Blogs

Hi everyone !!

Here is my Y6 (90 degree branch) !!! can fly in the wind with default parameters !!!

I can put photos of build details ! Thanks

flight in paris at 2 PM, cité universitaire.

Although I have been here for years, this is my first blog post and I would like to present yet another attitude estimator which I have been working in my M.Sc. Thesis. A friend of mine and me have developed an autopilot, but this is for another post. However you can find details about it in the thesis at the end of the post. For our tests we are using a Mentor from Multiplex, shown in the next figure.

The AHRS is based on an Unscented Kalman Filter, which has better performance than the classical Extended Kalman Filter for non-linear systems, such as the kinematic equation for attitude.
This algorithm is based on three axis magnetometers, three axis accelerometers and three axis gyroscopes, so it can estimates the yaw angle at low/none velocity without the GPS aid. As other filters, it uses the accelerometers and magnetometers to estimate and neutralize the biases of the gyroscopes, which estimate the attitude angles in quaternion form. The difference with other algorithms is that the measurements from the accelerometers and/or magnetometers are not put directly in the filter, but they are indirectly put through an algorithm called Fast Optimal Attitude Matrix (FOAM) as it is shown in the next figure (sorry for the Spanish).

FOAM builds the Direct Cosine Matrix (DCM) from the accelerometers and magnetometers readings allowing to weight the sensors, thus in critical stages such as take-off or "aerobatics", we can rely more in magnetometers readings than in accelerometers for correcting the gyroscope's integration in an autonomous way.

I have validated the algorithm using GPS readings for the yaw angle, despite the cross-wing during a turn (10-20secs, the wind speed was around 15m/s this day as you can guess from the video) the yaw and heading angle are closer. The roll angle was validated with a camera on board in the same experiment. The details of the vision algorithm, shown in the video, can be found in the thesis. In simulation (using X-Plane or mathematical model in Simulink), comparing with true values, the error is less than 1º in pitch and roll and 4º in yaw once the filter has converged.

Mentor allows me for automatic taking-off with a robust landing gear. It is nice to see how the AHRS works very well in presence of many vibrations during this stage. Look at the next figures how the trust in accelometers (red line) downs during the take-off moment and rises again when the flight is going to steady, not disturbing the pitch correction in any moment. As well, the algorithm converges very fast to true values (6º of pitch at the moment of take-off).

You can download the master thesis (in Spanish), detailing the algorithm and the hardware/software here: http://dl.dropbox.com/u/2689187/tesina_Hector.pdf

The next article is a resume (in English) of the related algorithm using TRIAD (a simplified version of FOAM). It will be published in the special issue about Kalman Filter Issues in Transactions on Industrial Electronics Journal within next two months, so if you want to cite it, you have to search it there: http://dl.dropbox.com/u/2689187/article_TIE.pdf

Here is a nice resume of several algorithms to estimate the DCM, it includes TRIAD and FOAM among other ones:

http://dl.dropbox.com/u/2689187/dcm_estimation.pdf

If you have questions, fell free to ask :P

http://www.eodevices.com/main_erc_2kit_frameset.htm

Electro-Optical devices sells kits and spare parts to build a real, far-ranged LIDAR ranger, such as: nanosecond timer, transmitter module (high voltage laser power supply included on-board), receiver module (APD photodiode, PIN photodiode), controller, laser diodes (power 10W - 75W).

The price of the cheapest kit ERC2-KIT is $ 429 , but you can get even cheaper if you buy just the modules and assemble it yourself.

The boards are really small and are thus ideally suited to fit an UAV plane which includes a rotating mirror system and a capable memory onboard.  

Maybe there are some restricting laws about the power of the laser? Anyone knows?

UAV Optimsed for Photogrammetry Acquisition

After XAircraft successfully launched new four axis aircraft X450 and X650 last year, its new generation aerocraft will be released on 15th July. This new type quadcopter has been named officially: X650 Value (Best Value Version) and X450 Pro (Enhanced Version). X650 Value has two versions: 4 propeller(X4 model) and 8 propeller(X8 model). And plus “-4″ and “-8″ in front of the name for distinction, for example, X650 Value-4 is 4 propeller, X650 Value-8 is 8 propeller, X650V4 and X650V8 for short.

This new generation XAircraft X650V4/8 and X450 Pro will be over-emphasized on aerial photography, which has more stable and positive fly performance, and can stay in the sky for longer time, with its stronger load capability and distinctive external appearance. We believe it will definitely become your indispensable aerial photography sharp weapon that let you fondle admiringly. In the meantime, XAircraft will continue to manufacture parts for old X650 and X450, and also provide the upgrade kit, in which you can upgrade the old version to the new one, save the cost of upgrading in maximum limit.

For X450 Pro
It is positioned for entry level player which has a higher drop number fuselage, provided simple aerial photography function and a simple GOPRO mounting plate(Simple Camera Mount). Besides, it has the same flight control system and power driven system as X650(brushless motor and ESC). 10 inches propeller and brushless motor is a specially made structure, used for lowering the center of gravity.

For X650V4
Cheaper than old X650, it has adopted a new designed fuselage with more cool external appearance and practicability, can be quickly folded. The fuselage cover can also be quickly removed and installed. The fuselage of and X650V4 and X650V8 are made of carbon fiber material, the Mounting Plate, Motor Mount, Landing Gear are made by high strength plastic. The camera mount and battery can be slide on the crossbeamis which means you can adjust the center of gravity easily according to the weight of photographing device attached.

For X650V8
It has adopted the same fuselage, flight control, brushless motor, ESC and propeller as X650V4. That is, X650V8 has all the outstanding characteristic of X650V4, the only difference is X650V8 has 8 brushless motor, thus can provide stronger load capacity. X650 V4 user only need to order other 4 brushless motor, 4 ESC and 4 propeller, to upgrade X650 V to X650 V8 immediately! Of course, if you want, Value-8 can also be degraded to Value-4, in this way, it can help save more electricity, get more flight time.

X650 Value series are all using the “x” shape flight style, cannot use the “+” shape flight style (however the flight control in itself support).

In addition, the development of XAircraft’s biaxial camera mount has finally come true; its photography effect stands in the first-class level in the small aircraft. This biaxial camera mount has two models, CMGOPRO-TP (two axle control including 2 servos) and CM130C-TPS (two axle control including 3 servos). The CMGOPRO-TP is specially designed for GOPRO camera, with lighter weight, fit for GOPRO camera user. The CM130C-TPS is mainly designed for the card camera and the EVIL(Electronic Viewfinder Interchangable Lens), but at the same time it can also install the GOPRO camera, has a extra steering engine to controll the shutter, can also be used on the old version X650C and X650G, but can’t be used on X450 and X450 Pro.

Note: The transmitter,receiver and battery are NOT INCLUDED, you need to prepare a 6-chn(at least) transmitter and receiver, 11.1V or 14.8V/15C/2200mAh polymer lithium battery pack and assemble X650 youself.

The GPS, compass, biaxial camera mount are optional accessories, customers can select according to their own requirement. There are OSD, light and power supply for option in the future.

X450 Pro Standard Configuration(Price:$399)：
- 1x X450 Pro Fuselage
- 1x GOPRO Mounting Plate
- 4x new type External Rotation Brusless Motor
- 4x 10A Brushless ESC
- 2x 10 inch Clockwise Propeller
- 2x 10 inch Counter-Clockwise Propeller
- 1x XAircraft FC1212-S Flight Control Unit
- 1x XAircraft AHRS-S Attitude Sensor
- 1x XAircraft USB-Link PC Linker
- 1x XAircraft Flight Control Management(Parameter Adjustment) Software
X650V4 Standard Configuration(Price:$620)：
- 1x X650V4 Fuselage(Landing Gear，Carbon Fiber, Plastic)
- 1x X650V4 High Strength Fuselage Cover
- 4x new type External Rotation Brusless Motor
- 4x 10A Brushless ESC
- 2x 10 inch Clockwise Propeller
- 2x 10 inch Counter-Clockwise Propeller
- 1x XAircraft FC1212-S Flight Control Unit
- 1x XAircraft AHRS-S Attitude Sensor
- 1x XAircraft USB-Link PC Linker
- 1x XAircraft Flight Control Management(Parameter Adjustment) Software
X650 Value-8 Standard Equipment(Price:$720):
- 1x X650V8 Fuselage(Landing Gear，Carbon Fiber, Plastic)
- 1x X650V8 High Strength Fuselage Cover
- 8x New Type External Rotation Brusless Motor
- 8x 10A Brushless ESC
- 4x 10 inch Clockwise Propeller
- 4x 10 inch Counter-Clockwise Propeller
- 1x XAircraft FC1212-S flight Control unit
- 1x XAircraft AHRS-S Attitude Sensor
- 1x XAircraft USB-Link PC Linker
- 1x XAircraft Flight Control Management(Parameter Adjustment) Software
Optional Accessories：
- XAircraft GPS+Compass(Price:$247)
- CMGOPRO-TP or CM130C-TPS Biaxial Camera Mount(Price:$250)
- Uniaxial Camera Mount(Price:$79)
Additional accessories needed for flight：
- At least 4 channel remote controller(suggest above 6 channel)
- Above 11.1V or 14.8V/15C/2200mAh polymer lithium battery pack
- Lithium battery charger

The full story is here  By R Colin Johnson, EE Times -- EDN, July 13, 2011

http://www.microsoft.com/robotics/

The best part here is:

"Last year Microsoft acquired the fabless chip maker, Canesta Inc (Sunnyvale, Calif) which makes a chip-level pattern recognition engine. Canesta's engine is said to outperform the PrimeSensor which Microsoft is currently licensing from PrimeSense Ltd. (Tel-Aviv, Israel) for its Kinect. 

When Microsoft commercializes the Canesta-invented chip-level work-alike of the PrimeSensor, it will be able to downsize the foot-long Kinect to about a square centimeter, enabling tiny robots and other mobile devices, such as the Windows Phone, to perform sophisticated gesture recognition for natural user interfaces, autonomous navigation and many other tasks."

Thanks Microsoft :)

https://www.youtube.com/watch?v=FOChBNAuHE4    : Video of our first flight.

Today we finalized construction of our primary prototype model of our concept aircraft. Using depron to construct the plane was a challenge; our "teardrop"-shaped fuselage is not easily constructed out of depron. To achieve this shape, we combined many geometric shapes that, once sanded down, would resemble a raindrop.

After finishing the fuselage, we added control surfaces to our aircraft. We simply cut out rectangles at the rear of the plane that would act as elevons. We mounted the battery for the plane at the front end of it in a case that gave it extra room to move. We purposefully did this so that just before flight, we could adjust it so that the Center of Gravity would be in the exact middle of the plane (not favoring one side of the plane). We were excited and nervous to test the plane, especially because of the added complexity of the elevons.

Our first test flight was great! Our plane managed to have a smooth, launched takeoff. It was able to pitch and roll effectively and had great maneuverability. When it was time to land the plane, all throttle was pulled back when the aircraft was at about 20 feet. It glided with elegance to the ground and had a smooth landing. Unfortunately, the model was damaged on a later test when it came in contact with a tree when we were testing turning radius (purely our mistake).

Future plans for the week include making a better model of the plane which we will attach the ArduPilot Mega to. We cant wait to see it fly itself and are optimistic about the design of our plane. 

Hello all.

I've been a long time lurker on this website, checking it almost daily. The last couple of months i was working on my bachelors project which consisted of designing from scratch an autopilot for a RC glider. During that time, this website proved to be invaluable and i would like to share my work hoping that, in return, it could help someone else.

The project was separated in two parts: a semester project which then continued as a bachelors project.

During the semester project, all the hardware was deigned, as well as the low level embedded programming.

During the bachelors project, an initial model of the aircraft was created in Simulink using XFLR5 and AVL.

Then using experimental data logs, I was able to determine simple transfer functions which were used to compute the different PID gains.

In parallel, I programmed a ground control station (Mission Control) which was greatly inspired from happykillmore's GSC (as you can probably notice).

The aircraft i used for the project was the AXN Floater from hobbyking. Here's a picture of the aircraft with the autopilot mounted:

For the final test flight, a small circuit was entered using the mission control application. The aircraft managed to complete two circuits before the battery ran out (it was the 8th test using the same battery). The two plots show the track the aircraft flew, and the pitch and roll closed loop angles:

For more details, you can download both reports here:

http://dl.dropbox.com/u/15692375/AXC-Glider%20Semester.pdf (Semester report)

http://dl.dropbox.com/u/15692375/AXCG%20Bachelor%20Report%20Public.pdf (Bachelor report)

If you guys have any questions / comments, or want more details feel free to ask :).

- Alex

A new Brookings Institute report with some worrying recommendations. The authors, who would put "Open Source" in a locked box, probably don't even know this stuff is so easily acquired from many different sources.  Please visit the link and give input. 

Arc Globe.

xyz Point cloud DEM

6 cm GSD Orthorectified imagery.

Do you have an APM1280 board? Are you worried that you won't be able to use it with the latest bleeding edge APM code? Read on for some tips on how to get some life from that old board.

The current generation APM board is based on the APM2560, which has 256k of flash instead of the 128k of flash of the APM1280. As has been discussed before, the rate of code development is such that we are rapidly getting to the stage that if you build with all the latest features enabled you won't fit all the code onto an older APM1280 board. Don't despair though, you can keep using a APM1280 for quite some time!

The first thing to know is that the dev team is working hard on keeping the code size small. In fact, over the last few weeks through some optimisation and code refactoring the total code size of the latest development APM code has shrunk, so it now fits on a APM1280 again with all features enabled.

Development will continue though, and new features are being added at a rapid rate, so it won't be long before the default image grows beyond the 128k boundary again. When that happens you have a few choices for your 1280 board.

Optimise your build for your needs

The key to staying on the bleeding edge with your APM1280 is to optimise the build for your needs. The default options of the APM build are designed to work for as many people as possible out of the box. This means that lots of code is enabled that you won't need on your plane/copter. If you open up the arduino environment and build the image yourself then its easy to disable a few features that you don't need and free up plenty of flash for future development.

To customise your image, just edit your APM_Config.h and add a few lines. Here are some space saving examples:

#define GPS_PROTOCOL GPS_PROTOCOL_MTK16

Choosing a specific GPS module instead of the default GPS_PROTOCOL_AUTO will save you about 4k of flash. You probably only have one type of GPS anyway!

#define LOGGING_ENABLED DISABLED

Disabling on-board logging saves more than 10k of flash. Personally I prefer to log my flights to a ground station over MAVLink, so if you are like me and don't need the on-board logging then you can save plenty of flash space.

#define CLI_ENABLED DISABLED

Disabling the command line interface will save you over 17k of flash. Up till recently it wasn't possible to setup an APM properly without having the command line interface, as you needed it to setup your flight modes and your radio ranges. Thanks to some great work on the APM Mission Planner by Michael Oborne you can now do the complete setup from the planner. That is still a very new feature, so you may find some rough edges, but you can be sure that the dev team are working on making that easier.

There are other examples of how to shrink your build, just take a look in config.h and look for things that are marked as ENABLED by default. If you don't need it then disable it and watch the image shrink.

If you disabled all 3 examples above then you would save over 32k of flash. That's a lot of room for more features, and should keep your APM1280 flying on the bleeding edge for a long time to come.

Using an APM1280 as a HIL simulation board

What if you've decided to get an APM2560 anyway, what can you do with your old APM1280 board?

My favourite use for an old APM1280 board is for HIL simulation. I keep my main APM2560 board in my plane along with my IMU, and I prefer to leave it in the plane between flights, so I'm not constantly having to disassemble things, which can put needless stress on the wires.

My older APM1280 board is kept on my desk, and I use it to fly HIL simulations. The trick to doing this is knowing how to configure your APM1280 to run HIL simulation without an IMU boad. I only have one IMU board, and I prefer to leave that in my plane, but the default APM build for HIL will try to access the IMU board, and will crash if its not there.

This is easily solved. The trick is to know that when built for HIL simulation there are only 2 things that the APM code tries to access on the IMU board - the slider switch and the 16MB data log. So if you disable the CLI and the on-board logging then you will find that your APM1280 will fly a HIL simulation perfectly. The defines you will need are:

#define LOGGING_ENABLED DISABLED
#define CLI_ENABLED DISABLED
#define HIL_MODE HIL_MODE_ATTITUDE

The resulting image will be just 66k in size, which means that your APM1280 will be able to fly HIL simulations with the latest bleeding edge code for a long time to come!

To connect your APM1280 for HIL, all you need is a FTDI cable, and of course a flight simulator. I prefer FlightGear, as I can hack on the code, but a lot of people use X-Plane with great success.

So, don't put that APM1280 in your parts bin just yet. There is plenty of life left in it if you tweak things a bit!

What do you think about making a variable pitch quad  with Trex 600 tail rotor assambly parts.

It's using a outrunner motor and a servo for each 70cm blade.

It's also for sale(around 400$)

http://www.rhcforum.ro/topic/40310-vand-platforma-quadrocopter-cu-pas-variabil/

So I have been waiting to fly this geobat plane I built for over a month now. I have previously been too nervice with all my unseccessful RC flights with numerous just RC planes...But today was different, I walked out side, notices little to no wind and thought... TODAY'S THE DAY!

I have both an onboard camera, and a ground camera to see everything thats happening!

Please Enjoy!

The Maiden flight of the Beeler UAV Part 10 "IFO"is above!

Just found it...Far away from UAV challenge, but could be fun

http://ardrone.parrot.com/parrot-ar-drone/usa/challenges/us

Hi,

yes, I did it : pilot two planes at the same time :p

The main plane is a FunCub equipped with UavDevBoard and on board tracking video camera.

The second plane is a stock EasyStar, carrying another UavDevBoard, only to send its position.

I took off with the FunCub and put it in autonomous mode. Me having in my hands two RC transmitters, my son kindly launched for me the EasyStar and I drove it all the flight long.

The hardest part was try to stay in the camera turret range. The FunCub speed is set to 50km/h, but even at this speed it is a challenge to follow it and stay in front, with a fully stock EasyStar.

At the end of the flight (FunCub autonomy), my son asked to land his plane :)

I landed the FunCub.

Many thanks to Bill Premerlani, Ben Levitt and Pete Hollands for great continuous support and all the smart UavDevBoard community ...

Best regards,

Ric