Wednesday, April 08, 2009

light Finder Robot Project

light finder robotBuilding an autonomous light finder robot
The design of our new robot is very different. It is cheap and you
will be able to build it from parts that are available almost
everywhere around the world. It is an autonomous robot
controlled by an AVR microcontroller. As an autonomous robot
(not controlled by a person) we programmed it to run towards
the brightest spot in the room.


Light Finder RobotIn this picture you can see the front of the robot with the light
sensitive resistors and my custom made touch sensor. The
touch sensor basically works by having the basic atom pro
reading the voltage on that line, if the front part is pressed it
closes the circuit and so pulls the voltage high. There is a
resistor there as well on the actual circuit part to prevent short
circuiting. Again we see obligatory judicious usage of gorrilla
duct tape, which is essential for any project.


Making an Amplified Color Sensor from an LED and an Op AmpPhotodiode Amplification
Unfortunately, even under the best conditions, photodiodes
(and reversed LEDs) don't provide a lot of current flow. The
output of the photodiode needs to be amplified for the
light-detection signal to be useful in most circuits. A photodiode
amplified by a built-in transistor is called a phototransistor.
You can connect a standalone photodiode to the input of a
standalone transistor. But, it isn't easy to control the gain of a
single-transistor amplifier, and there are issues with signal
noise and the amount of input current required. Instead, a
better method for amplifying low-power signals in a high-quality
repeatable way is an op amp chip (operational amplifier).


This is the project of a Light Chaser robot. The robot will turn
towards the brightest light and move forward chasing or
following it. It has two motors (left & right) in order to make the
turns; on top two light sensors (photodiodes) separated by a
PC board in order to simulate "a nose". This nose is
particularly important because it will provide a shadow thus
preventing both sensors from being illuminated when a side
light is present (the motor on the non-illuminated sensor
side will turn on thus aiming the robot towards the light).
When the light is right in front of the sensors, there will be
no shadow and both sensors will be equally illuminated, i.e.:
both motors will be running and the robot will move forward.


Relate Posts