Imported from GitHub: SRA-VJTI/sra-board-hardware-design · commit b1e04ee · license MIT

Description

ESP32-based Development Board for Robotics and Embedded Applications

README

LSA - Line Sensor Array

Table of Contents

• Overview
• Features
• Components of LSA
• Function of Components
  • LED
  • PhotoDiode
  • IC LM324
  • Resistors
• Connections
• Working Principle
• Appplications
• Scope of Improvement

Overview

• The Line Sensor Array(LSA) is used to detect the white/black lined surface and it sends this data to the microcontroller ESP-32. Analyzing and processing the data received by the microcontroller ESP-32, the purpose of line following is achieved.

• Physical PCB

• PCB Backside

Features

• Components used are readily available.
• Easy connections for output signals.
• Compact enough to fit into any project.
• Distinguished trace widths for Signal and Power Routes.

Components of LSA

Component	Description	Quantity
Infrared Emmitter	Emits infrared light	5
PhotoTransistor	Absorbs light	5
Resistors	Limit Current	10
JST Connector	Connect PCB with other circuits	1

Function of Components

• Infrared Emmitter

  • The specific Infrared Emmitter emit infrared light which is incident on the surface and some of it is absorbed by the surface. The voltage source for the Infrared Emmitter to emit is VCC.

• PhotoTransistor

  • Based upon the reflectivity coefficient of the surface( generally less than 1), the remaining light reflected from the surface is captured by the Photodiodes. Infrared Emmitter and complimentary phototransistor are used to efficiently detect the surface (white/black line). The amount of light received is directly proportional to the current generated by it. More the light, more the current, more the reading.

• Resistors

  • Now to limit the current and thus to protect the LEDs, PhotoDiodes current limiting resistors are used.

Connections

To connect LSA with the SRA Board, connect the JST connector in the following way:

Working Principle

• LSA works on the principle of reflectivity of light for different types of surfaces.
  • Black Surface -> HIGH absorptivity -> LESS reflectivity
  • White Surface -> LOW absorptivity -> HIGH reflectivity
• Demonstration

Applications

• Obstacle detection on a clear path.
• Line Following.
• Distinguish Colours on a path.

Scope of Improvement

• LSA sometimes provides slightly inaccurate readings due to external light and conditions due to non uniformity of the colour of the path. Therefore, LSA has low accuracy. Hence LSA should be kept close to the ground.
• As of now only white and black surfaces are being mapped. Given accurate sensors and proper mapping we can map LSA for any range of RGB colours.