Laptop and Turtlebot4 communication without internet

[Leo-Gut28]

Hi everyone,

I'm fairly new to robotics and ROS2, and I just had a networking question.

I have a TurtleBot4 and a laptop, and my goal is to have the robot operate in a room without internet access. I'm using ROS2 Humble and have set up a discovery server to manage communication following the turtlebot user guide.

Here's what I did so far:

Initially, I used an AP with internet to connect the TurtleBot4 and laptop so I could create a map of the room. This setup worked fine. However, in the real use case, I can't use the AP, so there won't be any internet or external Wi-Fi available.

Without the AP, the TurtleBot and laptop can't communicate, which breaks everything. I was thinking if I could connect the TurtleBot4 and laptop using a static Ethernet connection and run the discovery server that way? If so, is there anything I need to change from the regular discovery server steps besides the IP?

Any guidance would be hugely appreciated. Thanks in advance!

[slowrunner]

The absolute easiest way I have done this was to set my phone to broadcast a WiFi access point and have the robot (and laptop) connect to my phone.

It is possible to set the Raspberry Pi WiFi as an access point, but this gets nasty complicated and puts you in "custom configuration" land - especially for time synchronization which becomes very important for sensor topics you want to process off-board (on laptop).

If you don't want to use your phone - you can set up a portable WiFi router (not connected to Internet or LAN), and add the router credentials to the Turtlebot4 as a second WiFi (while the TB4 is connected to your LAN), and also connect your laptop to the WiFi router. This creates a local WiFi network with just your bot, the laptop connected to the portable router.

Warning - messing with the RaspberryPi network configuration can go wrong so make a backup of your SDcard before you start so if the Bot becomes isolated without any Wireless way to connect to it, you can start over. (It is also possible to use a cable with your laptop to the RPi, but you will have to learn how to do any of these - on your own. No one is going to be able to hand-hold you through it.)