1Design and Implementation of Autonomous Photovore Robot

with Obstacle Avoidance

School of Aerospace and Mechanical Engineering

Oklahoma State University

Presenter:1. SHUVRA BANIK2. BHARATH PAKALA

2Outlines Introduction

ConceptComponents

How It WorksDifferential DrivePhotovore AlgorithmObstacle Avoidance

CodingDemoApplicationProblemsRecommendationFuture Works

3Introduction

Concept and Design

Objective:Making a Photovore Robot which will follow the direction of light

Implementing Obstacle Avoidance to avoid collisions with any object

4Components

Hardwares:BreadboardWiresRobot ChassisWheels3 1K Resistors1 9V Battery1 1.5V Battery 2 Parallax Continuous Rotation Servo MotorsCCS PIC1854520 Development Kit

5Components…(continued)

ICs:2 Photoresistors1 Infrared Emitter1 Infrared Detector

6How It Works

Differential Drive

7Differential Drive…(continued)

Base Positive Pulse Time is 1.5ms Interval between positive pulses is 20msDecrease in Base Positive Pulse Time will increase

speed in clockwise direction

8Differential Drive…(continued)

Increase in Base Positive Pulse Time will increase speed in counterclockwise direction

9Photovore Algorithm Implemented using PhotoresistorPhotoresistor is a Light

Dependent Resistor (LDR) In a Voltage Divider Circuit

voltage across Photoresistor is measured

Difference between voltage of left and right Photoresistors are taken

If the voltage is more than 0.08V, then turns in appropriate direction

This difference is found after calibration

10Photovore Algorithm…(continued)

11Obstacle Avoidance IR Emitter emits IR light If there is an obstacle in the front,

this IR light bounces back An IR Detector receives the

reflected IR light IR Detector is actually an IR

Phototransistor It converts IR light into voltage In a Voltage Divider Circuit voltage

across IR Detector is measured For detecting a distance of 6 inches

in room light, if the voltage is less than 4.94V, then robot turns in right side

This voltage is found after calibration

12Obstacle Avoidance…(continued)

13Coding

When power is given to microcontroller, by default, it will work as an Obstacle Avoiding Robot

If anyone presses button (PIN_A4) on the development kit, then an external interrupt occurs at PIN_B0

Then the robot works as a Photovore Robot

These operations continue until power is taken off

14Demo

15Applications

A Photovore Robot can be used with a solar cell to get direct sunlight all the time of the day

Obstacle Avoidance can be used to avoid undesired collisions such as in Mars Rovers.

16Problems

Same speed in both servo motors is not found using the same pulse rate

The wheels slide on the floor due to lack of enough friction In order to keep the module compact, the chassis is made

smaller which in turn made the placement of circuit boards and batteries clumsy.

Calibration of photoresistos is difficult because their resistance changes with the change in light source

Calibration of IR detector is difficult because voltage across it changes with respect to light source (i.e. in sunlight or in room light) ,color and also surface structures of obstacle

17Recommendation

Using servos of same speedUsing wheels having better frictionAllocating enough space for the circuit boards and batteries

Using better photoresistors with better calibration

Using Sharp IR Range Finder sensors in stead of IR Detectors

18Future Works

A Fire Fighting Robot can be made using IR Detector of this robotA Line Following Robot can also be made using the Photoresistors of this robot

19Questions?

Thank You!