Reset external trajectory message upon activation

[nbbrooks]

Reset external trajectory message to prevent preserving the old goal on systems with hardware offsets

• Fix has_trajectory_msg() function: two wrongs were making a right so functionally things were fine

[matthew-reynolds]

to prevent preserving the old goal on systems with hardware offsets

What do you mean by "hardware offsets"? This seems like a good change regardless, I'm just not following this point.

[bmagyar]

Could be related to #161 ?

[nbbrooks]

Yes, by hardware offsets I am referring to the hardware_state_has_offset param introduced in #161. I was in a rush getting this pushed up and did not write a good description. This PR makes sure any existing trajectory is cleared out when the controller is activated.

Consider this workflow:

• Command movement through JTC topic
• // movement begins
• Deactivate JTC
• // movement stops
• An arm offset is introduced (see motivations in 161)
• Reactivate JTC
• // movement resumes, trying to jump to previous point in pre-offset trajectory

Currently, the above workflow would see the previous trajectory being preserved and resumed when the JTC was reactivated. I do not think this is intended behavior, or at the very least, should not be if operating with hardware_state_has_offset.

[destogl]

Consider this workflow:

* Command movement through JTC topic

* // movement begins

* Deactivate JTC

* // movement stops

* An arm offset is introduced (see motivations in 161)

* Reactivate JTC

* // movement resumes, trying to jump to previous point in pre-offset trajectory

This is actually also needed always when JTC is used along other controllers. So the issues exist always when robot if moved with another controller and switched back to JTC.

[bmagyar]

@nbbrooks I have a fix ready for you but can't push as you disabled Allow edits from maintainers.

Please run ament_uncrustify --reformat and push or enable me pushing

[bmagyar]

I'd even consider this a bugfix, thanks!

[codecov-commenter]

Codecov Report

Merging #185 (0eb9494) into master (7187083) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #185      +/-   ##
==========================================
+ Coverage   35.27%   35.29%   +0.01%     
==========================================
  Files         286       26     -260     
  Lines       24816     2258   -22558     
  Branches    16082     1463   -14619     
==========================================
- Hits         8755      797    -7958     
+ Misses       1452      132    -1320     
+ Partials    14609     1329   -13280     

Flag	Coverage Δ
unittests	35.29% <ø> (+0.01%)	⬆️

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Impacted Files	Coverage Δ
...int_trajectory_controller/test/test_trajectory.cpp
...ontroller/test/test_forward_command_controller.cpp
...dcaster/test/test_load_joint_state_broadcaster.cpp
...dcaster/test/test_load_joint_state_broadcaster.cpp
...test/test_load_joint_group_position_controller.cpp
...dcaster/test/test_load_joint_state_broadcaster.cpp
...test/test_load_joint_group_position_controller.cpp
...ory_controller/test/test_trajectory_controller.cpp
...ntroller/test/test_load_joint_state_controller.cpp
...include/joint_trajectory_controller/tolerances.hpp
... and 302 more