Stop the robot during aborting from the `exe_path` action about move_base_flex

[spuetz]

You are right. @corot You did that, right? It is highly problematic. We should find a better way for do replanning on controller level. @alireza-hosseini Thank you for the issue! Also we should ensure that the robot has stopped in case of message loss.

[corot]

I agree... makes fully sense to send a zero velocity when interrupting the controller. But then we need a nice way to start following a new plan without stopping the controller. Maybe we can add another service: new_path that just pass the new path to the controller w/o stopping it, or does nothing if controller is not working.

For the stopMoving method... well, it actually stops motion by interrupting the controller thread. What do you mean exactly, @alireza-hosseini? What would you propose instead?

[alireza-hosseini]

@spuetz Thanks for your fast reply,
@corot About the stopMoving method, what I meant was since it's just interrupting the thread, the code inside the catch statement of the thread will be executed which stops the controller from planning not the robot itself, so it's a bit confusing. I think the solution can be simpler if we just publish the zero command velocity in case of preemption or even we can let the action client decide about that by adding a new boolean field for example to the ExePath action goal and only if the value is True it will publish the zero.

[spuetz]

@corot Should we comment-in that line for now, and rethink the replanning strategy here?

[corot]

for me , ok.

@alireza-hosseini, I agree is bad naming, but is coherent, because "moving" here really means "controlling", not physical robot motion

[corot]

Easy part done. For better handling replanning, we must either switch to normal action server (not simple) or open a secondary channel apart from the exe_path action to feed new plans without stopping it

[corot]

So merged the PR, I have restored the zero-velocity message when exe_path is stopped.
Next step is to retarget exe_path to follow new plans without stopping, actually without stopping and restarting the action, but for this we need the new advanced action server @spuetz is working on