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3D Robotics

ArduPilot code now in beta!

Posted by Chris Anderson on December 29, 2008 at 7:37am
Jordi's finished the first beta of ArduPilot, in anticipation of the board's commercial release. Changes and improvements include:
  • The code is now hosted in a proper code repository (Google Code) for version control and to allow others to contribute to the project. You can find it here.
  • RTL (return to launch) and waypoint modes are user selectable
  • Waypoints have altitude as well as lat/lon
  • GPS parser now returned to ASCII NMEA, for compatibility with any GPS module, 1Hz or 5Hz. Very efficient code will allow it to run at any baud speed the module can support.
  • PID loops used in all control functions
  • Lots of bug fixes and error-trapping inserted
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3D Robotics

Test flying an EasyStar with EasyGlider wings

Posted by Chris Anderson on December 28, 2008 at 11:00pm

After testing the new 4-channel EasyGlider Pro and finding it a great flier but without as much internal space as our beloved 3-channel EasyStar, people suggested I just modify some EasyGlider wings (which have ailerons) and use them on the EasyStar. So I did that. It was a pretty easy mod--you just have to carve off a little foam from the Easy Glider wings and thread a aileron servo y-adapter through the EasyStar's existing servo holes. How does it fly? Just so-so (see video). It's slower, which is nice, but because the body is now too short for the wings (in aerodynamic terms, the plane is now "short-coupled"), the elevator control is too twitchy and it tends to wheel about the sky a bit. Also, the ailerons tend to create as much drag as they do banking power, so turns can quickly devolve into a wing-over dive. (Ailerons also tend to be pretty ineffective at slow speed, which is often the case with gliders) I'm sure I can fix this with differential throw on the ailerons (make them go down more than they go up) and limiting the throw of the elevator a bit more. But the truth is that both the EasyGlider and an unmodified EasyStar fly better than the hybrid of the two. I'm going to stick with this frankenplane and tweak it to fly better, since I need a beater aircraft I can use for UAV and sensor tests at the park. But I doubt it will ever become my preferred UAV platform for standard use.
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My Initial UAV Project Proposal

Posted by Jeremy on December 28, 2008 at 9:00pm
Hello all,This is my debut to the site and I will try to continue to post throughout the development of my project. I am a senior in Computer Engineering and for my senior design I have chosen to make a fully autonomous aircraft. I have no experience in flying rc airplanes but I just have extreme interest in airplanes. I have three other team mates (1 computer engineer, and 2 electrical engineers). For the last month, I have been researching rc aircrafts and devices that I will need to use to make my autonomous flight successful.My intent is for the airplane to take off, navigate to gps coordinates, either record video for a specific duration of time or take pictures, then return and land.Another team tried making one of these in the spring of 2008 but not with such high goals. They completed building but were not successful because interference from the microcontroller was preventing the transmitter from having full control.Based off my initial research, these are some things I will have to use:• Spread Spectrum Transmitter/Receiver to eliminate the microcontroller from interfering with manual control• GPS receiver to specify current position and altitude (heard mixed things about gps’s altitude measurement)• A two axis tilt sensor (Looking for one that does 360 degrees)• A SD card to store and retrieve all information on flight and camera output.I have been debating my choice in rc airplane. I heard multiplex has good material for crashing and easy repair. I would really like to use either the predator or a jet design but I have a hard time figuring out how much thrust and extra space models have. As far as thrust goes, I wanted to use ducted fans but I have no idea if this is a “no-no”. I say this because I haven’t seen any other experiments with them. From what I have read, they are better at high speeds but cause a lot of drag at low speeds. The team from last year used a Multiplex Easy Glider Electric. Any suggestions!???A few ideas that I was playing with:• I would like to sensor the battery life with the microcontroller to see if each flight is can be done• Even further if I can somehow make a base where it the plane easily taxi to and charge its battery without human intervention• Retractable landing gear (probably would have to buy the plane like this)• Send information wirelessly when in reach (either though Wi-Fi or Bluetooth• Object avoidance using RF signalsAs you can see, I have ran away with the idea of this project. I am open to all opinions, questions, comments, and random rants. I really need people to challenge my ideas. Thanks and FIRE AWAY!View my next project update HERE.
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A Loaded Question (I think)

Posted by Paul Marsh on December 27, 2008 at 6:41pm
I am curious to know how members of this community got to where you are with regard to knowledge of controllers and the associated programming. I have been reading this site for weeks, have gone through much of the Paparazzi site and am getting overwhelmed with just where to begin to learn; or more precisely, where to go from here. It's all a little haphazard and disjointed. I even downloaded the Basic Stamp training materials and worked through the exercises (mentally, at least).I can't believe that everyone here is an engineer who just happens to specialize in controllers, so just how have you become so knowledgeable? Where did you begin? What process got you from knowing very little to being able to write code for an autopilot? It almost feels like cheating, now, to go with a plug-and-play autopilot. I really would like to learn the hardware and software, but I'm not getting far on my own.Any suggestions will be greatly appreciated.Thanks,Paul
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Maiden flight of "The Kodel": autopilot-to-be

Posted by Koen Delvaux on December 27, 2008 at 9:06am
Today my autopilot hardware took the sky for the first time. Although this maiden flight was successful, its only a first step.

The primary goal of the test was to see if the autopilot failsafe mechanisms operated fine:- no lockup on division by zero- instant regain of control after brown-out causing reboot- no lock on uncaught interrupts- handover to servo failsafe positions on RC reception lost- instant regain of control when RC signal returns- no erroneous lockups in main state machine when rebooting whilst in flightAll mechanisms operated fine and none where triggered during normal flight. This proves the autopilot is a stable and reliable platform for airborne operation.Built in mixer test.The autopilot has a built in mixer. On first use you need to tell the autopilot what the channel and mixer arrangement of your transmitter/airplane combination is. To put the autopilot in calibration mode, switch on the transmitter, put all sticks in the center and switch channel 6 to "ON". Now turn on the airplane.At this point you can calibrate the autopilot by putting all sticks in the center and subsequently actuating the aileron stick from full left to full right and back to center, followed by elevator (fullup, then down, then center), rudder (left, right, center) and throttle (zero throttle, max throttle, center). The autopilot will confirm completion of the procedure by turning the rudder full left, then full right and then back to center. From this moment on, you can operate the airplane with the controls as normal, but the calibration values are not saved yet.The last step in calibration is to calibrate the IR sensor for horizon detection. You do this by holding the plane level (or even better: flying it, turn down the throttle and trim for a best glide scope) and switching channel 6 to "OFF". At this moment, calibration values for the transmitter arrangement and the IR sensor are saved to the permanent memory of the autopilot.When you now fly the plane and engage autopilot mode, the autopilot uses the same channel mix,offset and endpoint adjustment as you programmed in your transmitter.This all works fine. When you switch to manual control, channels are passed transparently. This also works fine.Only when using part automatic / part manual control (like when using the autopilot for stabilization alone and operating rudder/throttle manually), the manual controls don't have the same midpoint and endpoint settings than when in manual mode. This still needs to be looked into.I would like some feedback on the first-use calibration procedure. Do you think it is valuable to have support for random channel assignments/mixes/atv/trims? Do you feel the initial calibration procedure it too complicated?
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SkySailor - 27 hours autonomous flight

Posted by fom on December 26, 2008 at 4:34pm
I came across a nice project for those interested using some solar power for their UAV. It appears that this relatively small plane was able to fly autonomously for more than 27 hours over 874 km (in big circle, but still...).http://robotics.ethz.ch/projects/sky-sailor/http://robotics.ethz.ch/projects/sky-sailor/docs/SkySailor27hFlight-21June2008.pdfhttp://asl.epfl.ch/aslInternalWeb/ASL/publications/uploadedFiles/FSR05_Sky-Sailor.pdf
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3D Robotics

Arduino debugging tips

Posted by Chris Anderson on December 26, 2008 at 3:00pm

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If you're trying to upload code with Arduino and you get an error message that looks something like this:
"Problem uploading code.....

avrdude: stk500_getsync(): not in sync: resp=0x78
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x78"

(or any other error report when uploading code, aside from the obvious ones like compile errors or choosing the wrong serial port)

Here are the most common causes and things to check.

  1. Did you check the "Set RTS on close" box in the Windows Com port, as instructed in the manual?
  2. Are you selecting the right board? For ArduPilotMega, if your board uses an ATMega1280 processor (the big chip on the APM board will say "ATmega1280") select "Arduino Mega (Atmega1280)". If you've got an ATMega2560 chip, select "Arduino Mega 2560". For the original ArduPilot and ArduIMU, choose "Arduino Duemilanove".
  3. Is the cable plugged into a USB hub? That can sometimes cause trouble. Try plugging it straight into your PC.
  4. Are you using the latest FTDI drivers? Install them if not. If you're still having trouble, try reinstalling them.
  5. Check your solder joints! It's a good idea to reheat and reflow all of the ones you did, just to be sure.
  6. Other errors that have caused this problem in the past include a power source (such as your ESC) that is putting out a voltage outside the acceptable range of 4-7v, faulty USB or FTDI cables, and corrupted FTDI drivers. When in doubt, try a different power source, a different cable or a different PC.

Additional things to check if you're using the original ArduPilot board (not ArduPilotMega):

  1. [For original ArduPilot board only] Is your FTDI cable plugged in the right way? The black wire or side marked "black" should be on ArduPilot's BLK pin.
  2. [For original ArduPilot board only] Are you using the DIYDrones or Adafruit FTDI cable? We've had trouble with other ones...
  3. [For original ArduPilot board only] Is the ArduPilot board powered on, ideally through your RC system or ESC? (You can NOT power it from the FTDI cable; this is a safety measure to avoid power conflicts.)

If those all look fine and you're still getting the error message (especially if you can successfully load code to other Arduino boards), you may have a corrupted FTDI driver or a bad FTDI cable. Try reinstalling on another PC and see if that does the trick. If it doesn't, you may need a replacement FTDI cable.

In some rare cases, a power glitch may have resulted in a corrupted ArduPilot bootloader on the ATMega chip. This tutorial will show you how to reload the bootloader. (Warning--for experts only and requires an AVR programmer. This should not be necessary for most people.)

Other problems can include "Serial port not found" (just check that you've selected the right serial port in the Tools menu. It's the one assigned when you first plugged in the FTDI cable--probably 5 or higher), and the Arduino IDE freezing (try unplugging the FTDI cable. If that doesn't work, just reboot your computer).
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3D Robotics

Original DIY Drones UAV projects

Posted by Chris Anderson on December 24, 2008 at 2:00pm
These are projects from 2007 and early 2008 that were a lot of fun to do and are still worth checking out for UAV ideas. There is also a PDF/poster that shows how they compare to military and commercial drones.

GeoCrawler 1 (Based on a LEGO Mindstorms autopilot)

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GeoCrawler 2 (Based on a cellphone autopilot.)


Viking1

GeoCrawler 3 (Based on a custom BASIC Stamp embedded processor autopilot)


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GeoCrawler 4 (Predator airframe and AttoPilot autopilot)
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Reading PWM from a receiver

Posted by James Holbrook on December 23, 2008 at 11:30am
Hey all.I know this subject has been covered in many ways, but I am hoping that someone can assist me. I hope someone can have the patience to answer a few of my VERY NEWB questions.What I am trying to do is to send PWM to an arduino on an air vehicle which will then send the appropriate servo controls. Simple enough some may say, but I am in a bind since I just cannot get my head wrapped around this and frankly, I think my research has gotten me confused.My BASIC NEED is to be able to see the pulsewidth values in Milliseconds or in PWM values on Serial Monitor and see the values change as the sticks and knobs are moved.I know some may say, why not just use RC to control the servos without the Arduino? The answer to that is that I want to eventually turn control over to the Arduino like in ArduPilot, and use the Arduino as an IMU sort of. The ArduPilot code has been interesting to analyze but I have not gotten closer to my VERY BASIC need. Being able to look at the ArduPilot Pro code would likely be a very good insight......but that is not available to my knowledge.I have tried ServoDecode, ServoTimer2 and SerialServer libraries and I can capture the PPM for the channels alright on Pin 8, but it does not show me the changes to the pulsewidth when the sticks are moved. I thought I might have what I needed by downloading Chris' RCTest code but since I don't want to move anything like motors for thrust or vectoring and tried to uncomment the Servo stuff it doesn't do anything. When I compile it and run, it does nothing. It just sits there and the servos just jitter and sometimes go to extreme lock..I just need to see the pulsewidths and move SERVOS accordingly.. Jordi in his thread to Hack a receiver was a good piece of code, but the next file he released to read the PPM just displays a scattered array of numbers that don't relate to anything. In that code, and in finding the PPM string I get a value that goes like 214567. Is this a MicroSecond value and how could one convert this to a Milli-Second value? Multiply by 1000?Thanks to all in advance for any help or direction you may send my way.Happy Holidays to all.Jim
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Interesting 900MHz radio

Posted by Howard Gordon on December 22, 2008 at 1:30pm
Take a look at http://www.avalanwireless.com/product_list.htm. Click on OEM Radio Modules and check out the AW900mSPI.The AW900m is a 900MHz digital radio with lots of range and throughput - 1.54Mbps radio channel with 900-1100kbps delivered. SPI/UART version will retail for $129 per card. These look really good - I should have a couple of modules shortly and will report on performance. The UART version is actually designated AW900mUART.
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3D Robotics

How to program the Attiny on ArduPilot

Posted by Chris Anderson on December 22, 2008 at 11:30am

To load the failsafe firmware on ArduPilot's Attiny chip, you need to do the following. 1) You'll need an ICSP AVR programmer. We recommend AVRSIP2. Connect the cable to the correct ICSP port on your board, as shown above. The red stripe on the cable should be on the same side of the connector as the square solder pad on the back of the board. (On our boards that means that the red strip is on the side closest to the processor) 2) Now you'll need to change (turn off) one of the default "fuse" settings in the Attiny45, which divides the internal clock by 8 so it only runs at 1 Mhz. (Explanation of all that and more about fuses are in the excellent Sparkfun tutorial here). Run the AVR Studio program that came with the AVRSIP2 programmer. Ensure that the board is powered on by connecting it to an ESC or other power source! The red LED on the board should be on. 3) To change the fuse with AVR Studio, connect the programmer and go to Tools/Program AVR/Connect. Choose AVRISP mkII. You may get an error (choose cancel). On the "Main" tab of the dialog, click the "Settings" button and pick 125khz and click "Write". Then make sure "Device" is Attiny45 and "Read signature". At the bottom it should say that all's okay. If so, switch to "Fuses" tab and uncheck CKDIV8. Press "Progam", then "Verify" to make sure it's woking. [Note for those who are curious: the AVR programmer can only work at 1/4 of the clock speed of the chip. The Attiny ships with a 8Mhz internal clock, but when that DIV8 fuse is set it's only running at 1Mhz, so the programmer must be running at less than 250khz. Once you clear that fuse and the chip is running at full speed, the programmer can run at 2Mhz, which is 1/4 of 8Mhz]. Your processor is working fine and ready to program. 4) Now you'll need to burn the firmware. Still in the AVR Studio dialog box you used above, go to the Program tab. Where it says "Flash", input our firmware hex file. If you've already downloaded it in some folder, you can select that here. If not, switch to your browser and download this file. Click "Program". All should go well and you'll see the OKs below. If you want to make sure it's working, you can click "Verify". Now you can go back to the "Main" tab and change the Settings to 2Mhz. That's it! The failsafe should be working now. Connect the CTRL lead to channel 5 or 6 of your RC receiver and power on the ArduPilot board. When you toggle that channel a red LED should go on and off on the ArduPilot board, indicating that control of the output channels is being switched from the RC receiver to the autopilot or vice versa. For extra fun, toggle it back and forth fast five times. That should reset the autopilot (for in-air recovery).
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3D Robotics

New ArduPilot MUX code

Posted by Chris Anderson on December 21, 2008 at 9:10pm
We fixed some bugs in the ArduPilot's failsafe code, which runs on the board's second processor, an Attiny45. It now works great, and has a secret "reboot the autopilot" feature. Just toggle the autopilot enable switch on your transmitter five times fast, and it will reset the Atmega168. Great for times when you don't want to land just because a random bug froze the autopilot. Otherwise it just does what it's supposed to do: transfer control from RC to autopilot and back again on command--every time, without fail. The new code (source and everything) is here. If all you want is the hex file to load on the Attiny in AVR Studio, it's here.
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3D Robotics

Day two at DIY Drones HQ--success!

Posted by Chris Anderson on December 21, 2008 at 9:00pm

Jordi came over today and finished up the work on ArduPilot and the second simulator. He caught a lot of bugs that had been bedeviling us, especially unintended crosstalk between the main autopilot processor (the atmega168) and the failsafe processor (the attiny45) that made it impossible to load code when one or the other was on. All fixed now: it was a code error, not a problem with the hardware. The new MUX code is here. The ArduPilot code is still in alpha but we should be able to release it in a few days. But the important news is that the boards have checked out fine. You know what that means? GREEN LIGHT TO PRODUCTION! The picture above is the final version. The countdown to commerical release starts now. Stay tuned....
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Prototype of "The Kodel": a minimalistic PIC microcontroller based autopilot

Posted by Koen Delvaux on December 21, 2008 at 4:59am
I have been working on/off on an autopilot to use in RC airplanes. The goal is to fully automatically take pictures of an object like a house, construction site, etc.I made the hardware in last year's Christmas holiday. During the year I spend a few hours writing the embedded software for it (in C, works much faster then assembly).The hardware is super low cost: The PIC dsPIC30f4012 is very cheap and still has enough memory and speed (30 MIPS) to be self sufficient autopilot.

The goal for this Christmas holiday is to do in flight testing of the hardware and stabilization routines.
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Hi - My interest till now has been building scale RC aircraft. Lately I see that it is possible to be able to view the world from the rc aircraft, I can build a drone but it is dumb. I need to start l

Posted by Tack on December 20, 2008 at 11:32pm
Hi - My interest till now has been building scale RC aircraft. Lately I see that it is possible to be able to view the world from the rc aircraft, I can build a drone but it is dumb. I need to start looking at what equipment is required to be able to pilot the aircraft out of sight.Can any body help with where I would go to start to collect this information on the web? Not being an electronics person is a bit of a hindrance but I can learn. Any help appreciated.Thanks
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