Light Tracker Bot

Published July 25, 2023 © MIT

Light Tracker Bot

Arduino interfaced with a couple of photo resistors (LDR), mounted over servo motor tracks light and makes an angular motion toward it.

BeginnerFull instructions provided1 hour338

Things used in this project

Hardware components

Arduino Nano R3

LDR, 5 Mohm

SG90 Micro-servo motor

Resistor 10k ohm

Software apps and online services

Arduino IDE

Story

Light Tracker Bot:

The operation is based on the photoconductive property of Light Dependent Resistors (LDRs). LDRs are semiconductor devices whose electrical resistance changes in response to the intensity of incident light. When exposed to light, the LDRs generate varying analog voltage signals proportional to the ambient light levels they receive. The bot employs two LDRs, strategically positioned to sense light from different angles. By measuring and comparing the analog voltage outputs from the LDRs, the bot can determine the direction of the strongest light source. This comparison helps the robot ascertain whether the light source is to its left, right, or directly in front of it.

To respond to the light source's direction, the bot's servo motor comes into play. The servo motor is mechanically connected to the LDRs, allowing it to move horizontally. The robot is programmed to smoothly adjust the servo motor's position based on the difference in analog readings from the two LDRs.

As the LDRs sense changes in light intensity due to any movement of the light source, the robot's control algorithm continuously adapts the servo motor's position, keeping the light source within its field of view. This mechanism allows the Light Tracker Bot to precisely follow the light source, making it an intelligent and engaging light-tracking robot.

Real life Implementations:

1.) Solar Panel Orientation: It can be employed in solar panel installations to optimize their orientation, ensuring they are always aligned with the sun's position for maximum energy generation.

2.) Automated Plant Growth: Can be used in indoor gardening setups to move artificial light sources, ensuring plants receive the ideal amount of light for their growth at different stages.

3.) Smart Lighting Systems: In smart homes or offices, it can control motorized curtains or blinds, adjusting their position based on the sun's movement to regulate natural lighting inside the space.

4.) Security and Surveillance: In security applications, the bot could detect light sources and trigger alerts or actions, enhancing the capabilities of surveillance systems.

Connections & interfacing:

1. LDRs: Two Light Dependent Resistors (LDRs) are the primary light sensors in the circuit. LDRs are passive electronic components that change their resistance based on the intensity of incident light. They act as light detectors, converting light variations into varying electrical resistance.

2. 10k Resistors: Each LDR is connected in series with a 10k ohm resistor. These resistors act as voltage dividers, allowing us to measure the varying voltage across the LDRs. When light falls on the LDR, its resistance decreases, causing the voltage across the LDR to change.

3. Analog Input Pins: The analog outputs of the LDRs are connected to the analog input pins (A0 and A1) of the Arduino. These pins can measure the voltage variations from 0V to 5V and convert them into corresponding 10-bit digital values (0 to 1023) using an analog-to-digital converter (ADC).

4. Microcontroller: The microcontroller (Arduino or similar, in my case am using Arduino nano.) reads the analog values from both LDRs using the analog input pins. It then processes the data to determine the light source's direction based on the difference in analog readings from the two LDRs.

5. Servo Motor: The Arduino controls the servo motor using a digital PWM (Pulse Width Modulation) signal. The servo motor's signal wire is connected to a digital pin (I used pin 11 in Arduino nano.), enabling the microcontroller to adjust the servo's position based on the calculated light source direction.

6. Power Supply: The circuit is typically powered using a 5V power supply, such as from the Arduino board's power source or an external power supply. The LDRs and resistors draw very little current, making them suitable for use with the microcontroller's 5V power source.

In general, the circuit consists of LDRs and resistors as light sensors, an analog-to-digital converter in the microcontroller, and a servo motor for controlling the movement. As the light changes, the LDRs detect the variations, and the microcontroller adjusts the servo motor's position accordingly to track the light source accurately.

Here is the schematic diagram of the system:

Working Demo.

Code

Servo & LDRs

#include <Servo.h>
#define LDR1 A0
#define LDR2 A1

#define error 10
int Spoint = 0;

Servo servo;

void setup() {
  servo.attach(11);
  Spoint = constrain(Spoint, 0, 180);
  servo.write(Spoint);
  delay(1000);
}

void loop() {
  int ldr1 = analogRead(LDR1);
  int ldr2 = analogRead(LDR2);
  int servoPosition1 = map(ldr1, 0, 1023, 0, 180);
  int servoPosition2 = map(ldr2, 0, 1023, 0, 180);
  
  if (abs(ldr1 - ldr2) <= error) {
    
  } else {
    
    if (ldr1 > ldr2) {
      Spoint = constrain(Spoint - 3, 0, 180); 
      
    } else {
      Spoint = constrain(Spoint + 3, 0, 180); 
    }
  }

  servo.write(Spoint);
  delay(40); 
}

Credits

Anip Shah

9 projects • 4 followers

Tech enthusiast and programmer who also happens to be a Biomedical Engineer.

Light Tracker Bot

Things used in this project

Hardware components

Software apps and online services

Story

Light Tracker Bot:

Schematics

Schematics

Code

Servo & LDRs

Credits

Anip Shah

Comments

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Light Tracker Bot

Light Tracker Bot

Things used in this project

Hardware components

Software apps and online services

Story

Light Tracker Bot:

Schematics

Schematics

Code

Servo & LDRs

Credits

Anip Shah

Comments

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