Nandhi: Autonomous Vehicle

I am building a hobby autonomous vehicle (of 1:10 scale) to serve as a platform for implementing real-world Machine Learning algorithms, including Reinforcement Learning.

This project is divided into several phases, each focused on different aspects of the system:

Project Phases Overview

Phase I: System Setup and Hardware Integration

1. Hardware Integration

   • Assemble the Vehicle:
     • Chassis
     • Battery
     • Vehicle controller unit
     • IMU sensor, 2D LiDAR, and a camera
     • High-Performance Computer (HPC) — Nvidia AGX Xavier

2. Wiring and Connectivity

   • Connect all components for data and power transmission.

3. Power Management

   • Power management via Arduino or I2C/USB device:
     • Check power requirements.
     • Monitor power consumption.
     • Report battery status and detect abnormalities.

Phase II: Simulation Environment

1. Gazebo Simulation Setup

   • Simulate the vehicle in a controlled environment.

2. 4WD Ackerman Steering

   • Implement four-wheel-drive steering with Ackerman geometry.

3. Sensors Simulation

   • Simulate sensors including LiDAR and camera.

4. ROS Integration

   • ROS Bridge integration for connecting Gazebo to ROS.

5. Visualization with RViz

   • Visualize the vehicle and environment in RViz.

Phase III: Software Development

1. ROS2 Nodes for Vehicle Drivers

   • Develop ROS2 nodes for vehicle control:
     • Ego/Vehicle State Node
     • YDLidar ROS2 Node (using pre-existing implementations)
     • IMU Sensor Node
     • I2C Wrapper Node (for easy I2C integration)
     • Vehicle Controller Node
     • Keyboard Listener Node (for manual control)
     • Vehicle Visualization Node (for RViz)

2. Perception System

   • Implement perception using:
     • Digital environment data from 2D LiDAR and camera.
     • Vehicle state estimation for position and orientation using IMU, camera, and LiDAR data.

3. Vehicle Planning and Behavior

   • Develop vehicle planning and behavior control (in progress).

Current Progress: Phase I.2 and Phase II.1 are complete.
TODO: Add a picture/video of the current progress and describe it in more detail.

---

How to Launch Nandhi

Simulation Setup

To launch the simulation environment:

1. In the first terminal (Shell A):

   source install/setup.bash
   ros2 launch nandhi_sim_launch nandhi_sim.launch.py

2. To make the robot move, open a second terminal (Shell B) and use one of the following options:

   • Using ROS2 topic publishing:

     ros2 topic pub /nandhi/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 5.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: -0.22}}"

   • Using the keyboard control node:

     ./install/key_to_twist/lib/key_to_twist/key_to_twist

3. To listen to the Twist value, open a third terminal (Shell C) and run the test binary:

   ./build/key_to_twist/key_to_twist_test

---

Nandhi Constants and Vehicle Specifications

Maximum Linear Velocity

• Maximum speed: $50 \ \text{km/h}$
• Wheel Diameter: $0.1 \ \text{m}$

$$ \text{max linear velocity} = 13.89 \ \text{m/s} $$

Maximum Angular Velocity

• Wheel base $W = 0.29 \ \text{m}$

$$ \text{max angular velocity} = \frac{\text{max linear velocity}}{W} = 47.9 \ \text{rad/s} $$

RPM and Dimensions

• 8500 RPM

• Dimensions: $(L \times W \times H) = 532 \times 290 \times 195 \ \text{mm}$

• Vehicle Link

---

Helpful Commands with gazebo simulation with ros2 bridge

Setup the environment

# To enable the local models
# TODO: add it in the launch file
export GZ_SIM_RESOURCE_PATH=~/project/ros_ws/src/nandhi/simulation/nandhi_description/models/:$GZ_SIM_RESOURCE_PATH
# For gazebo plugins shared library, from root of colcon workspace
export GZ_SIM_SYSTEM_PLUGIN_PATH=`pwd`/build/distance
# This need for remote desktop, where the display server is set to 10
export DISPLAY=:10.0

Step Through the Gazebo Server

ros2 service call /ros_gz_rl nandhi_msg_types/srv/GetObservations "{step: true, multi_step: 500}"

Move the Robot

gz topic -t "/model/nandhi/cmd_vel" -m gz.msgs.Twist -p "linear: {x: 0.5}, angular: {z: 0.1}"
# OR
ros2 topic pub /nandhi/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 0.5}}"