Open DAVID-hardware project

[MagWeb]

Hi all Davidians,


Tomorrow is a special traditional day in Bavaria. It‘s the day the farm laborers‘ contracts of employment ended in former times and one began new projects. So it might be a good time to start something new

I´m really fascinated by open projects as the Arduino http://www.arduino.cc or the RepRap 3D printer http://reprap.org/bin/view/Main/WebHome .
So I thought about a open hardware project for DAVID.

Nowadays we all cook our own soup. Our constuctions do not take any care whether this or that part can be found in country xyz

As I understand „open hardware“ means to build a common hardware system from parts as simple and cheep as possible and available all over our nice planet.

At its basic level DAVID does exactly follow that way: Simple parts (boards, cam and laser )you should get everywhere. But if the direction, and I think it does, points towards an automated setup, we completely loose that way.

If I look at the last progresses DAVID made with the mirror support and plane-less scanning, I come to the conclusion that these are rarely used, for these wonderful work of Simon and Sven needs advanced equipment.

I know we have skilled people in this forum, so why not gather that skills to focus a common open hardware product.

Open hardware would mean, that we build a system with direct connections to David. As many parts as possible, circuits, driver software, mechanics and optics should be published, so that everybody should be able to rebuild the system without any special skills. Open hardware also means, that everybody should have the choice to build it brick by brick, to buy more complex modules and difficult parts or the ready made system. There may some commercial companies log in to build special parts.

e.G: If you look at the Arduino: From etching the board, buying every part from another source and soldering you can do everything. But you also can buy the ready made board. You can also clone the Arduino to a commercial product as an „XXXduino“

For DAVID I´ve in mind to develop a system of electronics and mechanics and optical components. The system should be scaleable to the needed object size, something as the REPRAP. So if anybody should decide to build and sell it completely, the buyer should be able to plug in the USB and starts scanning with DAVID.


Anybody interested doing some work for this project? How should we organize a possible development, any ideas or different points of view?

Without discussing some technical problems, what do you think of this idea?

Come on join the party
hope you will

Gunter

[WalterMo]

Hi Gunter,
Of course I would also join such a project. It's a good idea to concentrate the knowledge of all the members of our forum. Some are good in electronics, others in mechanics or in software programming. There is so much potential! This should (must) be used.
Sven and Simon have given the possibility to scan by David without the background panels. But I think only two or three members of this forum are able to use it. This should be changed by developing a suitable hardware. Not too expensive but precisely as possible.

In the last two years I have developed, built and published some devices on the forum. I do hope that some of them were recreated. Or at least turn something to advantage.
At the present I am building a scanner with the possibility for outdoor scanning. The mechanics is nearly the same as of my old proved scanner already presented in April 07. Only the outfit is a bit more professional. See the attached photos.
I really hope that much feedback to your offer will come up.

Walter

[RAYA]

Hi Gunter

I agree with you and join you but I have some items in mind that should be explained here these are all forum results which can be outputed,these are also limits or resistance to go forward (having grouped groups,having designed project,having more interested man here,....) :

1-Commersial devices should be insisted,so DAVID should increase it`s graphic interface to support us as user and give more hope and movement.(no supporting to digital video camera full HD resolution)

2-Structured light scanning has to be considered more because the price of laser system (laser and mover) going to equal a video projector (with our work included in) and speed of scanning is another reason and .... .

RAYA

[florin.topala]

Hi Gunter & WalterMo

I am happy about this project and you are oen step in front of me.
I want to build a stepper controler for a david laser scanner project [hardware I meean] using arduino but I want to use it for small objects ... ~ 10 cm and the sistem si limited at this size.

I live in romania soo for me iti is difficult to obtain all electrical components but with a little patience I hope I will heve some results.

I will join this project.

Best regards,
Florin

[MagWeb]

Hi,


sorry, for being little off... my two little girls caught a cold (do not ask me)...
so....

Hi Walter,

You were the very first, thinking about a motorized setup. So I´m not surprised to see you here.
That´s realy a well designed professional device for going outdoors. I `m allways dreaming to have a portable setup to scan my friends, the trees. Maybe if you´d allign this with a cam on a square pipe, calibrate it indoors (referencescan), you could scan everything?



Hi RAYA,

I would like to concentrate on the existing DAVID software. Structured light needs a different hardware. I agree, it would be some help, if we had an interface to DAVID, but that could be implemented into the firmware as an update later on, too. I´m sure Simon and Sven will do their best.
Another way would be a passive DAVID controlled by some piece of software via virtual clicks.

Hi Florin,

Romania should be our test - if you can get the parts in Romania, you should get it everywhere ???

----

In our Wiki main page there is an empty area called "Projects". I think a WIKI is a better place to develop. What do you think of opening a special page for this? Are you familiar with WIKI editing?
If we would put drawings, results, constructions... there, with the possibility to work on the content and discuss and announce here, when some work was done...think that´s good

Gunter

[florin.topala]

hi Gunter,

It is strage somehow because may parts whitch I've bought from germany arrived faster than if I bought something from .ro

I didn't use wiki before but I think I will learn and somebody I'll hope will correct my gramatical mistakes ... but I'll hope there will be a lot of immages

I'm still workint at a controller using arduiono and a stepper motor and some parts from an inkjet printer.
As soon as it is posible I'll put here my results.

Florin

[RAYA]

Hi Gunter

I´m sure also that Simon and Sven will do their best.

I also thank of their great software and forum.

My post meant only a remember of DAVID forum result not any thing else.

I thank you also.

Raya

[fz1]

I think I might have to also help out some with this. I am waiting first to see what everyone else choices are for controllers. I am thinking about using a arduino but not sure yet. Right now I am just driving the laser with a dc gearbox but plan on making everything controlled by a controller so I will try to help out as much as I can.

I also want to thank everyone for trying to communicate with the language barriers and it shows the world that we can all get along.

Some more info: I hit the jackpot today. Actually last year but had forgot about having this. I was given a old Ioline plotter. It powers up but drivers are almost impossible to find for it. All manual controls work fine. Taking it apart I found 2 nice stepper motors and one small high torque dc gearmotor. The carriage has 91.5 CM of travel. Movement is very smooth and should work for the laser with hardly any work on the mechanical end. I have no idea on how to use the controller boards inside so i plan on using the board everyone here selects.
Steppers are vexta
dc 4 volts 1.1 amp 2 phase .09 degree step.
So I will have to make sure to get the rest of the info needed to get the proper controller for them.
I build machines for a living and have so much old parts in the shop to use if needed. Many linear rails and slides i can use but they are really too strong for the needs of just moving a laser so this plotter should do the job with little effort.
Here are a few pics of the plotter. Sorry for the phone pics though.

[MagWeb]

Hi,

I launched a project page:http://www.david-laserscanner.com/wiki/the_open_hardware_project

@ Walter: could you take a look onto my conection diagram? This system works, but I ´m not sure whether I did everything right. Especially the laser´s power supply isn´t clear to me (so I drew a LED instead). The Arduino has a on board 3.3V pin: "external circuitry requiring a 3.3V nominal supply at a current of around than 50mA could also draw its power from the 3V3OUT pin" - but a green linelaser needs 300mA!
thanks a lot!

Gunter

[WalterMo]

Hi Gunter,

I have taken a look at the connections to the Arduino board. Of course we cannot use the 3.3V comming out of the microprocessor.
You need an additional stabilizer whose 5V supply can come from the USB port (max. 500mA) or from the 12V power supply. Using the 12V a heatsink at the LD-1117V33 should be used because maximal 2.6 W must be radiated there as heat.
And I think the 5V cannot come from the 5V port of the Arduino board but directly from the USB port on this board. Test it.

Does the LED with 10 KOhm really work? Normally a resistor of about 390 Ohm in series should be used at 5V.
About 0.3V will be needed internally of the BS170 FET between s(ource) and d(rain).

And to the Gnd connections on your schematic circuit diagram: You have drawn the Gnd connection from (-) of the 12V supply to the Arduino through the EasyDriver boards. Perhaps they were only drawn in that way but in reality this isn't allowed because current spikes from the motors can now come easily to the Arduino. Better is a direct connection from the (-) of the 12V to Gnd of the Arduino.

Walter

Edit 1: I have changed the schematic circuit diagram a bit to get a more precise 3V when a green laser is connected. With one BS170 I had measured 2.85V. Green lasers need more current than red ones. Therefore the voltage drop between D(rain) and S(ource) is a bit higher.
The 1k resistor isn't necessary absolutely. It should be a protection for the Arduino output port.

Edit 2: As just said, green lasers need much more current than red ones. Therefore it is very important to check the temperature of the LD-1117V33 by your fingers during use. Specially if a higher input voltage than 5V is used to suppply this IC. If you cannot let your fingers on this IC, its temperature became too hot! Then a bigger heatsink must be used and/or its input voltage must be reduced. If only 12V is at disposal reduce this voltage by means of a second voltage stabilizer, e.g. a 7808 (here = 8V). A suitable circuit diagram you can find here:
download/file.php?id=1791&mode=view
Fig. 3. Only substitute the 7805 for a 7808. The pin connection is the same.

[MagWeb]

Hi Walter,

thanks for your circuit and solving the powersupply of the laser. I´m going to update the connection diagram.

Does the LED with 10 KOhm really work? Normally a resistor of about 390 Ohm in series should be used at 5V.
About 0.3V will be needed internally of the BS170 FET between s(ource) and d(rain).

Yes, it worked --- three days: till the LED burnt down today to be corrected too.

And to the Gnd connections on your schematic circuit diagram: You have drawn the Gnd connection from (-) of the 12V supply to the Arduino through the EasyDriver boards. Perhaps they were only drawn in that way but in reality this isn't allowed because current spikes from the motors can now come easily to the Arduino. Better is a direct connection from the (-) of the 12V to Gnd of the Arduino.

Do´nt know why there are two GNDs on the board (think, one simply acts as a stand). I followed the tutorial http://danthompsonsblog.blogspot.com/2008/09/easydriver-v31-tutorial.html connecting the easydriver. One pin is named on the board (funny, the one next to the 12V+) . But without connecting the ground to the Arduino´s ground nothing works. But the best solution should be to connect as you suggested.

Thanks
Gunter

[WalterMo]

Hi, me again.

I hope my comment wasn't the reason (with the 390Ohm) that the LED burnt down. If yes, please give me your address and I will send you a new one.
I have made a test with a 10k resistor and a normal red LED was only glowing a bit at 5V. Perhaps yours was a so called low current LED.

Concerning the two gnds at the EasyDriver board: Sometimes such boards have two gnds, one as a power gnd and one as a signal gnd. So let the connection between EasyDriver and Ardunino as it is.


Walter

[MagWeb]

No need to worry, Walter!

it was the Cree LED (at the top) not the red (below Arduino). And it burnt as I ran it some time at 800mA to see how hot it gets. Result : Without heatsink (only the star platine) very quickly very hot>>> buff, magic smoke but that´s my way ... learning by doing. So you´ve to calculate some "buffs"
Running the red LED with a 10k resistor is the first example circuit, one builds if you follow the introduction to Arduino "Getting started with Arduino", written by a co-founder of Arduino - so I simply rebuilt that without any thoughts. But you´re right: I´ve also seen brighter LEDs.

regarding the double GND: it really looks like as if it is , as we German say :,"jacket like trousers" were you put in the Arduino ground. And it works without problems when you wire as drawn in the updated Wiki circuit. This weekend I´m going to order some needed electronic parts. For the Cree burnt out: Should one change something in that part of the circuit (besides a heatsink)?

Thanks for any advice - these small unknown electronic parts aren´t my thing
Gunter

[WalterMo]

Hi Gunter,

As I already discussed with Greg when he equipped a slide projector with a power LED:
A LED mustn't be powered by a voltage source but by a current source!

When I was looking at your schematic I thought that the Qree LED had a resistor already in series but wasn't drawn.
A resistor in series to a LED or another load is the simplest way to realize a current source. In your case with a Q4 or Q5 (max. 0.8A) this resistor should have a value of about 10Ohm when a 12V supply is used. It must withstand a power of 10W.
Better is to use a current stabilizer with an IC, e.g. with the LM317T. The resistor R on the attached schematic defines the current I which is to control.

R = 1.25V / I

R must be able to withstand a power P of:

P = I * I* R

A heatsink at the LED and the IC is necessary and should be contacted by a thermal grease. Only a „cool“ LED can radiate its nominal brightness and will life longer.
The LM317T has to radiate about 5.8W as heat. To reduce this a less voltage (9V ?) can be applied or an additional power resistor of about 5 Ohm in series can help the IC to shoulder the hard (thermal) work.

Walter

[MagWeb]

Hi Walter

As I already discussed with Greg when he equipped a slide projector with a power LED:
A LED mustn't be powered by a voltage source but by a current source!

When I was looking at your schematic I thought that the Qree LED had a resistor already in series but wasn't drawn.

Walter

There was a resistor drawn in the first version of the diagram (for I tried to understand the discussion in the white light topic) but after it burnt I wasn´t sure any more and removed it from the drawing (also labeling the Cree) . So you saw right. But with the explanation you´ve given above, I can see much clearer now.

Now I´m going to order the parts and again a Cree (maybe two ) and put them on the breadboard.

That done, I want to design a blank board to plug it onto the Arduino and the EasyDrivers onto it (as the available "shields" for Arduino). Think that should work on my CNC router... With such a blank board everybody could solder it together easily...

thanks for your patience and your time.
Gunter