Rf Based Spy

7/28/2019 Rf Based Spy

1/18

CHAPTER -1

INTRODUCTION


2/18

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.


3/18

CHAPTER -2

CIRCUIT DISCRIPTION AND WORKING


4/18

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


5/18

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 dont 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


6/18

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


7/18

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 batterys 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


8/18

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


9/18

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


10/18

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


11/18

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


12/18

data pin will represent logic1 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


13/18

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


14/18

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


15/18

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 states0,1 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


16/18

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


17/18

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.


18/18

REFRENCE:

Books

1. Electronic for you.

Internet

1. http:/www.google.com2. http:/www.ask.com

Rf Based Spy

Documents

Transcript of Rf Based Spy