Getting started with ROS

Folks and Emlid,

Please help me with getting started with ROS. I am using the latest Emlid distribution.

I was following the instructions in the ROS section of the Emlid documentation, and get stuck at the step where we start ardupilot:

pi@navio:~ $ sudo systemctl start ardupilot
Failed to start ardupilot.service: Unit ardupilot.service failed to load: Invalid argument. See system logs and ‘systemctl status ardupilot.service’ for details.
pi@navio:~ $ systemctl status ardupilot.service
● ardupilot.service - ArduPilot for Linux
Loaded: error (Reason: Invalid argument)
Active: inactive (dead)
pi@navio:~ $

I usually run arducopter-quad, but I had no yet started that when I got this error message concerning ardupilot.

Please advise as to what I am doing wrong. Thanks,


Hello there!

This is confusing indeed. You need to sudo systemctl start arducopter if you want to run arducopter and modify /etc/default/arducopter. We’ll update the docs.

/etc/default/ardupilot is for custom binaries.

1 Like

Ah, ok. Got it working. Brilliant! I was able to see the output of the command:

$ rostopic echo /mavros/state

It appears to update once per second. It can also simultaneously connect to my GCS. Very cool, and I was able to view lots of other topics shown by the $ rostopic list command as well.

Another question please: Should I be concerned that the logging could eventually run out of space and cause a problem? Excerpt from roscore startup:


pi@navio:~/.ros/log $ roscore
… logging to /home/pi/.ros/log/52ad025c-45a5-11e7-af5b-168811001898/roslaunch-navio-1605.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.


Thanks again,


Personally, I have never faced such problems. If you mean the messages that pop after you run rostopic, you shouldn’t worry as these messages are not getting logged on persistent storage. They just use up the RAM.

Thanks George, Paul

A post was split to a new topic: How do we actually use ROS to run our drone?