Tuesday, March 10, 2009

Sensors to be used in Line follower

Hi evryone out there , I hope evryone is fyn and njyoing robotics , last 4 months had been a very tough job for me participating in ROBOCON , though we were not successful , I learnt a lot from this compt.
The first thing I would like to share is

Which Sensors to be used to detect black line??

I tried different circuits which even removes ambient light effect ( I will be posting the ckt oif it ) and IR sensors .Though I liked IR sensors the most , I was amazed to see the results when I used LDR sensors and White light . I used white light as my transmitter and LDR with a black tape covered as my reciever. The results were very good but the opnly problem was this is more sensitive to ambient light than IR sensors , but the change in ouput voltages were arnd 2 volts where as ir sensors always gave a change in output voltage of .89 .

If u want you can use LDR sensors with out a potmeter and opamp which I showed you in my ir sensor ckt.Give a try with ldr reciver ckt by replacing the transmitter and reciver with white led and LDR sensor

4 amp Motor Driver ckt

This is a 4 amp motor driver ckt which i have used in my recent robotics competition ROBOCON where i was driving a power window motor which used to give arnd 25 kgcm torque.
Thinking abt all the financial crisis we had, I choose this ckt which reduces to dig our pocket .

As i have explained in my previous motor driver ckt that there will be two channels in a motor driver IC, each channel giving arnd 1amp in case of l2938d and 2amp in case of l298 . Now i drove both the channels in parallel and hence i was getting 4amp current, this is the most simplest of all motor driver circuits which need more current to drive motors.

W1 and W2 are the inputs, by varying the inputs with 1 and 0 we get different ouputs which drive a motor. Remember to use a heat sink and dont touch it when you turn on the power of it.
The diodes at the motor end are only needed as protective fly back diodes , to protect the motor driver ic , from the current which starts flowing from the motor in back ward direction because of switiching ON and OFF at most of the times. These diodes protect the flow of current to motor driver IC.