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1  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: December 02, 2013, 09:04:15 am
The frame is constructed that the Mics listen in the thin air/smoke  smiley..
so the sound of impact will travel trough the air, it is not measuring the surface
vibration..

Depending on the target material the sound should be a hard thumb,
this i say based on me being on a military spec shooting range where you
sit bellow the targets in a bunker, and there i could hear a very distinctive thumb
sound on impact.. smiley-roll-sweat

But yes, i did not smoke anything on the speed of sound :-)
the calculations maybe.. :-)
2  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: December 02, 2013, 08:48:02 am
Another Question,

How large do you guys think the effect of surface tension would be..
at this moment the target is made of a canvas material loosely fitted..

Would a hard surface improve the accuracy, and then if i use something rubber,
as the impact surface, would that have a huge impact on accuracy..

Conveyer belt works great as a target back stop as it heals (does not leave holes)
but i am concerned with the effect rubber would have..

I am rebuilding the target area, so i am considering all aspects that could affect accuracy..

Marcel
3  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: December 02, 2013, 08:43:14 am
Just did some interesting Math... Do you guys agree with the results..

In my mind the most practical method of getting accurate data is using Digital Interrupts to listen
to the sensors, to get the best accuracy..

Assuming the target size is 2.2M high by 3.2M Wide.. with the speed of sound at 340m/s
it should take sound 6.47 Mili Seconds to travel the 2.2Meters and 9.42 to travel the 3.2Meters.

According to this document http://www.gammon.com.au/forum/?id=11488
"I count 82 cycles there (5.125 µS in total at 16 MHz) as overhead plus whatever is actually done in the supplied interrupt routine. That is, 2.9375 µS before entering your interrupt handler, and another 2.1875 µS after it returns."

Based on the figures i tried to determine the expected accuracy of the Uno at this target size.
so i worked with 1cm to get an idea..

it works down to 0.029 Milliseconds to travel a CM...
if the process time is 0.005125 Milliseconds as per the reference information,

i should be able to get a expected resolutions of about 2 mm...

does this make sense.. or have i smoked something not good for me :-)

Marcel
4  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: December 01, 2013, 01:32:11 pm
Hi Rob, thanks for all the messages you sent, for some reason i never saw them,
What you are proposing is my plan, to try and do just the data acquisition on the uno
And the analyze and process the data on the pi..

I think the largest part of my failure the first time round was my sensor circuit..

Hope the improved circuit will increase the accuracy plus the fact that i will be reading
Digital instal of analog.. Hope that improves speeds as well.

Thanks for all your inputs thus far.. Hope we figure this out :-)

Marcel
5  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: December 01, 2013, 12:15:53 pm
Hi guys, i ma finally back to this project, or have been for a while but have been trying to sort out the hardware first..

I have now built a new sensor circuit, using 2xlm324n quad op-amps the first one amplifies the mic inputs, the second one is a comparator on which i have a pot to adjust the comparators voltage it compares with..

Hopefully this will help me improve my accuracy on the  inputs..

I have also played with different hardware, the Uno and a raspberry pi and python..

I am leaning on going back to the Uno, as i does not get constancy on the sensor values on the Pi.

Has anyone made any progress on this subject, i know there where a few geniuses here and they where interested
In this project...

Thanks again for everyone who have shared their inputs, and i hope this time round i can get this one figured out..


Regards
Marcel
6  Using Arduino / General Electronics / Re: Controll HDD Voice coil Position on: July 16, 2013, 05:54:06 am
I only have 2 wires, so yes i will need to do some trick..

What would one call the circuit that would move a 10V to -5 and +5 range..

I have been trying to google possible circuits but my crude search without knowing what i am looking for is not
giving me results

Thanks again for all the help..
7  Using Arduino / General Electronics / Re: Controll HDD Voice coil Position on: July 15, 2013, 06:33:15 am
Thanks, I will try your suggestion, thank you for the quick help and information...

:-)
8  Using Arduino / General Electronics / Re: Controll HDD Voice coil Position on: July 15, 2013, 06:09:29 am
Ok that makes more sense.. so a filter(if that is the right name) would then provide me the + voltages i need, how would you suggest that i get the full range from -5 to +5....

Thank you for the quick response, i am by any stretch of the imagination knowledgeable about electronics, i am still studying at the university of Google and Arduino.cc smiley

Thanks Again..


9  Using Arduino / General Electronics / Controll HDD Voice coil Position on: July 15, 2013, 05:49:46 am
Hi Gents,

I am trying to figure out how to control a hdd voice coil with the arduino uno.
i am just not finding a answer that can work for me, either i am not asking the right
questions or i do not understand the voice coil correctly.

So what i have so far is that the voice coil require a input of -5V to +5V to place it in different positions,
i have played with putting power directly onto it a 1.3V moves it a little bit to one side on + and the other side on -..

Now my understanding of the analog write function is that it is a PWM signal witch provides a 0 and 5v at varying frequencies..

So in my basic understanding there is one of two ways to do this, have the arduino control a voltage regulator circuit that send to required power.. How that work not sure yet as i am not sure if i can control a voltage regulator with PWM..

The Second option i have come with is using Audio/Sound frequencies generated from the arduino, but with that i am not understanding how i will be able to control -5V to +5V....

Like i say, it is completely possible that i just do not understand some basics, or that i am over complicating this..

Is there someone who can shed some light on this ?
what am i missing or not thinking about...

Or someone who have done a similar thing before...

Thank you for your time in advance...




10  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: June 11, 2011, 08:28:31 am
Thanks you guys for all the input, i have been busy with another project the past few months and did not get allot of time to work on this, but yes, it is not an easy solution but i am will find a way to make it work...

Thank you for all the new ideas, i must say the approach from necromancer sounds like it would be the simplest way..

I will keep you up to date as i make progress, still struggling to get the Comparator part sorted out, i am stupid with the electronics, so i need to go by trial and error..

Marcel
11  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: March 09, 2011, 01:37:52 pm
Hi Rob,

yes, i did try that, i seem to be getting better data from the preamp and mics...

The digital input i need to improve the acquisition speed..

Regards
Marcel

12  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: March 08, 2011, 09:06:35 am
Hi Gentleman,

I am looking for some more advice on this project,
i am using this sound sensor..
http://tinkerlog.com/2007/05/20/cheap-sound-sensor-for-avr/



I would like to add a comparator to the circuit so i can send the data to
the Digital inputs..
or do the ADC Conversion externally...

I have read quite a bit and most people advise OPAMP's but i have no idea
about the electronics, so some guidance or direction would be helpfull.

Thank you
Marcel
13  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: March 03, 2011, 04:24:51 am
Thank you..

Will start working on this approach,

Honestly, i understand you frustration, i have been trying to solve this for a long time now, and
every single person i present with the challenge says it is easy, until they need to prove it..

I have rewritten this application about 20 times now...

Hope this is the last one...

Thank again for all your inputs gents..

Quote
rewrite this system to express x0 and y0 and you're done.

funny that many come out on how to solve this (oh yeah, it's trivial, search wiki) problem, without actually presenting a working solution! In the end I got really annoyed, and here is a a solution to calculate the positions (mathemetica, matlab did not help much so I did it by hand) and you can find here the algo for this particular problem: http://www.schwietering.com/jayduino/#newtonmethod (in 4 iterations you get a 1E-09 result).

14  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: March 01, 2011, 03:30:56 am
Would i be able to implement some form of an interrupt on analog sensors ?
15  Using Arduino / Sensors / Re: Impact location, using four sound sensors. on: February 27, 2011, 05:46:03 pm
Hi Gentlemen,

I have a new question... relating to the same topic...
I have been doing some reading on the various ways to get the audio data
into the Arduino.

Well i am at the point where i am not sure what is the correct direction to take..

Option one:
Using the pre-ams on the analog ports as i am doing now.

Option two:
Using a OpAmp as a comparator and putting the data into the Digital ports,
and using one of the Hardware timers to create an interrupt to signal the arrival
of a new input..

Would Digital be faster than Analog, or the other way around ?

Does anyone have any advice regarding these options, it seems the prediction that
i will loose accuracy due to the speed of the processor.
so any improvements i can make will help me get more reliable data.

currently i get very random data, still trying to figure it out why, that is why i am looking at way to improve that
data input...

here is what i currently get, five impacts at roughly a similar location on a surface 940mm x 640mm
the times are in millisecond....

------1---------   
Time1 = 0.00
Time2 = 0.94
Time3 = 2.84
Time4 = 5.69

------2---------   
Time1 = 0.00
Time2 = 2.34
Time3 = 4.69
Time4 = 13.19

------3---------
Time1 = 0.00
Time2 = 3.75
Time3 = 4.70
Time4 = 5.65

------4---------
Time1 = 0.00
Time2 = 0.47
Time3 = 1.88
Time4 = 3.78

------5---------
Time1 = 0.00
Time2 = 3.76
Time3 = 4.70
Time4 = 8.03
---------------

Any Ideas????

Thank you
Marcel

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