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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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3D Robotics

UAVs at the Smithsonian

Posted by Chris Anderson on February 27, 2009 at 3:15pm

From BoingBoing: "The Smithsonian's National Air and Space Museum has mounted a display of unmanned aerial vehicles, essentially model airplanes outfitted with GPS, microprocessors, and surveillance tech for battlefield reconnaissance. Seen here is a prototype of the 5 pound, 45-inch AeroVironment Dragon Eye. It was launched by hand or slingshot style with a bungee cord. From Smithsonian: Unmanned and remote-controlled aircraft have a surprisingly long history. "The technology that goes into a UAV has been around for 100 years," (museum curator Dik) Daso says, "since before World War I." Henry Ford and other top engineers helped to design both full-size and scale planes that were radio-controlled. The Great War ended before any of them could go into action. Now, Daso adds, "there are so many UAVs in the air, it's hard to keep track of them all..." So why did (Dragon Eye co-developer Rob Colbow) decide to include this duct-taped veteran in the UAV display? "I wanted it for all the kids who, like me, have built things like this." Worth reading the whole thing: Under the Radar with Unmanned Aerial Vehicles
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Merging devices: ArduPilot + OSD

Posted by Michal on February 27, 2009 at 5:46am
I am happy user of OSD by Remzibi and ArduPilot (though Ardu not tested yet).OSD comes with MTK 5Hz 5V GPS. Info about this GPS here.It would be very nice to have both devices sharing GPS. They should be set to 9600 and require additional cable. Both masses should be connected and signal cable should be plugged into GPS, OSD and ArduPilot via servo cable. I managed to get fix with blue LOCK LED. The example of working OSD:
.Next task is to connect software GPS emulator that comes with OSD to ArduPilot via OTI cable. Despite it is able to generate pure NMEA code, the fix LED in ArduPilot remain unlit now.I would like to test ArduPilot with this emulator and then make some trials with real models.Best regardsMichal
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3Ch plane, why not?

Posted by Roberto on February 26, 2009 at 4:00pm
The question is simple: why spend money on 4Ch plane, Co-Pilot & co??I want to try to setting up a 3Ch plane with ArduPilot, somebody have any experience?I choose the Multiplex EasyCub, 1400mm wing span.

2008070412050466965_easycub.jpg

Maybe I will use a yaw gyro to fix unwanted roll.
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Hexarotor, folding multirotor helicopter

Posted by jlcortex on February 26, 2009 at 2:00am

It is a folding 6 rotor helicopter, inspired in X6 helicopter.i would like to build in polyethylene technical plastic, it is light, shock resistant and easy to work with my cnc mill.propellers are in a circle of 500mm diameter, i think best option in order to use standard RC parts is to use 6 x 12" counter rotating propellers.3 (counter rotating) propeller of 12" have an 8% more surface than 4 propellers of 10" (like typical quadrotors)Probably 14" propellers are better in order to get more performance but i think is not possible to find very low Kv motors with the necessary low power and low weight.Any idea are welcome!jlcortexnmine.com

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3D Robotics

Getting ready for ArduPilot 2.0

Posted by Chris Anderson on February 25, 2009 at 11:00pm

ArduPilot 2.0 uses the same hardware as ArduPilot 1.0 but new software to do both the navigation and stabilization functions itself, with no need for a FMA Co-Pilot (although we still use the FMA XY sensor). Here's how to directly connect the FMA sensor to ArduPilot. [Note if you're buying the FMA XY sensor by itself, you'll need to order a cable, too. Also, note that the sensors come from FMA with a thin film (usually red) over the thermopile lenses. You have to remove the film before using them.] Cut one of the cables that comes with the FMA sensor in half and pull the four wires apart for about two inches. Strip their ends by about a quarter of an inch. Slip on heat shrink tubing. If you have some red tubing, put it on the second wire in from the side of the cable with the red strip, to mark the positive power cable (yes, that's confusing. V+ isn't the wire with the red strip--it's the wire next to it!). Now solder each pair of wires to a two-pin male machine pin header, and shrink the tubing around them. (See photo above). Now, solder on one two-hole female machine pin header to the ArduPilot board in the VCC and GND holes, and another one in holes Analog 0 and 1, as shown in the diagram below. You can see the FMA sensor pin-out details here. Finally, solder a regular two-pin header on the ArduPilot's D6 and D7 holes. This is to place a jumper on when you're doing IR calibration the first time on the ground.

Note that in this version of ArduPilot, we do altitude control with the elevator, not the throttle, so plug in your servos as shown in the diagram below:

You can test your sensor by downloading and running this simple test program. Just load it on ArduPilot (make sure the board is powered and the GPS is not connected). With the FTDI cable connected, click on the serial monitor icon in Arduino and make sure the speed is set for 9600. The program will prompt you to tilt the sensor in certain directions and then strike any key and hit return when you're ready to take the X and Y sensor readings. Remember that sensor readings inside and near heat sources (like your hand) are nothing like the real thing outside. But it's still a good way to confirm that your sensor is working right. Note that when you mount the sensor on your aircraft, the wire should be coming out towards the tail, as shown in the picture of an EasyStar configuration below (you don't need to put it on a pod like that--any position that has a relatively unubstructed view of all four sides is fine). The "P"s on the sensor should be facing forwards and towards the rear, with the one next to the FMA logo in front.

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