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FLIGHT CONTROL

Posted by Sesan FESOBI on March 11, 2009 at 12:52pm
Hi everyone,I am new to DIY Drones. I am trying to develop the FCS for a small model aircraft. I want it to be able to perform flight control and navigation functions. Could you tell me what hardware components I can choose (with moderate cost) that can effectively perform these functions?Regards
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3D Robotics

Canadian police testing Dragan X6 multirotor

Posted by Chris Anderson on March 10, 2009 at 10:30pm

Calgary Police are testing the Dragan X6 multirotor. Excerpt from the article: "The key in expanding the service's use of the technology is going to be proving the images hold up in court, Engele said. The X6 was used previously by the Ontario Provincial Police to photograph a homicide scene in rural Ontario and could be used in tactical or surveillance operations, he said."
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3D Robotics

Using ArduPilot 2.x in the field

Posted by Chris Anderson on March 10, 2009 at 8:30pm

Instructions for using ArduPilot 2.x in the field:

ArduPilot 2.1 and above (with Z sensor). This version of the software auto-calibrates the IR sensors. The only thing you need to do at the field is to record the "home" GPS position in EEPROM memory, which will not be erased when you reset or power down the board. To do so, follow these instructions:
  1. Ensure that the autopilot is in manual mode (channel five toggle off) and GPS is connected
  2. Place a jumper cap on pins D6 and D7 (you can also connect a regular RC power switch to those pins if you want to control the autopilot from outside of the aircraft). Ensure that your aileron and elevator sticks are in the center position, and power on the board.
  3. The yellow status LED will blink for a few seconds as the autopilot programs the GPS for binary mode. Then the blue lock GPS will blink rapidly, which means the autopilot is waiting for GPS lock. You can now remove the jumper (or return the switch to the normal position)
  4. When the autopilot has established a GPS lock it will move the rudder. Note that ArduPilot puts the EM406 into binary mode, which disables the red LED on that module, so it will not blink.
  5. You’re now ready to fly! Press the reset button on the ArduPilot board to restart it (your calibration settings are saved in permanent memory and will not be erased).
  6. ArduPilot 2.0 supports two autonomous modes: waypoint and return-to-launch (RTL). If you have a three-position toggle switch or a proportional dial on your RC transmitter, the middle position is Waypoint Mode and the up (or full clockwise) position is RTL Mode. These can be changed in the software if desired. The Mode LED on the ArduPilot board will light up with it is in Waypoint Mode.
  7. To use fly-by-wire mode (just stabilization, like the FMA Co-Pilot), simply disconnect the GPS. ArduPilot also automatically switches into stabilazation mode if it ever loses GPS lock.
ArduPilot 2.0 (no Z sensor): This version requires that the IR sensor be calibrated in the field, on arriving and if the weather conditions change significantly:
  1. Ensure that the autopilot is in manual mode (channel five toggle off) and GPS is connected
  2. Place a jumper cap on pins D6 and D7 (you can also connect a regular RC power switch to those pins if you want to control the autopilot from outside of the aircraft). Ensure that your aileron and elevator sticks are in the center position, and power on the board.
  3. The yellow status LED will blink for a few seconds as the autopilot programs the GPS for binary mode. Then the blue lock GPS will blink rapidly, which means the autopilot is waiting for GPS lock. You can now remove the jumper (or return the switch to the normal position)
  4. When the autopilot has established a GPS lock it will move the rudder. Note that ArduPilot puts the EM406 into binary mode, which disables the red LED on that module, so it will not blink.
  5. Holding the aircraft without obscuring the thermopile sensor, point the nose at the ground. Switch the autopilot on with your RC toggle switch. The elevator will move, signaling that the sensor has been calibrated.
  6. You’re now ready to fly! Switch the aircraft back into manual mode for launch, and press the reset button on the ArduPilot board to restart it (your calibration settings are saved in permanent memory and will not be erased).
  7. ArduPilot 2.0 supports two autonomous modes: waypoint and return-to-launch (RTL). If you have a three-position toggle switch or a proportional dial on your RC transmitter, the middle position is Waypoint Mode and the up (or full clockwise) position is RTL Mode. These can be changed in the software if desired. The Mode LED on the ArduPilot board will light up with it is in Waypoint Mode.
  8. To use fly-by-wire mode (just stabilization, like the FMA Co-Pilot), simply disconnect the GPS. ArduPilot also automatically switches into stabilazation mode if it ever loses GPS lock.
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3D Robotics

ArduPilot 2.0 Beta Code Released!

Posted by Chris Anderson on March 10, 2009 at 8:30pm

I'm delighted to announce the release of the ArduPilot 2.0 software, now in public beta. This software uses the current ArduPilot hardware but handles the FMA Co-Pilot stabilization function itself, without the need for a separate stabilization unit. It is, in short, a complete integrated autopilot. That little ArduPilot board can do a lot! 2.0 Features:
  • All the ArduPilot 1.0 functions: programmable 3D waypoints; return-to-launch mode, in-flight reset ability, fully programmable actions at waypoint and totally expandable board.
  • Now integrates the stabilization and navigation functions, eliminating the need for a FMA Co-Pilot and vastly improving waypoint tracking
  • Controls elevator and ailerons/rudder. Throttle control coming in 2.1
  • "Fly-by-wire" mode stabilizes the aircraft in RC mode, duplicating the function of the FMA Co-Pilot
  • Stores home waypoints and sensor calibration in EEPROM, so they are retained even in the case of a system restart
  • Controls altitude with the elevator, vastly improving performance in wind
  • Currently optimized for the three-channel EasyStar. Versions have also been tested on Funjet and four-channel Superstar (code coming soon)
  • Simple in-field calibration process
  • Can use any thermopile XY sensors (default settings are for the FMA sensor, but Paparazzi, AttoPilot and custom sensors can also be used)
  • Currently supports the EM406 GPS. Support for Locosys and Ublox GPS modules coming soon
  • Uses "chained PID loops" to combine the stabilization and navigation functions seamlessly
What you need (if you already have an ArduPilot and FMA Co-Pilot you don't need anything else): Instructions for modifying the FMA sensor cable to use it with ArduPilot are here. Instructions for in-field calibration and setup of ArduPilot 2.0 are here. (Note: ArduPilot 2.0 put the EM406 GPS module into binary mode, which disables its onboard LED. That means that if you try to use the same GPS module with ArduPilot 1.0, it won't work (unless you program back into NMEA mode with a utility such as this one). However, if you let it sit for a few days without power, the onboard capacitor will run out and it will return to its default NMEA mode and will work with ArduPilot 1.0 again) The next version, 2.1, is now in private alpha. It will include the following:
  • Uses Z sensor for self-calibration in the field
  • Uses small desktop app to load ArduPilot settings and waypoints, without having to work with code
  • Adds throttle to altitude control, improving accuracy and wind performance
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OpenWrt UAV platform

Posted by Pekka Ahola on March 9, 2009 at 8:48pm
My idea is to use OpenWrt + Arduino for a futureproof/scalable UAV patform. I'm planning to do some testing in the spring with the basic Fonera router flashed with OpenWrt Kamikaze 8.09.This setup however doesn't have USB-ports that would enable live streaming webcam, 3G modems and in-flight high quality images through gphoto2 and a digital camera. I'm waiting to see how much the just finalized Fonera 2.0 with USB costs, but I'll still probably go with the Ubiquiti RouterStation (only about 60$).Additionally I just have to build a plane following servo mount for my cantenna wlan antenna to be used in the basestation :) Share your thoughts, and other possibilities (ie. VIA pico-ITX etc.)
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3D Robotics

Increasing the ArduPilot rudder authority for wind

Posted by Chris Anderson on March 8, 2009 at 8:00pm
I had a full day of autonomous flight testing in 20 knot winds, and it's clear that the default PID gains in ArduPilot were not high enough to handle any significant wind. So I upped them from 15 to 30 and the Superstar suddenly regained its tracking authority and was able to circle overhead well. I've modified the standard code in the repository with these higher gains so others who saw "flyaway" behavior in wind should now have sufficient rudder authority to stay on track. If you want to tweak your own PID gains, they're in the first tab of the code. The current gains are as follows: //PID max and mins #define heading_max 30 #define heading_min -30 Please note that with this higher rudder gain, it's important to ensure that your FMA Co-Pilot is doing its job with wing-leveling. Once you're in the air, set it to the highest gain it can take without oscillating (if it's a clear day and you've calibrated it right, that should be the maximum rotation of your gain knob on your transmitter). Another issue with using ArduPilot 1.0 in high wind is that altitude hold is pretty sloppy and it has trouble making progress upwind. That's because ArduPilot 1.0 just uses the throttle for altitude control. When the plane is going into the wind, it tends to rise. ArduPilot will then cut the throttle, but in a good headwind, the plane may not descend. Instead, it will just hover or even move backwards a bit. That's why we're shifting to elevator+throttle altitude control in the ArduPilot 2.0 software. With that the plane will point its nose down a bit and keep the throttle going to make headway against the wind. It's a much better way to control altitude. Jordi's testing it this weekend and may have the code ready to release this week.
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3D Robotics

New Predator UAV available (if you're rich)

Posted by Chris Anderson on March 7, 2009 at 4:30pm

A company called RobotAV has released a standard $80 Nitro Models Predator with an autopilot and RC system already installed. Sounds great until you get to the price: $2,500! To be fair, it's an IMU based autopilot and has other cool stuff like a gyro-stabalized nosewheel (not sure why, since the Predator with a standard steerable nosewheel handles fine on the ground). But it seems to have its functionality crippled to avoid regulatory or AMA issues. It isn't a programmable autopilot; instead it just seems to have return-to-launch and manually-triggered circling--no programmable waypoints. No ground station and the autopilot functions are just controlled by RC, so it sounds like it's designed mostly for FPV flying rather than true autonomous flight Given that you can make an identical-looking ArduPilot-powered Predator that's fully autonomous and programmable for less than $500, I'm not quite sure what accounts for the astronomical price. Does anyone know more about this outfit?
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Arduino powered GPS causes glitches....

Posted by HugePanic on March 6, 2009 at 10:24am
As i wrote in other threads, i power my em-406 gps module from a arduino data-pin.The gps module runns well, most of my code is written.I just started installing all of my hardware into my UAV_Eins airplane/drone.

3689311577?profile=original

Shortly after "power-on" i found that i get horrible glitches on all receiver channels i read.I saw that these glitches (about 20% drop of the signal) occour relatively periodic.....I recorded the signal an the millis(), and got this "wonderfull" graph:

3689311491?profile=original

Disconnecting the gps module resolved the issue for the moment. The code works well, without the gps module.It seems that the gps module draws to much power while sending data. The glitches are veryvery periodic by 1second. (1024,7ms in average)I think there are some options i have now:1. Power the GPS module from seperate battery (with gnd connected of course...)2. add voltage regulator to my doughter-board, to power the gps directly from the lipo battery3. use the 5V pin of the arduino10000 board4. add a capacitor to the data-pin i power the gps nowSolution 1., 2. and 3. would result in the fact that i would have to disconnect the GPS everytime want to upload new. code. currently i only have to reset the board, and start the upload within of 2seconds.The result for me: i have to give the capacitor a try!! I have to search my electronic stuff boxes, to find some capacitors i can use, hopefully it will work.Does anybody now how to dimension the capacitor???
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AUOOSB Project Autonomous Unmanned Open Ocean Sailboat Project

Posted by Michael King on March 5, 2009 at 2:00pm
Link = AUOOSB Project homepageFor those of you interested, I have created a site for the project I have been working on for the last year. I have decided to make the whole thing Open Source so this can be shared and developed with a bunch of IQs and not just my limited one! LOLAnyway i hope you join in for the discussions and the ultimate goal of sailing this thing around the world autonomously.
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3D Robotics

Correct ArduPilot LED behavior

Posted by Chris Anderson on March 4, 2009 at 10:00pm

The correct ArduPilot LED displays are as follows. See the above picture for reference: First power-up of board, straight from the factory:
Power: On
Stat: Flashing in sequence
GPS Lock: Flashing in sequence
MUX: Off unless a RC receiver channel is connected to CTRL pins and that channel is toggled on
Mode: Off
After ArduPilot 1.0 code is loaded, but no GPS connected
Power: On
Stat: On
GPS Lock: Off
MUX: Off unless a RC receiver channel is connected to CTRL pins and that channel is toggled on
Mode: Off
ArduPilot 1.0 code loaded, GPS connected but has not obtained a lock
Power: On
Stat: On
GPS Lock: Off
MUX: Off unless a RC receiver channel is connected to CTRL pins and that channel is toggled on
Mode: Off
GPS LED: On
ArduPilot 1.0 code loaded, GPS connected and locked
Power: On
Stat: Blinking
GPS Lock: On
MUX: Off unless a RC receiver channel is connected to CTRL pins and that channel is toggled on
Mode: Off
GPS LED: Blinking
ArduPilot 2.0 code loaded, autopilot in manual mode, jumper placed on digital pins 6&7, GPS connected
Power: On
Stat: Will blink twice as GPS is programmed into binary mode, then blink steadily
GPS Lock: Flashing while it attempts to aquire a lock; solid afterwards
MUX: Will turn on briefly during boot, then stay off
Mode: Off
GPS LED: Off
ArduPilot 2.0 code loaded, autopilot in auto mode 1 (middle position of toggle switch), jumper removed from digital pins 6&7, GPS connected
Power: On
Stat: Off
GPS Lock: Flashing while it attempts to aquire a lock; solid afterwards
MUX: On
Mode: On
GPS LED: Off
ArduPilot 2.0 code loaded, autopilot in auto mode 2 (high position of toggle switch), jumper removed from digital pins 6&7, GPS connected
Power: On
Stat: Off
GPS Lock: Flashing while it attempts to aquire a lock; solid afterwards
MUX: On
Mode: Off
GPS LED: Off
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Two questions

Posted by Pedro on March 4, 2009 at 4:51pm
1) Would it be possible to post the correct status of the LEDs?On the GPS board I have:1. a blinking red LEDOn the Ardupilot board:2. A steady blue LED ("Lock")3. A steady red LED ("Power")4. A steady red LED ("MUX")5. A blinking yellow LED ("STAT")The instructions mention a blinking white ("Lock") LED. Has this been replaced by the steady blue LED?The second question is, what voltage should I expect on the output pins? I am getting only about 0.2 volts. I am not using an ESC, but using a battery. I am not using the CTRL either, but, instead, I used Michal B's modification to the code from Jan 16.Thank you.Pedro
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3D Robotics

ArduPilot 2.0 update

Posted by Chris Anderson on March 4, 2009 at 8:00am
I'm in LA hanging out with Jordi and geeking out over the ArduPilot 2.0 code. You're going to love this--it's got all the capabilities of the FMA Co-pilot built-in, including a "fly by wire" option that just helps you stabilize the airplane when you're flying manually. In autopilot mode, it's now closer to AttoPilot in capability (save datalogging, which we'll save for ArduPilot Pro) and has a similar set-up procedure it's optimized for the EasyStar but can also fly aircraft as different as the Funjet. Stores IR calibration info and home lat/lon in EEPROM so you can restart the autopilot without having to reset those values. Right now we're still having you enter waypoints int the Arduino code, but Jordi's developed a desktop app/Ground Station that will make that process easy for you, with no need to see the code. It won't be ready next week, when we'll release ArduPilot 2.0, but do look for that in the next month or two. It's amazing how much Jordi's managed to squeeze out of the Atmega with careful use of interrupts and registers. We thought we would need two processors to do all of this, but we're doing it in one. There's a lot of capability in that little $24 board--and even more to come!
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Problems uploading software

Posted by Pedro on March 3, 2009 at 3:23pm
I finished assembling the board, installed the Arduino IDE, installed the drivers for the FTDI basic board (Sparkfun), removed the solder bridge that goes with the ESC option and soldered the one for the battery input, connected the FTDI board to the Ardupilot board, and powered up. I get the red "power" led on, and the blue "GPS lock" led and yellow "Status" led flashing. I am not sure this is correct, and I am afraid I may have fried something. The two flashing leds are showing the same code: looks like MMS in morse code. (dash dash dot dot dot),Ignoring that, I try to load the software. It compiles without any problem. When I select "Upload to I/O board" it pauses for a few seconds and then tells me that the Serial Port (COM7) is already in use by another program.There are no other programs using that por. When I unplug the FTDI board from the USB port, the COM7 serial port disappears from the Device Manager list, and re-appears when I plug it back in. That tells me that the only the FTDI board is using that port. Incidentally I am using Windows Vista. Any suggestions?Thank you, Pedro
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ArduPilot + Smartphone autopilot design

Posted by Michal B on March 2, 2009 at 2:46am
ArduPilot is great piece of hardware, no doubt. However it comes to its limits, mainly with limited memory, just one serial port, limited connectivity to other peripherals.So I have idea in my mind about improved setup, which would still use ArduPilot as hardware interface board for servo signals (5 channels IN from RC receiver,4 channels OUT for controlling plane), and of Infrared stabilization reading.Then it would connect to bidirectional serial link over Bluetooth module, which would connect ArduPilot with a smart phone located on the plane.One well-tuned firmware would be uploaded to ArduPilot once, this would provide work with signals and communication over BT module. These are ArduPilot's strong points.The central brain would be a mobile phone (or PDA) stored in plane. The phone would get servo positions from RC receiver through ArduPilot and over BT serial link, and the phone would also send servo positions back to ArduPilot for controlling plane. The phone would compute stabilization and navigation.GPS signal may come from external Bluetooth GPS module mounted somewhere on plane, or from phone's built-in GPS module (if the phone can be placed in plane with good signal reception).These are main benefits:- easier waypoint configuration (sending to phone over Bluetooth or memory card)- possibility to have multiple waypoint paths stored on phone, selectable on airfield from phone's menu- tuning autopilot parameters (e.g. PID loops) in phone's menu - no need for connecting laptop- using phone's camera for taking photos of video- logging flight data to memory card- much more memory for program and data- using mobile Internet connection or SMS allows for:> uploading new waypoints in mid-flight> reading telemetry in large distance> sending photos or video during flightThe phone would run on Windows Mobile or Symbian OS.Considering power, many phones and GPS modules allow charging over mini-USB plug, so this equipment could be charged during flight from same 5V source as used for ArduPilot. Or just left to use their own batteries.I'm waiting for my first Bluetooth serial module to come, then I'll make testing with such possible connection.And also still waiting for better weather, for trying original ArduPilot in air...
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3D Robotics

An example of EXCELLENT autopilot documentation

Posted by Chris Anderson on March 1, 2009 at 7:15pm
If you haven't had a chance to read the documentation for Bill Premerlani 6 DOF UAV development board, you should. It is 35 pages of the best education you'll get on IMU-based autopilots, including theory, code and usage instructions. All written in clear, easy to understand plain English. Bill's done a terrific job on this one, and I hope more people will start to use his board, which I think is the best open source IMU-based autopilot development platform on the market.
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