after have compiled the code of exercise 4.12a in the rostopic list appears this:
[…]
/fibonacci/cancel
/fibonacci/feedback
/fibonacci/goal
/fibonacci/result
/fibonacci/status
[…]
typing rostopic echo /fibonacci_as/result appears:
WARNING: topic [/fibonacci_as/result] does not appear to be published yet
the same for rostopic echo /fibonacci_as/feedback
the same message appears even after have typed rostopic pub /fibonacci_as/goal actionlib_tutorials/FibonacciActionGoal [TAB][TAB]
I have tried also to type rostopic echo /fibonacci/result (coherently with the rostopic list) but this appears:
WARNING: no messages received and simulated time is active.
Is /clock being published?
thanks for availability
Hi @karimsiena,
Welcome to the Community!
It’s expected that the first two commands rostopic echo /fibonacci_as/result and rostopic echo /fibonacci_as/feedback will give that message at first…
…but that should change once you run the third command rostopic pub /fibonacci_as/goal actionlib_tutorials/FibonacciActionGoal [TAB][TAB]. This third command calls the action server, which causes the first two topics to be published.
So, did you call the action server properly? After the [TAB][TAB], what else did you type? The [TAB][TAB] is just to help you autocomplete the message structure. After that, you must supply a message, even if it’s empty. Hint: Checking the structure of the Fibonacci.action message (Exercise 4.12a) will help here.
Solved.
I already have followed correctly all the steps and called the server properly. The problem was that typing “rostopic list” appeared
[…]
/fibonacci/cancel
/fibonacci/feedback
/fibonacci/goal
/fibonacci/result
/fibonacci/status
[…]
So i modified the server calling coherently from rostopic pub /fibonacci_as/goal actionlib_tutorials/FibonacciActionGoal [TAB][TAB] to rostopic pub /fibonacci/goal actionlib_tutorials/FibonacciActionGoal [TAB] [TAB]. In this way rostopic echo /fibonacci/result and rostopic echo /fibonacci/feedback worked.
Is it possible that "fibonacci_as doesn’t work because in the cpp file there is written fibonacci and not fibonacci_as?
if it is so, there is an error in exercise 4.12b
Thanks for your availability.
1 Like
@bayodesegun I recently encountered this problem as well. The directions in exercise 9.12b in ROS Basics in 5 Days (C++) are incorrect. The “_as” should be omitted.
@IMSETraining
I’m sorry I don’t understand what you mean. Could you please provide more context?
