International Journal of Pure and Applied Mathematics ...acadpubl.eu/jsi/2017-114-7-ICPCIT-2017/articles/9/25.pdf · The basic line follower robot follows the path either black or

Autonomous Obstacle Avoiding and Path

Following Rover

Sandeep Polina1, Pavan Kumar Barathula2and

K P Prasad Rao3

Department of Electrical and Electronics

Engineering

K L University, Vaddeswaram - 522 502, Andhra

Pradesh, India.

[email protected]

Abstract. With the advancement of automation

technology, the industries are adopting automated

robots in workplace instead of humans. This paper deals

with designing and implementing the basic prototype of

line follower robot with obstacle avoiding capabilities.

The basic line follower robot follows the path either

black or white colour in inverted surface but having an

obstacle in its path becomes a reasonable issue effects

its utilization in workplaces. This prototype of the robot

follows line, detects obstacle and take necessary actions

to avoid it. The 3 sets of IR transmitter-receiver and

ultra-sonic sensors are implemented in this prototype to

detect path and obstacles respectively. The Arduino Uno

board is the control system of this robot. The design

includes two modules- line following and obstacle

detection, both modules and its algorithm are

implemented individually and at final both are

combined in such a way that the robot performs

specified task. Arduino motor shield and sensors are

connected to control system and power is taken from

12V battery.

Keywords: Robot, obstacle, sensors, ultra-sonic, IR transmitter-receiver.

1 Introduction

Robot is usually a machine controlled by a computer

program or electronic circuitry. These are designed mainly to

reduce the work of a human. In most of the situations where

humans are under risks. So, to reduce the risk factors as well

as to increase the comfort these are developed. And by using

it we can achieve more efficient outputs with in a low span of

time. In olden days’ machines are only used to reduce the

human effort they don’t have any capability of making

decisions. But now, the world is moving towards the

autonomous in every aspect. By incorporating a little amount

International Journal of Pure and Applied MathematicsVolume 114 No. 9 2017, 271-281ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

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of knowledge to the robots they can take a bounded decision

on its own without any human involvement.

We have designed a robot that performs additional

tasks along with following a path. It avoids an obstacle in its

path and continuous to follow its path after the obstacle been

avoided. We can set the gap between the robot and intrusion

at that point which the robot take its deviation from the path.

Our robot follows the black line if it was removed from

the black line it stops and while following the line if any

obstacle was present in its path it detects the object from a

distance which we set in programme.

When the distance between obstacle and robot is

reduced to minimum value the robot control instructions

transfers from line following module to the obstacle avoiding

module. When the robot avoids the obstacle, and detects the

black line again the control sent back to the line follower

module. Our robot contains single ultra-sonic sensor mounted

on the servo motor helps to detect obstacles around 1800 in

front of robot

2. BLOCK DIAGRAM

This is the block diagram of line follower. The direction

of the arrow indicates the signal flow. The connection between

Arduino board and Arduino motor shield is bi directional.

Since we are using three motors (2 dc and 1 servo) it is easy

and comfortable to use the motor shield in controlling the

speed of the motors and if we want the four-wheel drive we

can increase the number of dc motor to four for heavy loads

with the help of motor shield.

Fig1. Block Diagram of Specimen model

The signal from IR sensors are the input to the Arduino

board. This signal helps in determining the position of the

robot with respect to the black line and Arduino gives the

necessary commands to the motor shield to adjust the motors

speeds in controlling the robots position. This loop continuous

unless any obstacle was detected.

The ultra-sonic sensor detects the obstacle and sent the

data to the Arduino, based on the data the Arduino calculates

the distance between the obstacle and robot.

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272

The servo motor helps in rotating the head of the robot

(ultra-sonic sensor) through 1800 to find the obstacles is

present in other direction.

3. LINE FOLLOWER MODULE

The IR sensors mounted under the robot near the caster

wheel helps in the detecting the black line. The line following

strategy can be achieved by minimum two sets of IR

transmitter and receiver to increase preciseness and

smoothness in operation we use three sets of them. Line

follower works on the principle that light reflects on white

surface and doesn’t reflect on black. IR transmitter transmits

IR waves on to the surface receiver sends the information

about the presence of black line to the Arduino board based on

the reflection of the IR wave, based on the information

Arduino sends signal to the motor shield to control the speed

of the motors to take turning.

The direction of the robot making a turn depends of the

individual speed of left and right motors. If the speed of the

left motor was more than the speed of the right motor the

robot takes right turn and vice versa. To move the robot in

straight forward both motors should be in same speed.

3.1 FLOW CHART OF LINE FOLLOWER

This flow-chart explains how the robot movement

related to the sensor inputs.

Fig 2. Flow chart for Line Follower

Number 0 and 1 under respective sensor indicates the

logical high or low value. When the wave is reflected that

means surface is white so, sensor output is logical high (1)

value and if the surface is black then the wave will not be

reflected so the sensor output is logical low (0) value.


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F indicates the label hence the robot should

continuously check for the black line and calibrate its position

per path the process should continuously run in the loop.

3.2 PSUEDO CODE FOR LINE FOLLOWER

Following code is used to explain how the coding is

done on Arduino to make the robot to follow the line. Include AFMotor library

Define left sensor to A0

Define middle sensor to A1

Define right sensor to A2

Assign right motor to the 3rd motor slot of Arduino

motor shield.

Assign left motor to the 4th motor slot of Arduino

motor shield.

Firstly:

Set left sensor(A0) as input.

Set middle sensor(A1) as input

Set right sensor (A2) as input to the Arduino.

Set the speed of left motor and right motor

Initially make the both motors stop.

Here loop starts:

If left sensor and right sensor is on white and middle

sensor is in black (case 1)

Make both motors to run forward

//it makes motor to move forward.

Delay for some time.

If middle sensor and right sensor is on white and

left sensor is on black (case 2)

Stop left motor and make the right motor to run

//this makes robot to turn left

Delay for some time

If middle sensor and left sensor is on white and right

sensor is on black (case 3)

Stop the right motor and make left motor to run

//this makes robot to turn right

Delay for some time

If all the sensors is on the black (case 4)

Stop the both motors

//this indicates the robot is at finish point


If all the sensors is on white (case 5)

Stop the both motors

//this indicates robot is out of track


If left sensor is on white and right sensor and middle

sensor is on black (case 6)

Stop right motor and run the left motor

//it makes robot to turn right

Delay for some time

If right sensor is on white and left sensor and middle

sensor is on back (case 7)

Stop left motor and run the right motor

//it makes robot to turn left

Delay for some time

If left sensor and right sensor is on black and

middle sensor is on white (case 8)

Stop both the motors

//it indicates invalid path

Delay for some time

Go back to the loop.

The entire loop executes repeatedly until the robot stops

Even we use the analog pins of Arduino board we read the

sensor inputs as digitally.


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4. OBSTACLE AVOIDING MODULE

In this module, we make the circuit and explain the

strategy followed by robot to avoid the obstacle present in its

path and continue following the path.

The robot head turns 180 degrees to check the obstacle

in three directions. Arduino is the brain of this robot it takes

the data from the ultra-sonic sensor and calculate the

distance between obstacle and robot. From the angle of the

servo motor Arduino gets the direction of obstacle.

By knowing the speed of the wave and time delay

between triggered wave and echo the distance is calculated by

formula.

Distance =(speed*time)/2

When obstacle is present it path it check the distance

in both directions and prefer the direction where there is a

large gap. It travels in that direction leaving the path and

travels through the boundary of an obstacle until it finds a

black line. After finding the black line it continues its path.

The threshold distance is set in the program when the gap

between the object and the robot is below the threshold

distance then the obstacle avoiding module gets activated.

4.1 FLOW-CHART OF OBSTACLE AVOIDING

MODULE


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Fig 3. Flow chart of obstacle avoiding module.

The above flow chart repeats continuously in a loop measures

the distances and take its course.

4.2 PSUEDO CODE FOR OBSTACLE AVOIDING

MODULE

Following code is for the obstacle avoiding module and

shows the connection between the line follower module and

this module by calling the line follower functions (discussed

under 5th heading) at certain constraints.

Include servo library

Include AFMotor library

Set servo to pin 9

Set trig pin to A3

Set echo pin to A4

Initially make the robot stop.

Check weather left distance is greater than right

distance.

If left distance is greater than right

Make robot to turn left

Delay for some time

Step 1:

make robot to move forward

delay for some time

check right greater than max distance.

If right greater than max distance

Make Robot to turn right.

Delay for some time

Step 2:

Make robot to move forward


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Delay for some time

Check right greater than max distance

If right greater than max distance

Make robot to turn right

Delay for some time

Step 3:

Make robot to move forward.

Delay for some time

Check for black line

If black line is present

Make robot to turn left.

Delay for some time

Go to line follower module

Else

Go to step 3

Else

Go to step 2

Else

Go to step 1

Else

Make robot to turn right

Delay for some time

Step 4:


Delay for some time

Check for left greater than max distance

If left is greater than max distance


Delay for some time

Step 5:



Check for left greater than max distance

If left greater than max distance


Delay for some time

Step 6:

Make robot to move forward.

Delay for some time

Check for black line

If black line is present

make robot to turn right

delay for some time

go to line follower module

Else

Go to step 6

Else

Go to step 5

Else

Go to step 4

This loop continuous

Check:// this function is used to check the left

distance is greater than right distance.

Turns servo to 0 degrees calculate distance

Store the value in left

Turn servo to 180 degrees calculate distance

Store the value in right

Turn servo to 90 degree

Compare left and right distances

If left is greater

Return Boolean true

Else

Return Boolean false

Distance:// this function is used to calculate

distance

make trig pin low

delay for 2 micro seconds

make trig pin high

delay for 10 micro seconds


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make trig pin low

calculate delay between triggered wave to

reflected echo wave

calculate distance = duration/58.2;

return distance

CheckLGM and CheckRGM is the functions works same as

check function but compare left distance to threshold and

right distance to threshold value respectively. The robot stops

controlling is in the line follower module. In line follower

module while following the black line the robot check the

presence of object in its path once in loop when distance is

below set distance then the control is back to the obstacle

avoiding module.

5. CIRCUIT

Fig 4. Circuit connections of robot.

6. WORKING OF ROBOT

Robot follows the black line as per the code of line follower

module while following it continuously check for presence of

an obstacle in its path. When an obstacle is detected it shifts

the robot control to the obstacle avoiding module. After the

avoiding obstacle, it sent back control to line follower module.

Several functions are used in code to reduce complexity and

increase preciseness of robot. The complete function of robot

as per the pseudo code that explained above.

X. RESULTS

Following figures are the results of specimen. It was

working fine by detecting obstacles while following the path


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Fig 5. Working of specimen snapshots

CONCLUSION

The robot that designed has different functionality

than other line followers and obstacle avoidance robots. By

using servo motor we reduced number of ultra-sonic sensors

from 3 to 1 and cover all the three directions by rotation of

robot head and we can know in which direction the robot was

looking by observing its head.

By making some changes in the programming of the

robot we can detect the obstacle at each degree around the

robot and get the position of the obstacle. By replacing

ultrasonic sensor with camera, it can capture the obstacles

and take a necessary action. By incorporating some logical

commands the robot it can be used for multipurpose. the

preciseness of the robot in following line can be increased by

increasing number of IR sensors. This robot can be used in

industries, hospitals and army applications. This robot can

replace conventional conveyor belts.

REFERENCES

1. K.H. Ng, C.F. Yeong, E.L.M. Su, T.Y. Lim, Y. Subramaniam, and R.S. Teng, “Adaptive

Phototransistor Sensor for Line Finding”, International Symposium on Robotics and

Intelligent Sensors 2012 (IRIS 2012), vol. 41, pp. 237-243, 2012.

2. F.H. Jen and B.T. Mai, “Building an autonomous line tracing car”, IEEE Intelligent Control

and Automation (WCICA), 2012 10th World Congress on, pp. 4478 - 4483, July 2012.

3. M. Engin and D. Engin, “Path planning of line follower robot”, IEEE Education and

Research Conference (EDERC), 2012 5th European DSP, pp. 1-5, September 2012.

4. N.M. Arshad, M.F. Misnan, and N.A. Razak, “Single InfraRed Sensor Technique for Line-

Tracking Autonomous Mobile Vehicle”, Signal Processing and its Applications (CSPA),

2011 IEEE 7th International Colloquium on, pp. 159-162, March 2011.

5. Y. Li, X. Wu, D. Shin, W. Wang, J. Bai1, Q. He1, F. Luo, and W. Zheng, “An Improved

Line Following Optimization Algorithm for Mobile Robot”, IEEE Computing and

Convergence Technology (ICCCT), 2012 7th International Conference on, pp. 84-87,

December 2012.


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International Journal of Pure and Applied Mathematics ...acadpubl.eu/jsi/2017-114-7-ICPCIT-2017/articles/9/25.pdf · The basic line follower robot follows the path either black or