Robotics 4

8/8/2019 Robotics 4

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copyright© IIT GuwahatiRobotics Club

EXPERT SYSTEMS AND SOLUTIONS

Email: [email protected]@yahoo.com

Cell: 9952749533www.r esea rchproj e ct s .infoPAIYANOOR, OMR, CHENNAI

Call For Research Projects Final year students of B.E in EEE, ECE, EI,

M.E (Power Systems), M.E (AppliedElectronics), M.E (Power Electronics)

Ph.D Electrical and Electronics.Students can assemble their hardware in our

Research labs. Experts will be guiding the projects .

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Robotics WorkshopRobotics WorkshopIIRobotics WorkshopRobotics WorkshopII

The New BeginningThe New Beginning

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Question # 1What is a robot??

An entity designed for some specific µTask¶

In other words ± Your imagination

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Machines v/s RobotsSensing Planning Acting

informationabout theenvironment

actionon the

environment

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Question # 2What is ROBOTICS ???

The science of making a robot

But is it a Science or an Art ??

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How Much Time do You Think A robotRequires ???

Depends on what everyone says

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What does a Robot consists of ??

Mechanical HardwareElectronics HardwareSoftware

And the toughest part is ?? Why ?

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Classification of RoboticsThree types:-

Manual RoboticsSemi-Autonomous RoboticsAutonomous Robotics

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Any thoughts about how tuff is makingan autonomous or semi-autonomousrobot???

Or which one is more tuff???

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The Components ofRobot

ROBOTP ow r

M m t

Motor/Lo omotioy t m

or

Co troly t m

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Power - The NeedIn any robotic system the basic need todrive it is Power.

Can be obtained from:DC batteryAC MainsIC Engines

Here we wont talk about IC engines for now

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Power ManagementOne can use battery directly or use anadapter/SMPS as the situation demands.

For Manual ² Adapter if wired remote² Battery if radio controlled

For Semi ² AutonomousSMPS if you can·t manage on a battery

For AutonomousYou have to manage on Battery

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Power ManagementTo operate the motors you will need higher

voltage supply than what is required by

general IC·s.To derive all those voltage values from agiven voltage supplyLM317, 7805 5V voltage regulatorPT5048C, PT5049 12V voltage regulator

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Moving a RobotHow will a robot move???

WheelsLegsWings

All these run on motors powered bybattery or IC engines.

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Types Of MotorsDC MotorsAC MotorsStepper MotorsServo MotorsIC Engines

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DC MotorsRun on DC power supplyCan rotate in both directionsTo handle one has to control the

speed

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DC MotorsDC motors are low torque and high

speed devicesGear set can be used to increase

torque at the cost of speedThe movement of the shaft is smooth

Easiest to operate

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Working of DC motorDirection of rotation of a dc motor

can be controlled by changing thedirection of voltage applied to themotor

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Working of DC motorHow to drive a dc motor without

using a remote?to drive a motor we need certain

circuits called Driver Circuits.Driver Circuits act as an interface by

providing a link to main power supplybased on input signalReadymade IC·s are available.

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Working of DC motorH-BridgeIt·s a c ircuit to allow the rotation ofmotor in both the direction

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Working of DC motorDriving and Braking using H Bridge

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Working of DC motorH-Bridge in short

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Working of DC motorThe Required IC ² L293D (Quad Half H-Bridge)

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H bridge using L293D

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Working of DC motor

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Working of DC motorSpeed control can be managed by

controlling the Voltage across themotor in other words by controllingaverage power fed to the motor

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Working of DC motorVoltage across a motor can be

changed using a resistor as apotential dividerBut is energy inefficient as a lot ofuseful power is wasted in resistor

A better method is PWM (PulseWidth Modulation)

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Working of DC motorPWM - It means to change the width

of a pulse train depending on thecontrol signal

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Working of DC motorHow does PWM help in controlling

speed?

It can be understood as using atypical average speed problem.

Technically the average power fedto the motor is reduced therebydecreasing the speed

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Stepper MotorsWidely use in Robotics ---why??Because More precise than DC motor

Measured rotation and can be held ata particular position- U can rotatethe stepper motor with an accuracyof 0.9 degree!!!!!!Alignment is much better...

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Stepper Motors contd..

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Types of Stepper MotorsMainly 2 types:² Unipolar- Current can flow only in one

direction in the coils² Bipolar- Current can flow in both the

directions

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ComparisonUnipolar

1. Current flow inone direction

2. Simple drivecircuit

3. Less torque

Bipolar

1. Current flow inboth direction

2. Complicated driveCircuit

3. High Torque

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Modes of OperationSingle Coil Excitation: Only one outof the 4 coils is excited at a given

timeDouble Coil: Two adjacent coils are

excited at a given time

Single and Double: It·s a hybrid ofboth..(refer diagram for details)

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Stepper Motor basicsThe stepper motor contains a permanentmagnet which is attached to the shaft atcentre and there are 4 coils on the 4 sidesActually the stator contains 100 teeth to

get a step angle of360/(2*100)=1.8degrees. But here for thesake of simplicity, we are showing only onetooth of stator. So don·t get misled intobelieving that it·s step angle is 90 degrees

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Single Coil Mode

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Single coil ExcitationN ote that until the next coil isswitched on, the stator remains in it¶s position only.

And as we can control when

to switch on a particular coilthru software, we can rotate itby exactly the angle wewish.. Compare this with DCmotor where the shaft keepson rotating as soon as thecurrent is switched on

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a. Single-Coil ExcitationEach successive coil is energized in turn.

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Double coil Excitation

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b. Two-Coil Excitation

Each successive pair of adjacent coils isenergized in turn.

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Single and Double coil

Excitation

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Interleaving the twosequences will cause the

motor to half-step

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ComparisonS ingle coil

1. Low torque

2. Consume lessenergy

3. Settling time ismore

Double coil1. High torque

2. Consume doubleenergy

3. Settling time isless

N ote : The advantage of hybrid mode is that the step angle getshalved.. So we can control the rotation with double precision

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Circuit Diagram

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Controlling motors thru

ComputerParallel Ports: It·s the easiest way to

control the motors from computer. Nocomplicated intermediate circuits arerequiredSerial/USB portsBluetooth

* The last 2 modes are beyond the scope of this workshop

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25-way Female D-Type

Connector

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The pin configuration ofthe other end of parallel

port connector

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Pin details

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Pin details contd.....

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Pin DetailsD0-D7 are the data pins(used foroutput)

C0-C3 are control pins. Note that C1and C3 are hardware inverted. Theycan be used for both input and output

S3-S7 are status pins. They are usedfor taking input from external circuit

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PC parallel PortThe PC's Parallel Printer Port had a total of

12 digital outputs and 5 digital inputsaccessed via 3 consecutive 8-bit ports in the

processor's I/O space.8 output pins accessed via the DATA Port5 input pins (one inverted) accessed via the

STATUS Port4 output pins (three inverted) accessed via

the CONTROL PortThe remaining 8 pins are grounded

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Controlling pins thru

programAlmost every programming language hascommands to control the ports. For

example in Turbo C, we can use the¶outportb· function defined in dos.houtportb(0x378,5)0x378 is the address of the data pins of the parallel port.The binary form of 5 will appear as an output in the data

pinsi.e the binary of 5 is 00000101. Therefore D0 and D2 are onand rest pins are off. The ouput can be upto 2^8-1=255

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Control pinsThe address for control pins can be

obtained by adding 2 to the address ofdata pins. For eg, here the address of

control pins will be 0x378+0x2=0x37aTherefore the commandoutportb(0x37a,3) will make both the 1 st 2control pins(C0,C1)low ! Because 3=0011

and C0 and C1 are hardware inverted

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Controlling DC motors by H-

Bridge

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Implementation of H

bridge

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Driving the DC motor

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Connections for a

stepper motor

DataPort1

DataPort2

Motor 1

Motor 2

N ote ²connect a 15v zener diode to pin 10 of IC as shown to prevent damageto the IC due to "back emf" when loads such as motors switch on and off

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Driving the Stepper

MotorIn the following slides, we discussthe code for driving the stepper

motor in various modes² Single coil mode² Double coil mode² Hybrid mode

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Single Coil ModeThe order of the values to be written to

parallel port(data pins)00000001 ² (1 st coil is on) = 1

00000010 ² (2nd

coil is on) = 200000100 ² (3 rd coil is on) = 400001000 ² (4 th coil is on) = 8For 2nd motor00010000 ² (1 st coil is on) = 16

0010000 ² (2nd

coil is on) = 320100000 ² (3 rd coil is on) = 641000000 ² (4 th coil is on) = 128

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Double Coil ModeThe order of the values to be written to

parallel port(data pins)00000011 ² (1st & 2nd coils are on) = 3

00000110 ² (2nd

& 3rd

coils are on) = 600001100 ² (3 rd & 4th coils are on) = 1200001001 ² (4 th & 1st coils are on) = 9For 2nd motor00110000 ² (1st & 2nd coils are on) = 48

01100000 ² (2nd

& 3rd

coils are on) = 9611000000 ² (3 rd & 4th coils are on) = 19210010000 ² (4 th & 1st coils are on) = 144

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Hybrid modeThe order of the values to be written to parallel

port(data pins)00000001 ² (1 st coil is on) =100000011 ² (1st & 2nd coil is on) = 300000010 ² (2 rd coil is on) = 200000110 ² (2 nd & 3rd coil is on) = 600000100 ² (3 st coil is on) = 400001100 ² (4 th & 3nd coil is on) = 1200001000 ² (4 rd coil is on) = 800001001 ² (1st & 4th coil is on) = 9

The values for the other coil can be determined by shifting the binaryrepresentation by 4 places left or multiply the decimal values by 2^4=16

Samp e co es to rotate in ccw

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Samp e co es to rotate in ccwdrn

//single coil mode

#include <stdio.h>#include <dos.h>

main(){ char a[]={1,2,4,8};for (int i=0;i<=100;i++){ outportb(888,a[i%4]);

delay(10);}

outportb(888,0);}

//double coil#include <stdio.h>#include <dos.h>

main(){ char a[]={3,6,12,9};

for (inti=0;i<=100;i++)

{outportb(888,a[i%4]);delay(10);

}outportb(888,0);

}

//hybrid mode#include <stdio.h>#include <dos.h>

main(){ chara[]={1,3,2,6,4,12,8,9};

for (int i=0;i<=100;i++){outportb(888,a[i%8]);delay(10);}

outportb(888,0);}

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Sample codes to rotate in cw drn//single coil mode

#include <stdio.h>#include <dos.h>

main(){ char a[]={1,2,4,8};for (int i=100;i<=0;i--){ outportb(888,a[i%4]);

delay(10);}

outportb(888,0);}

//double coil#include <stdio.h>#include <dos.h>

main(){ char a[]={3,6,12,9};for (int i=100;i<=0;i--

)

{outportb(888,a[i%4]);

delay(10);}outportb(888,0);

}

//hybrid mode#include <stdio.h>#include <dos.h>

main(){ chara[]={1,3,2,6,4,12,8,9};

for (int i=100;i<=0;i--){outportb(888,a[i%8]);delay(10);}

outportb(888,0);}

Sample codes to move the robot

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Sample codes to move the robotbackward

//single coil mode

#include <stdio.h>#include <dos.h>main()

{ char a[]={1,2,4,8};charb[]={16,32,64,128};

for (int i=100;i<=0;i--){

outportb(888,a[i%4]|b[i%4]);


}

//double coil#include <stdio.h>#include <dos.h>main(){ char a[]={3,6,12,9};char

b[]={48,96,192,144};for (int i=100;i<=0;i--

)

{outportb(888,a[i%4]|b[i%4]);delay(10);

}outportb(888,0);

}

//hybrid mode#include <stdio.h>#include <dos.h>main(){ char

a[]={1,3,2,6,4,12,8,9};charb[]={16,48,32,96,64,192,128,144};

for (int i=100;i<=0;i--){outportb(888,a[i%8]|b[i%8]);delay(10);

}outportb(888,0);

}

Sample codes to move the robot

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Sample codes to move the robotforward

//single coil mode


{ char a[]={1,2,4,8};charb[]={16,32,64,128};

for (int i=0;i<=100;i++){

outportb(888,a[i%4]|b[i%4]);


}


b[]={48,96,192,144};for (int

i=0;i<=100;i++)


}outportb(888,0);

}


a[]={1,3,2,6,4,12,8,9};

charb[]={16,48,32,96,64,192,128,144};

for (inti=0;i<=100;i++)


}outportb(888,0);

}

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Sample codes to turn the bot left//single coil mode


{ char a[]={1,2,4,8};charb[]={16,32,64,128};

for (int i=0;i<=100;i++){ outportb(888,a[(100-

i)%4]|b[i%4]);delay(10);

}outportb(888,0);}


b[]={48,96,192,144};for (int

i=0;i<=100;i++)

{outportb(888,a[(100-i)%4]|b[i%4]);delay(10);

}outportb(888,0);

}


a[]={1,3,2,6,4,12,8,9};charb[]={16,48,32,96,64,192,128,144};

for (inti=0;i<=100;i++)

{outportb(888,a[(100-i)%8]|b[i%8]);delay(10);

}outportb(888,0);

}

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Sample codes to turn the bot right//single coil mode


{ char a[]={1,2,4,8};charb[]={16,32,64,128};

for (int i=0;i<=100;i++){

outportb(888,a[i%4]|b[(100-i)%4]);


}


b[]={48,96,192,144};for (int

i=0;i<=100;i++){outportb(888,a[i%4]|

b[(100-i)%4]);delay(10);}

outportb(888,0);}


a[]={1,3,2,6,4,12,8,9};charb[]={16,48,32,96,64,192,128,144};

for (inti=0;i<=100;i++)

{outportb(888,a[i%8]|b[(100-i)%8]);delay(10);

}outportb(888,0);

}

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Cracking Techno

Tennis....Here we present some vague ideas fordeveloping your robot. Two important

considerations are:Basic movable base which can beaccurately positioned and moved inany directionHitting mechanism

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If u use stepper motorsThe data pins D0-D3 will be connected tothe left motor and D4-D7 to the right one(or vice versa)To control the hitting mechanism u can use

the 4 control pins. For example u canswitch on a control pin to trigger a flap

mechanism. A power amplifier must beused in between port pins and devicesinvolved in hitting mechanism

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Please note....Windows XP doesn·t allow to directly accessthe parallel port so we have to use thirdparty drivers which opens the specificports.One such software is Userport.http://www.embeddedtronics.com/public/Ele

Generally the address of the parallel port is0x378-0x37F.If not the check its addressin the specific port properties in devicemanager.

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PROGRAMMING IN MATLABPROGRAMMING IN MATLABPROGRAMMING IN MATLABPROGRAMMING IN MATLABBasics of MatlabBasics of Matlab

Image Capturing.Image Capturing.Image Processing..Image Processing..

Object Identification«Object Identification«

Movement Algorithm«.Movement Algorithm«.

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B i Of M l b

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Basics Of MatlabPre-declaration of variable is not necessary, you can use variable

whenever required.FOR loop

for i=1:nbody

end

IF conditionif(condn)statement

endImage is treated as an array in Matlab which can be in any

format like RGB,Grayscale,BW,Intensity.Function[output variables]=name(input variables).Function shouldbe written in an M-file.For calling function say ¶add· type add(4,5) in the prompt.

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Image Capturing.Make a video input object.

Set various attributes of the object.Take Snap Shots.Save images in an array.

Image Capturing

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x=0;

T=0;data=.2;imaqreset;imaqmem(inf);vid=videoinput('winvideo',1,'RGB24_640x480');set(vid,'FramesPerTrigger',Inf);triggerconfig(vid, 'Immediate');start(vid);dio=digitalio('parallel','LPT1');% for enabling parallel portsaddline(dio,0:1,'out');

Image Capturing.

««.continued

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for ui=1:10f=getsnapshot(vid);flushdata(vid);

enddisp('START');tic;

f=getsnapshot(vid);flushdata(vid);prev_cen=0;flag=0;

end_y=400;start_y=40;while x==0

T=T+1;f=getsnapshot(vid);

{insert your code}endstop(vid);

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Image Capturing.Preview a stream of image frames .preview(obj);

Acquire and display a single image frame.

frame = getsnapshot(obj);

Remove video input object from memory.

delete(obj);

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Image Processing

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Image Processing..

RGB componentsFor example, the red, green, and blue

color components of the pixel (10,5) are

stored in RGB(10,5,1), RGB(10,5,2), andRGB(10,5,3), respectively.eg

a=imread(¶name.jpg·);r=a(:,:,1);g=a(:,:,2);b=a(:,:,3);

Object identification

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Object identificationimcrop(image)Im2bw(image)medfilt2(image)bwlabel(image)

Distinguishing the ball, robot, red square.regionprops ² area,centroid,perimeter

Ratio of area to sqr of perimeter will befixed number for a circular object.

k [ ] f

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Take [R,G,B] components of image.Check for area where R >threshold &

G,B<threshold to identify red block.Use of rectangles of different shapes

or use different colors to identify theorientation & position of robot.

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Movement AlgorithmUse of only 90 degrees turns formotion using DC motor.Use of stepper motor to move along

shortest path.Implementation

At each step find the angle betweenball and direction of bot ¶ ·.

If I I < 45 deg. Then move botRepeat till bot hits ball.

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MATLAB CODEdio=digitalio('parallel','LPT1');addline(dio,0:3,'out');

putvalue(dio,[0 1 1 0]);Keep all the operating tactics of

steps same as shown in C

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For any help contactNiraj Murarka(B2,329,Kameng)[email protected] ; 9864167497Suhas Mishra(B4-206,Kameng)

[email protected] ; 9954248915Ashwin Chander(B4-211, Kameng)

[email protected] ; 9954249118Abhishek Anand(B2-020,Kameng)

[email protected] Khaddar (132,Dihing)

[email protected]

Robotics 4

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