Dozer Track Rig problem

I am trying create an automatic dozer track rig in blender. When I move the root bone I want the tracks to rotate. Also when i rotate the root bone I want one track to rotate back and one forward.

The way I am trying to achieve this effect is by use of transformation constraints. When I move the root bone along its y axes I have the transformation constraint convert the action to a rotation. However, when I rotate the root 90 degree and try and move it along the bones y axis again the transformation constraint no longer works.

What I need to be able to do is transform the action from “normal space”. I have it set to local space now.

Does any one know how to fix this problem?


Test rig.blend (258 KB)