When I make a simple robot with Action Graph, the wheels can't rotate

HI, I made a simple car, the rear wheel is a universal wheel,So I added two RevoluteJoint。I can control the Xform Rotate of the caster wheel with python. But I want to control the rotation of the universal wheel through ActionGraph, unfortunately I failed,In the same way, I can set the movement of the universal wheel,but cannot set the rotation。I haven’t been able to find the reason, I hope someone can answer my doubts。The USD file has been uploaded, and the Xform of the universal wheel is “wx”.I really hope that someone can help me to solve my doubts, I will be very very grateful

Collected_car_test2_4.rar (11.9 MB)

Hello! Welcome to the Isaac Sim forums :D

First off, I need to apologize for taking so long to respond. That’s my fault, and I’m sorry for that. I have a lot of different stuff going on right now and I have a hard time multitasking. I’m sorry I dropped this for over a month.

Second, this is actually a really cool stage you created here! You should checkout this tutorial stream Renato did. You should find it very useful! it starts with importing a robot but it goes into the rigging and physics setup, which is relevant for what you are trying to do.

The biggest issue is that you are trying to simulate physics without using any of the tooling we have for doing so (like joint drives, rigid bodies, articulations, etc…).

some useful rules of thumb!

Physical objects that move through the world are best described by RigidBodies. You can add the Rigid Body API to any mesh by selecting the mesh, and then navigating to the green + button in the property panel labeled “add” and selecting physics->RigidBody. If you didn’t already have colliders, you could also use Rigid Body With Collider Presets. This does things like define the mass of your meshes and other properties necessary for simulating physics.

Joints, by default, just define the motion constraints between two bodies. They can be driven by using the joint drive api in the same menu when selecting a joint. you can then set things like position, velocity, or force targets for the drive, and control the robot that way.

finally, once you have joint drives and rigid bodies, you can define an Articulation, which will allow you to use our driver omnigraph nodes.

I hope this helps! and sorry again for taking so long

Thank you very much for your help, I have solved this problem, thank you.

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