long distance sensor around 20 feet help

R

rkremser

Guest
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than 20
feet. The situation is there is a fixed sensor with a crate moving towards
it. the sensor reporting the distance of the crate up to 20 feet away where
it will register either no crate or further than 20 feet. ultrasonic seems
limited with being able to avoid objects around the "crate" ideally the
sensor range would be limited to a 4' diameter circle extending outward from
the sensor. any help would be great.
Thanks


** Posted from http://www.teranews.com **
 
not spherical but generally cylindrical extending out the 20 feet.

"David L. Jones" <altzone@gmail.com> wrote in message
news:289e9e67-3322-489e-9543-10aa49aa11b0@x1g2000prh.googlegroups.com...
On Jun 10, 1:45 pm, "rkremser" <rkrem...@rkremser.endjunk.com> wrote:
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than
20
feet. The situation is there is a fixed sensor with a crate moving
towards
it. the sensor reporting the distance of the crate up to 20 feet away
where
it will register either no crate or further than 20 feet. ultrasonic
seems
limited with being able to avoid objects around the "crate" ideally the
sensor range would be limited to a 4' diameter circle extending outward
from
the sensor. any help would be great.
Thanks

By circle do you mean flat horizontal (or vertical) circle around the
sensor, or both horizontal and vertical from the sensor (i.e.
spherical)?

Is the crate the same one all the time, or can it be any old crate
that comes and goes? i.e. are you allowed to attach something to the
crate?

Required accuracy?

Dave.
Click to expand...

** Posted from http://www.teranews.com **
 
not spherical but generally cylindrical extending out the 20 feet.

"David L. Jones" <altzone@gmail.com> wrote in message
news:289e9e67-3322-489e-9543-10aa49aa11b0@x1g2000prh.googlegroups.com...
On Jun 10, 1:45 pm, "rkremser" <rkrem...@rkremser.endjunk.com> wrote:
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than
20
feet. The situation is there is a fixed sensor with a crate moving
towards
it. the sensor reporting the distance of the crate up to 20 feet away
where
it will register either no crate or further than 20 feet. ultrasonic
seems
limited with being able to avoid objects around the "crate" ideally the
sensor range would be limited to a 4' diameter circle extending outward
from
the sensor. any help would be great.
Thanks

By circle do you mean flat horizontal (or vertical) circle around the
sensor, or both horizontal and vertical from the sensor (i.e.
spherical)?

Is the crate the same one all the time, or can it be any old crate
that comes and goes? i.e. are you allowed to attach something to the
crate?

Required accuracy?

Dave.
Click to expand...

** Posted from http://www.teranews.com **
 
"rkremser" <rkremser@rkremser.endjunk.com> wrote in message
news:668e$484df8e5$16731@news.teranews.com...
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than
20
feet. The situation is there is a fixed sensor with a crate moving towards
it. the sensor reporting the distance of the crate up to 20 feet away
where
it will register either no crate or further than 20 feet. ultrasonic
seems
limited with being able to avoid objects around the "crate" ideally the
sensor range would be limited to a 4' diameter circle extending outward
from
the sensor. any help would be great.
Thanks


** Posted from http://www.teranews.com **
Click to expand...
I'm sorry, but this makes little sense to me. What is a crate? A box, what?
How does it move. What other objects are present?

Secondly, if you want to report a distance of up to 20 feet, what is the
"limit of a four foot diameter circle?" all about? How come it's not a 40
foot circle?

Be clear.
 
"rkremser" <rkremser@rkremser.endjunk.com> wrote in message
news:668e$484df8e5$16731@news.teranews.com...
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than
20
feet. The situation is there is a fixed sensor with a crate moving towards
it. the sensor reporting the distance of the crate up to 20 feet away
where
it will register either no crate or further than 20 feet. ultrasonic
seems
limited with being able to avoid objects around the "crate" ideally the
sensor range would be limited to a 4' diameter circle extending outward
from
the sensor. any help would be great.
Thanks


** Posted from http://www.teranews.com **
Click to expand...
I'm sorry, but this makes little sense to me. What is a crate? A box, what?
How does it move. What other objects are present?

Secondly, if you want to report a distance of up to 20 feet, what is the
"limit of a four foot diameter circle?" all about? How come it's not a 40
foot circle?

Be clear.
 
On Jun 10, 1:45 pm, "rkremser" <rkrem...@rkremser.endjunk.com> wrote:
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than 20
feet. The situation is there is a fixed sensor with a crate moving towards
it. the sensor reporting the distance of the crate up to 20 feet away where
it will register either no crate or further than 20 feet. ultrasonic seems
limited with being able to avoid objects around the "crate" ideally the
sensor range would be limited to a 4' diameter circle extending outward from
the sensor. any help would be great.
Thanks
Click to expand...
By circle do you mean flat horizontal (or vertical) circle around the
sensor, or both horizontal and vertical from the sensor (i.e.
spherical)?

Is the crate the same one all the time, or can it be any old crate
that comes and goes? i.e. are you allowed to attach something to the
crate?

Required accuracy?

Dave.
 
"rkremser" <rkremser@rkremser.endjunk.com> wrote in message
news:668e$484df8e5$16731@news.teranews.com...
Repost i know but i'm desperate
I'm looking for a distance sensor sub $100 that will range out more than
20 feet. The situation is there is a fixed sensor with a crate moving
towards it. the sensor reporting the distance of the crate up to 20 feet
away where it will register either no crate or further than 20 feet.
ultrasonic seems limited with being able to avoid objects around the
"crate" ideally the sensor range would be limited to a 4' diameter circle
extending outward from the sensor. any help would be great.
Thanks

** Posted from http://www.teranews.com **
Click to expand...

Can the sensor be elsewhere? If so, you can use a laser pointer, a couple of
front reflective mirrors, and a photodiode (plus opamp to amplify it).

This arrangement won't work for circles, but it'll work for a line.

Get a 5V power supply, and buy some laser pointer cartridges off of ebay.
You can get front side mirrors from allelectronics.com. Arrange the mirrors
so that the outgoing laser pointer points at one mirror, which reflects the
light to the other mirror across the line, and then back to your power
supply.

If you are having a hard time making the laser pointer hit the photodiode,
you can use a flashlight mirror to focus the beam onto it by setting it up
like a reflecting telescope, i.e., the sensor faces away from the incoming
beam, and the flashlight mirror faces the beam, and focuses it onto the
sensor.

Use a standard photodiode or phototransistor sensor arrangement (search the
web) so that you get a clean signal when something blocks the laser path.
This will give you a good indication of something crossing the line at a
particular distance.

Another way to do this would be to use a video camera which is sensitive to
IR, and an IR laser. The WII uses this arrangement, in which there is an IR
camera and a set of IR diodes, allowing it to orient itself. You would need
to be good at software to do something like this, but it would be possible
to either split a beam, or spin it, directing it towards the floor, and then
analyze the path (on the floor) of the beam with the camera and software on
a PC. If the path deviates from the normal line or arc, you have detected an
object. There are cheapo IR cameras available, and continuous 5mW IR lasers
can be had for $30 or so. I've heard you can split a laser into a line using
a polished glass semi-circular rod. You could also use a motor to spin the
laser, but it might be hard to align properly. With this solution, the
software is the problem, of course. You would need to write software to
detect the object using the video input.

My final suggestion is to get some hefty ultrasonic transducers, and chirp
at it. Use a PLL chip to detect the reflection, and time the reflections
using software. The temperature will affect this reading, as will possible
reflections off of other nearby objects, ambient sounds, etc.

The easiest one is the first one, but it assumes some things about the space
that you might not want to assume.

Regards,
Bob Monsen
 
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