Car Rig problem


I made a car rig following these tutorials:

The first problem I encountered was with pointing wheels. The bone that should be tracked was not moving along the curve. It moved first few frames and then just goes off the curve. I managed to solve this by replacing it with another bone which was separated from the rest of the bones(Not the same armature).

But now I have two different “problems”. When I want to make the car move on another curve it just doesn’t work. So my question is do I have to use this curve all the time.
Second thing is I want to make animation with 2-3 cars(same), and I thought just to copy car, but when I do the car loses all of it’s functions. Is it possible to copy car and keep its rig?

This is my first time of doing rig so I don’t have much knowledge about this and I’d be glad if someone can tell me what mistakes I’ve made and how to correct them.

Thanks in advance.

Hi - I wanted to achieve a similar model to you and wrestled with the problem for a long time! I have attached a blend file, with the body of the truck removed so it would upload, which seems to solve the issue. If you select camera view (it should be saved like that) and press play, you can see the wheels turning and steering as they should. My technique uses icospheres tracking on a curve with two armatures with track constraints to achieve the results. Just turn on the invisible layers to see the icospheres, path curve and armatures. Feel free to download the blend file and “take it apart” to see how it works. I have not tried multiple vehicles, but all you will need to do is duplicate EVERYTHING as ONE operation, i.e. select everything you want to duplicate and then duplicate the lot rather than duplicating individual elements one at a time as this destroys the relationships. I am sure you can then move the two new ecospheres along the curve to separate your vehicles.

Anyway give it a try and let me know how you get on. One thing I found quickly was that you cannot use empties as tracker objects (they cannot have curve modifiers) nor does using bones work as I wanted hence the two icospheres. Also be aware that any distances that you move the tracker objects in X (in the case of my file) result in being translated to distances ALONG the path curve. All I did to animate the truck movement was to move the two icosperes in X and lock their location in the timeline. The truck had a tilting body, which you will see the bones for if you reveal the armature layers. I am quite happy for more knowledgeable Blender artist to provide a neater solution, but as you will see, this one works. :slight_smile:

One thing I have done in my clock mechanism (see my post about automating the clock) is to reduce the size of the icospheres down to very small so there is less distortion on them resulting in cleaner tracking.

Hope this helps.

wheels-path-test.blend (1.82 MB)

Have you noticed that wheels stop on first turn and start rotating backwards?

Jeez - I never noticed that - I thought what was happening was the tyres were effectively being “photographed” every 1/24 second, some times the NEXT tread on the wheel will be photographed just a little behind the first - it them APPEARS as though the wheel is going backwards - you will get the same effect when filming car wheels with a video camera if the spokes rotate so that they are photographed apparently moving backwards. You can achieve the same results also with tank tracks if you vary the speed at which they are travelling (I got the idea from a tutorial on this when people had complained about the method. Obviously I was wrong! I have looked again and it appears that the wheels go backwards as the direction of the truck is turned through 180 deg - then they turn the right way as the truck turns to face the original direction at the other end of the track. I must further investigate the cause and cure it!

Thanks for letting me know - still it works on a track that does not have a switch-back!

Sorry if this takes time to be posted - I am still on post reviews being a newbie here.

I have checked the rig - the target object driving the wheel bones transform is always effectively moving in positive X on the curve, although it appears to be moving “backwards” relative to the coordinate system, on the middle curve section. It should therefore always return a positive X value as it travels along the track and the transform should therefore always turn the same way, since it is simply a Location giving a Rotation. I have monitored the X location value as it moves and it steadily increases as the rig progresses, i.e X loc value NEVER goes negative, so how can it produce an opposite rotation of the bone? So is this a bug with the transform constraint (aaaargh!) or could it be a Local Space/World Space issue?

Can someone a little more skilled than me investigate this please.

With the follow path constraint, you can keyframe the influnce to swich tracks (constraints).

Hard to tell, usually when duplicating rigs, some settings require updating.

Hard to tell without seeing the blend file.

clockmender, I rigged one wheel kind of, using drivers, the rotation ratio is probably odd:
First I deleted the wheel.FR bone, then I extruded a new one, set rotation mode to XYZ Euler (better for rotation).
Added driver to Y rotation, mapped to front icosphere local X location.
The wheel.FR.001 bone is just for visual reference.

You should be able to do the same thing with a transformation constraint, probably best to map from Local to Pose Space.

Thanks for that - I tried using Pose Space on another wheel, but then it just spins about the World Z axis! I think your solution is much better - I will get my head around the ratios - my initial thought is that you have it right (1 unit of X location should be a multiple of pi rotation, wheel is 2 units I think therefore should be 2 * pi or 6.284-ish) - and then mod the other wheels like you have done.

Thanks again.

I have now modded all the wheels and it works fine i think… I used 2*pi as input for the Frame Key on the driver and 360 degrees as the Value - Blender translated this to a figure of 6.283 for me! I used negative values for the right side wheels and positive for the left side.

Here’s the revised model:

car_wheels.blend (1.74 MB)

Here’s the picture of the model with it’s other bits:

This project (above) is a simplified model of a larger project that I used to get the animation for the big model correct - here’s the real thing:

Don’t get me wrong, not pointing out fingers just letting you know so maybe you will solve the mystery for me :stuck_out_tongue:

Me too. I had the same issue and in the end I didn’t solve it (didn’t try as I didn’t need to - car in my animation was moving in the same direction for the most part).

I think that with dirty-stick’s help we now have a working solution that is bomb proof for any type of curve track.

Sorry for not replying on the time. I was busy with midterms and didn’t have time to check this.

I solved the problem of wheel tracker bone. I made wheel tracker the separate armature but all it’s constraints and properties I added to the first(main armature) and it’s working fine. It’s going along the curve as it should with no problems.

About copying I didn’t still solve but I’m going to make a new rig every time because I’ll use different cars in animation.

I’ll upload the model later