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Nox

Packages untested on ROS Lunar.

Nox is a DIY differential drive robot which uses SLAM (gmapping) with a Kinect to navigate in its environment. It is powered by ROS running on a Raspberry Pi 3 Model B and an Arduino Mega controlling two DC motors with encoders.

Packages and more (CAD model,...) are available on the Nox github. A functional schematic of the robot and its components is available here.

Hardware

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Nox is a low-cost robot built with simple hardware, allowing for easy replication. It is a differential drive robot with the motors placed on the same axis. The base is made of wood with two caster wheels for support. The rest of the structure is made mainly of wood and metal brackets, easy to find in any DIY retail store. On the rear part of the robot plates can be stacked to put the electronic boards on. More information on making the robot (such as components used) can be found in the Hackster page of the project.

The robot contains:

Software

Nox software is divided into three packages:

How to use Nox

Installation

These tutorials assume that you are comfortable with ROS and the catkin build system. Please familiarize yourself using the ROS and catkin tutorials.

  1. Download the github package:

    git clone git@github.com:RBinsonB/Nox_robot.git
  2. Place the "nox" and "nox_description" folders in "your_catkin_workspace/src" on both your computer and the Raspberry Pi and run:

    catkin_make
  3. Upload the Arduino sketch located in the Arduino folder ('motor_controller_v2_AFMS.ino') to the Arduino Mega 2560.

Running Nox

In order to navigate Nox you will need to start two launch files using SSH and ROS nodes over network.

Connect to Nox Wi-Fi

There are two options for communicating with Nox:

The Raspberry Pi network configuration isn't included here and the choice and implementation of the connection is left to the user.

Once connected and before launching any ROS command the Raspberry Pi has to be synced to the computer. Run the following command in SSH on the Raspberry Pi (remplacing 'ip_address_of_the_computer' with your computer's IP address):

sudo ntpdate ip_address_of_the_computer

You can also setup the ntpdate or use chrony to do that automatically.https://github.com/RBinsonB/Nox_robot#2-start-the-odometry-and-motor-control

Start the odometry and motor control

In the Raspberry Pi, use the following command to start the main program:

roslaunch nox nox_bringup.launch

It will launch the serial controller node connected to the Arduino, the Kinect node, the odometry calculation node and the joint state publisher. If this step succeded you should see the side light of the robot going from a series of three quick blinks to a slow "breathing-like" type of blinking.

Start the navigation

Path planning calculation and mapping are done on your computer and you have to launch a launch file from your computer. Before doing so, assure yourself that you exported the ROS master from the Raspberry Pi (modify the command to suit your own setup):

export ROS_MASTER_URI=http://localhost:11311

You can then launch:

roslaunch nox nox_slam.launch

It will launch the move_base node and RViz. By using the "2D Nav Goal" arrow you can give a goal for the robot to reach. Alternatively, you can use the ROS teleop keyboard to control the robot:

rosrun teleop_twist_keyboard teleop_twist_keyboard.py


2020-08-01 12:25