Week 1 - Before the first lab

Mostly did setup stuff. No programming yet

Connecting to the robots

As it turns out, Duckietown needs support for .local name resolution. This doesn’t happen by default if using systemd-resolved. This stackexchange provides a good overview

Additionally, use firewalld to unblock UDP on port 5353

firewall-cmd --zone=public --permanent --add-port=5353/udp

It likely won’t work with mdns_minimal so instead use mdns in /etc/nsswitch.conf and create another file /etc/mdns.allow with the lines

.local.
.local

See section 4 of the ArchWiki for more info

Webpage

I used the markdown notes setup I’ve been working on for this site the past week and slightly reworked it to suit the DuckieTown blog you’re reading right now! This also finished up a lot of styling problems that remained with the notes

GUI Tools

As it turns out, I didn’t have xhost installed, so of course the camera didn’t work.

please pacman -S xorg-xhost

With that, the camera now works at least… Use the following to get a camera window running over xwayland. Make sure dockerd is running in systemd

systemctl start docker
dts start_gui_tools <addr-no-.local>
rqt_image_view  # Run this in the docker container

Keyboard control

Keyboard controls also work!… except only in the non-graphic mode

dts duckiebot keyboard_control --cli <add-no-.local>

When the shell loads, it’ll ask for one of wasde. Sometimes it won’t register keys right away. I found that after stopping with e, immediately using one of the movement commands fails, since the duckiebot doesn’t seem to have understood it stopped. Instead send yet another e and then the movements should work

Conversely, if it’s already moving with w, immediately using asd tends to work. Additionally, if it’s refusing to start moving forward with w and the extra es aren’t helping, try doing the opposite movement with s then immediately switch into w

When things stop working

Sometimes, mDNS just doesn’t feel it today with systemd-networkd. In this case just gives up

systemctl stop systemd-networkd iwd
systemctl start NetworkManger
nmtui

Once everything is running, including docker, open a new terminal. Otherwise there’ll be errors like “QT Plugin not installed” and “Failed to open DISPLAY”. This has to do with updated environment variables