could someone explain me this? in the 40$ robot

[mohamed]

i dont really understand the function of the 2 RED LED's which are connected to the 1K resistor
what they exactly do in the circuit coz when i connect the battery they didnt light up only the green one did

[Pratheek]

The two red LEDs are used to indicate the presence of the line. When the left sensor detects the line the left LED is switched on. When the right sensors detects the line, the right LED is switched on.

[mohamed]

thanks very much one more question  where i solder the four wires which will be connected to the 4 pins coz i dont really catch this up
PS: i want to do the method by adding 270 ohm

[mohamed]

there is a question i want to ask how exactly the 4$ robot is goging to avoid craching to the wall as it's sensors are facing the ground or is it just going to hit the wall then it will reflect could anybody tell me how

[airman00]

there is a question i want to ask how exactly the 4$ robot is goging to avoid craching to the wall as it's sensors are facing the ground or is it just going to hit the wall then it will reflect could anybody tell me how

It is EITHER a line follower OR a obstacle avoider , not both at the same time

to make it only obstacle avoider , tilt the sensors forward facing

My tutorial has both at the same time , but it uses a microcontroller
http://www.societyofrobots.com/member_tutorials/node/55

[mohamed]

So why in the tutorial is said this
To use the robot as a black line follower and photovobe, make the following connections in the main circuit board.
and
To use the robot as a white line follower, photovore and obstacle avoider, make the following connections.

he didnt mention anything about changing the position o the sensors or does he mean by obstacle avoider that the robot sense anything on the ground and avoid it

[Pratheek]

The robot can avoid obstacles using two different techniques. One is that it can avoid shadows cast by objects and avoid colliding with the object(the sensors will have to face the ground). The other trick is to mount the sensors forward this way you can avoid objects(not their shadows). But the problem is that you wont get good range with the LDRs.

I'm planning to upgrade the sensors and use IR sensors, I will try to post the tutorial of the upgrade soon in the members tutorial section. After the upgrade the robot can do both line following and obstacle avoiding simultaneously. You will have to wait until I post the tutorial.

[mohamed]

u mean that is avoid the shadow of the wall when the sensors aced down and when i put them in a horizontal position it avoid the wall itself right correct me if i'm wrong

[Pratheek]

Yes, thats what it can do. But I did not get good range with LDRs (I placed them horizontally) for obstacle avoiding. By the time the robot senses the objects and steers away from it, the robot would have already crashed into it.