Chuck
Remember the magic words: "all you gotta do" !
Here are a few engineering questions.
What are the dimensions (HxLxW) of the pinfish and pigfish?
This is the area that will interrupt the IR beam.
Does the IR detector signal on/off or an analog signal?
If it is an analog signal then how will you do a D/A converter?
This is a key question if the spacing between the detectors is
significantly less than the size of the fish.
Is the sluice also pouring water or just allowing the fish to swim?
If you are counting from a verticle view, then the sluice should be
shallow and the detectors close togeather. Or if the detectors are
horizontal then the sluice can be narrow and possibly deeper.
It will be less complicated if the water flow is zero and the fish are
swimming between the two tanks. Then you can get them to
line up like a cattle gate.
In one post you mentioned that you would like to be accurate
within 5 fish. Five fish out of how many? What percentage?
The problem of counting has been asked before in the field
of industrial engineering. Significant time invested in a search
for publishd papers and solutions will definately be worth it.
The key to this is the D/A converter and the corresponding
signal processing. The sample rate should be 100 times the
rate of the fish in order to recognize a pattern the typical
pattern of expanding/decreasing shaddow to seperate two
fish head to tail. If a fish swims by at 1 per second then a
sample rate of 100/sec or 1 in 0.01 seconds is not to fast
to process with today's cpu's. The software will ask at each
sample: is this shadow getting bigger or smaller?
All you gotta do is count the fish.
Larry Sanders, P.E.
Civil Engineer
:-)
On Wednesday 18 December 2002 04:21 pm, Chuck wrote:
> This is a little project I am going to try to take on because
> the cost of a device available commercially is off on another
> planet.
>
> My wife has a live bait business, part of that involves delivering
> bait fish to bait and tackle shops. She has to count the buggers,
> and the count always is off regardless of WHO counts them. I started
> looking around for a fish counting device and found one that uses
> a optical scanner to count them as they go through a sluice. The optical
> part uses IR LED's to illuminate, and the detector or scanner uses
> what appears to be a column of detectors on the other side of the
> sluice, as a fish goes by it the detectors see the change in IR flux
> and can detect when one fish is ahead of the tail of the first fish
> thereby not opening all of the optical path.The fish will be anywhere
> from 3-6 inches in size.
>
> The manufacturer of this device wants more than $5K for it, I suppose
> that is ok for some government operation that has deep pockets but
> at $0.25/fish she will have to catch a lot of fish to pay for it, she
> also has to pay a truck used to deliver them and the guy and boat who
> actually goes out and catches them.
>
> The hardware does not look to be that great a deal. It is probably in
> the software where the cost is.
>
> My idea would be to feed the data from the sensors into the parallel
> port and read it at a rate such that I get each fish as it goes down
> the sluice.
>
> Now my question is this, do any of you have a idea of where I should
> start with this one. The hardware is a no brainer, I can get IR sources
> and detector arrays, I can build the sluice and other material, but I
> will need to come up with some software that can count the fish as the
> go in front of the detector. Has anyone done anything similar in terms
> of software?
>
>
>
> -----------------------------------------------------------------------
> Chuck Hast
> Telecomms Consultant, Utility Partners.
> WEB www.utilpart.com
> Office number: 813.282.8828 x 1175
> C-phone number: 813.765.6743
> E-mail: wchast@utilpart.com
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> ARS KP4DJT
>
> To paraphrase my flight instructor;
> "the only dumb question is the one you DID NOT ask resulting in my going
> out and
> having to identify your bits and pieces in the midst of torn and twisted
> metal."
>
>
>
>
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