One object moving around two axises


I´m trying to create a simple 4 wheel car with ackermann steering (front wheel turning RZ as on a regular car)

I have tried with two axis in one joint with two joint_motors but i cant get it working (i´m guessing as i have the base_object as parent).
I found an Bachelor degree project “Emulation of an AGV” where the authors seems to add only a joint through XML, but i can´t seem to get this working either as there is no Link. When i add another Joint&Link i get the problem of what to do with Link.

Any ideas?



Hi Martin, it sounds interesting to create a virtual automotive, I wish I could create one later. Based on your description, I have some doubts about your idea, if you use two joint motors in one joint, these two joint motors link to a single front wheel? and the two joint motors function is rotate in ry and rz on a single wheel which make the car can move and turn? from my point of view, if you want to active two behavior in one link object, maybe we should seperate this object into two joints, and each joint has the corresponding joint motor.


Thanks for your reply!

Yes, i have tried having two joint_motors in one joint, both linking to the same wheel, one RY and one RZ. That did not work.

Now i have tried creating one joint for RY and one for RZ (the two links that at the same time gets created i have ignored/moved the box to a “safe place”).

So now i have tried with the RZ joint having the body of the automotive as parent and its link as a child.
With the next joint for this wheel i have tried with the base of the automotive as the parent and the RZ link as child, that did not work.

I also tried having the left and right wheel parenting and “childning” each other which resulted in a car going bananas without instructions.

I can get the steering working and the back wheels, but the front wheels are locked tight in RY.

Any ideas/thoughts are very welcome!


Hi Martin,
Sorry for the delay. We have just prepared a litle system with a component to show how to build a 4 wheel vehicle. The tutorial is not published yet but we will have a video too. Just search for a system called “Tutorial: Building a car”.
Basically, the right approach is to add “ry” degree of freedom to all 4 wheels. But in addition, we have added an extra link on the front wheels to allow rotaton on “rz” (steering).
One of the main issues that can make the car be unstable are the collision shapes, in case the wheels collide with the chasis. Thas is why the demo car does not have a collision shape for the main body.
Hope that it helps!


That looks perfect, thank you so much!