Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: rox2007 on January 17, 2008, 07:37:02 AM

Title: what is the best photoreflector to use for a line follower?
Post by: rox2007 on January 17, 2008, 07:37:02 AM
I am building a line follower to compete. I was going to use photoresistors but i read in so many places on the internet that they are really slow in reaction. They are actually slow because i did some tests and thought the same. They mostly suggested infrared emitters but the best is photoreflectors. If anyone has had experiences with line followers please help me.
Title: Re: what is the best photoreflector to use for a line follower?
Post by: paulstreats on January 17, 2008, 09:27:34 AM
look at products like these

[url]http://www.sparkfun.com/commerce/product_info.php?products_id=246[url]

They are an ir emitter and detector in 1 package, basically the emitter sends out ir light and if it is reflected back from a surface the detector um detects it.
Title: Re: what is the best photoreflector to use for a line follower?
Post by: airman00 on January 17, 2008, 10:59:07 AM
I use the QRB1113 or the QRB1134 in my line follower project ( check member tutorials page)  .

the sensors are available from fairchild
Title: Re: what is the best photoreflector to use for a line follower?
Post by: rox2007 on January 17, 2008, 11:30:40 AM
i'll check those out
Title: Re: what is the best photoreflector to use for a line follower?
Post by: airman00 on January 17, 2008, 11:34:36 AM
may i ask which competition>
Title: Re: what is the best photoreflector to use for a line follower?
Post by: rox2007 on January 17, 2008, 07:26:55 PM
my school (rutgers university-new brunswick) is holding an ieee robotics competition. Line followers and all.
Title: Re: what is the best photoreflector to use for a line follower?
Post by: Admin on January 20, 2008, 06:07:22 PM
Quote
I was going to use photoresistors but i read in so many places on the internet that they are really slow in reaction
I disagree. The slowest of photoresistors have a full swing voltage time of ~100ms. The ones I use take like 20ms between a line and no line. Thats pretty darn fast.

Look at the photoresistor datasheet for proof ;D

Ive made two robots that use photoresistors for line following:
http://www.societyofrobots.com/robot_mobot_2007.shtml
Title: Re: what is the best photoreflector to use for a line follower?
Post by: airman00 on January 20, 2008, 06:11:57 PM
slow in reaction compared to IR
Title: Re: what is the best photoreflector to use for a line follower?
Post by: rox2007 on January 20, 2008, 07:17:27 PM
Quote
I was going to use photoresistors but i read in so many places on the internet that they are really slow in reaction
I disagree. The slowest of photoresistors have a full swing voltage time of ~100ms. The ones I use take like 20ms between a line and no line. Thats pretty darn fast.

Look at the photoresistor datasheet for proof ;D

Ive made two robots that use photoresistors for line following:
http://www.societyofrobots.com/robot_mobot_2007.shtml

please where did you get them from. I have those ones from Radioshack, but when i utilized the equation from the photoresistor tutorial to find the resistor to use with a black line sensor. i got a large number of about 12kohms. am i on the right part?

And Admin, do you know how much Mc Master cost to ship or do you know somewhere cheaper to get HDPE?
Title: Re: what is the best photoreflector to use for a line follower?
Post by: Admin on January 20, 2008, 08:02:51 PM
Quote
i got a large number of about 12kohms. am i on the right part?
sounds reasonable. try it on a breadboard with a multimeter first if you arent sure . . .

Quote
do you know how much Mc Master cost to ship or do you know somewhere cheaper to get HDPE?
you can find many suggestions in the forum:
hardware store (homedepot, lowes), kitchen cutting board, mcmaster, etc.

Quote
do you know how much Mc Master cost to ship
hmmmm have you checked the site? i order all the time from mcmaster, but i always have my coworkers handle the ordering so i never see the final price . . . i don't remember it being too expensive, and i always get my stuff within 2-3 days, but depends on size/weight of what you order, too . . .
Title: Re: what is the best photoreflector to use for a line follower?
Post by: SmAsH on January 20, 2008, 08:08:49 PM
i have used mc master before to get HDPE for the $40 robot and the shipping price wasnt to bad to australia :D
Title: Re: what is the best photoreflector to use for a line follower?
Post by: Kagi on January 21, 2008, 04:59:16 PM
*cough* dollar store cutting boards *cough*   ;D

Title: Re: what is the best photoreflector to use for a line follower?
Post by: SmAsH on January 22, 2008, 01:56:07 AM
i find that offensive! lol jk no i tried using the cutting boards first but didnt work to well. then i ordered...


~smash
Title: Re: what is the best photoreflector to use for a line follower?
Post by: BANE on January 22, 2008, 07:35:31 PM
SmAsh, what size board did you get and were was it shipped from?   Because a 24" x 36" is a different story$$$$$$$

Quote
*cough* dollar store cutting boards *cough*
lol, but it works! ;D

bane