Bicycle: 2Wheeler+CrawlerTrack. I need some help.

[Milko]

Hello there,

First I'd like to say thanks for making my life so much easier!
I really like CDT, everything works straight out of the box!

The case:
However, I have a few questions regarding a Bicycle rig.
I am using the Bicycle preset, with Crawler Track instead of Geared Chain, because I want the chain to be dynamic,
also there are two additional Suspension add-ons, and a few bones building the slightly complex custom rear suspension.

The issues:
A: My chain is always hanging more than it should, it looks more like rope than a chain, now matter the settings.
I tried playing with the Displacement, Bending and Flaccidity settings, but I could not get it to behave like a real chain.
Could you give me some pointers to start from?

B: The chain is always stretching (the gaps between the links is increasing/decreasing when it should be constant =0), how can I fix that?

C: If I speed up a bit more, it becomes unstable, some of the chain links are getting stuck beneath the drive wheel.
I tried to increase the accuracy and subFrames, but with no luck.

D: Is there a smarter way of attaching the HiPoly chain to the LowPoly one?
I have to do it link by link because my chain is made up of two different links (inner and outer), so I'm using instances of both and then attaching them manually.

E: This is how the setup of the gears looks like:

This is not the rigged chain, it is only a template.

The chain is going well around the blue, yellow, and red gears, but no matter what type of wheel or in what order the gears are created, the chain doesn't go around the green one.
Sometimes when it speeds up, the chain falls the by chance, but it gets stretched instead of getting tighter.
(which in reality is support wheel, to tighten the chain and to keep it from falling off the gear).

F: I'd like to start the recording in mid air, but once I press record it sticks to the ground on the second frame, where it should fall for at least a few frames, and then bounce up a bit.
With a fresh Bicycle tool, with nothing attached to it, and with the 'Jumpy' settings it works perfectly. Is there a workaround?


Err, well, I think that's it for now.
Sorry for the long rant!

Thanks!

Milko

[Patrik Martin]

Hi Milko,

A: My chain is always hanging more than it should, it looks more like rope than a chain, now matter the settings.
I tried playing with the Displacement, Bending and Flaccidity settings, but I could not get it to behave like a real chain.
Could you give me some pointers to start from?

I would first of all go for the GearedChain insted of the CrawlerTracks for this type of animation .
The main parameter to change to get more stiffness in the CrawlerTracks is the Flaccidity setting "Flaccidity Reduction" In my test I turned that up to 20 and I set the gravity to 0. Other then that I usually restrict by using the support wheels. In the picture here for example I have used extra wheels to restrickt the chain from bouncing off to much.

B: The chain is always stretching (the gaps between the links is increasing/decreasing when it should be constant =0), how can I fix that?

You can change the Displacement Stiffness and Damping for this problem. On the other hand it can make the chain quite instable and may blow off. I would say that its hard to get it to be 0 in displacement in the physics.

C: If I speed up a bit more, it becomes unstable, some of the chain links are getting stuck beneath the drive wheel.
I tried to increase the accuracy and subFrames, but with no luck.

You are able increase subFrames as you are saying but you are also able to make your scene have more fps. The other way is to make restrictions by using the support wheels to control the chain.

D: Is there a smarter way of attaching the HiPoly chain to the LowPoly one?
I have to do it link by link because my chain is made up of two different links (inner and outer), so I'm using instances of both and then attaching them manually.

I am sorry that you need to do this manually. The tool does not have a function for cloning two different types of links in the same chain. We have had a request for this one time earlier. I will add this to the wishlist of functions and enhancements.

E: This is how the setup of the gears looks like:
[ http://img841.imageshack.us/img841/5807/chaina.jpg ]
This is not the rigged chain, it is only a template.

The chain is going well around the blue, yellow, and red gears, but no matter what type of wheel or in what order the gears are created, the chain doesn't go around the green one.
Sometimes when it speeds up, the chain falls the by chance, but it gets stretched instead of getting tighter.
(which in reality is support wheel, to tighten the chain and to keep it from falling off the gear).

To get the chain to go around the green one you would use a non-static Outer Wheel. And if you like it to tighten the chain (not sure if this is going to work good, it will probably just stretch the track) you would set a keyframe for it to get thighter. In this case move up.

F: I'd like to start the recording in mid air, but once I press record it sticks to the ground on the second frame, where it should fall for at least a few frames, and then bounce up a bit.
With a fresh Bicycle tool, with nothing attached to it, and with the 'Jumpy' settings it works perfectly. Is there a workaround?

Usually what I know is that the tools can not start from the air but the only thing I can think of is to activate the "Enable Jumping" in the Jumping Parameters of the 2-Wheeler Extended.

Hope this got you somewhat on the right track.

Patrik