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Architecture using `ur_modern_driver`

asked 2018-03-15 06:40:27 -0500

prajval10 gravatar image

updated 2018-03-15 06:49:34 -0500

I'm building an architecture for my application and I'd like to know if the functionality represented in the ur_modern_driver part (image below) is correct. This is follow-up of action-completion.

ur_modern_driver Arch

I've put Joint velocities as by-default the driver publishes speedj commands.

Many thanks to @gvdhoorn and Thomas Timm in advance!

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answered 2018-03-15 07:15:14 -0500

gvdhoorn gravatar image

updated 2018-03-15 07:20:38 -0500

No, this is not correct.

ur_modern_driver only provides an action server.

Your node(s) is (are) the action client(s).

I've put Joint velocities as by-default the driver publishes speedj commands.

that is also not correct.

When not using ros_control, the driver uses servoj(..) in a small program that runs on the controller.

When using ros_control, it either uses speedj(..) when the velocity interface of the hw iface is used, or servoj(..) again for the position part.

The driver also doesn't publish anything to the controller. It's a regular TCP/IP connection over which a minimal, custom protocol is run.

Edit: it's a bit lame, but "read the source" is probably still good advice in this case: ThomasTimm/ur_modern_driver.

But as I wrote before: you might want to look into the Zagitta fork (PR#120).

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I'll change the Action client node. The action server takes robot parameters (robot IP, max payload, max velocity etc) from the ROS Param server, am I correct?

prajval10 gravatar image prajval10  ( 2018-03-15 07:25:21 -0500 )edit

Well, that depends a bit on how you interpret things: "the action server" is a small part of the driver node. Personally I would say that the driver reads ROS parameters from the parameter server. The action server is just one way to interact with the driver.

gvdhoorn gravatar image gvdhoorn  ( 2018-03-15 07:26:37 -0500 )edit

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Asked: 2018-03-15 06:40:27 -0500

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Last updated: Mar 15 '18