Maze Solver Robot Using Wall-Following Algorithm

By: Ali Ulku & Vardah MuhammadSupervized By: Dr. Mehmet Keskinoz

24.05.2015

Outline

Outline

• Introduction

Lego Mindstorm Construction Pack

Completed View

Wall-Following Algorithm

Different Types of Circuits

• Algorithm

Pseudo Code

Initialization Block

1st If Block

2nd If Block

Move Forward Block

Turn Right/Left Block

Medium Motor Turn Right/Left Block

Logic

• Result

Robot in the Maze

Escape Route on Matlab

Introduction

5

Introduction

Lego Mindstorm Construction Pack

Main Hardware:

• EV3 Brick (300 MHz ARM9 Controller)• 2 Large Motors• 1 Medium Motor• Infrared Sensor• Subassemblies

Comments

6

Introduction

Top View

Completed View

Bottom View

7

Introduction

Wall-Following Algorithm

Comments

Wall-Following Algorithm

•Follows the Right Hand Wall Rule•Simple•Fast•Unique Solution•Works for Open Circuits•No need for Memory Storage•Parameters can be easily controlled

8

Introduction

Open Circuit

Different Types of Circuits

Closed Circuit

Algorithm

10

Algorithm

Pseudo Code

Pseudo Code Blocks

Initialization Block

Turn Right/LeftBlock

Medium MotorTurn Right/Left

Block

2 If Blocks

Move ForwardBlock

11

Algorithm

Initialization Block

• Initializes x, y position and direction• Used to generate trajectory of robot and maze map

Comments

12

Algorithm

1st If Block

• Reads from Infrared Sensor• Checks if there is a wall on the right

Reading of less than 15 indicates that wall is present

Comments

13

Algorithm

2nd If Block

• Decides on the direction to move

Comments

14

Algorithm

Move Forward Block

• Moves robot forward by 1 step (pre calculated)• Updates its direction• Direction:

1: forward 2: right 3: backward 4: left

Comments

15

Algorithm

Turn Left Block

• Turns robot to the left• Increments direction by 1

Comments

16

Algorithm

Turn Right Block

• Turns robot to the right• Decrements direction by 1

Comments

17

Algorithm

Medium Motor Turn Right Block

• Medium motor holds the infrared sensor• Turns medium motor to the right

Add 90 to reading to get rid of drift• Uses proportional gain of 0.5 to reduce accumulated error

Comments

18

Algorithm

Medium Motor Turn Left Block

• Turns medium motor to the left Subtract 90 from reading to get rid of drift

• Uses proportional gain of 0.5 to reduce accumulated error

Comments

19

Algorithm

Check Right

No wall (proximity>15)

Wall (proximity <15)

Turn Right & Move Forward

Logic

Check Front

Move ForwardNo wall (proximity>15)

Wall (proximity <15)

Turn Left and Repeat from the start

Result

21

Result

Video

The Robot in the Maze

Constructed Maze

22

Result

Robot’s Escape Route on Matlab

• Red and straight lines show the borders of the maze Achieved by combining direction information

• Blue and dashed lines show the route that our robot traveled only once

• Blue and straight lines show the route that our robot traveled back and forth Achieved by combining position and direction

information

Comments

Thank You!