Phototropism is a natural phenomenon where organisms move in response to light. Inspired by this concept, a Light Following Robot is designed to move toward a light source automatically without human intervention.
The robot uses Light Dependent Resistors (LDRs) to detect the direction of light. A microcontroller processes sensor data and controls motors using a motor driver. When the light intensity changes, the robot adjusts its movement accordingly.
Key Features :
- Fully autonomous operation
- Detects and follows light sources
- Simple and cost-effective design
- Ideal for beginners in robotics
Connection Description (Wiring Map)
Main Components :
- Microcontroller: Arduino Uno / Nano
- Light Sensors: LDRs with voltage divider circuits
- Motor Driver: L298N / L293D
- DC Motors: For movement
- Robot Chassis & Wheels
Power Supply: Battery (9V / 12V)
CIRCUIT DIAGRAM
Wiring Summary :
Component | Arduino Pin | Description |
Left LDR | A0 | Detects light on left side |
Right LDR | A1 | Detects light on right side |
Motor Driver IN1 | D4 | Left motor control |
Motor Driver IN2 | D5 | Left motor control |
Motor Driver IN3 | D6 | Right motor control |
Motor Driver IN4 | D7 | Right motor control |
Motor Driver ENA/ENB | Jumper / PWM pins | Motor speed control |
Power Supply | Vin / GND | System power |
Common Ground | GND | Shared ground |
LDR Circuit :
- Each LDR forms a voltage divider with a resistor
Output voltage varies with light intensity
Working Principle :
- LDRs continuously sense light intensity.
- Arduino compares values from left and right sensors.
- Movement logic:
- Both sensors equal: Robot moves forward
- Left LDR brighter: Robot turns left
- Right LDR brighter: Robot turns right
- Low light on both: Robot stops
- Both sensors equal: Robot moves forward
- Motor driver activates motors accordingly.
Testing the Hardware :
- LDR Sensor Test
- View analog readings in Serial Monitor
- Shine a torch to observe value changes
- View analog readings in Serial Monitor
- Motor Test
- Test motors individually using motor driver
- Test motors individually using motor driver
- Directional Test
- Shine light from different directions
- Verify correct turning behavior
- Shine light from different directions
- Full System Test
- Place robot in dark area
- Place robot in dark area
Move light source and observe robot following it
Troubleshooting :
Problem | Possible Cause | Solution |
Robot not moving | Battery drained | Recharge or replace battery |
Robot moves in wrong direction | LDR wiring reversed | Swap LDR connections |
Erratic movement | Ambient light interference | Shield LDRs or adjust threshold |
Motors not rotating | Motor driver fault | Check driver IC and connections |
Robot keeps rotating | Sensor sensitivity mismatch | Calibrate LDR resistor values |
( A Light Following Robot, also known as a Phototropic Bot, is an autonomous robot that detects and follows a light source. The robot uses light sensors to measure light intensity and moves toward the brightest source. This project demonstrates the principle of phototropism and is widely used to understand sensor-based autonomous navigation in robotics. )