FINAL PROJECT

FINAL PROJECT

The AI Goal Sentinel is a portable device that turns any regular soccer goal into a smart training system. You simply attach it to the crossbar, and it is ready to use. It automatically detects your shots and sends data instantly to your phone, showing you the speed of the ball and exactly where it entered the goal. It turns a normal practice session into a fun, measurable game.

I am making this project because professional football tools are usually too expensive and hard to use for normal players. Most people cannot measure how fast they shoot or improve their accuracy with data. This project solves that problem by creating a cheap and easy-to-use device that lets anyone track their progress, just like professional athletes do.

THE ORIGIN STORY (MOTIVATION)

I have been passionate about football since I was a kid. It’s not just a hobby; it’s part of who I am. However, training alone can be difficult without feedback. I often wonder: "How fast was that shot?" or "Did I hit the corner precisely?"

This project combines my love for the sport with digital fabrication. My goal is to build a device that helps players like me improve their accuracy and power through real-time data, making training sessions more effective and fun.

The AI Goal Sentinel is an autonomous device designed to attach to any standard goalpost. To achieve portability and precision, the system integrates the following hardware components:

CRITICAL RESEARCH: BALL DETECTION

A major part of my recent project development has been dedicated to Research & Development (R&D). Before fabricating the final PCB or 3D printing the enclosure, I needed to define the exact optical hardware required to detect a football crossing the goal line at high speeds. I evaluated two different photoelectric sensor models to determine viability.

1. Solviora E3F-DS30C4 (Yellow)

• Type: Diffuse Photoelectric Proximity
• Range: 7 - 30 cm
• Verdict: REJECTED

Analysis: While cost-effective, this sensor relies on light bouncing off the object itself. Its maximum range of 30 cm is a critical failure point for this project. A football goal is much wider, meaning a ball passing through the center of the net would go completely undetected by this sensor.

2. Retroreflective E3F-R2NK (Blue/Green)

• Type: Retroreflective with plate
• Range: Up to 2 Meters (200 cm)
• Verdict: SELECTED

Analysis: This sensor uses a dedicated reflector plate placed on the opposite side of the frame. Because the beam bounces back directly from the reflector, it achieves a massive 2-meter detection range. This ensures that no matter where the ball enters the goal area, it will break the beam and trigger the system accurately.

FULL-SCALE GOAL CONCEPT

The system will be implemented on a **physical goal structure** with a size of 1 meter height and 1.3 meters width. This compact format allows portability while still providing a realistic training experience.

The design includes a total of 8 sensors, distributed symmetrically:

• 4 sensors on the left post
• 4 sensors on the right post

These sensors will create multiple detection zones across the goal area. When the ball crosses the goal, the system identifies:

• ✔ Entry position (left, center, right)
• ✔ Shot trajectory approximation
• ✔ Speed calculation using time difference between sensors

This configuration transforms a simple goal into an intelligent measurement system, capable of providing real-time feedback for performance analysis.

SYSTEM DIAGRAM

Fig 2. Sensor distribution along both vertical posts to detect ball crossing position and speed.

SYSTEM WORKFLOW