Electronics > Electronics
Following A Light
MegaLaDon:
I am new to robotics and am looking for some advice. What I want to do is make my robot follow a light source (like a flashlight). How would I go about doing this?
newInRobotics:
You probably want to read and complete (actually build) the famous $50 Robot tutorial :)
greywanderer012345:
When I made the $50 robot, I put the light sensors underneath the chassis so that it doesnt chase lights in the room. Instead, it chases light on the ground, like a flashlight. It works, but not great in a lit room. I think some photoresistors act differently for certain frequencies of light. Im thinking about looking into this to make a bot that follows a red laser specifically. Hope this helps.
Soeren:
Hi,
--- Quote from: greywanderer012345 on August 10, 2012, 04:20:38 PM ---I think some photoresistors act differently for certain frequencies of light. Im thinking about looking into this to make a bot that follows a red laser specifically. Hope this helps.
--- End quote ---
Photoresistors (CdS) all have a fairly wide spectre and you won't get that much difference by changing them. If you add a color filter over any photoresistor, you can dampen its sensitivity to other colors, well enough to get it to differentiate eg. a red and a green LASER, but white light contains both red and green, so a filter letting eg. red through will also let the red part of white light through.
Pulsing the LASER will make it possible to exclude all other light - color won't.
greywanderer012345:
--- Quote from: Soeren on August 10, 2012, 11:06:26 PM ---
Photoresistors (CdS) all have a fairly wide spectre and you won't get that much difference by changing them. If you add a color filter over any photoresistor, you can dampen its sensitivity to other colors, well enough to get it to differentiate eg. a red and a green LASER, but white light contains both red and green, so a filter letting eg. red through will also let the red part of white light through.
Pulsing the LASER will make it possible to exclude all other light - color won't.
--- End quote ---
Have you seen the "Follow Me Thomas" toy?
http://www.toysrus.com/product/index.jsp?productId=4048063
My niece got one of these, and it's the reason I wanted to try to get my bot to follow a laser. Instead of a laser(can't give those to 3 year olds) this toy comes with a red flashlight, and the train follows the circle where the beam is shone. I believe there is a sensor behind each bumper. I figured it used photo-resistors specific to red light. Do you think it just uses regular photo-resistors and covers them with transparent red plastic? The toy works very well, even following the light on red carpet or wooden floors and in brightly lit rooms.
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