is URDF model needed for ros control?

edit

Hi, all, It's first time to use ros control, and there's a confusing question.

In my project, I need to navigate a mobile robot (double steering type) to the target place. For navigation algorithm, maybe TEB or DWA will be used (both publish cmd_vel), and I think this won't be a problem for me. So the next thing to do is to construct the ROS control framework.

Follow the ros wiki, I can understand the framework. I need to write a robotHW by myself to Read/Write hardware data and transmit to ros controller. So the whole framework is that:

Navigation algorithms <---pub, sub data---> ros controller

ros controller <--- transmit ---> robotHW

robotHW <--- Read/Write ---> hardware

is it right? If yes, there's no URDF model included, so it is not necessary for the ros control. If not, there's something I missed or I misunderstood?

Thanks.