Pause and resume an action state

[WZHwerk5]

Hi, I just wonder how to pause/resume an action state with a ROS2 service. Thanks!

[mgonzs13]

Hey @WZHwerk5, the action state involves using ROS 2 actions which, as far as I know, cannot be paused/resumed. However, pausing/resuming a state could be a good feature. Do you have any suggestions?

[WZHwerk5]

Ok I see, thanks for quick reply! Let's step back a bit, how to cancel a running action state by a service (e.g. a Trigger)? Could you give me an example? Thanks in advance

[mgonzs13]

In YASMIN, all states can be implemented to be canceled. In the case of the action states, canceling a state means canceling the action server. An example of action state is shown here. Thus, to cancel the FSM sm, you can use the following code:

sm.cancel_state()

[mgonzs13]

Hey @WZHwerk5, how is this going?

[WZHwerk5]

Hi, it worked, thanks.

[jonyktan]

Hi, can I get some advice on how to cancel actions please? Given that the ActionState outcomes are (SUCCEED, ABORT, CANCEL), how can I trigger ABORT or CANCEL?

[mgonzs13]

Hi @jonyktan, you have how to cancel an action in the previous comments.

In YASMIN, all states can be implemented to be canceled. In the case of the action states, canceling a state means canceling the action server. An example of action state is shown here. Thus, to cancel the FSM sm, you can use the following code:

sm.cancel_state()

[jonyktan]

Could you give an example of where to insert `sm.cancel_state()` for an event to trigger the state cancellation while in that state please? I'm not too sure where to put it inside the ActionState

…

On Thu, Oct 10, 2024, 22:54 Miguel Ángel González Santamarta < ***@***.***> wrote: Hi @jonyktan <https://github.com/jonyktan>, you have how to cancel an action in the previous comments. In YASMIN, all states can be implemented to be canceled. In the case of the action states, canceling a state means canceling the action server. An example of action state is shown here <https://github.com/uleroboticsgroup/yasmin/blob/main/yasmin_demo/yasmin_demo/action_client_demo.py>. Thus, to cancel the FSM sm, you can use the following code: sm.cancel_state() — Reply to this email directly, view it on GitHub <#18 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJYCWNNXRYHFEJI36HBQUOLZ22IJ3AVCNFSM6AAAAABHV5ZGW6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDIMBVGM2TCNBVGU> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[mgonzs13]

Let us consider the action_client_demo.py. In this example, a FSM is created with an ActionState. Then, the FSM is executed inside the main thread of the program.

To overview an example of canceling a FSM we can execute the FSM of the demo in a new thread as follows:

    import threading
    t = threading.Thread(target=sm, args=(blackboard,))
    t.start()
    t.join()

This way, we can attempt to cancel the FSM while executing. Here you have the code modified canceling the FSM, for instance after 2 seconds of starting the execution:

    import time
    import threading
    t = threading.Thread(target=sm, args=(blackboard,))
    t.start()
    time.sleep(2)
    sm.cancel_state()
    t.join()

I hope this is helpful to you. I'll add an example to the demo pkg.