I made a robot according to the jetbot development document, but it can't walk

I saw the case of Articulation in the development document, imported jetbot, and it ran successfully. But I made a four-wheeled simple car by myself, and it doesn’t work in the same way, without any error or prompt, I don’t know where I went wrong. I still can’t find a solution, I hope you can help me solve this problem, thank you very much. USD I have uploaded, the name of the four-wheeled car is “jetbot_01”
Collected_car_shader_graph.rar (6.9 MB)

Hi @fsb0147

According to the USd provided, the revolute joints defined in your robot do not have the drive property (as shown in the picture for the jetbot).

The following link shows how to add a joint drive:

1. Assemble a Simple Robot — isaacsim latest documentation
By the way, the drives should be configured for Velocity Control rather than Position control

Thank you very much for answering my doubts, I try to increase the joint drive, and I can use the joint drive to move, I see


The case can be controlled by general Graph. I hope to use Action Graph to control the movement and rotation of the four-wheeled vehicle. The four-wheeled vehicle still doesn’t work after I finished it with Action Graph. Can’t find the reason, I have uploaded the modified USD, thank you very much for helping me.
Collected_car_shader_graph.rar (6.9 MB)

@toni.sm In addition, I have some doubts. In Action Graph, what does Inputs: arraySize in Make Array mean?Do I need to add Articulation Root to the body?Thanks again for answering my questions