parametric. This means that I can set up parts so that if I change the size of one part it can affect other parts and they will adjust accordingly. I can even assemble all the parts using 3D constraints and then move one part, a piston for instance, and the rest of the model will move as if it were an actual physical machine. The problem is that Inventor does not take into account mass, inertia, and kenetic energy. For most mechanical designs this is not a problem for animating the machine. However, this particular design requires that these factors be taken into account because at one point in each rotation a piston cound go either up or down even though the crank shaft continues in the same direction. I can't show why this happens because I don't have the design patented yet. But at this critical point in the cycle inertia needs to take the piston past the point where it could go back down rather than continuing up. It's just about 1 degree of rotation where this occurs. After that then there is no problem. This is where I run into a problem animating this engine in Inventor. Since Inventor does not take into account the inertia of the piston then the piston has a tendency to stop and go back down rather than continuing up. At one time when I initially started on this design I did it in Truespace and animated it by glueing it up and animated it with keyframes every 5 degrees of rotation. This was a very long process and required complex calculations in a spreadsheet to determine the amount of movement for the piston to achieve each 5 degree rotation of the crank shaft. It worked fine until I made some design changes. I don't want to go through that every time I make a design tweak. So this brings me to my question. How is the best way to do this in Truespace 7. I'm thinking about the possibility of using the Physics in TS to handle all the animation since supposedly V7's physics engine has been improved. Would this be the way to go or would a scripting method be the way to approach it. Or maybe some combination of both. I did try a small test with a few of the parts using the Physics engine and I ran into problems with parts passing through other parts and it just fell apart. But I understand that the next patch will have additional physics improvments that may overcome this. Any suggestions would be appreciated. Post by Délé // Mar 14, 2006, 9:31am Délé Total Posts: 1374 I can't say that I'm mechanically inclined in any way, but while I've been playing with procedural animation I keep thinking that this would be ideal for animating machines. Perhaps along with physics. I can see the "zigzagger" I made a while back being good for animating pistons moving. The "rock 'n roller" being good for something like a clock pendulum swinging back and forth. I haven't tried using these things in a mechanical way or with physics yet though. I personally think that a procedural approach would allow the most versatility for something like this. You could set precise rotation degrees and movements, but still be able to quickly and easily make any adjustments (even while the animation is playing). You could even have speed controls and such. This is kind of like walking new roads in TS but I'd be happy to assist where I can. :) Post by GraySho // Mar 14, 2006, 10:39am GraySho Total Posts: 695 If the pistons ly in row it would be fairly easy to animate them with a sine function. Post by Bobbins // Mar 14, 2006, 11:56pm Bobbins Total Posts: 506 If you are having problems with geometry passing through each other on a physical simulation, it's usually either because of insufficient geometry in the models or too low a value for the timesteps between physical calculations. My initial thoughts on how to animate this are to set up the model with IK joints then hand keyframe the positions of cranks and pistons. A bit hard to know for sure without seeing the engine design so this suggestion is based on animating a regular engine.

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