Droidworx, maker of excellent multicopter frames, is moving from Australia to Queenstown, New Zealand. From its website:

"Droidworx has moved it operation to New Zealand; we are now established here and have been focusing on some new manufacturing processes as well as working
on some current projects with Kimberly from Photohigher – firstly finalizing the 360 series of airframe mount combination, which are almost complete, and now
finalizing the cinema series airframes; the CS6 ad CS8. There is also a new offering for Droidworx, which is the revamped tilt only mount which Photohigher will
call (the AV100). Concept-X is also now in the final stages of industrial design and ready for tooling . We’ll be taking the time here to explore other possibilities
for droidworx to further increase the creative potential for the growing and dynamic multi-rotor industry.”

 

Interestingly, Helen Greiner, the co-founder of iRobot, also named her new quadcopter company Droid Works. But after some legal advice regarding use of trademarks from Lucas/Star Wars empire, she renamed it CyPhyWorks. The Lucas folks protect the word "Droid" pretty fiercely, and the mobile phone called the Droid in the US was approved only with a big payment to Lucas. I wonder if Droidworx will hear from Lucas eventually, too.

(via Multiroter News)

Kids, be careful out there. Full waypoint-capable UAVs are illegal to sell in the US without Export Control documentation and other safeguards.  Don't be this guy:

From Yahoo News: "ST. PETERSBURG, Fla (Reuters) – A Philippine man was arrested and charged with illegally selling an unmanned U.S. spy plane known as the Raven, the U.S. Attorney's Office in Tampa said on Monday.

A grand jury indicted Henson Chua, 47, of Manila on March 10 on charges that he sold the Raven to undercover federal agents on Ebay.

He faces up to 20 years in federal prison if convicted of smuggling and violating the Arms Export Control Act.

Chua was arrested when he came to Los Angeles in February.

The Raven is a four-pound plane equipped with three cameras that U.S. troops use for battlefield surveillance. It can be taken apart and carried by troops and then reassembled for use.

According to the U.S. Attorney's Office, agents with the Homeland Security Department found out last May that Chua was offering a Raven for sale on Ebay for $13,000.

They exchanged messages with Chua over several months, and he sent the Raven to them in separate packages in exchange for the money, officials said."

(via Gawker)

Here is video of first flights with the new lighter Hashcopter. PIDs make it a bit agressive and unstable because of reduced weight. Also you can see the massive camera flying with the copter.

Story goes like this:

I had a bad crash after few hours of flight time with Hashcopter. Crash was caused by flying the battery too empty and one off the ESCs cutting power off. The copter is capable of landing with 7 motors but I made a mistake flying to the direction of the broken motor to get it closer to pilot. This caused it to lean on the corner with no power and from that it couldn't recover, flipped and crashed from 20 meter height. Frame bent badly and one of the motors was never found. Fortunately most of the electronics survived from the crash. Lost only two motors and one ESC.

For some time had been thinking how I would change things if starting to build the frame from scratch. This was the perfect excuse to start all over again. So here are the changes made to totally the new frame:

- Used 10x10mm tubing with 1mm wall thickness. This saved 160g of the frame weight and frame is still strong enough for all practical purpose.

- None of the wiring anymore goes inside the tubing. These things are always being repaired and taken apart for some purpose. I don't want to do any extra soldering just because I need to get something detached from the frame.

- Made much lighter landing gear from 6mm aluminium tubing. Saved 60g from that.

- Built really simple Camera mount with no servos from 6mm tubing. I take only still images and usually the camera stays in one position or can be manually turned on ground.

Overall I got the whole copter over 400g lighter and that means minutes of more flight time. Overall flight weight after lightening is still 2700g. This includes 730g of camera and 530g of battery.

And here is a nice sunset shot from repaired copter:

Earlier parts of the story:

http://www.diydrones.com/profiles/blogs/arducopter-with-8-motors

http://www.diydrones.com/profiles/blogs/weight-testing-of-8-motor

http://www.diydrones.com/profiles/blogs/arducopter-quad-with-eight

Detecting the period was hard.  Fast fourier transform needed much more cycles than our flight time.

The best result was by testing all the possible periods on the last 1024 samples.  Take the period which has the most similar repetitions.  Get the maximum signal in the last period.  Get the time of the maximum signal relative to the time of the current sample.  The problem was when the most similar repetition was actually a region of 2 periods.


Next, it was an IR LED on the ground & the IR receiver from our 5 year old Picco Z in the air.  That would not detect ambient IR.  The problem was the receiver is digital.  It would detect reflected IR from random surfaces & output the same level as the incident signal.

Finally came the poor lion's machine vision.  Have an IR emitter on the copter & an analog IR receiver on the ground.  That didn't detect enough of a difference from the abient IR.  It would take some massive circuitry to get an analog IR receiver at 38khz.

All roads led back to the magnetometer.

HOW MAGNETOMETERS WORK

The Micromag 3 has a 600uH inductor, biased by 2 47 ohm resistors.  It measures the amount of time required for the inductor voltage to cross a certain threshold after alternating the 2 bias voltages.  The inductance changes, depending on the amount of magnetic flux.  It uses a standard microcontroller, not a custom ASIC.

The 1st thing you notice is normal inductors don't work.  You need a core which is a lot more sensitive to ambient flux.  The inductors in magnetometers use a thin film permalloy.

The 2nd thing you notice is the inductor saturates very easily, from a NdFeB magnet.  Readings make sense until the magnet gets too close.  Then it reports no flux, as its core is saturated.

The final trick is the reference voltage for the comparator is very important.  Ours had to be exactly 1.0V.  1.1V or 0.9V didn't show any response to ambient flux.  The inductor voltage only got to 1.4V & there was an optimum point in the waveform to detect flux variations.

To keep the inductor from becoming permanently gaussed, they use 2 comparators & alternate the polarity.  Since we're just interested in a binary result, we use 1 comparator.  It puts out a really faint signal.  Micromag 3 stacks hundreds of readings to get more sensitivity.

The CPU on Marcy 2 actually has 2 voltage references, allowing us to test the battery against a fixed voltage & test the mag against a ratiometric voltage, but even then, the ratiometric voltage needs tweeking for every flight.

This would all be easier with a hall effect sensor & an instrumentation amplifier, luxuries beyond our useful payload.



Got a standard azimuth waveform on a flight without any cyclic control.  Not as strong as the original Micromag 3, but think about the parts count.



As soon as cyclic was enabled, things fell apart.  1st of all, there's a lot of offset from having the motors & electronics in such a small space.

Secondly, the pulses from the tail rotor disturb the attitude enough to throw off the magnetometer waveform.  You get 1 pulse, then the tail rotor goes crazy for a while.  With such rapid attitude changes, zero crossings are no longer enough.  Time for derivatives.



That was a complete 150 second flight.  The derivative got us back to a centered waveform with clear 0 crossings.  That nailed the azimuth every time.  For the 1st time, we finally had enough cyclic control to hover something in the apartment, which introduced another problem.





The oscillation from Marcy 1 came back.  Pulsing the tail rotor started the same oscillation & the tail rotor wasn't fast enough to stomp it out.  Pulsing any spinning airframe just makes it swing like a pendulum.

Finally caved in & added weight.  The vertical flap actually did improve matters slightly, but now the tail rotor's slow response showed.  The blades on this copter have already run their course.

Set the tail rotor to always be on, which should have reduced the spinup time, but mainly decreased the difference between on & off.  It definitely appears as if some filtering is interfering with the tail rotor commands.  The main problem is the oscillation.  The functioning tail rotor, flybar, counter rotation & vertical flap didn't add any more control than the bare Marcy 1.

UAS are over 150 years old!

Saw this siteand this one, made me wonder why it took 150 years for the public and Govts (and me) to "discover" their existence.

During the Civil War, the Federal Govt used unmanned incendiary balloons programmed to land after a 30 mile flight to set Confederate areas on fire.

Started looking up more and discovered that unmanned airplanes with primitive autonomous systems were used in WWI and FPV was used in WWII. During the 30s the US military was converting off the shelf "model airplanes" with (primitive) RC for a variety of applications from flying bombs to target drones. Amazing stuff.

Nothing new under the Sun.

We should be proud to be carrying on a tradition older than manned airplanes!

for those in the bay area:

It is only a design exercise with a wingspan of 1640mm, and a lot of space for electronics and batteries and very easy access to electronics. Last image shows 6 x 5000mAh/3S.

I just came across this Wired.com article and it made me wonder if there are any projects out there in the DIY community that have a radio/audio broadcast or recording theme?
http://www.wired.com/dangerroom/2011/03/secret-libya-psyops/

Although the article focuses on people who scan radio frequencies my thoughts jumped to a having the actual vehicle broadcast music or some message over a radio frequency (think pirate radio a la Pump Up the Volume except mobile and less powerful).  I'm not sure of the distance but I was kind of thinking of a modified iPod FM transmitter that is used to broadcast your iPod music through your car speakers.

I'm also actually interested in knowing if it's technically possible (and financially possible from a DIY'ers budget) to record audio on the ground from the flying/hovering uav? Tons of challenges e.g. size/weight of antenna and microphone, noise from the vehicle itself etc...

Anyway, interesting article that immediately made me think of both 'Pump Up the Volume' and Coppola's 'The Conversion' and if anyone has thoughts or comments regarding the broadcast or recording of audio via UAV systems please comment. It's an angle I hadn't really thought about until I read this article.

- Stan

PS I can't think of any practical reason to have a flying pirate radio but the ability to do it still seems cool for some reason.

Another great demo from the ETH team, proving that if you have a Vicon motion capture system you can do anything! From Robots.net

" The video is made by the Control of Distributed, Autonomous Systems lab of professor at the Swiss Federal Institute of Technology in Zurich (ETHZ), Raffaello D'Andrea. It is shot inside the Flying Machine Arena, a facility that provides a control environment for motion control research. The two quadcopters are based on the 'Hummingbird' quadrotor made by Ascending Technologies with new controls and custom made electronics fabricated by the institute. A vital component is a state of the art Vicon motion capture system that provides the localization data to the robots and makes extremely precise and dynamic control possible. You can learn more about the labs other projects here."

Finally got my 'Tronics from the store

Up to the assembly work !

The boring work completed after a couple of minutes:

Soldering the magnetometer:

Had to solder the GPS to the header because the store didn't have the GPS cable

GND to GND, 5v to VCC,

TX on the APM to GPS IN

RX on the APM to GPS OUT

connecting...

that makes a nice sandwich !

and...

checking the reading....

SUCCESS !

Only the GPS is not outputting data...

I've checked in the terminal sending "S" during flight mode, but all the numbers in the end are 0.0000

the led on the GPS is constantly on after certain time... dont know what this means.

maybe it doesn't get enough satellites from my window ?

Starting an APM build from scratch, everything seems to be working fine on a Mac running VMware.  Some notes here:

http://eastbay-rc.blogspot.com/2011/03/ardupilot-mega-with-ardupirate-ng.html

http://eastbay-rc.blogspot.com/2011/03/hooray-ardupilot-mega-20-beta-works.html

http://eastbay-rc.blogspot.com/2011/03/hooray-ardupilot-mega-hooked-up-via.html

As you all know, the Tunigy 9X is very hackable and there are all sorts of open source firmware versions out there (such as RadioClone or ER9X). But it all starts with a little hardware hacking so you can get to the onboard ATmega chip in the first place. This guy has gone all the way and added a better power supply, an easy programming port and even soft buttons (see above)!

Here it is running the ER9X firmware:

Hello people, this is my new arducopter, is my first time with quads and i wish you all like it...

I hope it flies tomorrow for the first time, then i will post a video!!!!

other pics....

yes...... my frame is all balsa wood.........  :-)

Maybe someone has encountered a small scale parachute ?

I'd like to add a safety parachute to the Arducopter !! help me decide....

As part of the project is to use an expensive DSLR on the copter,

My GF said i must have some kind of emergency parachute... after joking at it, i thought deeper -

I'd rather feel much safer having a parachute as backup to all electronics (even though i plan on 6 or 8 motors)

Just imagine an emergency button that will immediately turn off all motors and shoot a parachute.

questions:

as parachute takes some time to open (=some free fall height), the benefits are sure and obvious for a 100m fall.

but if i'm around 5m above ground, (which can still be nasty to the DSLR) - would i have enough "falling time" to open the parachute and having enough braking force ?

think i better make one by myself ? is it rather simple as cutting and connecting wires to a cloth,

or it is more complex design that i could hardly achieve and i better get a ready one ?

i came across this as the only parachute i could find:

http://cgi.ebay.com/NEW-40-SPEED-RUNNING-POWER-CHUTE-training-parachute-/220760637799?pt=LH_DefaultDomain_0&hash=item33665c0167

It looks sturdy and well balanced & stuff... it's totally affordable !

they say the 40" version has 7KG resistance. i'm safe on this side, i dont want a much bigger one.

how about the opening technique ?

i could stuff it in a small plastic tube attached to the top of the dome, using a small solenoid or servo to kick it out...

how do i ensure it opens reliably ? i guess it depends on the folding inside the storage tube...

Following my previous post, I've also tried a new frame design, with my original round tubes cut in half and attached together with 2 MikroKopter.de carbon fibre central plates.

I wonder if these central plates have a vibration reduction role too, beyond just making it easier to mount.

Here is my initial design :

You can see the 2 extra graphs and the results / conclusion at the end of the original blog.

Now I'm really wondering if the ROUND tubes are more "vibration prone" than the "standard" square ones that almost everybody seems to be using ???

Also, what if, the vibrations I'm seeing, while quite important, are normal and people manage to fly their quads in spite of them !? I'm thinking maybe my ESCs (which are really the cheapest I could find on giantcod.co.uk) have a too low update frequency ?

As you can see, any feedback / idea would be welcome.

I've gone far beyond my expectations in testing/re-building the quad, without flying it for even 1 minute... which as you can imagine is quite frustrating ! :)

thanks,

dan

My quad (recently renamed to the "flying duckling") had a bit of a mishap today

the angle on that left motor and the shape of the prop isn't just an optical illusion unfortunately! Luckily I had already ordered some spares from jdrones, so I should be flying again tomorrow.

The crash happened when I was successfully flying in LOITER mode for the first time. The quad was holding nicely at about 20m, with just a little bit of wind drift, when one motor suddenly stopped. Unfortunately I didn't have my ground station running at the time, so I have no clue as to why it stopped. I certainly can confirm that a quad flies very badly on 3 motors - it tumbled to the ground and hit pretty hard. I think I was lucky it was on grass, and I only lost one arm and a prop.

It has been a week of unfortunately accidents for the CanberraUAV team. Last Sunday we were flying our UAV plane on autopilot for the first time, when we had a bad crash:

That bit of grey stuff on the right is the edge of the engine sticking out of the ground. It buried itself quite deep when it hit at nearly 30 m/s. Luckily we did have mavlink logging on for this one, and after looking at it for a bit we were able to determine that we'd screwed up the dip switch settings. We had the plane in elevon mode, which doesn't work well if you don't in fact have elevons!

We're trying again tomorrow with a cheaper foam plane, just to get some more experience with APM on a disposable plane. We'll move up to the more expensive planes again once we really know what we're doing.

Meanwhile, I'll put another arm on my copter, and make sure I turn on logging before my next flight, so I have some hope of working out why an engine stops (if it happens again). My best guess is that one of the connectors to an ESC may have become disconnected due to vibration, but thats just a guess. I'll also try running it on my bench for a while, in the hope that the problem may happen when its tied down.

More toys

Meanwhile, a new toy arrived from ebay. I bought a laser tachometer for the princely sum of $6.99 (plus $6.95 in postage). I used it to test the speed of the props on my quadcopter. Very handy! I just put little reflective stickers (which come with the tachometer) on the props and the tachometer quite happily locked onto them. You can see them in the above photo.

Came across this from an FAA pilot exam training program:

"Question: May a recreational pilot act as pilot in command of an aircraft in furtherance of a business?
 
 ANSWER: No, it is not allowed.
Recreational pilots may not act as pilot in command of an aircraft that is used in furtherance of a business. There is no exception." (Bolding mine, DB)"

Note the phrase "furtherance of a business", that includes a plethora of things such as advertising, product demonstrations and even product placement or use in a movie or TV show.

While this is referring to private vs commercial manned aircraft, this could be applied (via precedent) to differentiate commercial vs recreational as it pertains to (s)UAS uses, pilots and vehicles.

Marcy 1 actuator notes

So we tried making the actuator pull the flap instead of push it.  This made gravity the restoring force instead of air.  Maybe it wouldn't need as much power & could stay on full time.  FUGGEDABOUTIT.  It needed just as much power & quickly overheated.  Your best option is a pushing actuator.



Things went better with Marcy 2.  Payload test showed she probably could lift the Marcy 2 electronics package.  Now the IR protocol.






Inactive high.
960 bits/sec
start bit is 1/270 seconds low, followed by 1/1000 high
each bit is 1/960 seconds, beginning with a fall
1 bit is low for 1/2400 seconds
0 bit is low for 1/1200 seconds
1/40 seconds high between packets


From Darkstar2000's work on the obsolete 6020, we have the protocol:

http://www.rcgroups.com/forums/showthread.php?t=1231421&highlight=s107+protocol&page=2

8 bits: throttle 0 - 127
4 bits: yaw 0 - 15
4 bits: pitch 0 - 15
1 bit: left yaw if 1
1 bit: nose up if 1
1 bit: yaw trim left if 1
5 bits: yaw trim
2 bits: 11 for channel A
6 bits: chksum (sum of 1st 3 bytes + 0xf) & 0x3f
1 bit: 1


It transmits packets more frequently during a change.  Fortunately, Darkstar2000 also reverse engineered the S107, so changing protocols won't be a complete disaster.  Exactly why he did all this work is a mystery.







Next comes a new Marcy 2 board for azimuth sensing & sonar on only 3.7V.  It's pretty aggressively weight minimized.
















Converting it to 900mhz was a no brainer.  Mounting the board for flight was a nightmare.  Servo connector or soldering?  Enough power in the flight battery to test the board?  Can you justify the weight of a servo connector or an aux power source + diode?  2 pin + permanently soldered data connection or 3 pin connector?  Eventually, it came to a 3 pin servo connector.














Our 1st flight test of a photodiode as azimuth sensor, indeed the world's 1st flight, was disappointing.  The signal had so many peaks, it would take herculean processing to convert it to a period & phase.  It would have to be flown with a single light source, at night.

So today I finished building my first quadricopter based on APM+Oilpan and running ArduPiratesNG. I did some preliminary tests inside with no intention of flying the thing in my kitchen but just to get a feel of how it behaves up to the moment it actually would take off.

I noticed a couple of things:

• Motors don't start to spin all at once. I saw a couple of posts here discussing that and everyone seem to agree it's normal.
• Motors make strange noises (can be heard in the video)
• The quad only begins to feel light on the ground at 75% throttle. I'm using 10x4.7 props, maybe they are too small for the quad's weight, which I can only say is heavy because I don't have a scale :P

This is my first quad and I have no background flying RC Helis (beside crashing one on first flight and giving up on it a couple of years ago) so with the money and time invested in this quad I'm kind of afraid to fly it for the first time :P

Following my previous unsuccessful attempts at building a quadcopter (I have serious issues with the balancing and stability) I've decided that it's likely all this is due to VIBRATIONS and it was time to get into the nitty-gritty of some measurements...

While they are obviously far from complete or scientific, they do show how complex the "vibrations problem" is...

You can find the graphs on my blog (http://trandi.wordpress.com) and do let me know if :

- you would like some more details / numbers

- you have any other suggestions about how to reduce them

thanks,

dan