How to Animate Tank Tracks?


#1

I need to animate set of tracks similar to that found on a tank. Each track consists of 60 individual parts that need to follow each other around a path. I have tried using the method shown in the “simple roller coaster” sample, but the IK chain becomes too cumbersome after about 10 links (Tried 60 links but the IK precalc was still going after 10 minutes when I cancelled it).

I’ve watched videos on how to create tracks in other programs. The track parts are wrapped around the path as a flexible mesh. Then only the first part needs to be animated - the rest of the parts follow the first around the path.

Is there any way in Bongo to animate the 60 parts of the track as a single flexible/joined surface or mesh in Bongo in which only the leading parts needs to be animated?


#2

The track parts have been animated using the flow along a curve technique shown in the “Animate along a path” post video: The tank track path is a tightly spaced spiral (offset .0001) and the moving horizontal line is twice as long as the spiral length. The track treads are centered on the moving line.

Now I need to drive the moving line with a tangent circle the same diameter as one of the tank track wheels. I know how to drive the circle using an expression matching the rotation of the track wheel. But how can the circle circumference move the horizontal line?


(Marika Almgren) #3

Would it be possible for you to send the model to us?
You can upload it here:
http://www.rhino3d.com/upload
and put me (marika.almgren@mcneel.com) as the recipient.


#4

Thru more reading of the expressions help, I found that 3D tweening had to be disabled in order to enter an expression in the X position of the horizontal line. So the X position is controlled by the (tank wheel rotation*.01745)*wheel radius.