Omni_Control

The Omni_Control package is designed to facilitate interaction with the Name of Robot. It uses the Sabertooth drivers to manage and control the robot’s motors. Additionally, it uses Arduino as an interface between the computer and the motors.

This package has been tested in ROS Melodic.

Driver Demo

In the following link you can observe the impolementation of this driver.

Network configuration on Jetson Nano

For this specific application, the Jetson Nano is configured to connect to a specific network with an stati IP address so that it can be manipulated without using a monitor and a keyboard. This is stablished in the configuration file in /etc/network/interfaces.d

# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto wlan0
iface wlan0 inet static
address 192.168.50.200
netmask 255.255.255.0
gateway 192.168.50.1
wpa-ssid "Robotica_Movil_2.4G"
wpa-psk "turtlebot"

This way you can connect using SSH by connecting to the same network and typing the jetson nano username and static IP address

ssh nano2g@192.168.50.200

To clone this package you need to have access to internet so you may have to change the configuration file in /etc/network/interfaces.d to use a different network besides your specific router with nox connection to internet.

# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

#auto wlan0
#iface wlan0 inet static
#address 192.168.50.200
#netmask 255.255.255.0
#gateway 192.168.50.1
#wpa-ssid "Robotica_Movil_2.4G"
#wpa-psk "turtlebot"

auto wlan0
iface wlan0 inet static
address 192.168.2.210
netmask 255.255.255.0
gateway 192.168.2.1
wpa-ssid "WIFI_NAME"
wpa-psk "password"

In this case you can comment the previous wifi configuration and add a new configuration. Remember changing the WIFI_Name and the password of your network with wifi. With an static IP address you can connect to the Jetson Nano on headless mode via SSH without a monitor.

Installation on Jetson Nano

• Install ROS Melodioc on Jetson Nano 2GB (if not already done) by following this guide.

• You need to have this ROS packages in order to communicate with Arduino using serial port.

  sudo apt install ros-$ROS_DISTRO-rosserial-python
  sudo apt install ros-$ROS_DISTRO-rosserial-arduino
  sudo apt install ros-$ROS_DISTRO-rosserial

• If you want to control the robot using gamepads you need to have the following packages installed

  sudo apt install ros-$ROS_DISTRO-joy
  sudo apt install ros-$ROS_DISTRO-tf

• Create a workspace, clone this package and compile it.

  mkdir -p omni_ros_ws/src
  git clone https://github.com/Luispre99/omni_control.git
  cd ..
  catkin_make

• Add the setup.bash to .bashrc to avoid sourcing this file on every terminal

  echo "source ~/omni_ros_ws/devel/setup.bash" >> ~/.bashrc
  source ~/.bashrc

Arduino

The SaberTooth drivers for the motors can be found here in case you want to modify the robot behaviour. Otherwise, you can found the Arduino code needed for this ROS package here

Running the Package

This package is prepared to control the robot using a gamepad connected with a USB dongle. You can control the robot by running the following launch file:

roslaunch omni_control omni_joy.launch

Setting Up Automatic ROS Launch Execution at Boot

It’s possible to make your Jetson Nano execute a specific ROS launch file. You can achieve this using systemd to create a service that runs your roslaunch command. Here’s a step-by-step guide:

1. Create a Shell Script

There needs to be a shell file with the roslaunch command inside. This file is already in this package and it's called roslaunch_omni_teleop.sh:

Or you can create your own by doing:

cd ~/omni_ros_ws/src/omni_control/config
sudo vim roslaunch_YOUR_LAUNCH_FILE_NAME.sh

And edit it with the following structure

#!/bin/bash
source /opt/ros/melodic/setup.bash
source ~/omni_ros_ws/devel/setup.bash
roslaunch omni_control omni_teleop.launch

Make sure to give it execute permissions:

cd ~/omni_ros_ws/src/omni_control/config
chmod +x roslaunch_omni_teleop.sh

2. Create a Systemd Service

Next, create a systemd service file. This file will tell systemd to run your script at boot. Create a file named roslaunch_omni_teleop.service in /etc/systemd/system/:

sudo nano /etc/systemd/system/roslaunch_omni_teleop.service

Add the following content to the file:

[Unit]
Description=Start ROS Launch at boot
After=network.target

[Service]
ExecStart=/home/nano2g/omni_ros_ws/src/omni_control/config/roslaunch_omni_teleop.sh
User=nano2g
WorkingDirectory=/home/nano2g
Environment=DISPLAY=:0
Environment=ROS_MASTER_URI=http://localhost:11311
Environment=ROS_IP=127.0.0.1

[Install]
WantedBy=multi-user.target

Remember update if neccessary the User variable with your specific user name and ExecStart with the actual path to your shell script.

3. Enable and Start the Service

Enable the service so that it starts at boot:

sudo systemctl enable roslaunch_omni_teleop.service

Check the status of your service to ensure it’s running correctly:

sudo systemctl status roslaunch_omni_teleop.service

4. Stop or Disable the Service

To stop the execution of the launch file process

sudo systemctl stop roslaunch_omni_teleop.service

However, it does not prevent the service from starting again on the next boot or if it is manually started.

If you do want to prevent from starting again you can use the following

sudo systemctl disable roslaunch_omni_teleop.service

But this does not stop the service if it is currently running; it only affects future boots. Using both will stop the current execution and prevent from starting again.