Two things following a path

I have a vehicle following a path. works fine cos i was told to use Ctrl Shift P.
now i want the vehicle to tow another vehicel around the same path.
it kinda hangs out cos the point it is following is NOT under the car.
How do i do this? 2 paths? how do i move the point it follows on the second path?
blender 2.42

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Hmmm … I was hoping someone would respond to your post … but apparently not too many people animate cars towing stuff or trains along a path … I did a search and there were only 3 hits on this topic …

Well I did some playing around and and figured out a way of doing this, though I hope someone with more experience with this sort of stuff can give more insight into this problem …

Here is a basic blend just using armature bones : http://uploader.polorix.net//files/307/train_bones1.blend

And one just using mesh objects with front wheels that turn for your other post : http://blenderartists.org/forum/showthread.php?t=105313 , but this also has a “towed” object in it : http://uploader.polorix.net//files/307/turning_wheels_train1.blend

Basically to get the towed object to follow the car/path is to add an empty that the towed object copies the rotation and location of . You do not need to add a separate curve/path .

Nor do you need to Ctrl Shift P your objects to the curve/path, rather you will actually get an important functionality just by using the Follow Path Constraint (in F7 Object context of the Buttons window) instead (you could do both but this is not required) .

Just enter the name of the curve/path in the OB: field and turn on “Curve Follow” … And right next to that is the “Offset: 0.00” field - this is the functionality that you can’t access with path parenting, and is quite useful for “towing” stuff . If you offset an object in the negative direction it will move “up” along the path … which makes the towing object move forward faster then the towed object … which means problem solved … right ?

Unfortunately no . Because if you offset the objects to where they do not intersect each other the first offset object will zip way in front of the second in the middle of the path, and what is worse at the end of the curve both objects will intersect because the offsets are not absolute but are relative to the path …

The solution I came up with involves using an offset empty which has the follow path constraint on it to which the second towed object uses as the target for both the copy rotation and copy location constraint … But just this will not solve the above problem either … You have to key the copy location constraint on the second object into a bell shape curve relative to the path’s animation/duration other wise you will get the same effect as above … with some tweaking of the offset for the empty/the keys for the copy loc constraint you can get a pretty decent result . Probably not physically accurate but visually OK I think …

And rather then posting on your other post about the “steering” wheels, I’ll just explain how to do that here as well … And yes it is also an offset empty along the path that the front wheels simply copies the Z rotation value … By simply having it precede the object by a - 5.00 offset value the wheels seem to steer along the curve .

Hope this helps .

Thanks
I used two paths