Scaled jtc

[fmauch]

This is my take2 on #301.

I plan to finish this until Friday, @firesurfer feel free to poke me :-)

Currently missing

• tests for scaled execution
• There are some ToDos in the documentation:
  • Algorithmics
  • Handling tolerances

Things that will get changed, as discussed in the latest working group meeting

• Allowing scaling factors above 1 might get postponed to a later point.
• Report the scaling factor in the controller state
• Use a custom datatype for the scaling_factor subscriber (std_msgs are deprecated)
• Change subscription to transient_local. This will require documentation, as a standard ros2 topic pub will not work with this.

[fmauch]

Thoughts on tests I should implement:

• Execution with scaling factor of 0.5 takes twice as long (and does not fail, when no tolerances are set)
• Execution with scaling < 1 and goal time tolerance leads to an early halt and failed execution
• Execution with scaling < 1 and path tolerances set should not fail (if goal_time_tolerance is large enough)
• Execution with scaling > 1 should not fail independent of the tolerances set <-- is that true?

[firesurfer]

hi @fmauch Great to see this being worked on again. I added some comments to the code.

Regarding the tests:

Execution with scaling factor of 0.5 takes twice as long (and does not fail, when no tolerances are set)

Makes sense

Execution with scaling < 1 and goal time tolerance leads to an early halt and failed execution

Isn't this what we patched in: UniversalRobots/Universal_Robots_ROS2_Driver#882. As far as I can tell you also backported this patch. (And I still think the goal time should be also scaled ;) )

Execution with scaling > 1 should not fail independent of the tolerances set <-- is that true?

Same as above. From heavily using this controller in our system I have the opinion that in most use cases it makes sense (and is what a user would expect) that the goal time should also be scaled. But perhaps I understood your suggestion wrong.

[fmauch]

From heavily using this controller in our system I have the opinion that in most use cases it makes sense (and is what a user would expect) that the goal time should also be scaled. But perhaps I understood your suggestion wrong.

Thank you for your input. That's why I put my brain dump on that here, so we can discuss this :-) And that's also why I didn't write the documentation on that, yet.

I'll wrap my head around this a little more and try to get a better feeling for the current behavior, then come back to this.

[firesurfer]

@fmauch whats the current state of the scaled jtc efforts?

[fmauch]

@RobertWilbrandt would you mind taking a review on this, as well, since you use it yourself AFAIK.

[christophfroehlich]

Thanks for adding more tests, my points of the first review were fixed! @firesurfer @RobertWilbrandt do you have time for another review round soonish?