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FLY MARINES - Photo of Utah State TeamJoe Brennan, the competition director, has emailed me the results of the AUVSI student competition mentioned in the last post. After a lot of googling, I have discovered some of the UAV team websites. I've also included a link to each of the university websites. If any of these are missing or incorrect, let me know in the comments or PM me (little envelope) and I'll update it.Students searching for a college with an active UAS program should find this information useful.2008 AUVSI UAS Competition Results (listed in order of prize money won by each university)Mississippi State (UAS website, university website) – Wins $10,500 for First Prize Overall, First Place in Mission, 2nd in Orals and Journal, and Prize Barrels for Autonomous Mission Flight, Perfect Identification of the Off-Path Target, JAUS and Identification and Location of the Emergent TargetUtah State (UAS, university) – Wins $8,000 for 2nd Place Overall, 2nd Place in Mission, Honorable Mention in both Orals and Journal, and Prize Barrels for Autonomous Mission Flight, Autonomous Landing, JAUS and Perfect Identification of the Off-Path Target.University of Texas at Arlington (UAS, university) – Wins $5,250 for 3rd Place Overall, 3rd Place in Mission, 1st Place in Orals, 1st Place in Journal, and Prize Barrels for Automatic Takeoff and LandingUniversity of West Florida (UAS, university) – Wins $3,750 for 4th Place Overall, 4th Place in Mission, Honorable Mention in Journal and Orals, and the Safety Prize.Oakland (UAS, university) – Wins $3,600 for Honorable Mention in Mission, Orals and Journal, and three prize barrels for automatic takeoff, automatic landing, and JAUSNorth Carolina State (UAS, university) – Wins $2,750 for Tied for Second in Orals and 3rd Place in JournalUniversity of California at San Diego (UAS, university) – Wins $2,700 for Honorable Mention in Mission Performance and Journal and a Prize Barrel for Autonomous Mission FlightSherbrooke (university) – Wins $1,900 for Honorable Mention in Journals and Prize Barrel for automatic takeoffEmbry Riddle (Blackbird) (university) – Wins $1,900 for 4th Place in Journal and Honorable Mention in OralsUniversity of Manitoba (university) – Wins $1,800 for Honorable Mention in Mission Performance and a Prize Barrel for automatic takeoffEmbry-Riddle (SOAR) (university) – Wins $1,700 for Honorable Mention in Journal and a Prize Barrel for JAUSUniversity of Alberta (UAS, university) – Wins $500 for successfully flying at the competitionUCLA (UAS, university) – Wins $500 for successfully flying at the competition
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2008 AUVSI UAS Student Competition

The Sixth Annual Association for Unmanned Vehicle Systems International Unmanned Aerial Systems Competition was held on June 18-22, 2008 (see competition website).There hasn't been much buzz generated on the internet about the competition. However, one of the local Maryland newspapers has covered it.Student engineers send creations into aerial competition Webster Field hosts UAV contest
Students representing 16 colleges and universities gathered at Webster Field last week for the sixth annual Association for Unmanned Vehicle Systems International unmanned aerial systems competition.Joe Brannan, the competition’s director, said this year’s teams were among the best he’s seen since the event began in 2003.‘‘Both of the first two top finishing teams” in this year’s event, Brannan said, ‘‘were significantly better than I’ve ever seen” in past events.NAVAIR’s Program Executive Office-Weapons and AUVSI’s local Seafarers chapter co-host the annual competition.‘‘Northrop Grumman is our biggest supporter, with $10,000,” said Brannan, ‘‘with Boeing, Lockheed, The Patuxent Partnership and Johns Hopkins Applied Physics Lab each contributing $5,000.” More than a dozen other defense contractors also support the annual competition financially. This year’s competing teams were awarded a total of $44,850 in prize money.The college competitors must design and build an unmanned aerial vehicle that can be programmed to fly autonomously for a specified time over a specified area and, while airborne, locate and photograph targets on the ground below. When the aircraft lands, the digital information it captured during the flight is downloaded and analyzed.
See SoMdNews.Com for more.
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Arduino GPS shield with SD card logging.

I saw this yesterday over on the Make blog. Adafruit has come out with a new Arduino shield which looks excellent for UAV usage. The shield has support for several gps modules, and can log data to an SD card.

Even with the GPS and SD card, there are still 5 digital and 5 analog IO open.Here are the details(text below lifted from adafruit.com):GPS shield for Arduino kit with data-logging capability. After building this easy kit, you can create your own geo-locative project.This shield is designed to make GPS projects straight-forward and easy. Plug in a supported GPS module and run any of the example Arduino sketches for parsing GPS data (NMEA sentences), logging to a FAT16-formatted SD flash memory card and storing analog sensor data along with precise location, date and time in CSV format.The shield is designed specifically for use with the EM-406a module: the small surface-mount GPS connector is pre-soldered for you. (It is a high-quality engine with quick time-to-fix and excellent reception, even in downtown New York City!) It can also be used with a Tyco A1035D, EB-85A or Lassen IQ module (see the webpage for more details).GPS module, Arduino, and SD memory card are not included. Please check the parts list to see what is included. NG arduino users should probably also upgrade to an ATmega168.More Info
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Package galore, VPL, ideas, and thanks

No, i didn't look down, when i said that, i promise!

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Yeah, that was waiting for me when i got home friday night. I've been getting atleast a package a day now, with more to come.In one of those packages, was a box. In this box, from Electronics Goldmine, had this->

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I have never seen components used as stuffing before. I got a kick out of it so i took a pic. Yes, that box was FILLED with components. $5 too. I invited EVERYONE to get one because i've actually gotten some useful parts and headers out of that box. Saved me almost $20 already from going to radioshack:)OKay, now, for the project side...My Hawkings wifi adapter adapter arrived today, so, for the first time, i can go network on this bad boy. Ofcourse, there is nothing to really network it to....but that can change in the coming days hopefully!since i'm back home, and this project is now getting materials, i cleared off my workdesk of all my IBM R and T series parts. Also moved my twin Darth Maul Light Sabers, but they will be back when i take the picture. Due to the fact that this will now be a robotics desktop, my legos are there too, with my mindstorms in the top bin, and the bottom bin has the UAV parts.VPL programming is still in the learning phase. Every day i learn something new and useful. Today i learned that there is a Service that can receive and get messages from other windows programs. This is good because i wasn't too sure how to combine SPI/I2C code for the VTi borometer that just came in with the VPL code. I am realizing that i may have to run two programs side by side with the VPL code. The VPL will do the actual controlling of the UAV, in both the remote and autonomous functions, while the networking functions, such as video and data streaming, will be carried out by other programs, such as VLC and...well...i'll work on that...RoboRealm is looking kinda nice too. This, thus far, is kind of a map of what the data will look like, atleast coding wise, when it comes to sending and recieving data between programs

In order to keep the video in REALTIME, i may have to shrink them a bit, on the viewing end, although i will have full resolution recording on the PC end (i hope)One thing that disappointed me about VPL was that the service, although it uses DirectInput, doesn't care that i have many different POV hats and rotary controls. I was hoping to use the rotary controls that i have on the x45 for manual zoom and focus, although i was going to see if my focus can be automatic :). I am so tempted to just buy a camcorder, and tear it apart, as it may be 6 or more oz heavier, it will be sooooo much easier to control such things. Back to topic, one of the reasons i bought this particular joystick was that it was a programmable joystick that wasn't as expensive as the x52/pro. The keystroke/macro recording is VERY extensive, and talking to tech support, they prided themselves on that. It seems to work well, although, in aim, there was a split second delay on my main rig. I will try and see if this is a problem on the R 50eBeyond that issue, i will be attempting, before passing on the ball to one more skilled, to program a service for the Parallax Servo Controller. Trevor Taylor, on Microsoft Forums, has been most helpful in answering my questions and woes on VPL.Although this project is extensive, it is only so as i am playing to my strengths. These strengths are by no means limited to "personal" strengths. Most of my strengths are "resources" strengths, ie, my friends, supporters and advisers. I would like to thank my friend Bill Forde (NY) for his material support and coding help with explaining things i did not get and freely helping me with code i could not write on my own. I would like to thank my friend Mark Krieger (TX) for freely sharing is PIC, electronic engineering, and sensor coding help and moral support. Finally, when he has the freedom to work on the C# code with me and the Flash GUI, i would like that thank Roman (NY, Sony Brook University), who will be a partner in this as Software Lead Engineer :). Of course, thank you to the DIYDrones community members, such as Chris Anderson, Howard Gordon, and others like chopsuey for encouragement, support, and ideas.Right now, coding is primary. I can't build until i get the plane and that is about a week away. Hopefully, i can get everything talking to one another before it gets here. once i do that, its calibration. After that is done, its test flight. Oh that reminds me...i have a 54" emergency parachute coming to me. lol, yeah, i have no faith in myself...
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3D Robotics

[NOTE/UPDATE: All the below, from long ago, has been superseded by events. Basic ArduPilot proved capable of every this described here, so we cancelled this version of the product. Thinking about what the next version of ArduPilot could be can be found here. ]

Our main entry-level ArduPilot is designed to be simple, easy to use, and cheap so it just does navigation and leaves stabilization to an stand-alone FMA Co-Pilot with infrared ("thermopile") sensors. But you can tell by our release of our own IR sensor boards the other week, the ultimate aim of this project has been to release a more advanced version that does it all: navigation + stabilization in one. But a standard Arduino isn't powerful enough for all that. So what's the solution?

A dual-core Arduino! So here it is: ArduPilot Pro, with two Arduinos, a MUX/failsafe and built-in GPS onboard. Jordi's design incorporates everything you need for a fully-functioning autopilot, with a target price of under $100, including GPS and thermopile sensors. One ATMega168 processor handles stabilization and the other handles navigation, but because they talk to each other, you get a fully-integrated autopilot, with control over all aircraft channels.

We could have just switched to a much more powerful processor, but that would have cost more, be harder to program and wouldn't benefit from the easy-to-use IDE and the software libraries available for the fantastic open-source Arduino project. The downside of doing it as a dual-core board is that we have to program each Atmega168 processor, as well as the MUX's ATTiny processor, separately, which is why there are three ICSP ports on the board. But in the commercial version, which will come with all processors pre-programmed, there will be little need to fiddle with the stabilization and MUX code, so they can be treated as black-box hardware. (The ICSP ports are just there for anybody who wants to fiddle with them anyway.)

We haven't tested this one yet, so we're not quite ready to provide a link to buy the board. But the Eagle 5 files for the schematic and board are here and here.

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3D Robotics

The problem with neural networks

This, from the always interesting Jack Crossfire blog, is the smartest observation on neural networks and genetic algorithms I've seen in ages. Excerpt: "In our last experience with neural network feedback, the feedback always headed towards 0. That one used straight back propagation to predict cyclic from attitude change. That fiasco has cursed all future investments in the radically different genetic approach. The genetic approach would constantly evaluate the attitude tracking & standardize networks which track better. How do U keep it from forgetting high wind feedback when evolving in low wind?" To repeat: How do you keep it from forgetting high-wind feedback when evolving in low wind? As humans, we solve this with a mix of short term and long term memory. Do we need to create an analog in neural computing to avoid the problem Jack rightly spots?
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3D Robotics

CropCam user pushes for FAA exemptions

Farmer Uses Unmanned Eye in the Sky to Maximize Crops Idaho Business Review (06/23/08) (Excerpt, thanks to the AUVSI news roundup, follows): Kendrick, Idaho, farmer Robert Blair is heading the campaign to revamp agricultural information collection. Utilizing Unmanned Aerial Systems (UAS), Blair has been able to map, track, and study his fields with superior precision. The UAS employed by Blair is known as the CropCam, and has the appearance of a model airplane, with an eight-foot wingspan and a length of four feet. It is battery-fueled, weighs six pounds, and flies at an altitude of between 400 and 2,000 feet, at a maximum speed of 60 mph. It can be configured to fly a particular route on autopilot or under manual control, and is able to cover over 640 acres in around 25 minutes. The UAS is outfitted with a high-resolution camera and sends the data right to Blair's computer for evaluation. The photos he has taken have allowed Blair to look at elk herd damage to his crops and, employing color spectrum overlays, discover precisely which areas require more or less water or fertilizer. Having such in-depth and timely information helped Blair to better manage his crops and saved him more than $50,000 in 2007, he states. Presently, the U.S. Federal Aviation Administration (FAA) mandates civilian, commercial UAS operators to acquire a Certificate of Authorization for public use, a pilot's license with an instrument rating, and a tail number for the vehicle. Blair would like an exemption to the rules for natural resource management and new UAS rules that more closely match the standards overseeing model airplanes. With help from Congressman Bill Sali (R-Idaho), Blair got several members of Congress to sign and submit a letter to the FAA, asking them to include representatives from natural resource management industries on the agency's rulemaking advisory committee. The committee is working on new regulations for UASs, and Mike Fergus, FAA spokesman for the northwest mountain region, says the process has only just begun. Tom Curtin, Ph.D., chief knowledge officer of the Association for Unmanned Vehicle Systems International (AUVSI), says his organization has a seat at the table, and hopes the committee will eventually hand down a set of regulations that benefit operators like Blair. "[AUVSI wants] sensible rules that are going to allow unmanned aircraft to be integrated into the national airspace," he says. "And sensible to me means starting with the easy stuff," such as agriculture, forest fires and border control.
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First boot, and first problems lol

My computer has booted up, and is running Win2000 (ram restrictions made it the OS of choice, XP can be used, but maybe later, and with some trimming) and i will be working on servo control and figuring out why my usb decided to reboot the computer when i plugged in the Parallax Servo Controller. Yeah, i'm having issues with the drivers as the Boser site doesn't seem to like linking things. I have a picture of first boot i need to upload on photobucket, as well as a picture of the computer. I was trying to wait on the last of the parts to come in and be soldered on/connected, but i feel like my posts are worthless without pics .

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By a show of hands, how many people will laugh at me when this thing crashes?Anyways, Boser linked me to the drivers today and i am installing them now. Shame on me for not bringing more stuff on my 3 day disappearance from my nomral world. It took 3 computers to get this stuff on the HS-2605 because i didn't bring cables for my Compact Flash card reader. When i get servo control working, we'll see what happens next.I spent last night installing digital night vision in my friend's car, so i spent the day sleeping on and off, which is why i haven't been answering comments and questions. Same stuff is going into my plane. Firefox 3.0 became my favorite browser a second ago. i wrote a long response for you guys to my last blog post and my laptop shut down. Then i went to my other laptop, which had this blog on it, and it had been overheating, so i had to restart it. I thought i lost both posts. Firefox said "Think agian!"
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Materials list and basic Plan of Action

In one fell swoop i've bought almost everything i need for this project. Hoorah! This means its time to post because, well, too many people are in the dark. Since i already did the Goals List in the last one, this will be the materials listThis plane will use solid wireless broadband to accomplish the goals of flight control uplink and video and sensor output downlink There will be no receiver. The reason for this is that i will be well out of range of most, if not all radio transmitters. If it fails, i do have a failsafe "come home" signal, emergency drop zones, and an emergency parachute that will be separate from the wifi, but i do need these options explored further.Ground station-Hardware*R50e Laptop- Basically my spare laptop. It needs some love. That and its usb ports work lol.*Saitek x45 Joystick- Call me the Mad Hatter. mucho Hats= mucho control for my cameras!*Buffalo WHR-HP-54G loaded with DD-WRT and some sort of directional antenna that is TBD- This model was picked as not only did it have hte best range of all the DD-WRT models, but it did it at a high bandwidth with the built in amp! overclocked, pumped up with power, and full bandwidth dedicated to one purpose: data between the R50e and the Predator. Should get a minimum of 1000 feet of high bandwidth (esp since those are stock numbers) and a max of 2-3 miles. The Direction antenna will post likely have stepper motors on it to control where it is pointing.Software*VLC- have to. I am torn between having the onboard Boser HS-2605 just streaming the video, or having it do all the preprocessing and it streaming just the desktop and me using Remote Desktop, Maxivista, or the like.*Joystick2mouse3.0- does as the name suggests. Allows you to control while a bit of the joystick's functions and map them to keys. This is just so i don't have to do additional programming; i'd rather someone else do it ;)*My stuff- whatever God forced me to program, or in other words, forced me to ask a friend to do it lol.*Firefox 3.0- I think that, if i do it just streaming video, i will do a flash and java/C++/C# based webpage.Possible problems?*Video Latency- hopefully solved due to such a powerful router*Me sucking- generally solved by me asking someone else to help*Lost connection- to be solved by the HS-2605 monitoring the tx/rx of the wifi. If i do get out of range, a simple program to tell it to come back into range (come Home) is all that is necessary. "Home" will have a GPS location to it that will be updated every 10 seconds. I will also try to use a parachute where, if connection is completely lost, or there is a catastrophic failure, it is given several "safety zones" where it flys down to about 80 ft, kills power, and depolys a parachute. I will retrieve it from there.UAVHardware*Boser HS 2605- Via processor, 256 ram, PC104 goodies. this is what is the brains of the UAV operation*Jupiter JMM-512- This PC104 vechicle power supply can take a wide range of voltages and also has a +/- 12 and 5V outputs. Pumps out 50W of power.*Sensoray 311M Framegrabber- This PC104 frame grabber will be what is getting the camera feed. If i can get VLC to interface with this, all is good. Does 30fps with one camera, 15-8 with 2. Since i will be having two, i will be giving one high priority and the other low priority and switching between the two as neccessary, ie, if i tell hte plane to circle an area, i do not need to get a "realtime" feed of the FPV, but i would like a nice realtime view of the panoramic. The SDK allows for this. Another thing the SDK allows for is image scaling.*Parallax USB servo Control- From the computer, this sucker gets all the info it needs to guide the plane*FMA Co pilot 4 w/interface cable- To do all the cool things Chris said it can do and make life easierHawkings HUWG1 USB wireless adatper- picked SOLELY for the extremal removable antenna, all in a USB stick module. Range is exceptional. Hopefully the gain will be too*GM-11 GPS (magnetic mount removed)- GPS. nothing more i can say.*VTI SCP1000 MEMs Barometric Pressure Sensor- for an altimeter.*Ultrasonic Range Finder - Maxbotix LV-EZ0- So someone once said that take offs were not currently possible with the software and abilities. At some point, i want to change that :) I figured giving the plane the ability to see objects in its path up to 255 inches would be a good thing.*Sony SUPERHASS CCD and Computer (Some crazy number wiht AMS at the end, i'll read it later)- wiht manual zoom and focus, and the JMM512, i hope to power this camera lens and use it to spy at the ground belowSoftwareAUTOPILOTVLCRobo control (or whatever else parallax has for free on their site)FirefoxThe interface thing for the Co PilotGPS softwareMSRS
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3D Robotics
Cool news from Microsoft: its Google Earth competitor, Virtual Earth, is now accepting user-generated aerial imagery. Unlike Google Earth, where your own data can only be superimposed on the "real" Google Earth data, and people will only see it if they use a special URL, Microsoft is offering to integrate user-submitted data in the core data set. For DIY Drones and our RC aerial photography cousins, that means a great way to share our imagery in a maps context that can be appreciated by everyone, not just those with special software and the right URL. Here's an excerpt from the Virtual Earth blog: What’s the process for getting my data in VE? · First, evaluate whether your imagery enhances our currently available data by seeing what we have online at http://maps.live.com. If your imagery is newer and has higher resolution than what we have online, then we should talk. So, · Send us an email at GoVE@microsoft.com and tell us what you have. If we’re not planning an update on that area in the next few months, there’s a good chance we’re interested. If so, we’ll send you a copy of our specification. · Review the spec against your data and send us a short summary of the exceptions. Many times we can work around small exceptions to the spec, so send us an email and we’ll see what we can do. We may need a data sample . If the imagery meets the spec, we’ll send you a data release. · Sign the data release and return it to us. The terms of our release are non-negotiable because we have thousands of data sets in VE and we must treat all of our data sources equally. The data release gives us the right to publish your data under the standard terms of our VE portal. · Contact us for delivery logistics. We’ve found it easiest to put the data on an external hard drive and ship it. When we receive it, we’ll put it in the queue for processing and mosaicking, ingesting and incorporating into the next release. How long does it take for my data to show up in VE? It depends upon many factors, including the amount of pre-processing, custom tiling, timing of the next release, other data in the queue, etc. Typically, from the time we receive the data, it takes from 1-3 months for the data to be published online. Can I provide partial updates to the imagery? We prefer data updates in larger chunks, since each update requires edge-matching to the existing online imagery. However, if special circumstances arise where a partial update is merited, we’ll work with you to accomplish this. How will you use my data? Virtual Earth provides free, open access to imagery, maps, points of interest, business listings, etc. Most of our web site viewers use the site and it’s location awareness tools (search, driving directions, imagery , etc.) to get more information on their local environment. The public web site is free. Your data would become part of the Virtual Earth API which developers can leverage in creating their own web sites. Will you give us credits for the use of our imagery? As a rule of thumb, yes. VE seeks to provides credits and attribution for all of our data sources, and we’ll strive to do the same for your data. However, in some cases, there can be as many as 5-7 data sources on the screen at once, so we sometimes have to pare the credits down to the top sources on the page to avoid onscreen “credit clutter.” If you're interested in sharing your imagery with the Virtual Earth platform, let me know or send mail to GoVE@microsoft.com.
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BlimpDuino home page

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BlimpDuino is a very low cost open source autonomous blimp. It consists of an Arduino-based blimp controller board with on-board infrared and ultrasonic sensors and an interface for an optional RC mode, a simple gondola with two vectoring (tilting) differential thrusters, and ground-based infrared beacon.

It is available as a commercial kit from the Maker Shed or the DIY Drones store for $89.


[UPDATE: The current Blimpduino kit has been discontinued. Stay tuned for a new design in 2012]

  • What else you'll need
  • Instructions for making the kit are here.
  • Instructions for loading the code are here
  • Correct LED/servo/motor behavior modes are here
  • Instructions for using Blimpduino are here
  • The parts list is here
  • The discussion forum for teams using Blimpduino in the FIRST Robotics aerial robotics demonstration is here
  • If you want to build your own board from scratch, the necessary files and component lists are here
  • If you want to print out a cool DIY Drones sticker like the blimp above has, here's a pdf.

 


3689304786?profile=original


The Blimpduino board is the core of the kit. Features:

* 17 grams, with ultrasonic and IR sensors.
* Controls two motors and one vectoring servo.
* Built-in RC compatibility (can read two RC channels--throttle and steering)
* Designed for a 7.4v LiPo battery; has an automatic power cut-off at low voltage to protect the battery.

Here's the board with the ultrasonic sensor removed, so you can see the Atmega168 processor underneath it:

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Here is a video of BlimpDuino in flight, using a breadboard version of the controller board:


At the moment, we're using Pololu IR beacons as the ground beacon, but we'll eventually release our own, open source, versions of them, too.

Here's the board on the gondola with vectoring thrusters and the optional RC receiver:

3689304811?profile=original


The commercial kit consists of the following:

--BlimpDuino board, with all SMD parts already soldered on
--Other through-hole components, to be soldered by user (easy)
--A very simple laser-cut plastic platform for the board, battery, optional RC receiver, and motor components
--A servo, gears and motor shaft for the vectoring (thrust tilting) function
--Two motors and props
--One IR ground beacon
--52" mylar envelope


The following is a chronological list of posts describing the development of the project. This is mostly for those who want to follow along and learn about Arduino-based robotics. If you're interested in autonomous blimp development and want to know more about BlimpDuino features, they will give you some insight into the evolution of this project.


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3D Robotics

ArduPilot Pro home page

[UPDATE Jan, 2009: The description below is our original conception of ArduPilot Pro. However, we were able to achieve all of these features with the basic ArduPilot, so we are now reconsidering what additional features to add to a future dual-core ArduPilot. Things we are considering include SD-card datalogging and on-screen displays for first-person view flying. In the meantime, the below is provided as a reference platform for a dual-core Arduino-compatible autopilot, but should not be viewed as a forthcoming product as described here.] ArduPilot Pro is a low-cost, full-function autopilot based on the open source Arduino platform. It incorporates two Atmega 168 processors (for navigation and stabilization) and one ATTiny45 processor (for the failsafe) onto one board, along with a GPS module. It has all the functionality of the basic ArduPilot, but includes its own thermopile sensors and processing so it does not require a third-party stabilization unit. The thermopile sensors are on two daughterboards, one with four sensors for X-Y axis stabilization, and the other with two sensors along the z axis for calibration and upright/inverted orientation. These are modeled after the open source Paparazzi sensors. ArduPilot Pro will eventually be available as a commercial kit. At the moment it is a development project with the aim of going into beta in mid-2009. Basics:
  • If you want to build your own, the necessary files and component lists are here.
  • Autopilot code (for the board's two main processors, Atmega168s) is in development and will be posted here.
  • Latest multiplexer code (for the board's third processor, an Attiny, which runs the failsafe system) is here. (If all you want is to load our code, rather than modify it, just use AVR Studio to burn the antifail_system.hex file in the Default folder to the Attiny chip)
The following is a chronological list of posts describing the development of the project. Unless you're very keen to get started on this before it's released as a commercial project, we do not recommend that you order these boards, since they're sure to have some bugs. But if you're interested in autopilot development and want to know more about ArduPilot features, they will give you some insight into the evolution of this project.
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Is GPS good enough for altitude hold?

In our quest to create the simplest and cheapest autopilot available, we're debating whether we need a barometric pressure sensor or can do reasonable altitude control with GPS alone. The old answer to this was the GPS alone wouldn't work--not only were errors of as much as 10s of meters, but glitching could leave you without any altitude data at all for many seconds at a time. But the newer SiRF III chipsets are much better at altitude calculation, and the even newer yet uBlox5 GPS module is almost as good as a pressure sensor at altitude (it's too expensive for our purposes, but a glimpse of the way things are going). So let's look at that question agan: do we need a pressure sensor? The way to tell is to test a pressure sensor head-to-head against GPS under varying condition. Here's a paper that did just that, using the older (and worse) SiRF II chipset. A sample of the data is the graph above, which as you can see shows errors of as much as 60m in some cases. Needless to say, that would be unusable. (It turns out that many of those errors were due to GPS lag, and shifting the GPS line forward by 13 seconds improves the fit considerably. But if you're trying to fly on that data, you're stuck in real time, so those sort of corrections don't help.) Jack Crossfire has been testing more modern GPSs, including both the SiRF III-based EM406 that we use and the uBlox5, and his data is more encouraging. A sample post on EM406 data is here, and a chart from that post follows:

Unfortunately this isn't calibrated so there are no units on the scale, and we can't calculate the absolute error. (Jack, any chance you still have that data and can oblige?). But given that the data was taken in a heli and he's probably flying at around 30m, my sense is that we're looking at errors of less than 6m and no crazy glitches. If so, that's within the usable range for us. We're typically looking at holding altitude around 50-100m, so single-digit variation is acceptable. It's not perfect, but doing without a pressure sensor would save us about $25 on the autopilot (keeping it below the magic $100 figure), and simplify calibration and instrument-compartment design (no need to pressure-isolate it). I've got a pressure sensor coming and will do a proper head-to-head with the EM406 and the surface-mount EM312 (which will be built in to the autopilot on the production version) under various conditions before making the final decision, but for now we're betting on GPS being good enough (and getting better) to do the trick. Anybody disagree?
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XBee price increase

XBee Pros have been raised from $32 to $36. Feel like a fool for not buying more at $32, although the direct store still has some. Still have 2 $32 modules from last year. The higher priced model is the XBee ZB ZigBee PRO Series 2 supporting "more dense mesh networks". Maybe it even has Techron to clean your speed controller.In 5 years these obsolete modules will be $65. Should buy some paperclips. The next bull market is paperclips I tell U.The good news is a new 900Mhz module has appeared in the XBee form factor & all the way down to $75. Instead of upgrading those obsolete 2.4Ghz cameras to 900Mhz, could get 900Mhz XBee's for data & save a ton of money.

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3D Robotics

Review: new Arduino Nano board

Gravitech has now released a new Arduino board, the Nano ($49.99), which I think is the best one yet. I just got one, and have had a chance to compare it with the two other breadboardable Arduino options: the Stamp (AKA Mini) ($37.95--also requires a $20.99 USB board for most programming applications) and the Boarduino ($17.50 for kit, requires soldering and a $20 FTDI cable for programming).

First, the headline news: the Nano pretty much blows the Arduino Stamp/Mini away, and I would expect it to replace the Stamp in the marketplace. In most prototyping applications, a Stamp by itself is not enough--you also need the USB board, and together they are about $10 more expensive and 30% larger than the Nano (which has USB built in). The Nano also has a physical reset button and automatic hardware reset when uploading new code, while on the Stamp you have to connect another wire to get that and there is no reset button. Here are all of the Nano's technical specs and features.

The Nano also has a number of advantages compared to the Boarduino, although it's more expensive. Aside from being about half the size, it has the aforementioned automatic reset when uploading code, while the Boarduino, which uses the FTDI cable instead, requires a manual reset [UPDATE: see comments for some clarification on this]. It's also got two more analog input pins, thanks the surface-mount ATMega168 chip having more pins than Boarduino's DIP version.

As it happens, we still prefer the Boarduino in a few cases (and not just because we use its parts to make our ArduPilot and BlimpDuino kits). For certain low-power applications, such as our BlimpDuino, you want to run the ATMega at a lower clock speed than the usual 16Mhz, so in those cases you'll want to make the crystal removable. (Typically we'll put the crystal in to program the chip, then remove it to run at the lower speed). That's not possible with either the Nano or the Stamp.

Here they are all together on a breadboard for size comparison (click for larger version):

Finally, a point about breadboardable Arduino boards vs. stand-alone dev boards like the Decimila and its mini "proto shield" breadboard. The Decimila is a nice and compact combination of an Arduino, power supply and breakout connectors for the pins, but the tiny breadboard that fits on the proto shield is too small but all but the simplest projects.

For most projects I prefer to use a breadboardable Arduino with a proper full-size dev breadboard (I use a Parallax professional development board, which has loads of useful features and goodies but is too expensive if you're not planning to use Basic Stamps, too). The one shown above, for instance, is being used to prototype RC mode for our blimp controller, which is way too many wires for the little Decimila breadboard. My advice is to get a full-sized breadboard and power supply and use the Arduino Nano. I think it's the best version of the Arduino currently available.

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