Discussion - Adding a screen to the robot (Making a Mobile Robot Pt 17)

This is the discussion topic for the video and blog post linked above. Please keep all replies relevant to the content, otherwise create a new topic.

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Hello Josh. I am struggling here. I tried to flip the screen using the command you suggested but it fails as follows:

$ DISPLAY=:0 xrandr -o inverted
Invalid MIT-MAGIC-COOKIE-1 keyCan't open display :0

Any ideas?

I was trying to do it from the desktop through ssh before logging in in the GUI of the robot and it seems it would only work after you log in: xorg - X11: Invalid MIT-MAGIC-COOKIE-1 key - Ask Ubuntu so I enabled automatic login for my user, following these instructions: Enable or Disable Automatic Login in Ubuntu 20.04

Ah yes of course, I’m glad you got it figured out!

In case other people have this error, and that doesn’t fix it, here are some other things to try.

Hi Josh,

would you mind to send a link to the display which you are using , Thank you very much in advance!


Sure thing - I’m using this one!

Hi Its RobotRoss again with a Screen Question post this time. I installed your articubot_one_ui package on my Raspberry Pi4/4G attached to a Waveshare H screen you mentioned in your video which works great. It is configured with Ub22.04/ROS2 Humble, that also has turtlebot_create robot packages that teleop,(I’ll send a picture to your email). I had a scheduled robot Zoom meeting (Robot Society of Southern California) this afternoon EDT. On a whim, just an hour before the meeting, I compiled, installed and test ran your ui package. At first I got a bunch of errors, so I erased the --ros-args text from the launch command and wow-the eyes appeared on the display which responded to /cmd_vel in time for the demo.

This is not an issue for me as the /cmd_vel does not need remapping but FYI: Here are the error messages that appear when I do not use the --ros-args .

I realized that these error messages posted in my previously appear only when the ui_node is run from a remote Desktop. The package runs clean when the run command is executed directly on the Robot Raspi terminal, which I can easily do from the connected Screen. I plan to incorporate this package into a Launch file that launches the robot run scripts.

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Obviously I’m a bit late to this reply (have been somewhat out of action the last few weeks) but I’m so glad you got it to work!

I’ve found that package to be very finicky in terms of not always running if it can’t find every topic and service that it wants, instead of just ignoring them and moving on…haven’t had the time to properly look into it though.

That’s helpful feedback too that the experience is different when running via remote vs directly on the screen.