Dhananjay.v.gadre sir's great battery less dice

Here is the video of a battery less dice made by one of our faculty Dhananjay.V.Gadre sir.
This circuit employs an AVR microcontroller and uses a faraday generator for generating the emf.
First the device is shaken many times and then the charge is stored in a very large capacitor.This capacitor provides the required potential to light the L.E.D's that make up the dice.
A random function generator generates a random number between 1 and 6.

See the demonstrative video:

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Line follower

What is a line follower?

A line follower is an autonomous vehicle which follows a line path(straight or curved) that maybe of any colour.

what this statement means is that the line follower will move on its own by following the line.


I have always been fascinated by autonomous vehicles like micromouse, line follower the best thing about them is that they move without any external control.

So a line follower has the following requirements:

1. It requires a Sensory Device which would help detect the line.

2. It requires a Brain to control its motion helping to follow the line.

3. It requires Locomotion which would help it ro move along the line.

4. It requires a Mechanical Structure which would support all these devices.


SENSORY DEVICE:

The most important part of the line follower is its sensory part which detects the line.
It senses the line and produces an output in the form of potential drop.
For example, an LDR(Light Dependant Resistor) has different resistances for different intensities of light,low resistance for higher intensity and vice versa.

An IR sensor is also a good option as a sensory device it also produces a potential drop across it.

for more info on IR sensor:Link to IR Sensors

or u can also use an LED

For details for how to use LED as a sensor visit this site.

Though it is important to note that more the number of sensors employed the better the line follower becomes.But programming becomes more and more complex with increasing number of sensors

U can also use a web camera to detect the line and follow it using image processing for interpretation.
But it would increase the cost of the line follower by two folds.

BRAIN:

Now the signal produced by the sensors of the line follower is to be interpreted by a logic circuit.
This logic circuit can be purely electronic(if u are good at hardware) or using Microcontrollers like AVR or 8051 which u can program using C. Through a suitable program u can control the motion of the line follower. Suppose if u get a signal logic 1 as an input and if you're following a black line then u would move right or left accordingly.

for example if u have two sensors on both sides of the line and if detect logic 1 one and logic 0 on the other sensor(then u have moved on the left of the line) so to counter u will have to move to the right side.

This way u will follow the line.

Locomotion:

Now for locomotion of the line follower we require motors.We require lightweight motors which can have low torque and medium(now for controlling high rpm motors we require an H-bridge see article for fast change of change of direction)
The motors should be d.c. motors(it is preferable not use stepper motors instead use differential mechanism for the line follower).

Mechanical Structure:

We should use a lightweight chassis as the torque of the motors is low and so they cannot support large amount of weight. The chassis can be made of lightweight plastic or wood.
And we also need a large amounts of nuts,bolts and screws to fix the motors and the electronic parts of the line follower.

Watch this great video:

It is the video of a very fast Line follower and completes three laps in very less time.
It inspires a lot.
The name of the line follower is Jet.

UBUNTU 7.10 released

I am a relatively new user of linux, but i like Ubuntu because it requires less rsources(less use of RAM). It is very user friendly and easy to understand. And yes u can order your copy of Ubuntu online and it will shipped to your address for free.

The new 7.10 release has many new features:

1. A new GUI environment: The new Gnome 2.20
2. New 3D desktop effects
3. A new Desktop Search
4. Fast user switching
5. New extensions for Firefox browser
6. Dynamic Screen configuration
7. Fully Automatic Printer Configuration

and many other features like energy effecient mode

for more visit http://www.ubuntu.com/testing/710rc

If you want to try the trial version
download here: http://releases.ubuntu.com/releases/7.10

Innovision 2007

This Innovision was a lot better than the previous one.
This innovision had more technical events.
The participation was at a high.
People from different colleges participated in events like Line Following Robot,Micromouse,Robowars and Carnage.

The new attractions were the auto show,the robotics display(by techtronics).

The event that attracted the most number of people was Nexus (organized by TRI)
The participants had to make a robot thathad to lift 4 blocks one at a time from the ground and place it on a height.

The link to the site : innovision07.com


Here are some pics and videos :

STEPPER MOTOR

The most common problem we face when we use normal DC motors is that we don’t have precise control over how much it rotates. To rotate DC motors through a particular number of degrees what we can do is either calibrate it for a delay based operation i.e. if I switch it on for n seconds it moves 360 degrees; or what we can do is attach n encoder to the shaft which gives us a feedback on how much the motor shaft has rotated so that we can stop it when it rotates through the desired angle. Home made encoders give good results but don’t have such a high resolution and high resolution encoders are costly.
In such cases where we need to control the rotary position of the motor we can use stepper motors. Stepper motors have a tendency to make beginners feel uncomfortable about using them. But lets hope this air of discomfort about using stepper motors disappears once we are done through this article.
Stepper motors are motors available in round, square, rectangular shapes with 4 or more wires coming out of them.

In the permanent magnet stepper motor the rotor is a permanent magnet and the stator is a set of coils which are energized one after another. In the unipolar motors the direction of current in the coil doesn’t reverse (so UNI) while in the bipolar the current through the coil flows in both the directions (so BI).In both types of stepper motors there are two coils wound on the stator poles, which gives us 4 wires.

The difference is that in unipolar motors there is a center tap from each of the coil winding. These center taps are either brought out individually (which will give us 4+2 = 6 wires) or are shorted together and brought out (which gives us 4+1 = 5 wires)

Properties:

1) Digitaly controlled brushless motor that rotate a specific number of degrees (a step).
2) Number of degrees (resolution) can be between .72 to 90 degrees. General purpose steppers have a resolution of 15 or 30 degrees a step.
3) High precision, low torque.

The following figure shows a stepper motor deflected by 90 degrees

This occurs only when one coil is excited and other's are not.

The following figure shows half step where two adjacent coils are excited and therefore the rotor moves in between the coils .

By this we can move by 45 degrees.

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IR Sensors

The Infrared emitter detector circuit is very useful if you plan to make a line following robot, or a robot with basic object or obstacle detection. Infrared emitter detector pair sensors are fairly easy to implement, although involved some level of testing and calibration to get right. They can be used for obstacle detection, motion detection, transmitters, encoders, and color detection (such as for line following).

Line sensor:

In order to detect a line, we use the principle of reflection of light over different colors. As we all know, a white color object reflects almost all light incident on it while a black colored object absorbs all. Now, by measuring the variation in the intensity of reflected light we can easily determine the presence/absence of line under the sensor.

AMPLIFIED SENSOR CIRCUIT

Description:

The circuit uses an comparator to compare the value detected and ouput logic ‘1’ or ‘0’ or ON and OFF.

We use an IR LED which will emit Infrared light and it will be reflected by the surface. The detector acts as a variable resistor whose value depends on the intensity of light falling on its surface. The higher the intensity, the lower is the resistance of the detector. The detector and R2 act as a potential divider. When the intensity is high (reflected from white surface), the resistance of detector is low and so the value of the potential is high. Similarly when the intensity is low (reflected from black surface), the resistance of the detector is high and so the potential is low.

This potential is compared with a reference potential. The reference can be varied by the potentiometer (pot). Calibration is required. You have to record potentials of the white as well as black surface and then find their ranges. According these potentials ten set the reference so that for white surface output is .high and for white black surface output is low.

An LED can also be used as a visual detector so that you can see whether the surface is black or white.

R3 resistor prevents excessive current to pass through the LED. The value of the resistor depends on the size and the colour of the LED. More the diameter of the LED , more is the current it will sink in. R1 should be chosen according to the LED. Usually for 3mm Red LED and 5V supply 330Ω is enough. R2 should be larger then the maximum resistance of the detector.

THINGS TO NOTE:

• The LED and detector have very narrow emission and detection angles, so keep them close so that the circuit functions properly.
• Metallic or glossy surfaces reflect more tend to reflect more light, so make sure you calibrate the device properly.
• Many objects are opaque to visible light (that means light doesn't pass through it, like wood, black plastic, metal), but are transparent to IR light.
• If you work in the sunlight make sure it doesn’t interfere with the function of the circuit. Usually sensors placed below the body of the robot are the least affected by it.
• Depending on resistor values, your IR circuit can be tweaked to better detect color instead of distance.

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How to make a Javapath File??

My friends have problems with setting the CLASSPATH

so to set the classpath we follow the following steps

1. we open the notepad
2. we add the following data

set PATH=%path%;E:\program files\java\jdk1.6.0_01\bin;
set CLASSPATH=.;E:\program files\java\jdk1.6.0_01\lib;.;E:\java files\jchart2d-2.0.0.jar;
set JAVA_HOME=E:\program files\java\jdk1.6.0_01;

3. we save it as a .BAT file

my java was installed in E:\program files\java\jdk1.6.0_01\

if your java is in any other folder just replace this by the path where your java

files have been stored.

u must be thinking wat is jchart2d-2.0.0.jar

jchart2d is a java charting library and is used for dynamic charting