car rig not working

I amtrying to follow this car rig tut and I have come to a point where the chassis is suppose to track behind the empty. The empty will be moving the entire rig, so moving it to the right would cause the nose of the chassis to follow with the tail of it following behind like a car would.

Currently moving the empty causes the chassis to simply follow as if parented (this is what the tut calls for, so its an expected result) I unparented the chassis from the empty but then the chassis would not follow at all. The track to constraint has no effect.

Could you please take a look to see what the problem may be?

Attachments

car_rig_1.blend (363 KB)

It was not necessary to create a new topic for the same thing.

You can download the corrected blend file for Blender 2.62 on the link below.

Nothing was done in your rig : The tail and nose vertex groups were created but not assigned, so they had no effect.

A self tracking constraint on same object doesn’t work. You have to add an intermediary object : an empty parented to the tail vertex group, for example. You can also use as target the tail vertex group of the sensor, as it is parented to the chassis.

You hadn’t applied the same axis direction to all objects. Always Apply Scale and Rotation to all objects before parenting or adding constraints, by typing Ctrl-A !

You have to set up two keyframes for the tracking constraint : One set to 0 at frame 0 used to reset the rig, and One set to 1 at frame 1 to enable the tracking constraint.

I have duplicated the system and added a trailer to show you how to chain this kind of rig and make trucks with trailers.

Download the file here :

http://3d-synthesis.com/BlenderTests/car_rig_4.blend

Good luck.

Philippe.