Ricbot

Ricbot, a wheeled sensor platform

Ricbot is intended for fast deployment to areas of interest.

Main features:

• Reused motors and wheels from an old "Elector Wheelie" platform
• Designed to fit into a normal car for deployment, i.e can be disassembled to no more than 55cm in height.
• No more than 25-30 kg, requiring 1 or 2 persons to load or unload.
• Wheel-odometry recording (and timestamped)
• Camera image recording (and timestamped), the intention is Realsense D435.
• Maybe GNSS recording too.
• Manual remote control.

Tentative layout:

Length is 1m, free height 25cm, width 65cm.

Installation notes

Camera position

Forward-looking camera: Intel RealSense D455, FOV 87 x 58 deg, range 0.6 to 6m.

Down-looking camera: Intel RealSense D435, FOV: 87 x 58 deg, range 0.3 to 3m.

Cabling

DRI0042: https://wiki.dfrobot.com/15A_Single_DC_Motor_Driver_SKU__DRI0042

Regbot 6.3: Regbot hardware board

5V 5A: | Aliexpress link to device

DRI0042 to Regbot 4-pin PWM

DRI              Regbot PWM    Software
7 GND   (black)  1 GND         --
4 PWM   (red)    2 in1         PIN_xxxx_DIR
5 IN1   (white)  3 in2         PIN_xxxx_PWM
6 IN2   (yellow) 4 fault       PIN_xxxx_FAULT
3 5V out 

DRI0042 control values
IN1 	IN2 	PWM 	OUT1, OUT2 Motor Behavior
0 	0 	x 	Stop
1 	1 	x 	Vacant (relax)
1 	0 	1 	Forward 100%
0 	1 	1 	Reverse 100%
1 	0 	PWM 	Forward at PWM speed
0 	1 	PWM 	Reverse at PWM speed

Power control

Pin        IDC10-pin      Software       Function
1 (black)  1              --             GND
2 (red)    3              LS_1  (pin 27) power off (when low)  -- pt not working (wrong mod on power board)
3 (white)  4              LS_0  (A6)     battery voltage  (39k/4.7k)
4 (yellow) 6              LS_4  (pin 26) Alive LED

Intel RealSense

Install

sudo apt-get install automake libtool libusb-1.0-0-dev libx11-dev xorg-dev libglu1-mesa-dev
sudo apt install libssl-dev

Library and examples

cd ~/git
git clone https://github.com/IntelRealSense/librealsense.git
cd librealsense
mkdir build
cd build
cmake ..
make -j3
sudo make install

Copy udev rules to udev

cd ~/git/librealsense/config/99-realsense*.rules /etc/udev/rules.d/
udevadm control --reload-rules

All example commands start with rs-, e.g.:

rs-capture
rs-pointcloud

Teensy interface

The Teensy interface implements a bridge to MQTT, a motor controller (velocity and turn rate), and a remote control.

The configuration is in

/home/local/svn/teensy_interface/build/robot.ini

See also Robobot teensy interface.

Start at boot

See the similar start setup in [[1]].

Comment out (or delete) the start of the camera streamer (not compatible with RealSense 3D cam)

Install software on Raspberry Pi

Perform the same installation as Robobot install on Raspberry, except for the serial port configuration (which should not be needed).

Teensy software

This is the Regbot software, configured to match the Ricbot.

See more details here Regbot firmware.

Intel Librealsense

Installing support for Intel librealsense.

sudo apt install libssl-dev
sudo apt-get install freeglut3-dev
sudo apt-get install xorg-dev
cd git
git clone https://github.com/IntelRealSense/librealsense.git
cd librealsense
mkdir build
cd build
cmake ..

I also needed to install libusb-1.0-0-dev

sudo apt install libusb-1.0-0-dev

This path was not included in the CMakeLists.txt, so I added this line at the beginning of the CMakeLists.txt:

cd librealsense
nano CMakeLists.txt

add

include_directories( /usr/include/libusb-1.0/ )

like here:

cmake_minimum_required(VERSION 3.10)

set( LRS_TARGET realsense2 )
project( ${LRS_TARGET} LANGUAGES CXX C )

# Allow librealsense2 and all of the nested project to include the main repo folder
set(REPO_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
include_directories(${REPO_ROOT})
include_directories( /usr/include/libusb-1.0/ )

include(CMake/lrs_options.cmake)
include(CMake/connectivity_check.cmake)
...

ROS2

From https://docs.ros.org/en/jazzy/Installation/Ubuntu-Install-Debs.html

Install

export ROS_APT_SOURCE_VERSION=$(curl -s https://api.github.com/repos/ros-infrastructure/ros-apt-source/releases/latest | grep -F "tag_name" | awk -F\" '{print $4}')

curl -L -o /tmp/ros2-apt-source.deb "https://github.com/ros-infrastructure/ros-apt-source/releases/download/${ROS_APT_SOURCE_VERSION}/ros2-apt-source_${ROS_APT_SOURCE_VERSION}.$(. /etc/os-release && echo ${UBUNTU_CODENAME:-${VERSION_CODENAME}})_all.deb"

sudo dpkg -i /tmp/ros2-apt-source.deb

sudo apt update && sudo apt install ros-dev-tools

Install full ROS2 Jazzy

sudo apt install ros-jazzy-desktop

Start in this ROS2 environment, now and in new terminals:

source /opt/ros/jazzy/setup.bash
echo "source /opt/ros/jazzy/setup.bash" >> ~/.bashrc
export ROS_DOMAIN_ID=0
echo "export ROS_DOMAIN_ID=0" >> ~/.bashrc

Install ROS QT GUI stuff

sudo apt install '~nros-jazzy-rqt*'

Create workspace

From https://docs.ros.org/en/jazzy/Tutorials/Beginner-Client-Libraries/Colcon-Tutorial.html

Install colcon

sudo apt install python3-colcon-common-extensions

Create workspace directory

mkdir -p ~/ros2_ws/src
cd ~/ros2_ws

From within this directory clone (any) standard package

e.g. tutorial examples

git clone https://github.com/ros2/examples src/examples -b jazzy

Build the examples; this is memory and CPU-hungry, so the option --executor sequential may come in handy, especially on a Raspberry Pi, but it will take significantly longer.

colcon build --symlink-install --executor sequential

Allow use of colcon_cd

echo "source /usr/share/colcon_cd/function/colcon_cd.sh" >> ~/.bashrc
echo "export _colcon_cd_root=/opt/ros/jazzy/" >> ~/.bashrc

To use the mixin shortcut for some colcon options, add:

colcon mixin add default https://raw.githubusercontent.com/colcon/colcon-mixin-repository/master/index.yaml
colcon mixin update default

MQTT client

The un-modified mqtt_client package can act as a bridge between the teensy_interface and the ROS domain.

From MQTT to ROS, the translation is using the primitive ROS type string for the parameters of the teensy_interface messages. The MQTT topic name is translated to ROS topic names as specified in the parameter file below.

From ROS to Teensy, the message should be published on a topic that matches the desired destination. Topics for command messages to the teensy_interface:

• MQTT topic ricbot/cmd/T0 for the Teensy, the message is the string to send to the Teensy.
• MQTT topic ricbot/cmd/shutdown to schedule a shutdown of the RICBOT (power off), something like 20 seconds after the message.
• MQTT topic ricbot/cmd/ti for messages to the teensy_interface, the message is a string.

Install

The robot's interface is via MQTT. Install the MQTT ROS client

sudo apt install ros-jazzy-mqtt-client

Or directly as source

cd src
git clone https://github.com/ika-rwth-aachen/mqtt_client

Compile:

cd ~/ros2_ws
colcon build

Run

To start the mqtt_client:

cd ros2_ws/src/mqtt_client/mqtt_client/config
ros2 launch mqtt_client standalone.launch.xml params_file:="params.teensy.yaml", this should be extended with more mqtt2ros topics as needed.

This will launch the un-modified mqtt_client node with specific bridge parameters as specified in params.teensy.yaml:

/**/*:
 ros__parameters:
   broker:
     host: localhost
     port: 1883
     tls:
       enabled: false
   client:
     id: ros
     clean_session: true
     keep_alive_interval: 20.0
   bridge:
     ros2mqtt:
       ros_topics: 
         - /teensy/T0
         - /teensy/shutdown
         - /teensy/ti
       /teensy/T0:
         mqtt_topic: robobot/cmd/T0
         primitive: true
         inject_timestamp: false
       /teensy/shutdown:
         mqtt_topic: robobot/cmd/shutdown
         primitive: true
         inject_timestamp: false
       /teensy/ti:
         mqtt_topic: robobot/cmd/ti
         primitive: true
         inject_timestamp: false
     mqtt2ros:
       # Needs to be expanded to relevant topics
       mqtt_topics: 
         - robobot/drive/T0/info
         - robobot/drive/T0/hbt
       robobot/drive/T0/info:
         ros_topic: /robobot/info
         primitive: true
       robobot/drive/T0/hbt:
         ros_topic: /robobot/hbt
         primitive: true