CHAPTER -1

INTROD

UCTION

RF BASED SPY ROBOT

Introduction:

Robotics is a fascinating subject-

more so, if you have to fabricate a robot

yourself. The field of robotics encompasses a

number of engineering disciplines such as

electronics (including electrical), structural,

pneumatics and mechanical.

The structural part involves use of

frames, beams, linkages, axles, etc. the

mechanical parts/ accessories comprise various

types of gears (spurs, crowns, bevels, worms and

differential gear systems), pulleys and belts,

drive systems(differentials, castors, wheels and

steering) etc. The pneumatics plays a vital role

in generating specific pushing and pulling

movements such as those simulating arms or leg

movement. Pneumatic grippers are also used with

advantage in robotics because of their simplicity

and cost effectiveness. The electrical items

include DC and Stepper motors, actuators,

electrical grips, clutches and their control. The

electronic parts involves remote control, sensors

(touch sensors, light sensor, collision sensor,

etc), there interface circuitry and a

microcontroller for overall control functions.

CHAPTER -2

CIRCUIT DISCRIPTION AND WORKING

Project Overview:

What we present here

is an elementary robotic land rover that can be

control remotely using primarily the RF mode. The

RF remote control has the advantage of adequate

range (up to 200m with proper antenna) besides

being omni directional. On the other hand, an IR

remote would function over a limited range of

about 5m and the remote transmitter has to be

oriented towards the receiver module quite

precisely. However, the cost involve in using RF

modules is much higher than that of IR components

and as such, we have included the replacement

alternative of RF modules with their IR

counterparts for using the IR remote control.

The proposed land rover can move in

forward and reverse direction. You will also be

able to steer it towards left and right

directions. While being turn to left and right,

the corresponding blinking LEDs would blink to

indicate the direction of its turning. Similarly,

during reverse movement, reversing LEDs would be

lit. Front and rear bumpers are provided using

long operating lever of micro switches to switch

off the drive motors during any collision. The

decoder being used for the project has latch

outputs and as such you don’t have to keep the

buttons on remote control pressed for more than a

few milliseconds. This helps prolong the battery

life for remote.

The entire project is split up into sections

and each section is explain in the sufficient

detail to enable you not only to fabricate the

present design but also exploit this principles

for evolving your own design with added

functions.

Forward and reverse movement:

To keep your design as simple

as possible, we have coupled a 30rpm geared 6v DC

motor to the left front wheel and another

identical motor to the right front wheel. Both

these front motors are mounted side by side by

facing in opposite direction. Wheel rims (5cm

diameter) along with rubber wheels are directly

coupled to each of the motor shafts. This

arrangement does not require separate axles.

During forward (or reverse)

movement of the vehicle, the two wheel shafts, as

viewed from the motor ends, would move in

opposite directions (one clockwise and the other

anticlockwise). For reversing the direction, you

simply have to reverse the DC supply polarity of

the two motors driving the respective wheels.

Steering control:

There are different methods available for

steering a robotic vehicle. The commonly used

ones are:

1. Front wheels are used for steering,

while rear wheels are used for driving eg.

Tractors.

2. Front wheels are used for steering as

well as driving eg, in most light vehicles. In

these vehicles (such as cars), the front wheels

are coupled using a differential gear

arrangement. It comes into play only when one

wheel needs to rotate differentially with respect

to their axes.

Drive circuit for the motors:

Here is a typical circuit for

driving one of the motors, in forward or reverse

direction, coupled to, say the left hand front

wheel. Simultaneously, the right direction for

the moving the vehicle in the same direction. It

means that input terminals of the motor drive

circuit for the right hand motor have to be fed

with reverse polarity control signals compared to

those of the left hand motor drive circuit.

In the H-bridge motor

drive circuit when A1 input is made high and A2

is made low, transistor T1(NPN) is forward biased

and driven into saturation, while transistor T2

(PnP), being reverse biased, is cut off. This

extends the battery’s positive rail to terminal1

of the motor. Simultaneously with input A2 at

ground potential, transistor T3 (NPN) is cutoff,

while T4 (PnP) is forward biased and driven into

saturation. This results in ground being extended

to terminal2 of the motor. Thus the motor rotates

in one direction.

Now, if the two inputs are logically

complemented, the motor will run in the opposite

direction. When both the inputs are at the same

logic level (gnd or vcc), the motor is at rest.

Thus WI can control the movement (forward,

reverse and stop) as well as the direction of

rotation of the motor with the help of logic

level of the two control input signals to the

motor.

Motor control logic:

As per the preceding

explanation, the input logic levels required at

terminals A1 and A2 of the left hand motor drive

circuit and at input terminals B1 of B2 of the

right hand motor drive circuit are shown in fig.

Table can be rearranged as table

, which can be further simplified as table . The

equivalent hex values of the binary control

signals are indicated in table. It transpires

that if we connect(short) input terminals A2 and

B1 of the two motor control both the motors for

forward, reverse left and right movement of the

vehicle using the 3 bit binary number shown in

table

. This fact will be used while arriving at

the integrated circuit for controlling the motors

for appropriate movement of body.

Remote control:

For remote control we have used Holtek

encoder-decoder pair of HT12E and HT12D employing

these are 18 pin DIP ICs.

Operation of Holtek HT12E and HT12D:

These are CMOS ICs with working voltage ranging

from 2.4v to 12v. Encoder HT12E has eight address

and another four address/data lines. The data set

on these twelve lines is serially transmitted

when the transmit enable pin TE is taken low. The

data output appears serially on the Dout pin. The

data is transmitted four times in succession. It

consists of differing length of positive going

pulses for `1` and `0`, the pulse width for `0`

being twice the pulse width of `1`. The frequency

of these pulses may lie between 1.5 and 7 kHz

depending on the resistor value between OSC1 and

OSC2 pins. The internal oscillator frequency of

decoder HT12D is 50 times the oscillator

frequency HT12E. The values of timing resistors

connected between OSC1 and OSC2 pins of HT12E and

HT12D, for given supply voltages, can be found

out from the graphs given in the datasheet of the

respective chips. The resistor values used in the

circuits here are chosen for approximately 3 kHz

frequency for encoder HT12E and 150 kHz for

decoder HT12D at Vdd of 5V.

The HT12D receive the data from HT12E on

its Din pin serially. If the address part of the

data receive matches the level on A0 through A7

pins four times in succession, the valid

transmission (Vt) pin is taken high. The data on

pin AD8 through AD11 of the HT12E appears on pins

D8 through D11 of the HT12D. Thus, the device

acts as a receiver of four bit data (16 possible

codes) with 8 bit addressing (256 possible

channel).

The test circuit given in fig will help you

in checking the functional service ability and

synchronization of the frequency of operation.

Once the frequency of pair is aligned, on the

pressing of push switch S1 on the encoder, LED on

the decoder should glow. You can also check the

transfer of data on pin AD8 through AD11( the

data pin of the encoder can be set as a high and

low using switches S2 through S5), which is

latched on pin D8 through D11 of the decoder once

TE pin is taken low momentary using push switch

S1. This completes the testing of encoder decoder

pair of HT12E and HT12D.

RF transmitter and RF receiver:

The RF transmitter and receiver marketed by

Aplus India, Mumbai have been employed for RF

remote control. The RF transmitter TX433 is an

AM/ASK transmitter. Its feature includes:

1. 5V-12V single supply operation

2. ON/OFF key(OOK)/ASK data format

3. Up to 9.6kbps data rate

4. +9dBm output power(about 200m range)

5. SAW-based architecture

6. For Antenna, 45cm wire is adequate

The output power and current range of RF

transmitter for Vcc of 5V and 12V are tabulated

in table.

The pin configuration of the transmitter

module is shown. The RF receiver RX433 is a 433

MHz module.

Remote Transmitter

The receiver address to be transmitted can

be set with the help of 8way DIP switch DIP-SW2.

When any switch is open the pin connected to

that switch at logic 1, and when it is closed the

respective pin is at logic 0. the data pin are

pulled high via resistor R2 through R5. In this

condition, if TE pin is taken low (by depressing

stop switch), the binary data transmitted via

pins AD8 through AD11 will be

‘1111’ (decimal 15). When any other data pin

marked forward, reverse left, right alone is

pressed, a ‘0’ will be sent at that position,

while other data pin will represent logic’1’

state. The logic circuitry at the receiver

decoder end will be decoding the data

appropriately for controlling the two motor of

the land rover.

RF& IR TRANSMITTER

IR based alternative:

The RF modulator used in the

remote can be easily replaced with the IR module

circuit build around IC2 and transistor T1. The

RF/IR selection can be affected by moving the

shorting link of Con-1 connector. Similarly, the

RF receiver module in the RF receiver decoder can

be replaced with the IR receiver module shown in

fig.

For using the IR based

Encoder, the Dout signal pin 17 of HT12E is to be

connected to Din pin 5 of astable oscillator IC

CD4047 for modulating its output. The frequency

of the astable at output pin 10 is determine by

the timing component as follows

Frequency=1/4.71*(R6+VR1)*C3 Hz

This frequency is adjusted for 38 KHz with pin 5

held at logic 1. The modulated 38 kHz, after

amplification by Darlington pair of transistor T1

and T2, drives IR LED 1 LD271 (or equivalent).

RF receiver decoder:

The complete RF receiver decoder circuit

employing HT12D is shown. Assuming that identical

address is selected on the encoder and decoder,

when any of the switches on the transmitter

(marked as forward, reverse, and right, left) is

depressed, the corresponding data pin of the

demodulator will go low. The data output of HT12D

are fed to 8 bit priority encoder CD4532 via

inverter to generate appropriate logic output in

conformity with table. To control the left, right

of motor for required motion of land rover is

explained earlier. However, when stop button is

pressed on transmitter, all data pins (D8 through

D11) on the decoder will latched to the high

output state. After inversion by NAND gates N1

through N4, all the output will be low and hence

EI (pin 5) of CD4532 will go low to force all its

output to go low. As a result, both the motor

will stop running.

RF/IR RECEIVER

You may like to verify the code generated at

the output of CD4532 with the help of truth

table. The following is the exact sequence of

operation at the receiver and motor driver when a

specific push switch momentarily pressed on the

transmitter:

1. Forward: The D8 output (pin 10) of IC 3

goes low, which after inversion by inverter N1

goes high to switch ON the front LED (LED 2 and

LED3) via driver transistor T6 and take D3

input(pin 13) of IC5 high. This cause Q2, Q1 and

Q0 going to logic states’0’,’1’ and ‘1’,

respectively and as a result, both the motor

will run in such direction as to move the rover

in the forward direction.

2.Reverse: The D9 output (pin 11) of IC3 goes

low which after inversion by inverter N2 goes

high to switch ON the rear LEDs(LED 4 and LED

5) via a driver transistor T7 undertake and

take D4 input (pin 1) of IC 5 high. This

results in Q2, Q1 and Q0 going to logic states

‘1’,’0’ and ‘0’ respectively, and as a result

both the motor will run in such a direction as

to move the rover in the Reverse or backward

direction.

3.Left: The D10 output (pin 12) of IC 3 goes

low, which after inversion by inverter N3 goes

high to switch ON the left LED 7 after a second

inversion by inverter/ driver gate N6 and make D2

input pin 12 of IC5 high. This results in Q2, Q1

and Q0 going to logic states ‘0’,’1’ and ‘0’

respectively, and as a result only the right hand

side motor will run and left hand side motor will

be static. This cause the rover to perform a left

turn.

4. Right: The D11 output (pin 13) of IC 3 goes

low, which after inversion by inverter N3 goes

high to switch ON the right blinking LED 6 after

a second inversion by inverter/ driver gate N5

and make D1 input pin 11 of IC5 high. This

results in Q2, Q1 and Q0 going to logic states

‘0’,’0’ and ‘1’ respectively, and as a result

only the left hand side motor will run and right

hand side motor will be static. This cause the

rover to perform a right turn.

5.Stop: The D8 through D11 output of IC3 goes

high and, after inversion by N1 through N4

because blocking of diode D5 through D8. As a

result, ground is extended to EI pin 5 through

resistor R17 and all the outputs (Q2, Q1 and Q0)

of CD4532 go low to stop both the motors, all the

LEDs also stop glowing.

FUTURE APPLICATION:

1.This project concept is widely used in

ROBOTICS

2.The installation in loading vehicles may

carry the loads in industries

3.The new and widely used PLC systems are used

for AUTONOMOUS TECHNOLOGY.

4.It also used as servant robot by implementing

AUTOMATIC GUIDED VEHICLE (AGV) .

5.It also act as sample collector and observing

the behavior of animals where human beings

cannot reach.

6.By implementing NANOTECHNOLOGY in project, it

also generates power for itself and project

work 24 hours.

7.By using VOICE RECOGNITION SYSTEM we also

control the project on commanding in our

voice.

8.On implementing Microprocessor programming we

also used it as automatically controlled

robot or a vehicle.

9.The project also used in alma maters as a

supplementary carrier during examinations.

10. On implementing camera and spy devices

we also get the pictures and information

during charged suspect.

Wireless control devices are gaining enormous applications in robotics and industrial automation applications. The main objective of our project rf based spy robot is implement a radio frequency based wireless robot using a micro controller.  In This RF based robot project we high lightened the importance of automated robots in defense and automatic guided vehicle systems.

Wireless robot circuit:

The robot is controlled by means of an RF module, it advantageous when compared to IR transmission in high range accessing.

The forward and back movements are controlled by themicro controller. The dc motor is interface with themicro controller, based on the instructions from themicro controller the dc motor acts.

Holtek encoder-decoder pair of HT12E and HT12D is used as the remote controlling device.

The RF transmitter TX433 and RF receiver RX433 are used for receiving commands and transmitting instructions.

For over view on circuit diagrams used in this project see this video.http://www.youtube.com/watch?v=blv2eFh5U8I&feature=youtu.be

Remote control rf based spy robot circuitry:

The circuitry of robot  consists of Stepper motors, actuators, and electrical grips and Pneumatic grippers for pushing and pulling mechanisms and remote control unit, touch sensors, light sensor, collision sensor and micro controller interface for control operations the components used in this prototype model are flexible and cost effective.

Download RF Based Spy Robot Project Report

Advantages:

Used as confidential surveyors in military agencies. Hot spot wireless security. Remote area exploration, and in rescue operations.

Future enhancement:

In autonomous technology using PLC systems we can implement the automatic guided vehicle systems, these systems are converted into self powering automated devices using nano technology in their internal circuitry. By interfacing the voice recognition system wecan manipulate the robot based on voice commands; these systems can provide pictorial information using camera and wireless communication module.

REFRENCE:

Books

1. Electronic for you.

Internet

1. http:/www.google.com

2. http:/www.ask.com