raspberrypi

Raspberry+ROS

Since GitHub restricts file size to 100MB, you can dowload the compacted image from here.

This is a customized Ubuntu Bionic (18.04) image for running ROS on Raspberry Pi devices. By default, it supports Turtlebot3 and DJ Tello. You can enable other robots according to your needs. All the information about is based on Linux command line.

Automate them with Robot-Runner.

How to use the image?

It requires a 16 GB SD card.

$ wget http://www.iotrixx.com.br/imgs/raspberry/ubuntu-rasp-ros.img.xz
$ unxz ubuntu-rasp-ros.img.xz
$ dd if=ubuntu-rasp-ros.img of=/dev/<your_sd_card> bs=4M

Now, follow all the setups...

It has been run on Raspberry Pi 3 Model B+ and Raspberry Pi 4 Model B.

Package

• Ubuntu 18.04
• ROS2 (Eloquent) - We're migrating to Foxy
• ROS1 (Melodic)
• Turtlebot3 ROS Modules
• TelloPy Python Library

Log In

• Username: ubuntu
• Password: s2group

Remote - Ethernet Default IP (SSH)

$ ssh [email protected]

Network/WiFi Configuration

Edit the configuration file.

$ sudo nano /etc/netplan/50-cloud-init.yaml

Set up WiFi parameters:

...
network:
    ethernets:
        eth0:
            dhcp4: false
            addresses: [192.168.200.200/24]
    version: 2
    wifis:
        wlan0:
            optional: true
            access-points:
                "YOUR-SSID-NAME":
                    password: "YOUR-NETWORK-PASSWORD"
            dhcp4: true

... for Open WiFi (No Password)

    wifis:
        wlan0:
            optional: true
            access-points:
                "YOUR-SSID-NAME": {}
            dhcp4: true

Apply your changes.

$ sudo netplan apply

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Howto

Set Up the ROS1 environment:

Setup the environment variables:

$ source /opt/ros/melodic/setup.bash

Check the variables:

$ printenv | grep -i ROS

You should see this:

ROS_ETC_DIR=/opt/ros/melodic/etc/ros
ROS_ROOT=/opt/ros/melodic/share/ros
ROS_MASTER_URI=http://localhost:11311
ROS_VERSION=1
ROS_PYTHON_VERSION=2
ROS_PACKAGE_PATH=/opt/ros/melodic/share
ROSLISP_PACKAGE_DIRECTORIES=
ROS_DISTRO=melodic

Run master node (if you run on standalone mode)...

$ roscore &

otherwise, you set up ROS master parameters:

export ROS_MASTER_URI=http://<master_host>:<master_port>

Run a simple example:

$ rosrun rospy_tutorials talker chatter:=/wg/chatter

You should get this:

[INFO] [1611755100.147060]: hello world 1611755100.15
[INFO] [1611755100.258993]: hello world 1611755100.26
[INFO] [1611755100.347802]: hello world 1611755100.35
[INFO] [1611755100.447843]: hello world 1611755100.45
[INFO] [1611755100.547811]: hello world 1611755100.55
[INFO] [1611755100.647949]: hello world 1611755100.65
[INFO] [1611755100.747753]: hello world 1611755100.75
...

Set Up the ROS2 environment:

If ROS1 is running, kill the master node.

$ pkill roscore

Setup the environment variables:

$ source /opt/ros/eloquent/setup.bash

Check the variables:

$ printenv | grep -i ROS

You should see this:

ROS_VERSION=2
ROS_LOCALHOST_ONLY=0
ROS_PYTHON_VERSION=3
ROS_DISTRO=eloquent

Run a simple example:

$ ros2 topic pub /chatter std_msgs/String "{data: 'Hello there'}"

You should get this:

publisher: beginning loop
publishing #1: std_msgs.msg.String(data='Hello there')

publishing #2: std_msgs.msg.String(data='Hello there')

publishing #3: std_msgs.msg.String(data='Hello there')

---

Check it on a Turtlebot

To be done by Etienne/Joe

...

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Check DJ Tello (TELLO > WIFI -- RaspberryPy -- ETHERNET < ROS)

Raspberry WiFi connects to TELLO (AP Mode), while all the ROS communication goes on rasp Ethernet network. So far, you must write your own Python scripts by using TelloPy library to interact with Tello and manage to link rospy (for ROS communication) and TelloPy. Not a big deal at all!

Anyway, we'll be dropping here a simple example.

1. Turn the drone ON and wait for the yellow blinking light;
2. Connect to its WiFi network (see the WiFi configuration section);
3. Run the takeoff and landing script:

$ ~/check-tello.sh

The drone will take off, hover for a few seconds, and then land.

Raspberry terminal should report something like the following:

Tello: 16:51:56.579:  Info: start video thread
Tello: 16:51:56.579:  Info: send connection request (cmd="conn_req:9617")
Tello: 16:51:56.579:  Info: video receive buffer size = 425984
Tello: 16:51:56.582:  Info: state transit State::disconnected -> State::connecting
ALT:  0 | SPD:  0 | BAT: 39 | WIFI:  0 | CAM:  0 | MODE:  1
Tello: 16:51:56.636:  Info: connected. (port=9617)
Tello: 16:51:56.636:  Info: send_time (cmd=0x46 seq=0x01e4)
Tello: 16:51:56.636:  Info: state transit State::connecting -> State::connected
Tello: 16:51:56.637:  Info: set altitude limit 30m
Tello: 16:51:56.637:  Info: takeoff (cmd=0x54 seq=0x01e4)
ALT:  0 | SPD:  0 | BAT: 39 | WIFI:  0 | CAM:  0 | MODE:  1
ALT:  0 | SPD:  0 | BAT: 39 | WIFI:  0 | CAM:  0 | MODE: 41
ALT:  0 | SPD:  0 | BAT: 39 | WIFI:  0 | CAM:  0 | MODE: 41
ALT:  0 | SPD:  0 | BAT: 39 | WIFI:  0 | CAM:  0 | MODE: 41
ALT:  0 | SPD:  0 | BAT: 39 | WIFI: 90 | CAM:  0 | MODE: 41
ALT:  0 | SPD:  0 | BAT: 39 | WIFI: 90 | CAM:  0 | MODE: 41
ALT:  0 | SPD:  0 | BAT: 39 | WIFI: 90 | CAM:  0 | MODE: 41
...

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