Mobile Autonomous Robot with LEGO Mindstorm and NVIDIA Jetson Nano on ROS Melodic

Project Description

This project explores modern mobile autonomous robotics prototyping. Robotic platform is built with LEGO Mindstorm set with EV3 Brick as motor and sensor controller and NVIDIA Jetson Nano as more powerful computer with accelerated neural networks on CUDA. ROS Melodic is being used as software platform.

Project Goals

• Evaluate current state of the art of mobile autonomous robotics
• Evaluate of NVIDIA Jetson Platform to mobile robotics
• Evaluate of ROS Melodic

Hardware

• LEGO Mindstorm EV3 31313 Kit
• Jetson Nano

Technical formulation of the problem

Getting started

First step of this project is to get robot up and running. We would assemble robot platform using LEGO, flash SD cards for EV3 Brick and Jetson Nano. In the end we will be able to control robot using keyboard.

1. Flash Jetson Nano SD Image to 16+ GB MicroSD CARD
2. Flash Yocto Linux on 8+ SD Card for LEGO EV3 Brick
3. Assemble Crawler Robot following instructions. Stop at page 74.
4. Boot EV3. Connect keyboard and login as root (no password). Connect EV3 to Jetson NANO via USB. Type gadget_on to enable USB networking.
5. Set up USB Network interface on Jetson Nano using manual networking setting. Set IP to 192.168.10.X
6. EV3 brick will be available on 192.168.10.123. Add 192.168.10.123 ev3dev to /etc/hosts.
7. Install ROS Melodic on Jetson Nano via aptitude
8. Start roscore on Jetson Nano to start ros master.
9. Run ros_master_set 192.168.10.1 on EV3 ssh. Then run ev3_manager to start ros ev3 node
10. Copy this repo's src to $HOME/catkin/src
11. Run cd $HOME/catkin/; catkin_make
12. Run roslaunch ./motors.launch ev3_hostname:=ev3dev in one tab
13. Run rosrun teleop_twist_keyboard teleop_twist_keyboard.py to start remote controller via keyboard

At this point we will be able to control robot with keyboard.

Software Architecture

Robot has 3 joint which are controller through ev3_controller: Joint_A, Joint_B and Joint_C. Joints A and B are EV3 Large Servo Motor and joint C is Medium Servo Motor

ROS Nodes

EV3_manager

EV3_manager is a ROS node running on EV3. We will be using it to control robot movement. EV3 has four controller ports to which servos can be attached and four sensor ports. We have large servos attached to ports C and B and medium servo attached to port A. EV3_manager exposes these servos with [twist] interface (https://docs.ros.org/api/geometry_msgs/html/msg/Twist.html) interface.

ROS Types

# This expresses velocity in free space broken into its linear and angular parts.
Vector3  linear
Vector3  angular

ROS Topics

Mathematical Models

Acknowledgements

1. ROS Robot With Lego EV3 and Docker for ev3 control ros module

Future Work

References