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Nexcon
08-09-2005, 03:51 AM
Hi RI

I need to make an autnmus robt that wud trak a black line on a white. i hav tried leds wid ldrs to track line but they r too slow, i need at least 1 m/s, wat shud i use to track the line ??

yogi
08-09-2005, 07:25 AM
use IR sensors

Develop 38KHz with 555 and use TSOP 1738 as receiver.
It has better sensing or use IR led+photo diode.

U can do following ways using microcontrollers
1. see the time taken to cross line and reduce the speed of motor correspondingly using PWM. If you apply 40% PWM then 60% PWM to other motors. Use motors of good speed around 300rpm.

2. Increase number of sensors about 8 and apply reduction in such a way when first sensor enters black to 40% and then if first sensor is still in black reduce to 38% and so on.

But one thing PWM the speed is reduced less than original voltage applied

If you don't know microcontroller

1. to reduce the motor speed we had to reduce the voltage applied to mtor. This can be done using an LM317 by varying resistance using MOSFET or transistor. If sensor is high then transistor goes to saturation such that R2 will increase.If you increase sensor then better speed.
Remeber somewhat mechanical like weight consideration u have to see.

2. Use some zener diodes+MOSFET or transistor to reduce the voltage applied to motor