Ricbot ROS2

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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 MQTT_client

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"

The parameter file 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/cmd/T0
         - /teensy/cmd/shutdown
         - /teensy/cmd/ti
       /teensy/cmd/T0:
         mqtt_topic: ricbot/cmd/T0
         primitive: true
         inject_timestamp: false
       /teensy/cmd/shutdown:
         mqtt_topic: ricbot/cmd/shutdown
         primitive: true
         inject_timestamp: false
       /teensy/cmd/ti:
         mqtt_topic: ricbot/cmd/ti
         primitive: true
         inject_timestamp: false
     mqtt2ros:
       # Needs to be expanded to relevant topics
       mqtt_topics: 
         - ricbot/data/T0/info
         - ricbot/data/T0/hbt
       ricbot/data/T0/info:
         ros_topic: /teensy/T0/info
         primitive: true
       ricbot/data/T0/hbt:
         ros_topic: /teensy/T0/hbt
         primitive: true

Test interface

Start the teensy_interface with the right ini-file: 

cd ~/svn/robobot/teensy_interface/build
./teensy_interface -z ricbot.ini

This should respond with something like: 

$ ./teensy_interface -z ricbot.ini
# UService:: created directory log_20260118_083120.745/
# UMqtt:: connection to MQTT broker on tcp://localhost:1883 established
# UMqttIn:: connection to MQTT broker on tcp://localhost:1883 established
# STeensy:: opening to USB /dev/ttyACM0
# SRobot:: (t0) found IP 0: eno1 192.168.2.157
# STeensy:: just connected 
# UService:: setup of Teensy 0 modules finished OK.
# Type quit to stop, or 'h' for help

Start the mqtt_client in ROS 

cd ~/svn/ricbot/ros_config
ros2 launch mqtt_client standalone.launch.xml params_file:="params.teensy.yaml"

From MQTT to ROS

There should now be hbt (heartbeat) message on the ROS side: 

ros2 topic echo /teensy/T0/hbt

This should give something like: 

data: '1768722645.7425 1738.4885 93 1748 4.85 0 9 18.1 0 0
  '
---
data: '1768722646.2426 1738.9885 93 1748 4.85 0 9 18.0 0 0
  '
---
data: '1768722646.7431 1739.4885 93 1748 4.85 0 9 18.0 0 0
  '
---

The data is: timestamp (host), timestamp Teensy, Teensy ID, version, battery voltage, ... (the rest depend on the platform).

From ROS to MQTT

e.g. make the robot drive with velocity 0.25m/s and turn 0.1 rad/s CCV, followed by stop: 

ros2 topic pub /ricbot/cmd/ti std_msgs/String 'data: rc 0.25 0.1'
ros2 topic pub /ricbot/cmd/ti std_msgs/String 'data: rc 0 0'

Or send a request to publish gyro data every 12ms: 

ros2 topic pub /ricbot/cmd/T0 std_msgs/String 'data: sub gyro 12'

(RIC_pkg) HW sensor translate package

Create the package in the workspace. 

cd ~/ros2_ws/src
ros2 pkg create --build-type ament_cmake --license MIT --node-name ric_node ric_pkg

Add dependencies to other packages to CMakeLists.txt. Add to the list of find_package 

find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)
find_package(nav_msgs REQUIRED)
find_package(sensor_msgs REQUIRED)
find_package(geometry_msgs REQUIRED)

Make target dependencies available in the include path (and elsewhere as needed).

Add this after the add_executable 

ament_target_dependencies(talker rclcpp std_msgs nav_msgs sensor_msgs geometry_msgs)

To the package description package.xml add dependencies:

Add just after the buildtool_depend section: 

<depend>rclcpp</depend>
<depend>std_msgs</depend>
<depend>nav_msgs</depend>
<depend>sensor_msgs</depend>
<depend>geometry_msgs</depend>

RIC_node code

The code in ris_node.cpp is pt this (not functional yet): 

#include <cstdio>
#include <chrono>
#include <memory>
#include <string> 

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
#include "std_msgs/msg/int32.hpp"
#include <nav_msgs/msg/odometry.hpp>
#include "geometry_msgs/msg/twist.hpp"

class RIC_translator : public rclcpp::Node
{
public:
 RIC_translator()
 : Node("minimal_publisher"), count(0)
 {
   publisher_ = this->create_publisher<std_msgs::msg::String>("/ric/hbt", 10);
   //
   // Heartbeat
   auto topic_callback =
   [this](std_msgs::msg::String::UniquePtr msg) -> void {
     // RCLCPP_INFO(this->get_logger(), "I heard: hbt '%s'", msg->data.c_str());
     // strncpy(hbtParams, msg->data.c_str(), 100);
     printHbt(msg->data.c_str());
   };
   subsHbt =
   this->create_subscription<std_msgs::msg::String>("/teensy/T0/hbt", 10, topic_callback);
 }
private:
 rclcpp::TimerBase::SharedPtr timer_;
 rclcpp::Publisher<std_msgs::msg::String>::SharedPtr publisher_;
 rclcpp::Publisher<std_msgs::msg::Int32>::SharedPtr odo_;
 size_t count;
 //
 char hbtParams[100] = "";
 rclcpp::Subscription<std_msgs::msg::String>::SharedPtr subsHbt;
 void printHbt(const char * msg)
 {
   printf("# %lu got hbt %s", count, msg);
   snprintf(hbtParams, 100, "Hello RIC %lu %s", count++, msg);
   auto message = std_msgs::msg::String();
   message.set__data(hbtParams);
   this->publisher_->publish(message);
 }
};

int main(int argc, char ** argv)
{
 rclcpp::init(argc, argv);
 rclcpp::spin(std::make_shared<RIC_translator>());
 rclcpp::shutdown();
 return 0;
}

Run RIC_node

Compile (from workspace) 

colcon build --packages-select ric_pkg

Then add it to the path 

source install/setup.bash

and run 

ros2 run ric_pkg ric_node

If the teensy_interface and the mqtt-client are also running, then (with the code above), it should print something like this on the console. 

# 0 got hbt 1769340959.8623 13504.9463 105 1033 15.65 4 8 8.9 0.27 0
# 1 got hbt 1769340960.3625 13505.4463 105 1033 15.65 4 8 8.8 0.28 0
# 2 got hbt 1769340960.8626 13505.9453 105 1033 15.65 4 8 8.8 0.27 0
# 3 got hbt 1769340961.3622 13506.4463 105 1033 15.65 4 8 8.9 0.28 0
# 4 got hbt 1769340961.8625 13506.9463 105 1033 15.65 4 8 8.9 0.25 0
# 5 got hbt 1769340962.3631 13507.4453 105 1033 15.66 4 8 8.9 0.26 0
# 6 got hbt 1769340962.8624 13507.9463 105 1033 15.63 4 8 8.8 0.26 0

Ros2 relevant messages

One of the messages are probably twist: 

ros2 interface show geometry_msgs/msg/Twist
# This expresses velocity in free space broken into its linear and angular parts.
Vector3  linear
       float64 x
       float64 y
       float64 z
Vector3  angular
       float64 x
       float64 y
       float64 z

Where from here

Search for tutorials in https://docs.ros.org/en/jazzy/

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