Hi friends,
One of my junior asked me about FUZZY LOGIC.. so i learned about it.. i would like to share it with you all..
so it is..

if you ask me for the definition.. i would say as it is given in the Wikipedia..
"Fuzzy logic is a form of many-valued logic derived from fuzzy set theory to deal with reasoning that is robust and approximate rather than brittle and exact."
but if you ask me to explain.. i would be saying as below..

if someone is asked to write coding for controlling the fan switch.. probably the algorithm would be as
=>IF temperature IS HOT, switch ON the fan.. ELSE, switch OFF the fan..
this is crisp logic.. binary logic.. the term hot is considered as TRUE(1) and the rest considered as FALSE(0)..so when the sensor gives certain value nearer to hot and more than the median.. it will be considered as TRUE(1)..

But in the case of FUZZY LOGIC.. there are many values are given between the TRUE and FALSE..
if we are writing the same program in FUZZY LOGIC.. the coding would be..
=>IF temperature IS very cold THEN stop fan
=>IF temperature IS cold THEN turn down fan
=>IF temperature IS normal THEN maintain level
=>IF temperature IS hot THEN speed up fan
Thus the TRUE (1) and the FALSE(0) as many values between them.. fuzzy works on IF... THEN.. rather than IF.. ELSE..

In case of FUZZY LOGIC, we have ranges between the TRUE and FALSE..

if you ask for another example..
consider a 100ml glass with 30ml water in it.. and someone is asking, is that glass full?..

case i:  if you are saying that glass is empty since the water is less than half of the glass... then this is crisp(binary) logic...

case ii: if  you are saying that glass is 30% full and 70% empty.. then this is FUZZY LOGIC..

the control system designed using this logic is FUZZY CONTROL SYSTEM...

hope i have explained mean for FUZZY LOGIC.. if you have any clarification.. post me.. i will clear it..


HI friend, 
From my early days, i have been hearing a story about great personalities.. today i googled it to know the full story... but i end up with something else that i would like to share with you...


LONG LONG ago there was a farmer and his son lived in Scotland.. one day when the farmer was on his way to his farm, he heard a cry for help from nearby lake.. Our farmer went there and saw a boy struggling in the lake.. our farmer jumped and saved his life.. Then the boy went to his home and farmer went to his farm.. "THE END".. sorry sorry.. we need to have a twist in it.. so end is not in here..
Next day, a noble king arrived to that farmer's house to say thanks for saving his son's life.. and he offered him more money.. but our farmer didn't accept it... since it is not for the money, he save that boy's life.. it is a good humanity..

Then the king saw a little in that farmer's house.. and he asked "is this your son?"..
The farmer said "yes"..

then the king said.."I will make you a deal. let me take him and give him a good education. he will grow to a man you can be proud of"

And that he did. In time, Farmer's son graduated from St. Mary's Hospital Medical School in London.

Years afterward, the nobleman's son was stricken with pneumonia. What saved him? The medicine discovered by that farmer's son... "THE END"....

would you like me to give some name for those personalities in this story.. then, i will give the same name as people says to me...  

The name of the medicine is PENICILLIN... of course, the farmer's son is SIR ALEXANDER FLEMING...
the noble king is LORD RANDOLPH CHURCHILL.. and the name of the king's son is SIR WINSTON CHURCHILL..



If you're thinking this story rings too good to be true, you are absolutely right. "Charming as it is," observes a Churchill Centre page devoted to alleged convergences between the lives of Winston churchill and Alexander Fleming, "it is certainly fiction."

Among the reasons set forth in support of that moral are:
  • There is no record of Winston Churchill nearly drowning in a Scottish bog when he was young.
  • There is no record of Lord Randolph Churchill paying for Alexander Fleming's education.
  • Though it is true that Winston Churchill contracted pneumonia more than once during World War II and was treated with an antibiotic called sulfadiazine ("M&B"), he was never, according to available medical records, treated with penicillin.
That said, Sir Alexander Fleming was indeed the discoverer of penicillin, and Churchill did apparently consult with the brilliant physician and professor of medicine once in 1946 when he had a staph infection that proved resistant to the drug.
The Churchill Centre attributes the apocryphal tale, which has circulated in email form since 1999, to a 1950 book called "Worship Programs for Juniors" by Alice A. Bays and Elizabeth Jones Oakbery.


hi friend,
last month the picture i have captured through my mobile cam have been published in THE HINDU weekends, under the heading "CAUGHT SNAPPING".. i would like to share those pictures..

NOTE three things in it..which attracted my eyes..
2. REVERES in reveres
3. Get Off My Tail!

i have took some more photos alone with it.. here it is

Global Positioning System (GPS)

hi friend,
since my final year project is about GPS-GSM based vehicle tracking and theft control.. i got a chance to learn about the GPS module working.. so i would like to share it with you all..


Our ancestors had to go to pretty extreme measures to keep from getting lost. They erected monumental landmarks, laboriously drafted detailed maps and learned to read the stars in the night sky.
But today a small device can guide us all through the world.. which is know as the GPS.. even the latest versions of mobile phones has inbuilt GPS module in it..


The Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). The U.S. military developed and implemented this satellite network as a military navigation system, but soon opened it up to everybody else.

A GPS receiver's job is to locate four or more of these satellites, figure out the distanc­e to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration


2-D Trilateration

Imagine you are somewhere in the United States and you are TOTALLY lost -- for whatever reason, you have absolutely no clue where you are. You find a friendly local and ask, "Where am I?" He says, "You are 625 miles from Boise, Idaho."
This is a nice, hard fact, but it is not particularly useful by itself. You could be anywhere on a circle around Boise that has a radius of 625 miles, like this:

You ask somebody else where you are, and she says, "You are 690 miles from Minneapolis, Minnesota." Now you're getting somewhere. If you combine this information with the Boise information, you have two circles that intersect. You now know that you must be at one of these two intersection points, if you are 625 miles from Boise and 690 miles from Minneapolis.

If a third person tells you that you are 615 miles from Tucson, Arizona, you can eliminate one of the possibilities, because the third circle will only intersect with one of these points. You now know exactly where you are -- Denver, Colorado.

This same concept works in three-dimensional space, as well, but you're dealing with spheres instead of circles. In the next section, we'll look at this type of trilateration.

3-D Trilateration

Fundamentally, three-dimensional trilateration isn't much different from two-dimensional trilateration, but it's a little trickier to visualize. Imagine the radii from the previous examples going off in all directions. So instead of a series of circles, you get a series of spheres.
If you know you are 10 miles from satellite A in the sky, you could be anywhere on the surface of a huge, imaginary sphere with a 10-mile radius. If you also know you are 15 miles from satellite B, you can overlap the first sphere with another, larger sphere. The spheres intersect in a perfect circle. If you know the distance to a third satellite, you get a third sphere, which intersects with this circle at two points.
The Earth itself can act as a fourth sphere -- only one of the two possible points will actually be on the surface of the planet, so you can eliminate the one in space. Receivers generally look to four or more satellites, however, to improve accuracy and provide precise altitude information.
In order to make this simple calculation, then, the GPS receiver has to know two things:
  • The location of at least three satellites above you
  • The distance between you and each of those satellites
The GPS receiver figures both of these things out by analyzing high-frequency, low-power radio signals from the GPS satellites. Better units have multiple receivers, so they can pick up signals from several satellites simultaneously.
Radio waves are electromagnetic energy, which means they travel at the speed of light (about 186,000 miles per second, 300,000 km per second in a vacuum). The receiver can figure out how far the signal has traveled by timing how long it took the signal to arrive.


On the previous page, we saw that a GPS receiver calculates the distance to GPS satellites by timing a signal's journey from satellite to receiver. As it turns out, this is a fairly elaborate process.
At a particular time (let's say midnight), the satellite begins transmitting a long, digital pattern called a pseudo-random code. The receiver begins running the same digital pattern also exactly at midnight. When the satellite's signal reaches the receiver, its transmission of the pattern will lag a bit behind the receiver's playing of the pattern.
The length of the delay is equal to the signal's travel time. The receiver multiplies this time by the speed of light to determine how far the signal traveled. Assuming the signal traveled in a straight line, this is the distance from receiver to satellite.
In order to make this measurement, the receiver and satellite both need clocks that can be synchronized down to the nanosecond. To make a satellite positioning system using only synchronized clocks, you would need to have atomic clocks not only on all the satellites, but also in the receiver itself. But atomic clocks cost somewhere between $50,000 and $100,000, which makes them a just a bit too expensive for everyday consumer use.
The Global Positioning System has a clever, effective solution to this problem. Every satellite contains an expensive atomic clock, but the receiver itself uses an ordinary quartz clock, which it constantly resets. In a nutshell, the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy. In other words, there is only one value for the "current time" that the receiver can use. The correct time value will cause all of the signals that the receiver is receiving to align at a single point in space. That time value is the time value held by the atomic clocks in all of the satellites. So the receiver sets its clock to that time value, and it then has the same time value that all the atomic clocks in all of the satellites have. The GPS receiver gets atomic clock accuracy "for free."
When you measure the distance to four located satellites, you can draw four spheres that all intersect at one point. Three spheres will intersect even if your numbers are way off, but four spheres will not intersect at one point if you've measured incorrectly. Since the receiver makes all its distance measurements using its own built-in clock, the distances will all be proportionally incorrect.
The receiver can easily calculate the necessary adjustment that will cause the four spheres to intersect at one point. Based on this, it resets its clock to be in sync with the satellite's atomic clock. The receiver does this constantly whenever it's on, which means it is nearly as accurate as the expensive atomic clocks in the satellites.
In order for the distance information to be of any use, the receiver also has to know where the satellites actually are. This isn't particularly difficult because the satellites travel in very high and predictable orbits. The GPS receiver simply stores an almanac that tells it where every satellite should be at any given time. Things like the pull of the moon and the sun do change the satellites' orbits very slightly, but the Department of Defense constantly monitors their exact positions and transmits any adjustments to all GPS receivers as part of the satellites' signals.

Thus by these information and with above calculation, our device give us our location..

Newer Posts Older Posts Home

About Me

My photo
Hi everyone,myself Alagappan...electronic and communication engg. student... living in madurai... interested in everything... want to achieve something great in my lifetime...


Recent Comments