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Successful reverse thrust landing in 28+ mph gusty wind

Posted by Tj Bordelon on October 9, 2010 at 7:50pm

Ever fly on days you know you shouldn't? Trees were swaying, and my gut was saying no. But I guess you never know until you try. I'd have to say that I couldn't fly in this wind. The ground track of the aircraft was so unintuitive, especially on landing. At times it was just hoovering overhead making minimal progress.

Days like this that really test your autopilot.

Anyway, this video shows my full auto-landing sequence, complete with the dive from 180 feet down to 50, and final flare with reverse thrust. The throttle you hear on landing is reverse, not forward thrust.

Entire flight is automated. Takeoff, flight to 3 waypionts, and finally landing. Enjoy :)
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First version of Yagcs (combined GCS and mission generator) released

Posted by Andre S on October 9, 2010 at 2:50pm



Hi guys,

I uploaded the current version of my QT-based GCS to google code. The sources are available via the SVN repository at https://code.google.com/p/yagcs/ .

Current features:
- Real-time map display (native interface, does not rely on google earth plugin, allows offline access)
- Real-time data plot for distance, altitude, etc.
- Simple presentation of roll and pitch via opengl
- Easily extendible (at least that was the goal) via QT ports/slots
- Should be relatively platform independent due to QT

Also, it now functions as a generator of mission header files which can be loaded via the APM waypoint writer. The GUI, however, is still a bit rough on the edges, meaning it's still lacking quite a few features.

The code only relies one two libraries in addition to QT (one for the data plotting, one for the serial port access), which are itself based on QT. That means you do not need google earth plugins, labview, etc., and all is based on open source. For installation instructions see INSTALL.txt and for more information README.txt.

Would be great to get feedback of course. Also, if somebody from the windows users would try to compile it and tell me if this works, that would be very interesting. Also thanks to the person who pointed me to qextserialport, don't quite remember who initially suggested that.

Cheers,
Andre
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3D Robotics

Proposed Open Source Hardware guidelines

Posted by Chris Anderson on October 8, 2010 at 7:14pm
I'm part of the process attempting to codify what "open source hardware" means and how to ensure the people who want to be part of the movement can make wise choices about licences, file formats and encouraging the best aspects of the open source:

Here's how the latest version of the definitions start:

"Open source hardware is hardware whose design is made publicly available so that anyone can study, modify, distribute, make and sell the design or hardware based on that design. The hardware's source, the design from which it is made, is available in the preferred format for making modifications to it. Ideally, open source hardware uses readily-available components and materials, standard processes, open infrastructure, unrestricted content, and open-source design tools to maximize the ability of individuals to make and use hardware. Open source hardware gives people the freedom to control their technology while sharing knowledge and encouraging commerce through the open exchange of designs."

You can read the whole thing here. What do you think? Are we on the right track?
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Ardupilot goes into the water Part 14

Posted by Harald Molle on October 8, 2010 at 3:30pm
What happened to the boat and the lake ?
Not really much, there seems to be a kind of stagnation in the air...
I tried the radio-control on the boat several times, but found out, that this is not the solution to the swimming recovery problem. Several reasons for that:


The first try ended up in wading through the mud and recovering the boat, that managed to get stuck in some roots on the shoreline. I tried to get the boat managed by RC, but the diameter of the turn was too big to get it right back to the point, where i have started.
Why that?
The turn diameters were OK, when running in AP-mode.
Seems, that the RC outputs servo pulses only for +- 45 degrees.
The AP can output pulses for up to +- 90 degrees.
To cope for that, i modified the rudder-horn steering to its largest extends so that there was more "angle".
With this modification, the AP still worked and the RC-control of the boat was also possible.

Second, the ESC i am using, can only drive the motor in one direction. So, when the boat gets stuck on the shoreline, there is now way to get the boat shifted into reverse.
The only way to rescue the boat is: still swimming.

Third, adding more technology onto the boat´s electronics makes it more prone to errors than before.

For that reasons (and for the thrill) i decided to dismantle all the RC stuff and turned back to the "old" configuration.

I kept the RC equipment to start some crash-flying experiments with an EASYSTAR, but this is another story...

Some days later, i went back to the lake to do some "long-leg" measurements, to see, how the control loop
behaves on a long trip. (a 400m straight line path and a 180° turn).


The first run was OK.
On the second one, the boat made some weird turns on the opposite end of the lake and crashed into the shoreline, mowing away some reed, until the propeller gets stopped by something hard.
Swimming...
Walking back on the shoreline with the boat in my arms, giving comments to the russian fisherman....

What happened?
It was a windy day and maybe the boat had trouble, moving against the wind, the speed went down and the GPS did not output valid direction data.
This must have been the reason!

I tried again some days later, when it was absolutely still air.
The first run was OK.
The second one...
see above.

This time, the propeller milled away some tupperware housing and the servo had shifted the windmill assembly into an extreme 90° position.
Post mortem analysis of the GPS and control loop outputs showed, that the AP behaved absolutely correct.

hmmm...
thinking...

Bingo!

The following picture shows, what happened:

The Rudder Horn steering was still at its extreme positions, that i had used for the RC experiments. And, in some situations (e.g. a full 180° turn) it could happen that the steering rod acted as a "piston" as we have in internal combustion engines. The assembly kept stuck in a 90°+ position.
So it was no wonder, that the boat made some weird turns.

Next, i reduced the angle of the steering and introduced a "push-pull" assembly with two steering rods.
That was it!

Absolutely perfect straight line behaviour. No stalls, no further swimming.
The world was perfect again...

Not absolutely perfect.

The mounting position of the sonar transducer was still something that should be enhanced. Too much drag, too much irritation.

So i mounted the transducer into the right hull.


I expected a faster boat after that modification, but the inrease of speed was neglegtible compared to the the "old" configuration. Anyway, the boat glides much smoother trough the water and there is no more chance for water plants to hook into the transducer.

In the next episode:

A new lake and new Dr Depth pictures....

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Moderator

QuadFox Stable mode test

Posted by Roberto Navoni on October 8, 2010 at 3:00pm

In this video is possible to see the incredible stability of DCM V3 developed by Jose Julio a member of Arducopter DEVTEAM.In this video I enjoyed playing with my QuadFox. Tell me your impressions. Iported this algorithm and the original code of Arducopter multipilot
hardware and controllers i2c hardware as well as original APM impressive
results in terms of stability in this video you can see how the
aircraft is stable and easily implementable with automatic flight control systems, GPS, magnetometer, sonar and so on.Congratulations to Jose and all members of the DevTeam. I am proud to help develop Arducopter project:) Thanks Chris for this opportunity and Jani:)

for more info check original post : http://www.virtualrobotix.com/profiles/blogs/quadfox-stable-mode-outdoor

Regards Roberto
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Current State of Commercial SUASs (& New(ish) FAA Fact Sheet)

Posted by Paul Marsh on October 7, 2010 at 8:29am

I did a little digging into the current state of affairs with regard to commercial small unmanned aircraft systems (SUASs) and I'm not really sure what it all means. On the one hand, there seem to be quite a few companies developing and/or manufacturing SUASs. Presumably, many of these are for private, commercial use as opposed to pure research, governmental or recreational activity. On the other hand, judging by what I'm reading from the FAA, the current state of allowable SUAS use does not come close to justifying this level of commercial development. What do these people know, and where are all the SUASs currently in existence being used?

I'm sure that anyone developing a hobby SUAS would love to allow it to fly outside of the range of manual control. Right now, the hobby community is pretty much restricted to the pure excitement of watching a plane fly on autopilot, but within the same airspace as a manually flown R/C plane. The point, and I know it's not new, is that as goes commercial SUAS regulation so goes (to some extent) recreational regulation (hopefully in a positive and/or more unrestrictive way). So, this is the tie-in relative to DIY Drones.

First of all, if you haven't read this FAA fact sheet, it's both interesting and encouraging, so you might want to (it's short).

http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=6287

For what it's worth, I think there might be some confusion on this site regarding COAs, or Certificates of Waiver or Authorization. These are only available to public entities, i.e. not private commercial ones, who want to fly SUASs in public airspace. As of September 2010, there are only 251 active COAs. By definition, none of these relate to private commercial SUAS use.

The only certification available to civil operators of SUASs is a Special Airworthiness Certificate in the Experimental Category. Since 2005, only 78 have been issued.

While the FAA seems to be very positive about SUAS development and use, it appears that, in reality, there just isn't much practical use of these systems going on in the private sector. Yet, a whole lot of companies and their investors must see something coming, and soon. Is all of this activity based on speculation, or are there current, practical uses of SUASs going on? If so, what are they? Personally, I would love to see an SUAS surveying a corn field as I drive by! I think it's going to be while, though.

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Moderator

QuadFox Stable mode test

Posted by Roberto Navoni on October 6, 2010 at 4:42pm

This evening i finish to implement the code QuadFox on multipilot this is the first flight test. This code is a porting of Arducopter on my Multipilot board . The different respect of original project is I2C ESC , Mixertable that support Quad , Hexa , Okto , 20 Mhz of clock cpu instead of 16 Mhz and 1 wire RC input compatible wit jeti radio and Robbe - Futaba receiver 2.4 ghz. Other advanced feature is Multi Processor architecture for sonar, gps, magnetometer and ir sensor.

Check the stable mode at minute 4.20 :)

Great Job Arducopter DevCore Team ;) Next Step i would test GPS Hold .... Jose your new revision of DCM v3 ... work fine .. great job Jose ...

Check my blog for more info about the project : www.virtualrobotix.com

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Folding Quad Rotor for Avalanche Rescue

Posted by Firefly on October 6, 2010 at 9:08am

I found this quad while browsing through the James Dyson Awards. There is a link above the pictures to translate to English.

I couldn't find much on the company but they seem to be planning for this to be part of a full UAV system that marks the location of Avalanche victims.

I like the simplicity of the design. This may inspire my next quad...

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The perfect anti-vibration foam

Posted by Earl on October 4, 2010 at 9:30pm

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I found the PERFECT foam for the gyros and mags for anti-vibration on the AreoCopter
You all have heard and seen the commercial for Tempurpedic mattress
where the girl jumps on one end and the glass of wine on the other end
that doesn't spill ?
Look them up on the internet and request a free sample. Perfect size and
it REALLY kills the vibration, especially on ArduCopter.
Put this stuff in the Professional housing box under and around the mega and you will be all set.
Earl

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Quad position hold with mouse sensor - some details

Posted by Marko Kleine Berkenbusch on October 4, 2010 at 6:00pm

Hi,
Some people asked for a few more details on the mouse sensor position hold I am experimenting with on my quad (originial post here), so here we go:
As I mentioned in the original post, the sensor is an ADNS 2610 made by Avago. This is a fairly ubiquitous sensors found in many cheap mice - the reason I chose this one is two-fold: there is good documentation available for it (e.g. the datasheet, or just google for it, there are plenty of people who hacked it), and it provides a mode in which the 'raw' 18x18 pixel image can be read out of it, significantly simplifying the setup of appropriate optics.
I ended up not finding a mouse with that particular sensor, so I ordered the raw sensor on Digikey instead. According to the datasheet, 3 caps and 1 oscillator are required in a minimal circuit - all of these are cheaply available at digikey.
Above is an image of my prototype circuit: on the right you see a lens with a screw-type lens barrel from a cheap (around $10 at Walmart, I think) keychain camera, in the center you can see a raw ADNS 2610 and on the right is the circuit itself. The lens I ended up using is not this exact one, but one from a different camera which looks very similar - either one would have worked.

On the second image you can see the sensor again (this time upright), as well as the bottom of the pcb (never mind the sloppy soldering). In the prototype, I basically hot-glued the lens barrel lined up to the bottom of the board and used the screw-mechanism to adjust the focal length (more on that below). My final design looks very similar, except that I used a single-piece perforated circuit board and drilled a 1/4" hole in the center for the sensor aperture - I did not include a picture because it is wrapped in a small, hot-glued foam box and mounted on the quad at the moment, and I am too lazy to take everything apart.

The image above shows the raw image data output of the mouse sensor with the optics adjusted. You can see my hand in front of a bright wall, making the hand itself appear dark. The distance sensor-hand is approximately 0.5 meters (give or take). The image is read out from the sensor via an Atmega which passes it on to a Perl/Tk script via serial. The serial protocol used by the ADNS 2610 is documented in the datasheet and fairly easy to emulate on a microcontroller. Since I knew that the keychain camera lens must have a focal length of a few millimeters, I basically determined the correct focal length by trial-and-error (I pointed it at a dark shelve on a bright wall and adjusted until it was clearly visible). Because the focal length is short compared to the object distance (~5mm versus something of the order of 1m), this setup does a reasonable job at focusing anything further away than 0.5-1m. On the actual quad, I do not look at the raw image data, but let the optical flow implementation on the mouse sensor to the hard work for me and just read x- and y- displacements.
I use the altitude data from the sonar range finder together with tilt information from the IMU to get an absolute position reference.

The mouse sensor rigged in this way appears to work quite well in daylight conditions outside, I have not tried to use it indoors yet (I would imagine one needs a reasonably well-lit environment). I did notice once that the quad seemed to get slightly confused by its own shadow in bright sunlight around noon, but I have not systematically tested this. You can see a screenshot of my GCS during a typical flight above. The window on the left just shows the attitude and other assorted information about the quad (the software is written in Perl/Tk - I mostly use Linux). The window on the right shows the ground-track in position-hold mode as detected by the quad. The blue bar indicates one meter, the trace starts in the center of the cross-hair. It did a reasonable job holding its position, it was a tad windy that day, I think. I am sure with some patience one could fine-tune the PID parameters to tighten the position-hold considerably.
Hope this was interesting,
Marko
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TriWiiCopter, a tricopter design using the Wii sensors

Posted by Simone Chiaretta on October 4, 2010 at 2:00pm
I just stumbled into this project of a super-cheap tri/quad copter build ripping apart the Wii controller (gyros) and the Nunchuck (accellerometers): TriWiiCopter
It is based on Arduino Mini. Quite a difference from most other copters that use dedicated sensors and super-powerful boards.



Tricopter 06 - TriWii NK test 1 from Joël Cordier on Vimeo.


Another interesting thing from this project is the frame. It looks all carbon fiber, very nice.

img_0397.jpg

Also look at this video showing how to tune the PID constants on the field, directly from the radio: this guy is a genius


Tricopter 05 - TriWii led & buzzer demo from Joël Cordier on Vimeo.

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3D Robotics

White House official highlights DIY Drones in innovation speech!

Posted by Chris Anderson on October 4, 2010 at 11:00am

O'Reilly Radar has a cool report on a speech at Maker Faire last week by White House Office of Science and Technology official Thomas Kalil.


Key sentence: "We are seeing the early beginnings of a powerful Maker innovation ecosystem. New products and services will allow individuals to not only Design it Yourself, but Make it Yourself and Sell it Yourself."


He highlighted DIY Drones as a good example of that: "For example, one community called DIYDrones has developed a $500 unmanned aerial vehicle using open source chip sets and gyroscopes."


The full speech is here.


(picture from Kalil's talk earlier this year at AUVSI)

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3D Robotics

FPV with DIY Tricopter

Posted by Chris Anderson on October 3, 2010 at 2:30pm

From Robot Dreams:


"The Shrediquette DLXm is an amazingly clean and efficent tricopter design weighing a scant 628 grams yet capable of carrying a payload of up to 550 grams in
sustained flights lasting as long as 18 minutes. It has a lift to weight
ratio of 2.87:1 and incorporates features that make it an absolute
pleasure to operate and experience (at least from the video since we
haven't had the opportunity to fly it in person, yet…).


The tricopter designer, W. Thielicke, is a PhD student and research assistant at the University of Applied Sciences, Bremen, Germany. He's generously posted the latest versions of
the project publically on his blog including the instructions and
manual, source code, PCB layout (Eagle format), configuration tool
(GUI), and PC -> PWM converters."

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