Freescanning Rig

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Freescanning Rig

Postby MagWeb » Sat Jun 20, 2009 3:14 pm

Hello,

here´s my new scanning setup.
It is designed to perform a repeatable lasermotion, using a steppermotor that is fully controlled by DAVID via COM messages.
For every frame DAVID recieves, it sends a message to the port and the stepper performs one synchronized step. To control the stepper I use an Arduino and a plugged onto Adafruit Motor Shield. This shield controlls the stepper as well as the integrated 12V cold cathode lamp (as a "DC motor") and the laser (also as a "DC motor"). The voltage for the laser is reduced by a selfmade array that was suggested by WalterMo (see:http://www.david-laserscanner.com/forum/download/file.php?id=1791&mode=view fig.2 - I use a LD 1117V33 instead LD1117V30 at an input of 12VDC). The shield could drive 2 hobby servos additionally.
To move the laser an old 7,5°/step stepper is used with a 1:125 gear I found on a hobby DC motor (Conrad: Igarashi Motors). It needs little tinkering to get the gear plugged onto the stepper, but it performs nice motion with only a little backslash, that can be easily avoided with some rubber band.

The controller/motor/gear/laser-combo can be moved and fixed on an aluminum rectangle tube (24x44mm), into which the cam (logitech PRO for notebooks) is integrated without possibility to be moved. The lamp to light the scene (only for near distances up to 50cm) is integrated in the tube too. A microprojektor can be plugged onto the tube as well.

Costs:
Tripod : 19,95 €;
Alu 24x44x1000 mm: 7,45€;
Cam: Logitech PRO for Notebooks: 49€;
ColdKathodeLamp 7,95€;
Gear from a DC motor: 18,25€;
Stepper (recycled printermotor, but if you have none:) 25,-€;
Arduino: 25,- €;
MotorSield Adafruit (Kit): 20,-€;
small electronics : maybe 7,-€;
Material for brackets and case: maybe 20€;
Power supply 12VDC: 7,50 €

To complete the laserscanner setup:
+ laser (my case 178,-€)
+ DAVID license (199,- €)

Gunter
Attachments
FREESCAN.jpg
FREESCAN2.jpg
FREESCAN3.jpg
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Re: Freescanning Rig

Postby hal » Sat Jun 20, 2009 3:33 pm

:shock: Hey Gunter, you are heavy armed! Maybe the NASA or the U.S. Army haven't this great "piece of artillery" :shock:

Great work and perfect solution for David. Really impressive device. How heavy is the structure?
Thanks for sharing your project.
As we well know, you are every time a reference for us.

Bye,
Mattia

p.s.: you need the licence to carry weapons, for it? :wink:
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Re: Freescanning Rig

Postby MagWeb » Sat Jun 20, 2009 3:55 pm

Hi Mattia,

2600g all together.

8) Now I need a violin case to carry it hidden 8)

Gunter
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Re: Freescanning Rig

Postby RAYA » Sat Jun 20, 2009 7:36 pm

Hi Gunter

Nice design

Would you please mention your design factors ?
Why you choosing horizontal array for laser/cam ?

RAYA
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Re: Freescanning Rig

Postby MagWeb » Sat Jun 20, 2009 7:43 pm

Hi to Iran,

there´s actually no prefered orientation of this setup. You can use it horizontal as well as vertical. When you´ve done a reference scan, you can move it in whatever direction you like. The object can determine the orientation.

Which other factors?
Gunter
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Re: Freescanning Rig

Postby RAYA » Sat Jun 20, 2009 7:52 pm

Hi Gunter

Thank you

Horizontal assembly give more unstability to system(center in middle).

Other factor can be :

compacting,stability,easy to make,easy to use,expensity,.... .

RAYA
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Re: Freescanning Rig

Postby MagWeb » Sat Jun 20, 2009 8:14 pm

Hi again,

for me the main factor was to guarant a stable cam/laser relation, that makes it possible to transport it easily. So I think one can transport it in a case 1,1mx 0,25m x 0,15m and it can be build up in 2 minutes. (so it may be possible to do calibration + referencescan at home and to go to the scene outside without planes).

With the electronics I searched for a solution that needs as little tinkering as possible. The adafruit shield comes as a kit but its building is documented very good - its's easy to do - the voltage reduction is as easy as could be, think you may do it without any board simply by soldering the parts together.

Parts should be available almost everywhere.

I routed the bracket parts on my CNC mill but I think one may do it with rather simple tools too.

I would love to find cheaper solutions, sure....

Gunter
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Re: Freescanning Rig

Postby RAYA » Sat Jun 20, 2009 8:34 pm

Hi again

Why not Walter design or My design as in DAVID MECHANICS ?

Any advantage your system (mechanism) has ?

RAYA
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Re: Freescanning Rig

Postby MagWeb » Sat Jun 20, 2009 9:17 pm

Hi,

to scan a fixed or big object you need to move the rig. So you´ve to tilt it, scan from left, from right, above, below. Means you´ll need some rotation axes at the tripod or stand.
I think a single bar is easier to handle than a triangle structure, easier to balance. A single slide seems to be enough to vary the distance cam/laser.
This setup tries to integrate all you might need in a compact design.

Gunter
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Re: Freescanning Rig

Postby RAYA » Sat Jun 20, 2009 9:29 pm

Hi

Thank you

You are right ,for fixed and big object it is better to rotate about center in middle of laser/cam assembly.

RAYA
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Re: Freescanning Rig

Postby onkino93 » Sun Jun 21, 2009 1:14 am

Hi Magweb

I'm eager to start building this but have many questions, I have at long last the money to purchase everything except for the high end laser and David software so they will have to wait, but for now I think I can make use of my my Trust5400 and TV lens , Here's link to a Stepper i found that might be suitable.

http://cgi.ebay.co.uk/Portescap-Stepper ... 1|294%3A50

I can't seem to find the DC motor you mentioned?

Would you care to shed more light on how I can accomplish a rig like yours.

Thanks so much.
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Re: Freescanning Rig

Postby onkino93 » Sun Jun 21, 2009 1:31 am

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Re: Freescanning Rig

Postby MagWeb » Sun Jun 21, 2009 8:27 am

Hi, onkino93

if you don´t find a suitable stepper from a old machine (e.g. printer, 2Dscanner, fax..) and you´re going to buy one, I would choose a type with a higher resolution and a less reducting gear (less backslash). For my person I prefer the NEMA type of steppers for these are easier to integrate.
eg: Sanyo Denki 103-54-52500 http://www.shop.robotikhardware.de/shop/catalog/product_info.php?cPath=69&products_id=172

You found the right shield - but do you need all the motors included in that package? here you find the shield kit alone:
http://www.adafruit.com/index.php?main_page=product_info&cPath=17_21&products_id=81

I used the gear from "1:125 type 33G gearb. motor" Conrad Part no .: 244031 - 62 (links to Conrad search results do not worK - sorry)
To choose the right reduction you have to keep your stepper resolution in mind. If your stepper is a 7,5° like mine it uses 48 steps /round so with a 1/125 reduction I get 48x125=6000 steps/round at the gear's output. So if you use a 1.8° stepper (as linked above) it does 200 steps/round so you get the same resolution at the gears output using a 1/30 gear (6000/200=30). I found a resolution of 6000 steps/round a rather good one to get good quality in a reasonable time if you do one step progress/frame DAVID analyzes( but you accept some missing pixels). So if you wish to have no gabs maybe 8000 ? If anybody finds a readymade gear fitting to small steppers please post!

I used the Conrad cold cathode lamp 30mm Part no.: 581265 - 62 . This lamp runs best at 12VDC. Its purpose is to light the scene for calibration and texture grabbing - while it is switched off while scanning ( works only for short distances).

Gunter
EDIT: forgot to mention: My 6000 steps/round are enough using microstepping mode of the Adafruit motorshield. (I didn´t find its characteristics 1/8??? until now)
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Re: Freescanning Rig

Postby joecnc2006 » Sun Jun 21, 2009 10:04 pm

Like to test the pde file i have the same board.
Joe

David-Laserscanner Professional Edition, Logitech Pro 9000 Webcam, LC532-5-3-F(16x65)

www.joescnc.com
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Re: Freescanning Rig

Postby Bongobat » Sun Jun 21, 2009 10:11 pm

Hi Gunter,

Very nice rig :!:

Could you post some renders you have done useing your final version. I like seeing the pretty pictures that are a result of all the hard work :wink:

Greg
DealExtreme red line laser, Microsoft Lifecam HD-5000
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