Low Power Triangulation Circuits

Hello,

What I would like to do:
Capture motion (not specifically human motion) in a room that is about
3*3*3 meters. The system should be able to capture 16 'active' points
in said room.

What I thought I could do:
- Get something from the market, but whatever i try to search for,
google does not provide me with what I really want which is a system
that allows me to locate transmitters in a room.

The second thing I though of is doing the following:
- Get 3 radio receivers to form a base for triangulation
- Get transmitters to send 100 times a second an ID + count
- Get a circuit that is able to use the data from the 3 bases to
triangulate the position of the object through a microprocessor or
something like that

The problems kinda start now:
- I do not know of any company that provide that kind of equipment (or
I am searching for the wrong stuff on google) so if someone can orient
me in the correct direction in this regard I ll be glad
- I have pretty much no knowledge of electronics except my classes
from 10 years ago. I do not mind learning but I do not even know where
to start, once again any guidance will be appreciated. (I especially
do not understand how digital data can be sent on analog radio
frequencies)
- If you know of any circuits that allows to triangulate the position
of an RFID (for example) and that can do that for more than 1 I ll
gladly take the information.

In the hope someone may help in a way or another,

Best Regards

 

[Phil Allison]

<chrysoinnuke@gmail.com>

What I would like to do:
Capture motion (not specifically human motion) in a room that is about
3*3*3 meters. The system should be able to capture 16 'active' points
in said room.

** This is a problem you solve optically - ie with cameras.

What I thought I could do:
- Get something from the market, but whatever i try to search for,
google does not provide me with what I really want which is a system
that allows me to locate transmitters in a room.

** That mad idea is a complete non starter.

The second thing I though of is doing the following:
- Get 3 radio receivers to form a base for triangulation
- Get transmitters to send 100 times a second an ID + count
- Get a circuit that is able to use the data from the 3 bases to
triangulate the position of the object through a microprocessor or
something like that

** See above.

Consider that the speed of radio waves is 1 foot per nanosecond !!

Location by time of flight is impractical on such a small scale as yours.

However, as few as two video cameras could locate an object in plan position
and height above floor ( ie 3D) in a small room.


.... Phil

 

[Tim Wescott]

On Sat, 03 Jan 2009 13:54:49 -0800, chrysoinnuke wrote:

Hello,

What I would like to do:
Capture motion (not specifically human motion) in a room that is about
3*3*3 meters. The system should be able to capture 16 'active' points in
said room.

What I thought I could do:
- Get something from the market, but whatever i try to search for,
google does not provide me with what I really want which is a system
that allows me to locate transmitters in a room.

The second thing I though of is doing the following: - Get 3 radio
receivers to form a base for triangulation - Get transmitters to send
100 times a second an ID + count - Get a circuit that is able to use the
data from the 3 bases to triangulate the position of the object through
a microprocessor or something like that

The problems kinda start now:
- I do not know of any company that provide that kind of equipment (or I
am searching for the wrong stuff on google) so if someone can orient me
in the correct direction in this regard I ll be glad - I have pretty
much no knowledge of electronics except my classes from 10 years ago. I
do not mind learning but I do not even know where to start, once again
any guidance will be appreciated. (I especially do not understand how
digital data can be sent on analog radio frequencies)
- If you know of any circuits that allows to triangulate the position of
an RFID (for example) and that can do that for more than 1 I ll gladly
take the information.

In the hope someone may help in a way or another,

Best Regards

Radio won't do, certainly not if your radio knowledge is as basic as you
say.

Phil's suggestion of cameras is good, if you can do something to
distinguish one "transmitter" from the other optically (big painted
numbers comes to mind).

This sort of thing is done sonically to locate _receivers_, but I don't
know if it's been done the other way around (although it could be).
Basically one makes an "ultrasound LORAN" system. I've heard that these
are on the market, but I've never tried to figure out where.

If you are allowed to build the floor you can make a system for each
transmitter to sense where it is electronically and then just transmit
it's position.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

Ok,
So if I understand this right radio waves moves too fast to measure
small distances.

So it could work forslower waves right ?

As for optical detection, I ll check on google

Thanks for the input

 

[Phil Allison]

<chrysoinnuke@gmail.com>
....

Ok,
So if I understand this right radio waves moves too fast to measure
small distances.

So it could work forslower waves right ?

** Yep - slow poke EM waves are you saviour pal.

Find lotsa dem up in the Ozarks - any times ..........

As for optical detection, I ll check on google

** Question:

We get this SAME fucking IDIOTIC idea posted about three time a year
here.

WHY the fuck do YOU want to electronically locate mysterious fucking
objects in some a small room ??

NO-ONE has ever said why !!!!!!!!!!!

Is some fucking lunatic prize hanging on doing it ???





..... Phil

 

[Jasen Betts]

On 2009-01-04, chrysoinnuke@gmail.com <chrysoinnuke@gmail.com> wrote:

Ok,
So if I understand this right radio waves moves too fast to measure
small distances.

well, differential GPS gets some pretty good performance using radio,
works best outdoors though.

GPS hardware is highly specialised, and only cheap because of mass
production.

So it could work for slower waves right ?

for indoors using ultrasonics with either mobile beacons and fixed
microphones or the other way round will probably be easier than using
GPS.

As for optical detection, I ll check on google

Thanks for the input

 

[David L. Jones]

On Jan 4, 8:54 am, chrysoinn...@gmail.com wrote:

Hello,

What I would like to do:
Capture motion (not specifically human motion) in a room that is about
3*3*3 meters. The system should be able to capture 16 'active' points
in said room.

What I thought I could do:
- Get something from the market, but whatever i try to search for,
google does not provide me with what I really want which is a system
that allows me to locate transmitters in a room.

You don't need transmitters, you just need a bunch of video or still
cameras, one centrally located on each wall minimum, or more if needed
due to field of view etc.
Then it becomes simply a software and calibration issue. Code for
image detection in video and still images is readily available.
And you can use colour filters too if that makes your job easier.

Unltrasonics is another way, but that can get messy.

The second thing I though of is doing the following:
- Get 3 radio receivers to form a base for triangulation
- Get transmitters to send 100 times a second an ID + count
- Get a circuit that is able to use the data from the 3 bases to
triangulate the position of the object through a microprocessor or
something like that

Forget radio transmission, it's too fast, you won't get such a small
resolution.

Is this a real practical problem? or some uni project?

Dave.

 

[Chris Jones]

chrysoinnuke@gmail.com wrote:

Hello,

What I would like to do:
Capture motion (not specifically human motion) in a room that is about
3*3*3 meters. The system should be able to capture 16 'active' points
in said room.

What I thought I could do:
- Get something from the market, but whatever i try to search for,
google does not provide me with what I really want which is a system
that allows me to locate transmitters in a room.

The second thing I though of is doing the following:
- Get 3 radio receivers to form a base for triangulation
- Get transmitters to send 100 times a second an ID + count
- Get a circuit that is able to use the data from the 3 bases to
triangulate the position of the object through a microprocessor or
something like that

The problems kinda start now:
- I do not know of any company that provide that kind of equipment (or
I am searching for the wrong stuff on google) so if someone can orient
me in the correct direction in this regard I ll be glad
- I have pretty much no knowledge of electronics except my classes
from 10 years ago. I do not mind learning but I do not even know where
to start, once again any guidance will be appreciated. (I especially
do not understand how digital data can be sent on analog radio
frequencies)
- If you know of any circuits that allows to triangulate the position
of an RFID (for example) and that can do that for more than 1 I ll
gladly take the information.

In the hope someone may help in a way or another,

Best Regards

Here is a company which sells the things you require:
http://www.polhemus.com/

Alternatively, if you must build something, then you could put six loops of
wire, each loop tracing the circumference of one square face of your 3
metre cube room. At any one time you could drive one pair of loops on
opposite faces of the room, first with in-phase signals, then with
out-of-phase signals, then drive the next set of two coils, and so on. You
could drive the coils with an audio frequency tone, e.g. 10kHz, and each
coil could be driven for a few milliseconds or a bit more.

For each moveable receiver, I suggest using three mutually orthogonal coils
(i.e. at coils in three planes 90 degrees to each other), which could be
wound around a cube a couple of inches across. I used polystyrene foam and
coated the assembly with araldite epoxy to keep the coils in place. You
then need to amplify the signal from the coils with some low noise
amplifiers, I suggest OP27 or NE5532 etc. You could either digitise the
output of the opamps directly, or put the signal from each coil through a
phase sensitive detector that is synchronised to the transmitter signal,
low pass filter the output of the phase sensitive detectors and then
digitise that.

From the vector sum of the signals from the three receiving coils, you can
determine the amplitude and direction of the magnetic field relative to the
receiving coils. If you do this when the two coils on opposite faces of
your cubic room are energised in phase with each other, then this will tell
you roughly the orientation of the receiving assembly. If you then reverse
the signal to the coil on one face of your room then the field will have a
gradient across your room and you can determine the position in the axis
orthogonal to the plane of the two transmitting coils that you were using.
You can then repeat for the other two planes.

You could then look-up from the initial position estimate some coefficients
to correct for the field not being quite at right angles to the
transmitting coils in some locations near the walls. As long as each
location in the room gives a unique position estimate, you should be able
to calibrate out the field non-uniformities using some look-up function.

You would want to avoid big lumps of metal in the room as these would cause
distortions to the position estimates.

Chris

 

@ Chris Jones:
Thanks for the info but i did not mean to actually build the whole
system from scratch either , but electrofields (have no idea how to
translate the term in my language and dictionaries ain't helping) and
me is really not a love story. I tend to dislike physics which is
mainly why I kinda suck at anything related to waves.

@Phil Allison:
If I get my stuff to work I ll be sure to answer why I want to do
this

@David L.Jones:
It is not a uni project and since I am working in a bank there is not
really any direct real link to it. But same with Phil Allison, I ll
answer why I want to do this either when I get it working or once I
give up on the hardware part of this project which is the main step
for me.
And I would do this as a hobby

 

Bah, stupid of me not saying what I want to make. Especially since
giving my need and not the solution would probably get me better
answers anyway.

So I want to place for example 2 sensors in said room and follow the
motion of it.
But I want it to be wireless (because lines are damn annoying). I want
the system to be able to operate a number of wireless sensors.
Also, I am not interested in the position per say, but the motion.

To go back to technical stuff:
So after my first post I tried to look at other stuff than radio.
Ended up on accelerometers and they seem like they can handle the job.
I don't really care about the position so accelerometers can do the
motion job just fine and if need be even relate the position though
with slight errors (rounding issues)
Yes I know, commercially available for 2000$ for 2 wireless sensors.
But:
- Less fun to do
- More expensive than the DIY way
- Won't learn how to write drivers for PCs
- Won't learn about how it works generally
- Won't be as customizable as I might want it to be

And here is what I am now thinking of building:
Get for example a set of Accelerometers on own boards. Place them on
an object lets say a club for example. Connect both sensors to a
'controller' that also has wireless capabilities on its board. It
would be something like:
Sensor ---- wiring ---- Controller + Wireless ----- wiring ---- Sensor
Then have a wireless base that receive the transmission and send it to
the CPU through USB for example. Then I treat the data as I want it.

The issues I have seen so far:
0/ Is 1m a long distance in regards to cabling. (Some documentation on
accelerometers tells that Sensor should be near MCU)
1/ How many Sensors can be controlled by a MCU unit using a SPI
interface (maybe better ways exists but seems like lots of components
use it). (And I still don't understand how a MCU can tell which Sensor
it wants to talk too on the SPI line)
2/ How can I make the Base receive signals from more than one wireless
controller + sensor system.
3/ How can I identify which sensor is the data from
4/ How do I make the link between a MCU and a Wireless unit (need to
read docs here I guess)

Other question:
1/ Do I need a MCU between the sensors and the Wireless Unit?
2/ Is it practical to have 1 wireless unit per sensor (I am not for
this, I d rather aggregate stuff through wiring, less dangerous, less
radio cluttering and such)

If you see any other issues, have ideas on how to better that kind of
system. Know of already build circuits and such (with documentation
(at least a minimum)) it would be great.

Best regards,
Chryzo

 

[Phil Allison]

<chrysoinnuke@gmail.com

Bah, stupid of me not saying what I want to make. Especially since
giving my need and not the solution would probably get me better
answers anyway.

** Halleluiah !!

At least one fuckhead can see how dumb it is not to describe the
application.

So I want to place for example 2 sensors in said room and follow the
motion of it.
But I want it to be wireless (because lines are damn annoying). I want
the system to be able to operate a number of wireless sensors.
Also, I am not interested in the position per say, but the motion.

** Oh dear.....

He is still a complete fuckhead.

Cos he has chosen NOT to describe what is going on in the room that makes
the sensors move about nor the purpose of the whole thing.



...... Phil

 

On Jan 6, 10:30 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:

chrysoinn...@gmail.com

Bah, stupid of me not saying what I want to make. Especially since
giving my need and not the solution would probably get me better
answers anyway.

** Halleluiah !!

At least one fuckhead can see how dumb it is not to describe the
application.

So I want to place for example 2 sensors in said room and follow the
motion of it.
But I want it to be wireless (because lines are damn annoying). I want
the system to be able to operate a number of wireless sensors.
Also, I am not interested in the position per say, but the motion.

** Oh dear.....

He is still a complete fuckhead.

Cos he has chosen  NOT to describe what is going on in the room that makes
the sensors move about nor the purpose of the whole thing.

.....   Phil

lol

I won't describe the application whatever happens. I expressed a need
with a bit of technological requirements, should be enough to get me
going in the right direction. Though, found some stuff on freescale
but it does not do exactly what i want .

You do not need to know about the end application to help though

Anyway, to answer my self, a ZSTAR3 system from freescale seems cheep
enough to get me going though it is full wireless which isn't as good

Anyway

Thanks for the help and info

 

On Jan 7, 8:39 am, chrysoinn...@gmail.com wrote:
<snip>

I won't describe the application whatever happens. I expressed a
need
with a bit of technological requirements, should be enough to get
me
going in the right direction. Though, found some stuff on freescale
but it does not do exactly what i want .

You do not need to know about the end application to help though

Anyway, to answer my self, a ZSTAR3 system from freescale seems
cheep
enough to get me going though it is full wireless which isn't as
good

Anyway

Thanks for the help and info

Could an ultrasonic car alarm be adapted?

G˛

 

[Phil Allison]

<chrysoinnuke@gmail.com
"Phil Allison"

Bah, stupid of me not saying what I want to make. Especially since
giving my need and not the solution would probably get me better
answers anyway.

** Halleluiah !!

At least one fuckhead can see how dumb it is not to describe the
application.

So I want to place for example 2 sensors in said room and follow the
motion of it.
But I want it to be wireless (because lines are damn annoying). I want
the system to be able to operate a number of wireless sensors.
Also, I am not interested in the position per say, but the motion.

** Oh dear.....

He is still a complete fuckhead.

Cos he has chosen NOT to describe what is going on in the room that makes
the sensors move about nor the purpose of the whole thing.

I won't describe the application whatever happens.


** Then you are a TOTALLY STUPID, ARROGANT CUNT.


You do not need to know about the end application to help though


** That is 100% wrong.

Go drop dead.



...... Phil

 

[Bob Masta]

On Wed, 7 Jan 2009 08:39:24 -0800 (PST),
chrysoinnuke@gmail.com wrote:

I won't describe the application whatever happens. I expressed a need
with a bit of technological requirements, should be enough to get me
going in the right direction. Though, found some stuff on freescale
but it does not do exactly what i want .

You do not need to know about the end application to help though

The reason it's good to explain the final
application is that there are often other
approaches that are much better than the one
that is asked about, once we know the full
details. You are missing out on the collective
wisdom and brainstorming of the group, which is
one of the big benefits of newsgroups.

Sure, you may have a million-dollar idea that you
don't want to make public. But why would you
expect anyone to provide free help for that, when
you won't even explain what you are really trying
to do?

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

 

I can even give you more info now though. Finally found how to
translate what i wanted so google could start giving some good
results.

I d like to build some wireless 6DoF board sensor with a base than can
receive inputs from up to 16 board sensors.

To point me in the right technology / direction, I really do not see
why you need to know of the end application especially since it is
plainly a curiosity thing on my part. I ain't gonna resell anything at
the end. If I am able to get that working I ll just have satisfied my
curiosity.

Regards,

 

[Robert Monsen]

On Sat, 3 Jan 2009 13:54:49 -0800 (PST), chrysoinnuke@gmail.com wrote:

Hello,

What I would like to do:
Capture motion (not specifically human motion) in a room that is about
3*3*3 meters. The system should be able to capture 16 'active' points
in said room.

What I thought I could do:
- Get something from the market, but whatever i try to search for,
google does not provide me with what I really want which is a system
that allows me to locate transmitters in a room.

The second thing I though of is doing the following:
- Get 3 radio receivers to form a base for triangulation
- Get transmitters to send 100 times a second an ID + count
- Get a circuit that is able to use the data from the 3 bases to
triangulate the position of the object through a microprocessor or
something like that

The problems kinda start now:
- I do not know of any company that provide that kind of equipment (or
I am searching for the wrong stuff on google) so if someone can orient
me in the correct direction in this regard I ll be glad
- I have pretty much no knowledge of electronics except my classes
from 10 years ago. I do not mind learning but I do not even know where
to start, once again any guidance will be appreciated. (I especially
do not understand how digital data can be sent on analog radio
frequencies)
- If you know of any circuits that allows to triangulate the position
of an RFID (for example) and that can do that for more than 1 I ll
gladly take the information.

In the hope someone may help in a way or another,

Best Regards

You can set up ultrasonic receivers, and chirp from the moveable
object every few ms. If you also flash some kind of infrared LED when
you chirp, you can use that as a timing reference. The relation
between the time of the infrared pulse, and the reception of the
ultrasonic pulse indicates the distance.

If you have one receiver, you can determine that the transmitter is on
the surface of a sphere. Two gives you a circle in space, and three
gives you a point.

Getting this to work will probably be very difficult.

Regards,
Bob Monsen

 

[BoldInventions]

I just read this on Slashdot, perhaps this would be adaptable to your
needs. We'll have to see if they can actually make it to the
marketplace.

"One of my top picks at the Consumer Electronics Show was Sixense's
TrueMotion, a game-controller technology that resembles the Wii's
remote, but uses an electromagnetic field to provide far more
precision — it knows the exact location of the controller in 3D space
and which way you're pointing it. (The Wiimote only knows which
direction you're moving the controller.) TrueMotion-based remotes are
due by Christmas, bundled with a PC game for under $100."

http://technologizer.com/2009/01/10/truemotions-way-better-than-wii-game-controller/

-Kevin

On Jan 8, 10:22 am, chrysoinn...@gmail.com wrote:

(..)

I d like to build some wireless 6DoF board sensor with a base than can
receive inputs from up to 16 board sensors.