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Adding RSSI signal monitoring for Xbees

Posted by Reto on July 5, 2009 at 3:18am
In my SIG Kadet Senior "near future" UAV, I've a nice feature in my video OSD: there's a RSSI connector to which one can apply a 0-5V tension and the OSD then displays a graph bar with RSSI signal strength.On Xbee side, I knew I had a RSSI output in form of a PWM signal on pin #6. I configured the Xbee RSSI/PWM0 timer to 99 (which translates in the Xbee to retain the last valid Signal Strength measure for 99 x 100ms, ie approximately 10 seconds. I also activated the PWM0/RSSI pin with the Xbee config tool (It is not active by default, I think).The task was to convert that signal to a 0-5V scale for my OSD. I used my Arduino Pro Mini, in charge of parsing data to my OSD, to receive the Xbee PWM signal on its digital pin #2. This board then computes the PWM (pulseIn function of Arduino). I experimented a maximum pulse length of 32us by placing both Xbee's at 30-40cm distance. so I figured out an RSSI in the formMeasured pulse length / Maximum pulse lengthThis gives me an interval of 0-100% signal strength value.I then just had to map this interval from 0-255 for the output on pin #3 in PWM form, which translate in a 0-5V tension on the pin.On the OSD (Inspire OSD), I plugged in the RSSI cable from Arduino Pro Mini (pin 3 / GND). Now I have an Xbee signal strength in the graph bar of the OSD. If there's no signal received from the ground Xbee during 10sec, the RSSI signal bar shows 0. When signal is good, the graph is oscillating between max and just below.I will finally try to stabilize the RSSI value on the graph bar, probably with some averaging of the read pulse widths. Maybe I'll also limit the reading of the Xbee RSSI pin every second instead of a continuous reading.Well that's a nice add-on for inflight monitoring of signal, especially since it is well known that the Xbee RSSI signal is directly proportional to distance between the Xbees! Maybe I will one day do some empirical measurement about the relation between RSSI and distance.
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Autonomous flag 4 U

Posted by Jack Crossfire on July 4, 2009 at 9:30am

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No match for North Korea's 7 missile salute, but we tried.All flights have to take off pointing North & turn into the wind because of the 3DOF IMU. Managed to pull off some stiff wind without blowing string into the propellers. Forget about underslung payloads unless everything from takeoff to landing is automated.
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Moderator

UK RCAP meet

Posted by Gary Mortimer on July 2, 2009 at 2:00pm
Managed to maiden a new version of Airframe3 today ahead of the weekends aerial photography meet at Leamington Spa, twenty plus aerial photography types flying camping and perhaps some tall stories. Heres the RCgroups link if you fancy joining us. I reckon this will be one of the biggest meetings of RC photographers in the world.

The kit of parts

All together

Robert from Flying Wings

The first couple of flights were pretty shocking, after some ballast on the nose things improved, still as ever a work in progress. Went like stink though ;-)Still 1kg for 1 hour as a target.
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Admin

What level of ESD protection is on your workbench?

Posted by Thomas J Coyle III on July 2, 2009 at 1:00pm
Hi all, I have been a System Engineer for over 30 yrs and have gone from tubes to ICs during my time in the Aero Space industry. Tubes were virtually immune to ESD (Electrostatic Discharge) and could be handled just about any way we wanted to. But when it comes to ICs, ESD can damage or destroy an IC in an instant. Many of the boards offered for sale in kits by DIY Drones contain static sensitive parts/components that can be damaged even when attached to their respective circuit boards. Therefore it is extremely important for all of you who have built or intend to build DIY Drone kits to exercise basic ESD handling procedures: 1) Buy a static safe pad/mat and attach it to the closest earth ground that you have access to. This will help to prevent static discharge from destroying the static sensitive parts on the DIY Drone boards. 2) Buy a metal wrist strap and attach it to the static safe pad to insure that you are at the same potential as the work pad so that you can pick up a static sensitive board and not risk destroying it with a static charge on your body. 3) Keep all of your completed boards in static safe packaging. Try to minimize board contact with the foam in the foam aircraft. 4) Buy a temperature controlled solder iron with a grounded tip. If you follow these simple tips concerning ESD and your static sensitive circuit boards, you will most likely have a project that works the first time and will not suffer a latent defect while your plane is high in the sky! Just a thought. Regards, TCIII
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Availability of source code of ArduConfig Beta.

Posted by Mikil P on July 2, 2009 at 4:57am
Hi,I am currently using a Linux based system and was wondering if the source code for the Ardupilotconfig tool (beta3 version) was available as I can't upload the waypoints on the board at the moment. I'm extremely interested in writing a platform neutral clone of ardupilotconfig, and would be quite happy to share the results. Is there any other way/method of uploading the waypoints manually assuming I am using the latest ardupilot code (Version 2.2.3) for the easystar ? Any help with this will be greatly appreciated.Regards,Mikil
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Ardupilot Success Stories

Posted by Bryan Cuervo on June 30, 2009 at 6:30pm
At this point, the only way to get my plane flying with Ardupilot is to buy a different FTDI cable which may or may not work with my setup(I don’t have the programming skills to bypass the configuration utility and add waypoints directly into the code). I’m running Windows Vista on my laptop and have the latest Ardupilot board with the shield kit as shown below. I’ve also installed the latest code, configuration utility and the newest version of the Arduino IDE.Before I invest any more money in this project, can I get some feedback from anyone running a similar setup to mine but with the newly recommended FTDI cable where they are successfully downloading code, read/writing from the configuration utility and flying autonomously with Ardupilot?I’m sure there are success stories out there and they would really help those of us that are struggling to hang in there. I believe in the Ardupilot project and Chris' clear approach to explaining concepts and products has helped me immensely in understanding autonomous systems and in choosing the best equipment. This is a fascinating hobby and always a challenge.

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Dead multiplexer?

Posted by Damon Pipenberg on June 30, 2009 at 8:17am
Wondering if anyone might have experienced a problem that I'm having. My ArduPilot has been working fine, but yesterday, the servo outputs suddenly quit working. After doing some troubleshooting, I think I've narrowed the problem down the the multiplexer (74ACT157). It gets power, and gets a proper signal from the failsafe, and I found a 50 Hz signal on the inputs. However, the outputs are always low, at 0V.I've been using a 4-cell, 4.8V receiver battery to power my setup. When fully charged, it gets up to 5.3V, which should be safe for the multiplexer. Maybe I shorted out one of the outputs, or zapped it with static? Anyone else had a similar problem?
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VicaCopter 4

Posted by Jack Crossfire on June 29, 2009 at 1:42pm

After spending 3 hours waiting for web pages to load, VicaCopter 4 is finally available for download. If U ever succeeded in building your own VicaCopter, U still probably wouldn't know half of what she can do.The idea with VicaCopter is to have a reference design that works but not to have you copy it exactly. It's mainly our own personal reference.It's amazing after all these years, VicaCopter is still the only English language source code for a fully functional helicopter autopilot that you can download without paying for. There is no support or warranty.Vicacopter uses a ground computer for flight control. An airborne microcontroller handles rate damping, PWM, & sensor capturing. The ground computer handles navigation & provides a simple instrument panel. Because you need a radio modem & ground station either way, it's the cheapest way to fly.VicaCopter supports 2 configurations:3 gyros & a sonar transducer for the minimal autopilot.6 DOF IMU, magnetometer, barometer, GPS for the full autopilotSome things VicaCopter can do:Can fly with under $100 of parts including a complete sonar positioning system.Automated landing & takeoffSonar position sensing for indoor flightGPS position sensing for outdoor flightGround station instrument panelUntethered communication from pilot to ground stationFully autonomous missions written in picoC scripting languageManual altitude & position changes from stick commandsCurved or linear pathsTurning towards a pointCamera trigger
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Pros and cons of the Ardupilot Configuration Utility

Posted by Bryan Cuervo on June 29, 2009 at 4:24am
I first started flying with Ardupilot before the configuration utility (CU) was created. At the field, I’d pull up the Arduino IDE on my lap top, make the changes I wanted in the code (waypoints, altitude, tuning parameters, etc.), upload to my Ardupilot, then fly. After seeing how the flight was affected, I’d go back to the IDE make another change and fly again.Then the CU was created and it looked cool but, at the field, it just created another step to go through before flying. I now had to also pull up the CU program to enter my waypoints, altitude and other parameters and upload to the board, then open the IDE, make my changes and upload a second time.Now, for a lot of us, the CU is the single break in the chain that is keeping us from flying. We have the Sparkfun FTDI cable that works fine with the old and new versions of Ardupilot for uploading code and it works with the old version for reading and writing from the CU. The problem is that the CU doesn’t allow you to use this cable with the current Ardupilot and there is no other way to upload waypoints.As you can tell, I’m not a big fan of the Configuration Utility! Since an .h file was created as an interface between user and code, couldn’t this same file be used for entering waypoints? This sounds more user friendly since you wouldn’t have another program (CU) to open, make changes to, and upload. Also, the current problem with Sparkfun FTDI’s wouldn’t exist!
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Simple way to use Google Earth as ground station.

Posted by jlcortex on June 28, 2009 at 9:26am
I am looking for use google earth as ground station.i have download this program.

http://goopstechnologies.comit is easy to interface to any application:GooPs can receive data from other applications via a TCP/IP socket. GooPs listens on port 51234 for messages containing NMEA data.and another similar program:http://mboffin.com/earthbridge/it demostrates it is possible butWhere can we found information to handle google earth directly? without bridge programs.jlcortex
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I Heart Robotics UAV Crosspost

Posted by I Heart Robotics on June 27, 2009 at 12:00am

While not all of the information on the I Heart Robotics blog is related to UAVs, there is a significant amount that should be of interest here. I would like to highlight a few specific posts.Autonomous Indoor HelicoptersHighlighting the development of an indoor helicopter navigation system.Crash TestThis is a series of posts that shows the process of developing an autonomous quadrotor helicopter based on the Dragan FlyerUAV Damage ControlSome information about adaptive control and morphing aircraft.Analog Devices IMU now available with integrated MagnometerInformation about an analog devices IMU, ideally this sensor could be supported by the next version of ArduPilot.If this kind of summary crosspost is considered helpful I can probably do it on a semi-monthly basis, otherwise this post can be deleted.
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Moderator

Government Grants 100,000 handed out to secret types

Posted by Gary Mortimer on June 26, 2009 at 12:00pm
How do you win a Government Grant for something that is largely illegal in your country??Helen Greiner's Droid Works Wins First Gov't Grant for Flying BotsHelen Greiner's stealthy new start-up, The Droid Works, has said almost nothing about what they're up to, except that they're working in the field of UAVs (unmanned aerial vehicles.) So far, Greiner has been funding the Framingham-based company herself, so there aren't any VCs to blab about what they're working on. And the company is small -- just a handful of engineers, including one superstar HP veteran who helped develop the inkjet printer -- so employee leaks are unlikely. All this makes a curious journalist sad.But when I saw Greiner last night at 'What's Next in Tech,' she mentioned that the company had just landed its first government grant through the SBIR program (Small Business Innovation Research.) I did some searching, and discovered that the company is receiving almost $100,000 to develop flying bots that can operate indoors and out. The description of the work is fascinating, so I'll share it here -- and also mention that Greiner's last company, iRobot, was initially funded not by VCs but by government grants from agencies like NASA.Best you all get onto it and get yourself a slice those of you in USAhttp://www.thedroidworks.com/
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Developer

DIYDrones Store: New Products Available!

Posted by Jordi Muñoz on June 25, 2009 at 8:00pm
Hello everybody. I have some news here:1.-The shipping system right now is a nightmare for everybody (including me). Finally i found a good solution that will let me ship overseas for less than 5 dlls (under 4 oz). Yes i will accept First Class Mail soon, YEAHHH!!! It will be ready in two weeks.2.- The Infrared boards arrived, but i still waiting for some components in order to start the fabrication. Please be patient.3.- I ran out of ArduShield Kits!!!! Guys.. Let me breath! Tomorrow the new parts should arrive, sorry about that.Now lets talk about the new products:Ok ArduStation is now stocked, so you can order today and i will ship the same day (before 3pm California, Sun, Beach, Pacific time or 10pm Zulu time). You can buy it here.

As i already mentioned this in another post, I'm about to release the new ArduLogger in collaboration with Raúl Helvia and Eduardo Garcia (the Satellite guy) from Spain. Its an Atmega328@8Mhz and you can use it to data log the 6 analogs channels or data coming from the serial port:

(If you look carefully the picture, you will see my new Open Source ServoSwitch).And yeah! I finally entered to the gyro market. My goal is to one day offer everything you will need to build your own UAV and have an old school slogan like: "The official UAV store" or maybe "Satisfying all your UAV needs since 2009", LOL:

I'm offering right now the smallest LISY300AL breakout board. Same price as SparkFun and free shipping world wide (web?):

And for limited time i will offer the ultimate 6 degrees of freedom, super tiny IMU that can be adapted to your system very easily:

(Ardupilot just as size reference). Featuring the ADXL330 3g accelerometer and the famous LISY300AL with 300deg/sec. The best part is that you can upgrade it. You can choose between 4, 5 and 6 degrees of freedom by just soldering the gyros you need (without buffering underrun your Paypal account) and because the main board is vertical you can solder it to your current home made autopilot PCB or even in a breadboard!This pic shows with arrows the gyros you will need depending the configuration you may want:

Another pic of the back:

You can buy the IMU here, and you can buy the extra gyros from here.The diagrams and schematics of the boards:gyro_lisy_single_sch.pdfgyro_lisy_single_brd.pdfgyro_lisy_mother_sch.pdfgyro_lisy_mother_brd.pdfThanks for you support and for reading this!
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Developer

ArduStation Assembly Instructions

Posted by Jordi Muñoz on June 25, 2009 at 2:00pm


What you will need:
-ArduStation Kit
-Soldering Iron:

-Solder:

-Flush/diagonal cutters:

Recommended:
-Low Profile Multimeter:

-Disordering Tool:



-This is what you will find inside the ArduStation components antistatic bag (LCD is included of course):


-Lets start soldering the non polarized capacitors (.1uF), when you are done place the xBee headers:


-After you placed the xBee headers, place any xBee module you have available to hold the headers in the right angle, then solder:


-Continue with the Atmega328 socket and the buzzer, watch out with the buzzer polarity!:


-Now place the protection diode (check the white strip) and the power regulator, be careful both have polarity too:


-Lets continue with the potentiometers, one is for the contrast with the number "103" or 10Kohms (UP) and the other with the long pins is for the backlight LED, with the number "502" or 5Kohms (down).


-An extra picture:


-Now solder the first 100uF polarized capacitors, check out the white strip (negative).


-Now solder the second 100uF polarized capacitors, check out the white strip (negative).


-No solder the 16Mhz Resonator (orange/brown one), is not polarized, the reset button and the power jack (easy):



Now we need to solder the LED's, but i have chosen very bright LED's in order to see something under the sun, but they are clear, so no way to see the color and one of the was inverted polarity (the long pin is the negative). A solution for that is using a the multimeter, just choose the continuity option or diode test (both will work):

This trick works great for SMD LED, for normal LED will not be so effective but it will work. Anyway just place the multimeter probes in the LED and see in with side the LED turns on and check the color also the LED side that the multimeter red probe is touching is the positive polarity of the LED. In the back of the board you can check the positive polarity of the LED holes:


-After you solder the LED's in the right way, is time to solder the funniest part, the buttons:


-Turn the board and place the Atmega328 carefully (the little half-circle divot on the chip should be on the side with the little half-circle in the socket; ignore the position of the red dot on the chip, which is not meaningful). The processors comes with bootloader pre-loaded:


-Now just solder the LCD (you can use female headers so you can remove the LCD anytime) and the FTDI port. You are ready to connect it. Note: You can't upload code when the xBee is connected.


-When you are ready, just upload the ArduStaion demo code here. It should work with ArduPilot and show you real time telemetry as indicated:


-By pressing the buttons left and right you can change the screen data.


You can find the latest code here:
http://code.google.com/p/ardu-station/
The example is commented and you adapt this system to any of your projects!

Enjoy!
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