24-03-2011, 03:37 PM
Presented by
M.s.prasad
K.Sushma
A.Shiva shankar
B.Divya deepthi
J.Ratna raju
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INTRODUCTION
It is a robot which gives alarm when it interfaces with a metal or bomb
It is a computer controlled robot with a navigable camera
It can be operated in remote areas as it is wireless controlled robot
DESCRIPTION
SOFTWARE
… LABVIEW
HARDWARE
… TRANSMITTING MODULE
… RECEIVER MODULE
SOFTWARE:LABVIEW
Graphical interface version enables us in smart controlling.
We use labview to communicate with the hardware such as data acquisition,vision and motion control devices.
We use parallel port programming for control of robot.
It is also called as Application Specific Development Environment(ADE).
Parallel port programming
WHY ONLY PARALLEL PORT ???
In serial ports, there will be two data lines: One transmission line and one receive line.
To send a data in serial port, we have to send one bit after another with some extra bits like start bit, stop bit and parity bit to detect errors.
But in parallel port, all the 8 bits of a byte will be sent to the port at a time and an indication will be sent in another line.
HOW TO PROGRAMME ???
The Parallel Port
Now we can say that to communicate through parallel port you should communicate with the following three ports or registers:
1-The Data Port (278h/378h) which (input/output) 8 bits (the input or output data).
2-The Status Port (279h/379h) which reads 8 bits for the printer.
3-The Control Port (27Ah/37Ah) which transmit 8 bits to select output or input operation.Base address
General Information:
Pins 2 to 9 are taken as outports.
Pins 18 to 25 are ground.
The port names in the previous slide are in hex. Like (378h) is 378 in hexadecimal.
HARDWARE
TRANSMITTER MODULE
RECEVING MODULE
RECEVING MODULE
ISOLATOR
We use optocoupler as isolator
The basic purpose of isolator is to protect our pc from hardware i.e; to avoid direct signal connection.
There are many situations where signals and data need to be transferred from one sub system to another within a piece of electronics equipment or from one piece of equipment to another without making direct ohmic connection.
Relays can of course provide this kind of isolation , but even small relays tend to be fairly bulky compared with IC’s and many of the today’s other miniature circuit components. Because they are electro-machanical, relays are also not reliable and only capable of relatively low speed operation where small size, higher speed and greater reliability are important .A much better alternative is to use an optocoupler. There we use a beam light to transmit the signals or data across an electrical barrier and achieve excellent isolation.
ENCODERS/DECODERS
The bits we get from the pc(labview) are 8 in number.This might be tough to transmit all 8 bits individually to the transmitter section.so,we use 8 bit encoder/decoder to convert and regenerate into a single signal.
Ht 640/s encoder
Ht648/L decoder
ENCODER APPLICATION CIRCUIT
DECODER
RF TRANSMITTER/RECEIVER MODULE
It is a 433MHZ radio metric limited to 100mts Rx/Tx modules.
It is of 5v supply having a small antenna.
We use directly pre-existing modules.
DIGITAL LOGIC CIRCUIT
The bits obtained from the receiver to be manipulated for driving the specific motors we need a demultiplexer logical circuit of 28 data lines .A digital logic circuit is to be designed with 8 input lines for 28 output data lines using digital logic circuitry. The simple operation of demux can be obtained by using logic gates(and,or,nand….). Let us consider the data is 00000001.Then the function of output for this particular data bit is (d0*d1’*d2’*d3’*d4’*d5’*d6’*d7’)
DC MOTOR DRIVERS
The term "H-bridge" is derived from the typical graphical representation of such a circuit. An H-bridge is built with four switches (solid-state or mechanical). When the switches S1 and S4 (according to the first figure) are closed (and S2 and S3 are open) a positive voltage will be applied across the motor. By opening S1 and S4 switches and closing S2 and S3 switches, this voltage is reversed, allowing reverse operation of the motor.
s1 s2 s3 s4 result
1 0 0 1 right
0 1 1 0 left
0 0 0 0 free running
0 1 0 1 break
1 0 1 0 break
H-bridge circuit
DC MOTORS
In any electric motor, operation is based on simple electromagnetism. A current-carrying conductor generates a magnetic field; when this is then placed in an external magnetic field, it will experience a force proportional to the current in the conductor, and to the strength of the external magnetic field.
As you are well aware of from playing with magnets as a kid, opposite (North and South) polarities attract, while like polarities (North and North, South and South) repel.
The internal configuration of a DC motor is designed to harness the magnetic interaction between a current-carrying conductor and an external magnetic field to generate rotational motion.
Let's start by looking at a simple 2-pole DC electric motor (here red represents a magnet or winding with a "North" polarization, while green represents a magnet or winding with a "South" polarization).
N∞ V (speed is proportional to voltage) at constant voltage motor drives with constant speed
Bomb Detection Circuit
The circuit described here is a metal detector.the operation of circuit is based on superheterodying principle which is commonly used in superhet receivers.
The circuit utilises RF oscillators.
The frquencies of both oscillators are fixed at 5.5MHZ.
The first RF oscillator comprises transistor T1(BF 494) and 5.5MHZ ceramic filter commonly used in T.V sound Ifsection.
The second oscillator is a colpitt oscillator realised with the help of transistor T3(BF 494) and inductor L1 shunted by trimmer capacitor vc1.
These two oscillator frequencies(Fx and Fy) are mixed in a mixer transistor T2(BF 494) and the difference or beat frequency(Fx-Fy) output from collector of transistor T2 is connected to detector stage comprising diodes D1 and D2.
The output is a pulsating dc which is passed through a low pass filter realised with the help of 10k resistor R12 and two 15 nF capacitors c6 and c10.
It is then passed to AF amplifier IC1(2822m) via volume control VR1 and the output is fed to 8ohm/1W speaker.
The inductor L1 can be constructed using 15turns of 25SWG wire on a 10cm diameter aircore former and then cementing it with insulating varnish.
For proper operation of circuit,it is critical that frequencies of both oscillators are the same so as to obtain zero beat in the absence of any metal in the near vicinity if the circuit.
The alignment of oscillator-2(to match oscillator-1 freq) can be done with the help of trimmer capacitor vc1
When the two frequencies are equal the beat frequency is zero i.e;B.F=Fx-Fy=0 and thus no sound from the loud speaker.
When search coil L1 passes over metal,the metal changes its inductance there by changing the second oscillator freq.so now Fx-Fy is not zero and the loud speaker sounds’
thus.,we can detect prsence of ametal(bomb).
Applications
Detection of metals or bombs in remote areas.
The robotic arm can be used to transport the suspected things.
It can be operated over 100m range.
Advantages
Remote operation
Portable in size
Less manual work
Reliable cost
