I have completed the topics quiz for unit 4 of ROS in 5 days but it keeps giving me a mark of 1. I have tested out the program multiple times and I do not understand what is wrong. I can see in the simulation that the robot avoids the wall and when I do rostopic echo /cmd_vel, I can see information being published to the topic. However I keep getting zero marks for these. Can someone please help me? I am so lost and my professor doesn’t understand my mark either.
Hi @joubr13,
- Can you run
catkin_make
successfully? When I tried it didn’t complete because of an error. - Can you run
roslaunch topics_quiz topics_quiz.launch
successfully? Here’s what I got when I tried:
user:~$ roslaunch topics_quiz topics_quiz.launch
... logging to /home/user/.ros/log/559216fa-0e02-11eb-be1b-0242c0a82008/roslaunch-6_xterm-1307.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.
Invalid roslaunch XML syntax: no element found: line 8, column 4
The traceback for the exception was written to the log file
With these errors in place, it’s not surprising that the quiz is failing.
Next steps:
- Please fix the errors above and any that comes up. You need to test your code using
roslaunch
, not just run the python code. And, of course, your package needs to compile. - Please check that you have created the package exactly as specified. Otherwise, the grader could mark you down even if your package works.