Assignment Nano

Embedded Autonomy: PCB Design and Ultrasonic-Driven Navigation

MSc Autonomous Intelligent Vehicles | ELEC73151 | University of Staffordshire | January 2025

A two-part embedded autonomy project: a custom KiCad PCB integrating ESP32 and Arduino Nano via I²C for ultrasonic-driven servo actuation, and a maze-navigation algorithm on the Mbot robot using reactive obstacle avoidance and differential drive.

PCB Gerber Files (Google Drive) →

Overview

Task 1: PCB Design and Development

System Architecture

HC-SR04 Ultrasonic (5V)
        |
    Voltage divider (5V → 3.3V echo)
        |
      ESP32 (3.3V) ──── I²C (3.3kΩ pull-ups) ──── Arduino Nano (5V)
        |                                                   |
   Sensing + logic                               Servo motor (7V external)

The ESP32 handles sensing and decision logic. The Arduino Nano drives the servo — mirroring the distributed ECU architecture of real autonomous vehicles, where perception modules feed into steering/actuation units.

Component Voltage Map

PCB Design (KiCad 9.0)

Designed as a single-sided board with:

• 0.8 mm track widths with 45° bend pattern for current handling and clean machining
• 3.3 kΩ pull-ups on I²C lines tied to ESP32 3.3 V rail
• Short, direct I²C routing to minimise noise susceptibility
• Clearance around ESP32 Wi-Fi antenna to reduce RF interference
• Jumper points where trace crossovers would otherwise be needed
• Gerber files generated and PCB successfully fabricated

Behaviour

• Obstacle detected < 12 cm → ESP32 sends command via I²C → Arduino Nano rotates servo to 90° (evasive steer)
• No obstacle → servo holds at 0° (straight ahead)
• All validation conditions met: stable I²C, correct voltage compatibility, consistent servo actuation

Industrial Comparison

Task 2: Mbot Maze Navigation

Algorithm

Reactive obstacle avoidance in C++ (Arduino IDE) using the Mbot's built-in motor drivers and ultrasonic sensor.

while true:
    if distance > 27 cm  →  moveForward()
    else                 →  stop → turnLeft() or turnRight() → resume

Threshold: 27 cm — selected after 5 iterative tuning runs balancing early detection against over-rotation.

Tuning History

Differential Drive Turning

void turnLeft() {
    leftMotor.run(-50);   // Slower left
    rightMotor.run(200);  // Faster right
}
void turnRight() {
    leftMotor.run(-200);  // Faster left
    rightMotor.run(50);   // Slower right
}

Results

Full Mbot source code: src/mbot_maze_navigation.ino

Tech Stack

PCB Design     KiCad 9.0
Microcontrollers  ESP32 (sensing/logic), Arduino Nano (actuation)
Sensor         HC-SR04 ultrasonic
Robot platform Mbot (Makeblock)
Language       C++ (Arduino IDE)
Protocol       I²C
Standards ref  ISO 26262, CISPR 25, ISO 11452

Files

Academic Context

Module: ELEC73151 – Autonomous Intelligent Vehicles Institution: University of Staffordshire Instructors: Dr. Masum Billah · Dr. Manilka Jayasooriya Author: Oluwakorede Solomon Bamidele (ID: b023666p)