Using RSSI to locate an object

[Andrew Rich]

Why the heck did u ask such a dumb ask question ?

 

[The Real Andy]

Thanks for everyones help, RSSI was mentioned to me by a fellow
academic and I'm at the stage of researching its possiblilites.

He seems to think that it is possible.

I will keep looking into it as I also have a backup plan using the
webcam.

Go with the backup plan, usehhte webcam. Processing power is cheap
these days.

 

[David L. Jones]

Having done some more research today it looks like other posibilities
include acoustic positioning or infrared positioning (e.g.http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2004/rd...)

What does everyone think about the other technologies mentioned above?

You are wasting your time, visual object recognition is the best
method in this particular instance. All the other methods (RSSI,
acoustic, and IR) require a transmitter on the boat and multiple
receivers. Visual recognition on the other hand doesn't require any
transmitter, will work with almost any size or type of object, is
simple, fairly accurate, will most likely only require one receiver,
and reduces the problem to essentially a software solution.

The decision is blindingly obvious.

Dave.

 

[Josh916]

You are wasting your time, visual object recognition is the best
method in this particular instance. All the other methods (RSSI,
acoustic, and IR) require a transmitter on the boat and multiple
receivers. Visual recognition on the other hand doesn't require any
transmitter, will work with almost any size or type of object, is
simple, fairly accurate, will most likely only require one receiver,
and reduces the problem to essentially a software solution.

The decision is blindingly obvious.

Dave.- Hide quoted text -

- Show quoted text -

Thanks for everyones help, especially David Jones, I will be going
with the visual recognition. It was originally my first choice though,
as you do, I wanted to exhaust all possible options before finalising
the decision as you never know there might of been an easier, more
efficient way.

Josh

 

[Mark Harriss]

Thanks for everyones help, especially David Jones, I will be going
with the visual recognition. It was originally my first choice though,
as you do, I wanted to exhaust all possible options before finalising
the decision as you never know there might of been an easier, more
efficient way.

Josh

I've worked on someone else's image processing software that used a
camcorder to track a lizard's frame to frame movement down a small track
~1.2M long or so.

You'll need to correct for parallax unless the camera is very high above
the tank, so having a X,Y marks around the edges of the tank would help.

Python and Python Imaging Library was used to convert the colour image
to greyscale first and then to two bit black and white if a pixel was
either side of a set threshold value. This gave a black background with
a white moving object on it that could be scanned vertically in my case
to give the amount of movement in pixels which was then corrected for
parallax and converted to millimetres.

 

[Rich Grise]

I would like to use RSSI to locate an object in a 3D space. The space will
be a square box with transmitters located on the 4 corners. An object will
be place at certain positions within the box and I want to be able to
determine its location inside the box. Much like an internal GPS.

What's "RSSI"? Repetitive Stress Syndrome Imaging? ;-)

Thanks,
Rich

 

[martin griffith]

What's "RSSI"? Repetitive Stress Syndrome Imaging? ;-)

Thanks,
Rich

received signal strength indicator


martin

 

[Rich Grise]

received signal strength indicator

Oh, gosh. Than that's definitely a non-starter. I'd at least try
ultrasonics, or maybe lidar and triangulate. But, as has been said,
just imaging from the top is probably the best, since compute power
is cheap these days, and Josh916 seems to have total control over the
environment.

Of course, if you're out on the lake, it'd probably be pretty expensive
to hire a blimp for the camera. ;-)

Thanks!
Rich

 

[James Thompson]

Oh, gosh. Than that's definitely a non-starter. I'd at least try
ultrasonics, or maybe lidar and triangulate. But, as has been said,
just imaging from the top is probably the best, since compute power
is cheap these days, and Josh916 seems to have total control over the
environment.

Of course, if you're out on the lake, it'd probably be pretty expensive
to hire a blimp for the camera. ;-)

Thanks!
Rich

I think if he can equip the box with a wire grid and have a receiver on the
boat, then each wire of the grid could have a different tone signal on it.
The antenna on the boat receiver would pickup the tones so the 2 strongest
tones would indicate the position of the boat. He could simply program a pic
micro to sample the tones and output the x,y coordinate via a radio signal
from the boat. This would be an example of RSSI.
This same setup may well work with the robot soccer games. Jus my 2 cents
worth JTT

 

[Genome]

I would like to use RSSI to locate an object in a 3D space. The space
will be a square box with transmitters located on the 4 corners. An
object will be place at certain positions within the box and I want to
be able to determine its location inside the box. Much like an
internal GPS.

I would like to know what components (IC's?) I need to perform such a
task.

Or if anyone else has any other more effective methods to acheive such
a task your comments are welcomed.

Thanks,

Josh

Personally I think Phil is quite right to call you a stupid troll. It's not
as if you are not fishing for ideas.

I'm even less amazed that one of your skills appears to be hunting down
information about someone who has the gall to call you stupid.....

Strange that.

Did you use Google to find out Phil is occasionally slightly obnoxious
rather than reading this 'newsgroup' for a while?

Uuuuuhmmmmmmmmm............

Anyway.

Since I am brilliant, capable of thinking outside the box and it sounds like
a 'fun' way of solving your problem. What you should really do is this....

Think in polar coordinates.

Pick one of the 'vertices' of your box as your 'origin'. Get yourself three
'dual light pipe' type things and lay them out along the XYZ edges of your
box as defined by that origin.

Plug the mechanical ends of your light pipes into some mechanical type
rotating scheme, stepper motors with microstepping drive systems, so you can
rotate them.

You will probably need some blu-tac to stop the water dribbling out.

Excellent opportunity for mechanical design of things that overcome dribble
problems.

Then you shine a bit of light up one side of your dual light pipe thing and
you recieve the reflected light back down the other side of it.

Lots of opportunity for transmission/modulation/detection/demodulation stuff
there.

And rotate the pipes for maximum signal.

Lots of opportunity for feedback/control stuff there.

Once you have aligned all your pipes. Then all you have to do is do sums to
convert the angles to where your object is.

Good stuff for the mathematics of the problem.

Now, kindly piss off and do your own research.

DNA

 

[Alex Gibson]

Thanks for everyones help, especially David Jones, I will be going
with the visual recognition. It was originally my first choice though,
as you do, I wanted to exhaust all possible options before finalising
the decision as you never know there might of been an easier, more
efficient way.

Josh

Look at opencv , it has most of the functions you need , its free and os
available on
linux , mac and windows. Use it with c , c++ or python.

Could even do object tracking fairly easily.

Make sure you boat has a nice bright colour that stands out wll.
Once you have the detection working , then you can change the colour to one
with a lot less contrast to see how well your solution works.


Alex