Added a service to setup the active payload

[fmauch]

This PR adds a service to setup the active payload through a ROS service.

This PR depends on ros-industrial/universal_robot#470 being accepted which is why this is a draft PR.

[gavanderhoorn]

Is relying on << to convert floats/doubles to string locale -safe?

Could end up with multiple commas in the string, which would probably upset UR's parser.

[fmauch]

I did not think about that. I would never have though about the stream operator using locales in the background.

In a quick example I could not get a stream into locale-like formatting without explicitly setting the locale of the stream. However, to make sure, we could set the string's locale explicitly to classic

[gavanderhoorn]

I just want to avoid another ros/urdfdom_headers#41.

If stream io doesn't suffer from this, all the better.

[ethanfowler]

Is there anything holding this up that I can help with? We (Shadow robot) want this functionality as soon as possible, though we can run on a branch in the meantime.

[lavarock1234]

Any update on this PR? Thanks very much in advance

[gavanderhoorn]

The referenced PR has been merged into ros-industrial/ur_msgs.

@fmauch: I'd appreciate it if you could test the service a bit before I release it into Melodic.

[fmauch]

The referenced PR has been merged into ros-industrial/ur_msgs.

@fmauch: I'd appreciate it if you could test the service a bit before I release it into Melodic.

Sure thing!

[fmauch]

Just tested with a

rosservice call /ur_hardware_interface/set_payload "payload: 2.0
center_of_gravity:
  x: 0.2
  y: 0.3
  z: 0.1"

and verified with

rostopic pub /ur_hardware_interface/script_command std_msgs/String "data: 'def myProgram():

 textmsg(get_target_payload())

 textmsg(get_target_payload_cog())

end'"

Which printed

[fmauch]

It would be nice if we could add a check for success into the service. Currently, it succeeds, as soon as the script code got successfully sent to the socket.

Unfortunately, this isn't very easy to do as far as I understand. To my knowledge, there is no interface to get information about the payload data in

• the primary interface
• the RTDE interface
• the dashboard interface

It could be implemented together with #171, where we would receive a PROGRAM_XXX_STARTED, PROGRAM_XXX_STOPPED message sequence on success and a PROGRAM_XXX_STARTED, RuntimeError, PROGRAM_XXX_STOPPED sequence in case of illegal input. Timing out on an answer should also be a failure.

Another option would be of course to send payload data back through a custom socket, but then we would be highly dependent on our actual program script code.

[gavanderhoorn]

Update: ur_msgs was released into Melodic (v1.3.1) and includes the SetPayload service definition.

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Edit: until Melodic sees a sync, the main repositories will not provide ur_msgs.