Subject:
|
Re: May SMART meeting; retro-reflector data
|
Newsgroups:
|
lugnet.org.us.smart
|
Date:
|
Wed, 9 May 2001 19:46:24 GMT
|
Viewed:
|
981 times
|
| |
|
|
In lugnet.org.us.smart, Gustav Jansson writes:
> > The values I got in a moderately lit room are as follows:
> >
> > Rest of room: 760-800
> > Reflector at 3 feet: 750-760
> > Reflector at 9 inches: 740-750
> > Reflector at 6 inches: 730-740
I tried another light sensor I had, and it's readings were 670 around the
rest of the room, and 655 at 9 inches. In other words, not only were the
readings lower, but much less sensitive. You might want to search for your
'best' light sensor for this task. (I'm actually wondering now if I could
return this particular light sensor to Lego as being defective!)
> Also, when using the lamp you can switch it on and off to see the difference
> between the ambient light and the reflected light.
First, you'll have to make sure that the light from the lamp can't directly
shine into the light sensor. That will pretty much nullify any useful reading!
However, if you do it right, using a lamp will probably help. The nature of
the reflector means that you'll have to have the lamp very close to the
light sensor. The retro reflector will reflect back light along the same
direction it comes in on. If you can think of a way to put a silver
reflector dish behind the lamp, that will also probably help out, though it
will make it difficult to put in close proximity to the light sensor. A
trade off you'll have to play with to see if it's worth it.
Here's a table of values I got with a third light sensor, using a lamp
attached under the light sensor, and back one row so that it doesn't shine
into the light sensor itself.
Rest of room: 810-825
Reflector at 3 feet: 750-770
Reflector at 9 inches: 720-730
Reflector at 6 inches: 700-710
I like this light/light sensor combination!
Here's a picture of the setup:
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=44589
> David, how tall is block with the reflective tape?
It will be approximately 4 inches tall, and I'm aiming to make it a 4 inch
cube, so it will be bigger and heavier than the last one. Hopefully 4
inches will be high enough for everyone to detect, but I'll bring something
to raise it another inch or so if there's a robot that has its light sensor
higher than that.
--
David Schilling
|
|
Message has 1 Reply:
 | | Re: May SMART meeting; retro-reflector data
|
| (...) nicely on the lamp. If you use it then you don't have to worry about any light coming directly back into the light sensor. It also focuses more light forward thus increasing the amount reflected back. Look at: (2 URLs) (24 years ago, 10-May-01, to lugnet.org.us.smart)
|
Message is in Reply To:
| | Re: May SMART meeting; retro-reflector data
|
| (...) Thanks, David. I would like to add that using a Lego lamp will significantly improve your ability to detect the reflector. These lamps are part if the ultimate accessory kit and can also be purchased from Lego Shop-At-Home and/or Lego Dacta. (...) (24 years ago, 9-May-01, to lugnet.org.us.smart)
|
4 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
This Message and its Replies on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
