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So tweeked the nacelle angle to compensate for wind. GPS was only giving 0-2Hz. After autopilot took off & tried to turn her unsuccessfully, switched to manual. A gust of wind combined with the tweeked nacelle angle probably flipped her over. That was the end of Vika 1's 2nd fuselage & 3rd camera. $100 + $150 tax by our calculations.
You can see the tweeked nacelle angle in that 1.
Maybe we should just buy cameras in packs of 10. The A480's last stand.
Tilting the fuselage to tilt the camera is never going to be practical
because it requires tilting the IMU & the GPS. Since only the forward
propellers can be tilted while the aft propeller must point down, that
creates a tendancy to flip over. All propellers should point the same
way.
After repairing Vika 1 & fixing the GPS problem through redundant
packets, did some static hovers to look for problems. This produced the
1st long exposures of Vika 1 under the stars since Major Marcy appeared
9 months ago.
This has been a risky affair as regards making men fall in love.
Then she had yet another crash. Took off normally, then she started
tilting left & heading towards the parking lot. Took over manually,
propellers stopped because collective was still off. Raised collective
& she started flipping over uncontrollably right & forward. Flight
recording showed what appeared to be a loss of the right forward motor.
So why does Vika 1 have so many problems when the stock Mikrokopters are
shown working effortlessly, crash free, & maintenance free? Maybe the
full time attitude hold. Maybe they're not optimizing every last ounce
of weight with crazy camera mounts. Maybe they're not using super cheap
Chinese parts with exposed windings & barely reflowed solder paste.
Maybe they're not documenting daily experiences with them in all
weather.
MARCY 2 HELL
Marcy 2 isn't going so well either. Ran another board with shorter
radio traces but hopefully common enough to be used with Marcy 1.
Yet another blown photoresist job. It appears any ambient UV light is getting into the mask.
Everyone is switching from double sided tape to grip tape. Double sided
tape stretched too much but grip tape is now proving too slippery.
OTHER AEROSPACE NEWS
Maybe being shut down by an Air Force heroine makes you appreciate the mundane, but finally shot the huge swarms of birds that rise in
the thermals produced by local parking lots. They autonomously organize
into rows that we guess parallel the shore & rise over 1000ft.
The other autonomous system of note was the Ares 1 launch abort test.
Pretty tough getting something to take off autonomously, control
attitude in 16g of acceleration, turn itself upside down, separate from
its 1st stage, & deploy parachutes all using solid rockets.
Despite what our rulers say, don't think private industry will have the
business case to fund anything like that in our lifetimes. Any commercial
human spaceflight program would have to be commercial in name only.
- 50 x 50 x 7 mm, 10 grams
- RPSMA for antenna, 17 PC edge connections for power and data
- 0.75 Watts transmit, 0.5 Watts receive, 3.3 VDC
- Synchronous high speed SPI (Serial Peripheral Interface)
- UART (Universal Asynchronous Receiver/Transmitter) to 115.2 kilobaud
- SPI or UART interface chosen by firmware
I'm curious... has anyone used a pair of these to construct a self-stabilizing pan/tilt gimbal for their aerial shots (plane or copter)? It would certainly make for less parts and wiring, being that servos will still be required to do the job (so why not cram the gyro in the servo and kill two birds with one stone). I'd really like to research a good looking and sturdy gimbal ball turret for my particular design (Sony FCB-EX1000 block camera with 432x zoom, and FLIR PathFindIR). I've scoured the net and, short of commercial systems, was not sufficiently impressed. Ideas are welcome!
In various groups and blogs I peruse on here, there's been talk about I2C control of servos (as opposed to standard PWM). This certainly solves several problems, as it allows one I/O port (I2C) to service over a hundred servos with ease. With some built-in intelligence, the servo itself can take care of interpreting and following commands without the need for continual updates from the system (i.e., true asynchronous operation). In addition, servo power lines are kept separate from the autopilot board, thus eliminating the possibility of overheating board traces due to excessive current draw (a stack of 8 servos, especially digital ones, can easily exceed the amperage rating of the traces and wiring used in some autopilot boards). The one drawback to I2C control... if one servo's electronics fails and "latches" the bus, the entire network is toast. However, that possibility can be mitigated through an isolation network built onto the servo control board.
Coincidentally, today I read a message on the UAV Dev Group about an open source servo project called (not surprisingly) OpenServo*. Among other things, they offer complete ready-to-go boards that fit inside some standard servos and convert them to I2C. Here's a list of features, directly from their page:
- High performance AVR 8-bit microcontroller
- Compact H-Bridge with high performance MOSFETs
- Precision control over servo position and speed
- I2C/TWI based interface for control and feedback
- Feedback of position, speed, voltage and power
- Advanced curve based motion profile support
- EEPROM storage of servo configuration information
- Software written in C using free development tools
- I2C/TWI bootloader and GUI programmer
I thought I'd mention it here, since there seem to be people from several diverse groups interested in this (I2C servo control). Price is $14.95 from SparkFun Electronics.
*Credit to Peter Holands of UAV Dev Group for spotting this.
A few batches of the GS407 (uBlox) modules came defective. This problem includes units sold by SparkFun and DIYDrones Store ... The problem seems to be around the antenna solder joins, they are weak and break easily, so any little crash may break it. You can try to solder them by removing the hard glue, but is not recommended because you will void the warranty.
If you carefully check the picture you will see three tiny gold pins, those pins support all the stress and weight of the whole antenna. The big solder balls you see are mine, not from factory...
The uBlox chipsets are intact and fully functional but they are unable to catch satellites.
If you are a victim of this situation, please send it back to me and i will chip them out to the factory for a FREE repair!
Don't send me the remains of your module if you hard crash it, your burn it or something else is not related to this issue. Only units ordered from DIYDrones Store in good conditions will be accepted.
I see that the chaps down under, where woman blow and men chunder, have opened their store.
The first product I see of interest is the GPS which can be used with Ardupilot
The OpenPilot GPS is an ideal upgrade to the U-Blox unit normally used with the ArduPilot. To specifically make this upgrade easier for the community, the ends of the wire that is supplied with the OpenPilot GPS has been pre-crimped with JST SH pins. This means that you can free the pins from the housing of your old unit and just plug these crimped wire ends straight in to your old connector.
http://wiki.openpilot.org/OpenPilot_GPS
Heres the store link
http://store.openpilot.org/openpilot-gps.html
"This is a triple axis ST MEMS gyroscope board, it has one LPR530AL for Pitch and Roll and one LPY530AL for Yaw. Capable to measure the angular velocity with a full scale of 300°/s. Three different analog outputs are provided for the x- , y- axes and z - axes - one 1x amplified and the other 4x amplified. This boards is designed with a removable edges, in case you don't want to screw the board to your project you can just easily break them away to keep the minimal size" ($39.90)
HMC5843 - Triple Axis Magnetometer
"This is a 3-axis digital compass board based on the Honeywell's HMC5843. Communication with the HMC5843 is done through an I2C interface. The board has an I2C translator and 3.3V power regulator that will easily let you use it with 3.3V and 5V applications using a solder jumper. This magnetometer can be used on our ArduIMU+ and ArduPilotMega Shield or any microcontroller." ($44.90)
Pressure Sensor SCP1000-D11 Board (I2C)
"The D11 version of the SCP1000 is similar to the D01, but it communicates via a two-wire (I2C) interface, rather than SPI. The SCP1000 is the first absolute pressure sensor on the market to use MEMS technology.
This sensor has a 30kPa-120kPa measurement range at up to 17-bit resolution. Under ideal conditions, this sensor can detect the pressure difference within a 9cm column of air. On top of absolute pressure measurements, the SCP1000 can also measure and report temperature in the range of -20 to 70°C. The pressure and temperature output data is calibrated and compensated internally, and the communication between the SCP1000 and its host micro-controller is realized using an I2C interface." ($34.95)
I2C/SMBus Voltage Traslator (I2C Level Shifter)
"This great tiny board will allow to interface slave 3.3V I2C devices like magnetometers and pressure sensors with master 5V devices like AVR/PIC microcontrollers WITHOUT THE USE OF DIRECTIONAL PIN. It also features a build-in 3.3V power regulator and dual pull-resistors (5V and 3.3V sides). The pull-up resistors can be optionally and independently disabled with the two solder jumpers located on the top of the board.
But why do you need it? Well some 3.3V sensors are not capable to handle 5V signals coming from some microcontrollers (like Arduino), you always can do it but you will reduce the life span of your sensor. Not just that, you will also need to supply the I2C sensors with 3.3Volts, so an external power regulator is required and just that makes things more complicated. All this problems are solved with this little board. " ($12.90)
And finally, one just for fun:
Limited Edition Collectible Ardupilot MEGA and Shield Prototype Boards
"Limited Edition Collectible Ardupilot MEGA and Shield (V1, V2) Prototype Boards
You get 3 boards: MEGA, V1, V2. They are fully functional if you want to build your own. OR you can use them as paper weights, coasters, magnets, souvenirs or any other creative application." ($1.95)For Jack Crossfire, who is no doubt way beyond this. It was new to me, anyway...
SparkFun's 2010 Autonomous Vehicle Competition from SparkFun on Vimeo.
This picture got me thinking that Ardupilot is inside this Airframe?
vs.
- Three Serial Ports (2 com + USB) (full duplex telemetry plus GPS) vs. 1 com/USB on Atmel.
- 12 bit ADC vs Atmel's 10 bit. (4 times better resolution).
- Included USB (faster everything, more reliable, and save $ on FTDI)
- Matrix divider (Both have fast multiply, but Freescale includes Fast divider as well)
- Freescale runs at 48Mhz vs 20 Mhz
- Both have 6 PWM
- USB bootloaders vs. Serial Botloader
So the bigger question is really to the heart of Open Hardware and Arduino - is it worth paying 5 times the price for weak hardware, and a weak IDE just because some components of the tool chain are more open than Freescale's free IDE (which is arguably less "light" than then infinitely light Arduino IDE). Is the Atmel's proprietary chip really "Open Source" if one tool chain component is "open Source" - and is the premium worth it. I have lots of Arduino's and I like them, but I can't help feeling they are a closeted serial device in a USB world, and overpriced (a Freescale Arduino-Clone would probably cost $6 vs. Arduino's $32 because the USB is built-in.)
Just Saying...
Photo: Chris talking to Pete Hollands at SparkFun
I'm sorry for the delay, this episode was recorded by Chris' phone and my laptop and the background noise required a lot more edits than usual. Jack Crossfire will be pleased to note that I found the source of the reverb and confined it to a theoretical vacuum. Of course the background noise probably didn't help (it's better at the end) but the quality should be up from here on out!
AAC: http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=330632997
MP3: http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=330633212
RSS feed
AAC: http://feeds.feedburner.com/diydrones
MP3: http://feeds.feedburner.com/diydronesmp3
Guests include (although a couple of them may not have spoken):
- Chris Anderson
- Bill Premerlani
- Ben Levitt
- Adam Barrow
- Tim Trueman
- Pete Hollands
- Earl Campbell
- Jordi Muñoz
- Ryan Beall
And thanks to Doug Weibel for hosting the podcast in his home!
More infos here: http://www.draganfly.com/uav-airplane/tango/
Finally, the article I wrote is out in the May 2010 issue of Circuit Cellar Magazine. Unfortunately I have yet to get my hands on it. From http://www.circuitcellar.com/magazine/; it's $2 to buy or go to Barnes and Noble and get yourself a copy of the magazine.
The FreeSpace IMU: A Quaternion-Based Algorithm for Attitude Estimation by TJ Bordelon
An unmanned robotic vehicle requires a working inertial measurement unit (IMU), which outputs an estimation of the attitude, or orientation, of a vehicle in 3-D space. For attitude estimation, you need MEMS sensors (e.g., gyros, accelerometers, and magnetometers) and a sufficient algorithm to “fuse” them together. This article covers a simple quaternion-based algorithm for an IMU project. p. 14
From BotJunkie:
"The Indoor Aerial Robot Competition was held at Drexel University last week, featuring a bunch of the chubbiest fully autonomous robots you’re ever likely to see. The bots were tasked with locating and retrieving small boxes, and doing search and destroy on hapless red balloons."
New Features of ArduPilot 2.6:
- Supports IMU or thermopiles
- All-new control laws. PI and D for all functions
- Two fly-by-wire modes: A (with airspeed control) and B (without airspeed control)
- Designed for ArduIMU code 1.7 if you're using the IMU (upgrade if you haven't already)
- Support for absolute pressure sensor and magnetometer add-ons to IMU
- Optional performance reporting; sends IMU quality data (gyro saturation, etc) to ground station
- Experimental support for autonomous takeoff and landing!
Some of this is documented in the code and the configuration comments. I'm in the process of updating the manual to reflect all the 2.6 changes, so please be patient for the next few days until I'm done.
Words fail me. Found here.
