I am looking for a distance sensor emitter/receiver pair with a range
of about one foot. Reflective sensors, such as those offered by sharp,
will not work for my application, as I need to be able to detect the
distance to a specific point, as opposed to the distance to any
surface. This device will be used to let a small autonomous robot know
when it is getting close to, and reaches, its destination. In getting
to its destination, it has to navigate an obstacle course with several
walls, thus the reason a reflective sensor would not work- it would be
unable to distinguish between the destination, and just another wall on
the course. Can anyone give me some ideas as to where I might find such
a sensor? Thanks.
I haven't done this yet, but I've read about it...
Your target transmits pulses via infrared (or RF) as well as
ultrasonic. The robot is capable of receiving both. When the robot
receives the IR of RF pulse, it measures the time until the ultrasonic
pulse arrives. Multiply that time by the speed of sound and you get
the distance to the sensor (with some small error).
Your obstacle course may prevent this from working.
Sounds interesting. The obstacle course shouldn't be a problem, as
over the distance I need this to work (about a foot) the course will
be clear. I'll have to look into that. Any chance you could give me
links to more information, such as circuit diagrams, or sensor
selection information? I would like something simpler, both because of
space limitations and my skill level, preferably along the lines of a
single sensor that outputs a voltage proportionate to the distance
between it and the emitter, but this idea definitely has merit.
Bennet Williams <> wrote in message
Sorry. It's been awhile since I looked at it, and I don't seem to have
any web links. But there is info out there.
Digi-key and/or Newark sells everything you need. I'm afraid my idea
for implementation was not simple (none of my ideas ever are).
However, I was thinking in terms of triangulation to determine the
robots position. Your case is much simpler.
I'm not aware of any pre-packaged emitter/sensor pairs that give this
functionality. I thought I would build a little "beacon" tower with
the multiple IR transmitters and U/S transmitters. A PIC would control
these. Likewise on the robot end, multiple IR and U/S receivers would
be monitored by a PIC. But the U/S sensor cannot be monitored
directly. I had found a circuit diagram for the U/S receiver
On 8 Oct 2004 09:46:15 -0700, firstname.lastname@example.org (Macavenger) wrote:
Ok, I think I have found a potential solution, but I need a little help
with some details. For the purposes of navigation, I have set up at the
destination point a Pololu IR beacon that outputs a modulated IR signal
at 56.9 kHz. With a detector designed to detect signals at that same
frequency, It would appear that I could determine the distance by
looking at the output of said detector. There are, however, two issues I
would need to deal with.
1) The output fluctuates fairly widely even at a set distance. At the
range I want to start detecting the signal, the output of said detector
varies between 3.50-3.60 Volts, while at the range I want to consider my
robot as having arrived, it varies between 3.40-3.50 Volts. This can be
easily solved with an averaging filter of some kind. My question for you
folks is where might I find an IC that performs that function?
2) The range of variation over the distances of interest is probably
large enough to be able to detect, even with the fluctuation in readings (
100 mV) However it is still fairly small, and it might be nice to
amplify it somewhat to achieve better resolution. How might I accomplish
this-Just run the signal through a run-of-the-mill op-amp? The detector
outputs a high voltage, decreasing as the input gets stronger, so I
would think the signal might need to be inverted first (inverting amp?)
I have a basic understanding of amplifiers, however it is VERY basic, so
circuit diagrams would be appreciated.
Thank you for any assistance you may be able to provide. The simpler the
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