Saturday, December 31, 2011

ArudpilotMega2 + Arcticopter III maiden

will type some more later, but I'm really pleased with how it went!

Didn't intend to take any pics (the hat portion of ye olde hatcam being misplaced), but things went so well I was able to fly one-handed and hold the iphone in the other hand.  Beautiful!!

From the air.  I hadn't planned on doing this either, but things were so smooth I taped the GoPro and sent it off.  Simple mode is going to be a Godsend for arial photography.

Spinning one-handedly.  This is cut from the first video, but it's so unique and impressive I wanted to hilight it by itself.

Using a DSO Nano oscilloscope to troubleshoot APM

An oscilloscope turned out to be a pretty handy debugging tool when trying to troubleshoot my APM2 ESC problem.  Here's a shakycam showing how I used mine to verify the problem was with the ESC and not with the APM2.

APM2 indoor maiden and simple mode test

I got everything together last night and couldn't wait until the morning to go out, so I took a quick flight in the basement.  Stability was pretty good.  I made a quick video of simple mode too.

Thursday, December 29, 2011

The Unbearable Lightness of Universal Serial Busses

 Here are the flavors of USB cables I've got.  From the lower right, going clockwise:
  • Apple iPhone
  • proprietary -- Casio Camera
  • Micro A (?)- Ardupilot Mega 2
  • Type B -- Arduino Uno
  • proprietary -- Panasonic Lumix camera
  • FTDI programmer -- Arduino [*]
  • mini-B lots and lots of stuff
  • update: AVR programmer

Fortunately, the computer end of these cables are all the same, classic Type A!

[*] The FTDI adaptor probably shouldn't count, since it connects to a Mini-B cable, but it's a serial thing I have around.  Of course if I mention the FTDI programmer I should also mention the AVR programmer for completeness.  It comes in two flavors as well; 10 pin and 6 pin.

Here's a diagram from Wikipedia, identifying the various types of USB connectors. Here's another good page from a cable vendor.

Here's the AVR Programmer from Hobby King.  They sell it for their KK Multicopter board.  It's nice an inexpensive, and comes with both a 10-pin and 6-pin cable.  I have one from ebay, and you have to jigger your own 10-pin to 6-pin conversion.

Update: now added a lightning connector for iphone 5.

Wednesday, December 28, 2011

DS1307 Real Time Clock

Here's some notes on a real time clock.  I'm not so much interested in knowing the time, but it uses I2C to communicate and I've been looking for something relatively simple to try I2C.

Quad EPS blade protection

The website is down now, but here's a quad with an eps blade guard.  The guard is sold separately as well.  It's four circular pieces with straight edged that attach together.

It would be great to be able to provision a homemade quad with something like this.

DSO Nano 2 Oscilloscope notes

Santa just arrived from a side trip to Hong Kong and dropped off my new oscilloscope.  It's pretty low-end, but I already used it to solve a problem with my new Ardupilot 2 board, so no complaint from me!

Here's some links for the thing:

Handy Glue Tip

 Here's something I did for my opened glue containers that have made them last longer and make less of a mess.

I have a box for all glues and adhesives... I put a piece of old foam in the bottom, and made a few holes and slots to hold opened containers with the opening down.
Here's a shot of the holes.  I think I made the round ones with a drill bit, and just hand-cut the slots to be more or less the right size.

Monday, December 26, 2011

xbee attempted unbricking and troubleshooting

xbee not working... contacted diydrones store, they recommended starting with unbricking procedure here.

Here's shakycam documentation of the procedure.  It's not working, so suspecting other xbee problem.


Sunday, December 25, 2011

CF Reinforcement for Skywalker Wings

Here's a few notes from the Skywalker thread on RCG about reinforcing the Skywalker wings.  Daemon is one of the masters there.

Basic Idea:

  • Cut four 36'' ribbons, two pieces for each wing
  • Cut into top and bottom of wing, one directly above the other.
  • Glue in edgewise.
  • Size: 0.8x6mm

Do the same to the vertical stabilizer.

Daemon describes it:
I use a long straight edge and X-acto blade to cut the slot using my finger on the side of the blade as a depth gauge (something you can't do with a soldering iron tip) and then expand the slot slightly with the tip of a screwdriver.  0.8x6mm ribbon spar installed edgewise into the wing on the bottom. Another one just like it on top.

Here's a flight with the reinforced wings:

ArduPilot Mega 2, Initial install notes

Initial install went well.
  • APM quick start here.
  • Need to install a Windows driver, here.
  • Mac seems to need no installation, using /dev/tty.usbmodem621
  • On mac, be sure and set "Carriage Return" line ending.

Saturday, December 24, 2011

H Gantry design

I was listening to the crashcast, and Crash was interviewing the phlatprinter guys.  They're working on a new device, which will use an "H Gantry" design.  It sounded pretty intriguing, so I googled it.  The basic idea is that two motors control a full x/y coordinate range, while not carrying the motors on the gantry.  This makes the gantry more stable, since it's not having to carry the extra weight.  In addition, the crossbar is supported on both ends.

Here's a commercial product that uses an H Gantry.  It's apparently a well-known technique and patents have expired.

And here's a frame showing the mechanism a bit more clearly.  If both motors turn at the same rate, motion is in the X axis.  If only one motor turns, motion is in the Y axis.  Turning both motors produces motion on both axes.

Friday, December 23, 2011

My Farm Fresh Quad Helmet

Here's how I attached a vegetable container from the supermarket to act as the cover for the Arcticopter 4.  I used these standoffs:

Nylon 6/6 Male-Female Standoff 4-40
1/2" Body Length,
3/16" Male and Female Thread Lengths,
White (Pack of 100)

Even though the vegetable container is very thin, the standoffs keep the surface taut.  If you tap on the top it will reverberate like a drum head.

I attached the standoffs to the frame, and colored the tops with a Sharpie to align the holes. I handheld a drill bit to cut the holes in the plastic.

 4/40 bolts attach the stack of standoffs to the frame.  This stack is 1.5 inches, but I think you could double that and still be reasonably stable.

One nice feature of the nylon threads is that they will break before anything else.  If you break the threads off of a standoff, it becomes a perfect candidate for being the top screw.
I put a piece of blue tape on the back to block off the green LED, which I found to be too bright in the evening.  I added a 3-LED strip plugged into the balance port which works pretty well: visible without being blinding.

Thursday, December 22, 2011

Some Spectrum Analysis and RF Resources from Agilent

arocholl reports:
Agilent is starting a webcast series of sessions about Spectrum Analysis and RF basics. It may be of interest of (most) RF Explorer users and RF enthusiast out there.
RF Back to Basics: Part 1 - Signal Analysis on Jan 25, 2012. 

For those of you who don't know, Agilent is the spinoff of HP for testing instruments and RF devices, a worldwide reference in RF for many decades. Besides that, they are the actual guys implementing the closest vision Bill and Dave had about their company when they created HP in the 30's, nothing close to main HP brand these days.
I recommend all the Agilent general guide I recommended to many people already. The link may get invalid anytime as it is internal to Agilent, but if it doesn't work just look for the famous "Application Note 150", the "5952-0292EN.pdf" document or simply "Spectrum Analysis Basics" within the Agilent site.

The Application Note 150 seems to be very well known.  I've downloaded it and started reading it. A lot of it's going over my head so far!

Monday, December 19, 2011

Ritewing Zephyr II + Ardupilot Maiden

Great success with Andreas' Zii/APM combination.  Flew beautifully, APM control was good, able to tune things in the air. All around a great success and left everyone feeling very pleased.  Andreas has named it Beast of Kandahar.

We flew with two batteries... 3S/5000, and then a 4S/3000.  The 3S seems to provide plenty of power -- enough to accelerate straight up. Andreas had also just upgraded the power system to:

    NTM Prop Drive 35-36A 1800
    Turnigy Trust 70A
    10x6 prop

Ground Video. This contains most of the flying modes, takeoffs, landings, and low passes.  I'll make a trimmed down version later if this one seems repetitive.

Airborne Video.

Thursday, December 15, 2011

The IOCCC Flight Simulator

"The IOCCC Flight Simulator was the winning entry in the 1998 International Obfuscated C Code Contest. It is a flight simulator in under 2 kilobytes of code, complete with relatively accurate 6-degree-of-freedom dynamics, loadable wireframe scenery, and a small instrument panel.

IOCCC Flight Simulator runs on Unix-like systems with X Windows. As per contest rules, it is in the public domain."

Here's the source code:

Sunday, December 11, 2011

Adding Failsafe to the Turnigy 9x transmitter with Autopilot

some quick notes:


The Turnigy 9x doesn't have a failsafe function when used with the 2.4ghz receiver.  Instead, when the radio signal is lost, the receiver "freezes" all channel signals to the last received value.


Add a heartbeat function.


Pick a channel, alternate between high and low PWM signals over some period.  As a concrete example, on channel 7 transmit a 1200 ms followed by an 1800 mhz signal, each for 1000 ms.

We can upgrade the Turnigy 9x to use er9x and add the code there.


In the arduino software, we can add a check in the 1 hz event loop.  Compare the current values with the previous values, and save the current values for the next check.  If after some number of comparisons we don't detect a change in any values, invoke the failsafe routine.


  • Is the timing fine-grained enough?  If not, we can increase the frequency of the checking rate.
  • Open source is wonderful.
Update: some discussion of this idea over at the 9x forums.

Saturday, December 10, 2011

Microdan motor for EZ* and related planes

From the EZ* thread on rcgroups, somebody pointed out the Microdan 2505 2535KV motor as a really good (light weight, high thrust) upgrade for EZ* and similar planes.  Apparently several of the EZ* gurus use this motor.  Definitely in the high end, both in terms of performance and price. I will pull out the numbers on the Grayson upgrade I did for comparison.

    weight: 34g, cost $55

    APC 5x5, 21175rpm, 10.9V, 22A, 22oz thrust.
    APC 6x4, 19900rpm, 10.7V, 25A, 25oz thrust.
    APC 7x4, 16300rpm, 10.2V, 36A, 36oz thrust.
    APC 7x5, 15200rpm, 10.1V, 40A, 36oz thrust.

Microdan has a video of it flying in a Hawk Sky:

Friday, December 9, 2011

The Birth of Arduino

Here's an article about how the Arduino was born, and why it's called Arduino.

Elevon Gyro Stabilization

Scott Page has an interesting post on rcgroups where he has mounted gyros on a superfly.

It seems like this couldn't be done without moving the elevon mixing onto the plane, since there's not a direct correlation between axial pitch and roll movement and the control surfaces.  The trick is to put two gyros mounted at 45 degrees relative to the front of the plane, and connect the gyros to the servos on the opposite side of the frame.

By doing this, both servos react to pitch and roll, and feed their corrections to the proper (opposite) elevon.

He put a video up with the results of his experiments.  He also talks about rate and AVCS (heading hold) modes and their use in fixed wing flight.  Executive summary: use rate.

Sunday, December 4, 2011

My SparkFun Signature Edition Solder Fan

 So after looking around for some fans for a solder fume extractor, I came across some old PCs being recycled. I took out one of the PC cooling fans and tried that... it worked so well that it would scoot across the table under its own power!  So, I opened up one of the power supplies and removed the fan... it seems like the perfect size for a benchtop solder fan.  I hotglued it onto a piece of cardboard I cut out of an old SparkFun box I had sitting around.  Instant class and DIY cred at no extra charge!
For power, I attached a JST-RCY connector so I could power i from one of the small LiPo batteries I keep on my bench.  The fan uses .5A, so the battery in the picture will keep the fan going for two hours without problem. I measured this with my watt meter.  If you are doing anything with RC or motors you should have one.

If I would have had a spare 3-pin or 4-pin JST-XH I would have used that, so that it could have been powered off of any battery's balance port.

Here it is in action, shot with genuine shakycam:

Friday, December 2, 2011

Troubleshooting my xbee

Here's the system I've got:

It's got an XtreamBee Board, an   XtreamBee USB Adapter, a matched pair of xbee modules, and all the bits needed to get things set up.

It was working before:

And now it's not working.

symptom: The blue power light comes on on both sides, but the Rx/Tx lights don't come one, and the ground station can't make a connection.

I went ahead and fixed the problem I had where the xbee was soldered inside the socket.  You can see one of the pins has a glob of solder on the side.  It was obvious which pin it would be, as the connection for the socket had a "sucked in" look instead of a "dimpled hershey kiss" look, from where the solder had been pulled into the socket.  Heating the socket leg from the bottom allowed the xbee to be pulled out nicely.

  This allowed me to get both xbee modules attached to the PC and get this information, which seems to verify that the two xbee units are functional (at least in talking to the PC), and that the xbee pro unit is likewise functional.

Likewise, both xbee modules respond to +++ and AT commands from a terminal session.

So, I'm reasonably confident that those three pieces are OK.  What to do next?  How to verify the xtremebee board?

I'm going to solder some new headers onto the xbee remote carrier, although testing the continuity with a multimeter showed that the pins were all making contact.

I can't find anybody that's a real xbee guru to advise me on this.  If I ever get these working again, I am going to really study these things until I understand them really well.  My xbee skillz will be my ticket to fame and fortune!

Thursday, December 1, 2011

er9x upgrade notes

Prompted by their KK quadcopter board, HobbyKing is now stocking an AVR programmer. It looks like this might be good for for upgrading their Turnigy 9x radio as well.

I'm going to gird my loins (such as they are) and give it a go.  I'll update later, but here's a few links on doing this. All of them are by Richard Mr├ízek, the Michaelangelo of er9x.
Cable Installation

    cable installation video.
    written instructions.
    photos of upgrade.

Software Installation

    er9x home page
    eePe, the er9x simulator.