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ROS Noetic Mobile Robot Guide — Raspberry Pi | Day 1 to Day 4

Complete ROS Noetic Mobile Robot Guide (Raspberry Pi)

This is a 10/10 end-to-end beginner-to-working-robot guide documenting the real journey of building a 4WD mobile robot using a Raspberry Pi, Ubuntu 20.04, and ROS Noetic.

By the end of this guide, you will:

  • Install Ubuntu on Raspberry Pi
  • Install and configure ROS Noetic
  • Create a ROS workspace
  • Test motors safely
  • Drive the robot forward, backward, left, and right
  • Control the robot using keyboard teleoperation

DAY 1 — Setting Up Raspberry Pi with Ubuntu

1. Flash Ubuntu 20.04

  • Download Ubuntu 20.04 LTS (64-bit) for Raspberry Pi
  • Use Raspberry Pi Imager
  • Select OS → Ubuntu 20.04
  • Enable SSH before flashing

2. First Boot & Basic Setup

sudo apt update
sudo apt upgrade -y

Enable SSH (Critical)

sudo systemctl enable ssh
sudo systemctl start ssh
sudo systemctl status ssh

DAY 2 — Installing ROS Noetic

1. Add ROS Repository

sudo apt install curl
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu focal main" > /etc/apt/sources.list.d/ros-latest.list'

2. Install ROS Noetic

sudo apt update
sudo apt install ros-noetic-desktop-full

3. Initialize rosdep

sudo rosdep init
rosdep update

4. Environment Setup

echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc
source ~/.bashrc

5. Install Build Tools

sudo apt install python3-rosinstall python3-rosinstall-generator python3-wstool build-essential

DAY 3 — Motor Driver Wiring & Test

Motor Driver (L298N) Logic

  • ENA → GPIO 18
  • IN1 → GPIO 17
  • IN2 → GPIO 27
  • ENB → GPIO 13
  • IN3 → GPIO 22
  • IN4 → GPIO 23

Standalone Motor Test Script

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

pins = [18,17,27,13,22,23]
for p in pins:
GPIO.setup(p, GPIO.OUT)

GPIO.output(18, True)
GPIO.output(13, True)

GPIO.output(17, True)
GPIO.output(27, False)
GPIO.output(22, True)
GPIO.output(23, False)

time.sleep(3)
GPIO.cleanup()

This confirms wiring and motor direction before ROS.

DAY 4 — ROS Motor Driver Node

1. Create Catkin Workspace

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws
catkin_make
source devel/setup.bash

2. Motor Driver ROS Node

#!/usr/bin/env python3
import rospy
from geometry_msgs.msg import Twist
import RPi.GPIO as GPIO

ENA, IN1, IN2 = 18, 17, 27
ENB, IN3, IN4 = 13, 22, 23

GPIO.setmode(GPIO.BCM)
for pin in [ENA,IN1,IN2,ENB,IN3,IN4]:
GPIO.setup(pin, GPIO.OUT)

GPIO.output(ENA, True)
GPIO.output(ENB, True)

def move(cmd):
lin = cmd.linear.x
ang = cmd.angular.z

```
if lin > 0:
    GPIO.output(IN1,1); GPIO.output(IN2,0)
    GPIO.output(IN3,1); GPIO.output(IN4,0)
elif lin < 0:
    GPIO.output(IN1,0); GPIO.output(IN2,1)
    GPIO.output(IN3,0); GPIO.output(IN4,1)
elif ang > 0:
    GPIO.output(IN1,1); GPIO.output(IN2,0)
    GPIO.output(IN3,0); GPIO.output(IN4,1)
elif ang < 0:
    GPIO.output(IN1,0); GPIO.output(IN2,1)
    GPIO.output(IN3,1); GPIO.output(IN4,0)
else:
    GPIO.output(IN1,0); GPIO.output(IN2,0)
    GPIO.output(IN3,0); GPIO.output(IN4,0)
```

rospy.init_node('motor_driver')
rospy.Subscriber('/cmd_vel', Twist, move)
rospy.spin()

Keyboard Control

Install Teleop Package

sudo apt install ros-noetic-teleop-twist-keyboard

Run Order

roscore
rosrun my_4wd_robot motor_driver_node.py
rosrun teleop_twist_keyboard teleop_twist_keyboard.py

Use keyboard:

  • i → Forward
  • , → Backward
  • j → Left
  • l → Right
  • k → Stop

Final Result

  • Robot moves smoothly
  • Safe motor control
  • ROS-compliant architecture
  • Keyboard teleoperation working

This is the foundation for joystick, autonomy, and navigation.

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