Corvus Corax

finally managed to backport the new developments on simposix to "next"

simposix is now handled as a "board" so to compile it you type

make simposix

and it will build a firmware in buid/fw_simposix/fw_simposix.elf

theres also an opfw file, but as long as we use Linux as our bootloader u start it by executing the elf file directly

please test and tell me if it works or if it doesnt what doesnt.
you should be able to connect with the GCS via IP network telemetry on UDP port 9000

Assume you happen to have one of those:

 BAT1.JPG   57.26K   12 downloads

What to do, what to do... ah, I know! Lets open it up!

 BAT2.JPG   74.35K   17 downloads

Hmmmmmmmmmm LiPo cells :-)) The Apple MacBook has 6 cells in a 3S configuration in pairs by two.

They sit in a metal frame and have really wriggley bits around them (like flexible copper band connectors connected to the integrated battery control circuitry)

 BAT3.JPG   89.16K   28 downloads

This is really dangerous, it could short, so I unsoldered ground and +12V and clipped the balancer connectors (those were regular wires).
Never let a single open connector fly around loose on a life LiPo battery, never ever ever ever two of them, so first thing after unsoldering any is to wrap it in insulation tape. (sticky tape is fine too for these voltages)
Same goes for the balancer connectors.

Then this scary bit of falling apart circuitry comes off:

 BAT4.JPG   93.18K   34 downloads

(Note the two heat sensors they added, I hadn't cut those since they are loose in the frame)

Taking out the cells is tricky since the bastards glued them in. Screwdrivers, knifeblades or anything else metal is out of question when handling LiPo cells, I even put off my wedding ring (gold is a superb conductor, you certainly don't want several carat of fine gold melt on your fingers while it shorted a cell)

I used something akin to a plastic knife to pry them out.

 BAT5.JPG   53.57K   33 downloads

Two cells are each "soldered" together with this copper band. I tried unsoldering it but whatever they used to connect them didn't  melt. Maybe the didn't solder but spot-welded them or something (almost looked like it). In the end I just ripped the band off.

And then I cut the connecting bridge between two cells in the middle, since those two wouldn't come apart either. That reduces the connector length by about 2 mm but its a safe procedure. Again all connectors are wrapped safely to prevent involuntary shorts.

 BAT6.JPG   95.78K   28 downloads

After testing which cells were good, I chose three of them and soldered them back together with new wires for current and for a to be connected balancer. Soldering batteries isn't as scary or hard as it sounds.
Just coat your wire ends in solder before you start so they will attach cleanly. Then also add a blob of solder to the connector on the battery. You can see if its spread out nicely. Don't keep the soldering iron there for longer than absolutely necessary so the heat can disipate before it reaches the inside of a cell.
When this is done, just put the wires on the freshly prepared solder pad and let the solder melt for a split second, you'll end up with a perfect solder connection without risking a heart attack.

 BAT7.JPG   110.76K   26 downloads

The Macbook 13'' battery is advertised with 56 Wh. considering its 3S and assuming they calculate that with nominal voltage of 11.1 V that'd be roughly 5000 mAh. Since they have two cells in parallel, each cell should have roughly 2500 mAh.

 BAT8.JPG   114.59K   22 downloads

There we go, a perfectly fine 3S 2500mAh pack. - I'd assume its around 2C judging by the connectors they used. I did a couple of high current tests, but the voltage drops almost to zero above 30 A and the wires get really hot. (Shoulda used something bigger than my 0.8mm solid core copper)

I still need to attach a XT60 plug and a 3S balancer connector, have to get those in town, and then run test how much mAh these cells can keep long term.
At the least this will make a superb transmitter pack.

(Experiment inspired by Reddog's brave open LiPo surgery to rearrange cells, performed in Portugal)

Ich wurde eingeladen am 17.12. eine Vorstellung von OpenPilot am Shackspace in Stuttgart zu machen:

http://shackspace.de...ct:thundertalks

Das wär IMHO eine gute Gelegenheit für Leute aus der Gegend um sich dann dort zu treffen zwecks Kennenlernen, Erfahrungsaustausch, ...
Hier sind ja ein paar Leute aus dem Raum Stuttgart

Ich bring meine DH110, OpenPilot beta Hardware und ein Coptercontrol board mit zum mit rumspielen, wer Interesse hat, einfach vorbeikommen

Anfahrtsplan siehe Shackspace Webseite.

Gruß

Corvus

Hi everyone, I thought I'd share this:



I had the old OpenPilot PRO (beta) hardware on board (OP Mainboard, AHRS, GPS) - Xbee telemetry for giving the navigation command, and a custom flight logging board connected via USB:

(See http://forums.openpi...facing-with-cc/ )

Frame:

Aircraft

Log files of the flight:

logs


I reworked the OP Fixed Wing Guidance Experimental branch ( /origin/OP-165_CorvusCorax_Fixed-Wing-Guidance ) to support the "ReturnToBase" flight mode introduced with CC_Guidance.
This already allows a crude way of navigating to a remote waypoint (set via Telemetry) and back (by engaging ReturnToBase)

The waypoints distance was chosen at 500m distance to the home location, which is at the edge of visual range with this frame, as well as telemetry range and radio Tx range, but still doable somewhat safely in case something goes horribly horribly wrong.

Considering the amount of unique hardware put in this frame that was a lucky decision, as things indeed went wrong (but only after the plane was already back from its "first solo flight" and loitering over base). What I think was a sudden wind gust joined up with a GPS fluke and caused a somewhat exaggerated dive > (I am still reviewing logs to see exactly what happened first there).

But lesson learned: Better play it safe then sorry, and set up coefficients and limits a bit more conservative next time.  

I got myself one of these:

http://www.ic-board....-MX353-OEM.html


Its a system on a chip 532 MHz AMR11 with 256MB DDR2 RAM - running linux - the board is roghly the same size as CC and weights only 7 gram. Perfect any powerful on-board number high level computation tasks. (It could run the GCS if it wanted)

It interfaces with 4 50-pin Hirose connectors which unfortunately do not interface with anything we have directly, so it needs a breakout board, IC-board offers a variety of dev-boards which are nice for development, but too big and way too heavy for anything airborn. Also needs power supply and stuff in a way compatible with OP/CC

So I designed and built my own - interfaces with CC/OP-PRO via USB. (The mx353 has an inbuilt host controller)  and also features some serial uart's for its own IO, and an on-board micro-SD card for mass storage:

Schematics: http://cybertrench.c...b/mainboard.sch

I used as little SMD components as possible. The big through-components have the advantage of spanning significant board area which helps routing more on the front layer:
http://cybertrench.c...b/mainboard.brd


The guys at http://www.shackspace.de (a hacker space in Stuttgart) have an ink-jet printer capable of printing acid resistant ink directly on copper. I used that to print and edge this little baby

Soldering those 200 tiny pins was a PITA:

But it was worth it:


Since I had almost no things on the back, I skipped the back layer and used bridges/wires instead


And it works!!!!