robotics club (rtist)

7/29/2019 Robotics club (Rtist)

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Developed by:Aamir saddam

Abhishek rajan

R-TIST CLUB NITJ



TRANSPORTER

Description

A robotic arm is a robotic manipulator, with similar

functions to a human arm .motor is used for joint

rotation. It has about same number of degree of

freedom as in human arm. Humans pick things up

without thinking about the steps involved. In order

for a robot or a robotic arm to pick up or move

something, someone has to tell it to performseveral actions in a particular order — from moving

the arm, to rotating the “wrist” to opening and

closing the “hand” or “fingers.”



For constructing manual robot-

Manual robot should have the feature of robotic

arm that can pick an object and place it on another

autonomous robot which will carry the object to

drop zone.

Overview-

Degree of freedom- 3

Payload Capacity (Fully Extended) -250 gm.

No. of motors required- 3 (D.C geared motor)

3 switches to control three motors

Chassis

Ciruit board for soldering 3 switches on board and connecting

the three switches to 3 motors.

Mechanical stand(clamp) for connecting different motors to

each other.

12 volt power supply. It can be reduced accordingly using

diodes and resistors



Base motor which is installed on chassis is generally selected of

low r. p.m as 10 rpm and can sustain upto 3 kg torque.in

human arm, this motor is just like our shoulder. This motor

gives up and down movement of the arm

Then second motor which is just like our elbow provides

second degree of freedom is generally selected of 30 rpm .This

motor gives left and and right motion to the arm.

Third motor is used as jaw to grab the object tightly and lift it. It

is generally selected of 60 rpm.

Chassis D.C geared motor of 30 rpm



Switches- the wires of three motors are connected

to three switches .

We use bipolar switch having 6 pins as shown in the

figure . The middle two pins are connected to

power supply. The upper two pins is connected to

the motor which gives one specific direction . and

the lower two pins are connected to the motor with

opposite terminal, reverse to that of upper pins.It

rotates the motor in reverse direction.



ROBOTIC ARM PICTURES-



Line Following Robot

A line follower is an autonomous bot that can

follow a specific colored line painted on a surface of

different contrast, such as white on black.

To start with first of all I will be discussing a small

concept of light. I believe you all know that the light

that strikes any platform is reflected. The reflection

and absorption coefficient of light depend upon

material, color of platform and other factors. In

simple words the black surface absorbs the light andthe white surface reflects it, this is the basic

concept behind making a line follower.



So the line follower has an emitter and a reflector.

The reflector receives the light and generates a

voltage proportional to the intensity of the light, if

this voltage is above a threshold it means SIGNAL=1

(logic one) else SIGNAL= 0 (logic zero).

Let’s take up an example where we have to move our

bOt on black surface having white line. Suppose I

have two Infra Red (IR) sensor pairs that are on

different halves of a bOt with respect to geometrical

central axis of the bOt. The sensors are placed in

such a way that the white line lies in between both

the sensors when the bOt is placed on the white

track painted on black surface to move. Now if the

white line is between both the sensors while moving

forward both the sensors will be on black surface

and the detectors/receivers will receive less amount

of light since black absorbs light and hence signal

provided by both the infra-red receivers will be low.



Now if the heading/direction of the white line

changes one of the sensors will move in the region of

white line and will start giving output signal as high.

This information can be used to ‘turn’ the bOt and

orient itself in the right direction. For example in theabove figure if the bot is located in position 1, then

bOt will move forward and if the bOt is in position 2

it will have to turn left .

Let’s move on and discuss everything step by step in

detail.

We will be discussing the making of line follower under three heads:

1. Chassis of robot { those familiar can skip this

section}



2. Electronics/Hardware Designing

3. Programming/Software Designing

CHASSIS OF ROBOT

1. Base of robot: The base or the material of the

platform of robot can be made with any easily

available material like switch board, wood, acrylic

sheet or steel sheet. As our robot will be very light,

you don’t have to think a lot about strength and other

such factors. We recommend you to make a small

size and light weight bOt. Here we are using steel

base:

2. Motors and Driving Mechanism:

1. We will need a set of two motors that have same

rpm (revolution per minute).

2. We will be using differential drive for maneuvering

our bOt i.e. we will have three wheelsfor our bOt,



the front two will be powered and the rear will be

free wheel.

3. When the bot is moving straight both the motors

should have equal speed.4. For turning, one of the motor is switched off. If we

switch off the left motor, the bot will turn left and

vice versa.

1. You can choose a motor of rpm around 100 and a

torque of 1kg-cm



3. Coupling wheels & clamping motors: For clamping

the motors you can use pipe clamps or make right

angled clamps. The right angle clamps ensure more

rigidness. To couple the motor ensure that the

shaft of motor and hole of wheel have equal diameter

(if you can’t find one check the tutorial on wheels).



ELECTRONICS

Below is a flow chart that explains the working of

the bOt:-



The Infra Red sensors are used to interact with the

environment. The emitter sends a ray which is

received by detector in the form of voltage and it

then amplified by amplifier since the signals areweak (more on this later). Below are the circuit

diagrams of Infra-red LED emitter and receiver.



Op-Amplifier (LM324)

If the rays received by the IR- LED receiver are above

a particular threshold then an amplified signal isgenerated by the amplifier (LM324). Note that the

sensors cannot directly send a signal to the

microcontroller as the signal voltage generated by

them is too low and even when sensors are on white

surface signal generated by them will interpreted

low by the microcontroller.



Microcontroller (AT89S52)

The microcontroller receives the signal and respondsaccordingly. It takes the decision based on input

signal received by both the receiver LEDs. It will give

command to motors through H-bridge to move

forward, or take a left turn or a right turn.

H-bridge (L293B)

The microcontroller sends a signal to the H-bride

that acts as a switch. If the signal received by the H-

bridge is high it will rotate the motor or else it won’t

do so. Note that microcontroller only sends a signal

to a switch which gives the voltage required by the

motor to rotate. Here we are using L293B which can

be used to control two motors.

Pin connections for H-bridge:

1. En1 & En2 are given logic 1 from microcontroller

or give 5V from outside and are used to

activate/deactivate one ‘half’ of the H-bridge.2. V is the voltage that you want to supply to the

motor(s) : 9 or 12V

3. Vcc is the logic 1 or 5V



The complete circuit diagram with all the integrated

circuits required for making a line follower is shown

below:-



Here we are using pins P1.0 and P1.4 for taking

inputs from the IR sensors after being amplified by

LM324.1. P1.0 – Input from left sensor

2. P1.4 – Input from right sensor

There are six outputs from AT89S52 microcontroller

to the H-bridge.

1. Pins P0.0 and P0.4 are connected to enable pins of

the H-bridge. We can use them to

deactivate/active the two halves of H-bridge i.e. if

pins are set to logic 1 the corresponding half of

the H-bridge will be activated.

2. P0.1 – will drive the left motor in forward direction

3. P0.2 – will drive the left motor in reverse direction



4. P0.3 – will drive the right motor in forward

direction

5. P0.5 – will drive the right motor in reverse

direction

Programming

Below is the code in C for the line follower -

C Code

#include <reg51.h>

/*

Sensors input port - P1 P1_0 --------> Left sensor

P1_4 --------> Right sensor

Motors output port - P0



P0_0 --------> Enable pin of the left half of

the H-bridge

P0_1 --------> will drive the left motor inforward direction

P0_2 --------> will drive the left motor in

reverse direction

P0_3 --------> will drive the right motor in

forward direction

P0_4 --------> Enable pin of the right half of

the H-bridge

P0_5 --------> will drive the right motor in

reverse direction

*/

/*Delay function runs an idle loop to create a time

delay. If the crystal used is of 11.0592 MHz then the

argument passed in delay is in 'milliseconds'.*/

void Delay(unsigned int itime)

{

unsigned int i,j;

for(i=0;i<itime;i++)

for(j=0;j<1275;j++); //Idle loop

}

void Forward() {

P0_1=1;

P0_2=0;

P0_3=1;



P0_5=0;

}

/*Generally for turning we use a pulsated wave sothe bOt doesn’t get out of control i.e. we run the

motor for sometime then again stop it and this is

done very quickly to create an effective pulse. See

the function below.*/

void TurnLeft()

{

P0_1=0; /*Left motor is not running in any

direction.*/

P0_2=0;

P0_3=1; /*Right motor is running in

forward direction. bOt will eventually turn left*/

P0_5=0;

Delay(50); /* Wait for 50 ms*/

P0_1=0; /*Motors are not running*/

P0_2=0;

P0_3=0;

P0_5=0;

Delay(50); /*Delay of another 50 ms*/

}

/*So in the above program we have effectively

created a pulse of 100ms which is on for 50ms and

off for another 50ms. You can change this value to

suit your needs*/



/*Similarly we can write a function to turn right*/

void TurnRight() {

P0_1=1; /*Left motor running in forward

direction.*/

P0_2=0;

P0_3=0; /*Right motor is not running.*/

P0_5=0;

Delay(50); /*50ms time delay*/

P0_1=0; /*Motors not running in any

direction*/

P0_2=0;

P0_3=0;

P0_5=0;

Delay(50); /*50ms time delay*/

}

void main()

{

/* The pins which are receiving inputs from the

sensors should be initially set to logic 1.*/

P1_0=1; /*Left sensor input*/ P1_4=1; /*Right sensor input*/

P0_0=1; /*Enable pin of the left half of the

H-bridge*/

P0_4=1; /*Enable pin of the right half of



the H-bridge*/

//main loop of the program

while(1){

if ((P1_0==0)&&(P1_4==1))

TurnRight();

else if ((P1_0==1)&&(P1_4==0))

TurnLeft();

else

Forward();

}

}

*************** THE END*************

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