beepboop3000 [bb3]

A cool, SLAM-based, smart robot. bb3 is a proof of concept for low-cost, autonomous vehicle designed to fulfill tasks in warehouse-like environments. Built on ros2, it exposes steering functions and on-board sensor data over a local network, enabling the user to control and monitor it through a control panel.

Platform

bb3 runs on raspi with ros2 Foxy and is built with

• Raspberry Pi 3B
• Raspberry Pi HQ Camera with 6mm lens
• YDLIDAR X4 2D-lidar (5Hz, 0.5deg resolution up to 10m)
• x4 TT DC motors w/ 65mm rubber wheels
• x2 L298N dual h-bridges
• x16 AA NiMH 1.2V 1900mAh (in 2 x8 packs, one per bridge)
• MPU9250 9-DOF acc/gyro/mag breakout
• HC-SR04 ultrasonic sensor
• pre-cut plastic chasis with 3d-printed ABS lidar mounting plate

We're planning an upgrade for most of the components, including:

• Pi 3B -> Jetson Nano (edge visual recognition, complex ros setup)
• 65mm rubber wheels -> 80mm plastic meccanum wheels (naviagion flexibility)
• TT DC motors -> 12V 775 motors (more power)
• AA NiMH -> 4S LiPo battery pack (more power)
• L298N bridges -> breakout 4 motor bridge (lower power losses)
• plastic chasis -> fully custom chasis

Current version of bb3

Installation

Install raspi

1. Donwload the raspi imager from here and burn the image onto the MicroSD card.
2. Plug the MicroSD into the pi and power. The system will take a couple of minutes to set up.
3. Connect to the local network.

Connect remotely

You can connect to the pi remotely on a local network through SSH. To enable SSH go to

top left corner -> preferences -> Raspberry Pi Configuration -> Interfaces -> toggle SSH

To find the local address type ifconfig in the console. The inet address that starts with 192.168 is the local IPv4 address.

• eth0 is the wired connection
• wlan0 is the wireless connection

You can then remotely connect to the pi with ssh username@192.168.x.x (default username is pi). Note that there are issues with the wireless connection that require further configuration.

Install pigpio

Download and build using cmake (per this)

wget https://github.com/joan2937/pigpio/archive/master.zip
unzip master.zip
cd pigpio-master
make
sudo make install

Install ros tools

1. Add in ROS apt repos (per this)

   sudo sh -c 'echo "deb [arch=amd64,arm64] http://repo.ros2.org/ubuntu/main `lsb_release -cs` main" > /etc/apt/sources.list.d/ros2-latest.list'
   curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
   sudo apt update

2. Get colcon

   sudo apt install python3-colcon-common-extensions

If the Python part of the install fails it may be because you need the setup tools.

sudo apt install python-setuptools python3-setuptools

3. Get rosdep

   sudo apt install -y python3-rosdep2
   sudo rosdep init # if already initialized you can continue
   rosdep update

4. Get ros2 foxy by following this.

Note that locales do need to be updated on raspi. You can verify if locales are set up correctly with the guide here.

Install bb3

Download the source from master and build with colcon

cd ros2_ws
source /opt/ros/foxy/setup.bash
rosdep install -i --from-path src --rosdistro foxy -y
colcon build --packages-select bb3
. install/setup.bash

Run bb3

Run pigpiod (pigpio daemon)

sudo pigpiod

Run bb3:

ros2 run bb3 bb3

Remote control with a joystick

To control the robot using a joystick, use teleop_twist_joy:

sudo apt-get install ros-foxy-teleop-twist-joy

Follwing this tutorial, check what device number has been assigned to your joystick:

ls /dev/input

By default joysticks start with js and are appended with consecutive integers. In my case, the joystick is assigned to js0. Now let's test the joystick:

jstest -l /dev/input/js0

You should see something similar to

crw-rw-XX- 1 root dialout 188, 0 2009-08-14 12:04 /dev/input/jsX

If XX is rw: the js device is configured properly.

If XX is --: the js device is not configured properly and you need to:

sudo chmod a+rw /dev/input/jsX

Now run the teleop_twist_joy node:

ros2 launch teleop_twist_joy teleop-launch.py joy_config:='xbox'

Depending on the controller its messages will be translated differently. In my case I have to press RB and move the left stick.

How does bb3 work?

beepboop subscribes to the cmd_vel topic and accepts Twist messages (geometry_msgs/Twist). To steer the robot run teleop_twist_keyboard on the same network and press keys, or set up a joystick through teleop_twist_joy and move the robot using its controls. Fun!