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Phase 1 - Define the goals of your UAV project

Posted by xn2001 on May 26, 2009 at 9:30pm
Goals:-I want my UAV to be able to go from point A to point B, take a picture, go back to point A and then land safely.-My UAV should be built using the cheapest commercial available products and the total cost should not exceed 1000$.-I'm giving myself no more than a year to complete this project.List of my skills:Update: 2009-05-27: Thanks to David for pointing out the excellent article of Cory about the list of skills set which are nice to have if you want to build your own UAV.Here are the skills that I think I have.ProgrammingExperience with CAble to compile softwareCan program embedded systems - NoKnow how to find the appropriate resources for support (forums, mailing lists, wikis, etc.)Radio Control AircraftBe able to take off and land with confidence - NoBe able to fly simple patterns - NoUnderstand model aircraft setup - NoBe able to make simple repairs to model aircraft - NoBe familiar with tools and techniques used for model aircraft - NoUnderstand the care and usage of lithium polymer batteries - NoBe a member of the Academy of Model Aeronautics (For access to certain flying fields) - NoElectronicFamiliar with embedded systems - NoKnow how to interface electronic components to micro controllers - NoBe able to locate, read, and understand data sheetsKnow how to troubleshoot electronic systems - NoUnderstand signal timing - NoBe able to solder small components and wiresBe able to fabricate wiring harnessBe able to read schematicsControl TheoryUnderstand PID control - NoGeneralAble to learn without guidanceStrong ability to troubleshoot systems
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Picoc notes or "don't use assert in autopilots"

Posted by Jack Crossfire on May 26, 2009 at 10:30am
Integrated picoc as a runtime thread in VicaCopter. The current version locks up, it doesn't do floating point, it crashes your entire autopilot when it encounters an internal error, but after working around all the problems, managed to get some nifty flights out of it.It's like turtle graphics with a very very expensive turtle. U can build up incredibly complex flights out of reusable maneuvers. U can repeat maneuvers. U can nest maneuvers in maneuvers.Ironically, picoc was written to fly airplanes but its author never flew it in an airplane. His only application was that Surveyor rover.The lack of floating point means we can only do relative waypoints & no latitude & longitude.

That was a 15m altitude change & 2 pirouettes in picoc.

That was the cross mission & 2 circuits in picoc.

That was 4 orbits with the nose pointing in different directions in picoc. Impossible with tables of waypoints.It locks up if you forget a comma in an argument list. Don't use "assert" in programs which are intended to fly things. Run it in a thread so if it locks up, it doesn't crash you. A floating point trig library would be nice.
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T3

PicPilot + Ardupilot Ground Station

Posted by Brian Wolfe on May 25, 2009 at 10:21pm
I got the Radio Interface running today and am talking thru the XBee radio to the Ardupilot ground station. I'm not sending all the data yet, but most of it. That's my house down there!

That just leaves the SD card as the last bit of hardware to validate. I'll probably wait a bit on that and focus on getting the magnetometer integrated with the attitude estimator. Then I think I'll put it on an RC car and tool around to collect some data. I need to start thinking about what plane/helicopter to put it on first so I can start down the stabilization/navigation path.Power Supplies - workingProcessor - working12 bit AD - workingGyros - workingAccelerometers - workingAirspeed Sensor - workingUSB - workingAltitude Sensor - workingMagnetometer - workingGPS Interface - workingRF Interface - workingCurrent Monitor - workingVoltage Monitor - workingSD Card - Not DoneServo Outputs - workingPWM In - working
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T3

Pic32 Autopilot Progress.

Posted by Brian Wolfe on May 25, 2009 at 12:00am

Got the Altitude sensor working (BMP085). This graph shows the responds from holding the autopilot near the roof then lowering it to the floor, then back again. All in all about 8 ft. A little noisy, but not too bad. I haven't attempted any filtering of the data yet.

This graph shows the accelerometer data as I hand held it and did several rotations about the roll and pitch axis.

This plot shows the noise floor of the IDG500 and LISY300AL. The LISY300 is a little quieter, but not by a whole lot. For the most part I'm happy with the performance of the IDG500. Check out the video of the Attitude Estimator if you haven't already.I also got the PWM inputs done for measuring the pulses from the RC Receiver. Here is a quick rundown of status.Power Supplies - workingProcessor - working12 bit AD - workingGyros - workingAccelerometers - workingAirspeed Sensor - workingUSB - workingAltitude Sensor - workingMagnetometer - workingGPS Interface - workingRF Interface - Not DoneCurrent Monitor - workingVoltage Monitor - workingSD Card - Not DoneServo Outputs - workingPWM In - workingI'll get the RF Interface running tomorrow and start sending messages to the ArduPilot ground station. After that I need to finish up on processing the magnetometer to give a heading for removing drift in the Yaw axis of the Attitude Estimator, then it's time to start looking for an airframe to install the autopilot in and begin the stabilization process.Regards,Brian
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3D Robotics

A better failsafe: one fifth the size, one fifth the price

Posted by Chris Anderson on May 24, 2009 at 11:00pm

The more we get into the RC world, the more we're shocked by how overpriced and underpowered a lot of RC equipment is. Most of the specialty electronics, from ESCs to servo amplifiers, are just cheap PIC chips with a few support components. The parts cost a few dollars, but the completed boards often sell for as much as ten times that A good example is the failsafe/multiplexer ("MUX"), which allows you to switch between two inputs for RC control (in our case, that would be RC or autopilot control). The main one on the market is the RxMUX, which costs $79 (shown below).

We thought we could do better. So Jordi created the DIY Drones Failsafe/MUX (shown at the top of the page), which uses the same Attiny45 and multiplexer as ArduPilot. Ours is $16.90, and is literally both one-fifth the size and one-fifth the price as the RxMUX. It also includes all sorts of other goodies, such as recognizing the middle position of a three-position switch and having a programmable signal-loss behavior. Plus it's open source, so you can do anything you want to the code. Our failsafe/MUX is four channels, rather than eight (everyone preferred the smaller one and thought four channels was enough) but if you want an eight channnel one like RxMUX we can make it for you easily for about the same price. Here are the two side-by-side, with a 9V battery for scale.

What else can we take 80% of the cost and size out of?
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Developer

Unofficial ArduPilot 2.2 Release

Posted by Jordi Muñoz on May 23, 2009 at 8:30pm
This version has many additions, including the support for three different GPS protocols (SIRF, NMEA and UBX) and can be added as many are possible.Has the well integration of the pressure sensor and battery level conversion with an offset for the ADC voltage to increase accuracy in the conversions.Has been debugged using the ArduPilot Shield. So it should be 100% compatible.The rest of the code stills the same as 2.1.To change the GPS protocol looks for this definition: “#define GPS_PROTOCOL“. Next to it I have included some commands for Locosys and SIRF GPS. So you can use them as needed (just trying to save you some time).The Ground Station now has the battery level indicator.This code is a just a Beta, demo, preview, not official release , I never air test it (use it at your own risk). The goal is that you can start digging into it and report any bugs before releasing the official version. We are only trying to involve more the community on this. ;-)Be advice is not easy!Other notes:When you power up the ArduPilot try to open the Terminal and see the message at the beginning saying something likes this:"Pressure offset: 205"You should go and place this value in the declaration of the air_speed_bias variable, like this:int air_speed_bias=205;In order to zero the airspeed sensor. All the pressure sensors have different values.I know "bias" is wrong. ;-)Files:ArduPilot_EasyStar_V22.zipGroundStation_Alpha2.zip[UPDATE: I forgot to compile the EXE, sorry about that]:GroundStation_Alpha2_EXE.zip
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GPS Problem

Posted by LazyPilot on May 23, 2009 at 1:00pm
Guys,I was out test flying my project today. Came home, wanted to run some ground tests, found my GPS will not lock and I get no red indicator on the GPS. I know it should indicate lock and blinking red when working properly. Any Ideas?? Im powering the system off a 2.4 spektrum rec. Im running a 3 cell Lipo to the Parkzone ESC. any problems with that??After getting the unit back inside, I can tell the Red LED on the GPS is very dim. Its trying to come on but not really. I think something has decided to not work anymore. any ideas??
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Rudder deflection and Roll cross-coupling control in ardupilot?

Posted by Todd Berk on May 23, 2009 at 11:34am
How is the cross-coupling between Rudder and Roll being controlled in the ArduPilot since there are no ailerons? I'm doing some autopilot research for my Parkzone Radian, similar to the EasyStar in that there are no ailerons. Basically, a simple PID loop for heading by actuating the rudder won't work since you will impose roll and sideslip. What is the ArduPilots method for heading and roll control?Thanks!-Todd
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Simulation

Posted by sushil pangeni on May 23, 2009 at 10:14am
I am trying to make an autonomous UAV controller using the UAV-GPS dev board. I want to ask whether there is any simulation system where i can simulate my codes.
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3D Robotics

200 Blimpduino boards, programmed and tested

Posted by Chris Anderson on May 22, 2009 at 10:31pm

Just finished programming and testing 200 Blimpduino boards. Jordi wrote me a batch file that made it easy. Only one board blew up in my hand, sending sparks everywhere (I think a polarized capacitor was on backwards). All the other boards tested fine. The kits will ship from the Maker Shed on Monday, and will be for sale at Maker Faire. They'll be in the DIY Drones store in late June, when we manufacture the next batch.
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Software based horizon finder for SRV-1 Blackfin camera

Posted by Howard Gordon on May 22, 2009 at 3:16pm
Here's an updated version of the software-based horizon finder for SRV-1 Blackfin. An actual slope and intercept is now being computed, and some filtering has been added as well ...Here was the original post ...
Noting the interesting discussion about optical flow and horizon finders in this thread, I undertook to add a simple horizon finder to the SRV-1 Blackfin Camera firmware. The algorithm uses a basic edge detection function that is already build into the SRV-1, dividing the image into 16 columns and searching from top-to-bottom for first edge hits. From the video, it appears that the edge threshold could be set a bit lower, but the results are pretty good without any tuning or filtering.The Google Code project is here - http://code.google.com/p/surveyor-srv1-firmware/ . Next step is to add a least-squares fit to draw a line through the edge segments and then compute pitch and roll angles.
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Civilian UAVs: the new barbarians

Posted by Mike on May 22, 2009 at 2:24pm
“The FAA wants us to show these things are safe, but they make it difficult to fly them to collect the information needed to prove they are safe,” says Massood Towhidnejad, a professor of computer and software engineering at Florida’s Embry-Riddle Aeronautical University who studies potential UAV applications. Source: Unmanned Traffic Jam, To the Federal Aviation Administration, civilian UAVs are the new barbarians at the gate. By Douglas Gantenbein, Air & Space Magazine, July 01, 2009.
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Modeling the brushless motor

Posted by Tom Yochum on May 22, 2009 at 7:52am
I am trying to put together a Simulink 6-DOF model of a complete UAV. I have the aerodynamic data for the Rascal UAV from this paper. The only thing left to model is the electric motor. I need to create a model that takes in the throttle setting and outputs the current draw, rotation speed, and motor torque. I found some papers on the math of an AC motor, but I couldn't make heads or tails of it. Does anyone know of a good paper that outlines the math? Or better yet, a free Matlab or Simulink model?Thanks.
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Groundstation Display Suggestions?

Posted by Garry Qualls on May 21, 2009 at 11:20pm
Tablet PCDoes anyone have a computer display that they are happy with when they are outdoors? I am looking for a laptop, tablet, netbook, or stand-alone monitor that has even barely acceptable contrast and readability outside in the sun.The iPhone and iPod Touch have transflective screens (320x480 px resolution) that work pretty well in direct sunlight, so I was hoping someone had put a similar display into a larger system. There are VNC clients around for the iPhone, but that's not really a satisfactory solution, no matter how much fun it would be to try.Otherwise, I think it would be smart to have a high contrast mode or "skin" for the ground station software that would allow for safer and easier operation by displaying graphics in a more or less a black & white mode with no important information represented by color, gradients, etc. in this vein, some kind of e-paper solution like they have in the Kindle would be pretty awesome.MacBook running XP Has anyone had a good experience outdoors with a computer display?
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Purchase list

Posted by Bryan on May 21, 2009 at 11:00pm
I have no idea what I'm doing at this point. Here's the list of stuff I got, just based on the ArduPilot:https://www.sparkfun.com/commerce/product_info.php?products_id=8785https://www.sparkfun.com/commerce/product_info.php?products_id=465https://www.sparkfun.com/commerce/product_info.php?products_id=9115https://www.sparkfun.com/commerce/product_info.php?products_id=116https://www.sparkfun.com/commerce/product_info.php?products_id=117https://www.sparkfun.com/commerce/product_info.php?products_id=743https://www.sparkfun.com/commerce/product_info.php?products_id=7915http://store.diydrones.com/ProductDetails.asp?ProductCode=BR-0002-10Got a breadboard and wires from Radioshack to help with prototyping. Still need the FMA X-Y sensor, and possibly a Z sensor, but I'm a n00b, and not quite sure what I need at this point.Also need to find some foam to build the airframe, electric motors and metal gear servos.
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