Ackermann steering with steering angle and sub_topic.

[bperseghetti]

🎉 New feature

Closes #1863

Summary

Option to use <steering_only> to enable a mode that does not drive the wheels. It instead only controls the central steering angle phi in radians on a /model/{name_of_model}/steer_angle gz::msgs::Double. This is usefull for simulating the control of a real vehicle without direct cmd_vel capabilities.

Test it

Example:

<plugin
  filename="gz-sim-ackermann-steering-system"
  name="gz::sim::systems::AckermannSteering">
  <steering_only>true</steering_only>
  <left_steering_joint>MR_Buggy3/FrontLeftWheelSteeringJoint</left_steering_joint>
  <right_steering_joint>MR_Buggy3/FrontRightWheelSteeringJoint</right_steering_joint>
  <steering_limit>0.4</steering_limit>
  <wheel_base>.2255</wheel_base>
  <wheel_separation>.2</wheel_separation>
</plugin>

UpdatedAckermannPlugin.mp4

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #1860 (6cd2907) into gz-sim7 (1eb3a95) will decrease coverage by 0.03%.
The diff coverage is 75.97%.

❗ Current head 6cd2907 differs from pull request most recent head 4b053e8. Consider uploading reports for the commit 4b053e8 to get more accurate results

@@             Coverage Diff             @@
##           gz-sim7    #1860      +/-   ##
===========================================
- Coverage    64.71%   64.68%   -0.03%     
===========================================
  Files          343      343              
  Lines        27430    27495      +65     
===========================================
+ Hits         17750    17785      +35     
- Misses        9680     9710      +30     

Impacted Files	Coverage Δ
...rc/systems/ackermann_steering/AckermannSteering.hh	100.00% <ø> (ø)
...rc/systems/ackermann_steering/AckermannSteering.cc	80.44% <75.97%> (-5.11%)	⬇️

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[mjcarroll]

Changes look good to me, but can you add some tests to cover this new functionality?

[bperseghetti]

Mmmmm, found one last interesting use that needs addressed. 4 wheel steer and multiple vehicles, guess I get to add sub_topics to it as well.

[bperseghetti]

@ahcorde thanks for the reviews, just finished adding them all.

[mjcarroll]

A few more nits

[mjcarroll]

@osrf-jenkins retest this please

[mjcarroll]

Only known CI issues remain on this one, so I think we are good.