I have finished my Master's Degree, and so I have to return all of the planes and paparazzi hardware which the school bought for my project. So I have begun working on my next project. So far I have purchased a cheap ($100 receiver ready + 2 free lipos!) 2 meter electric glider from Hobby City so that I can continue to fly. If it has enough space in the fuselage, then I may add an autopilot to it later. The glider will keep me flying, so my thumbs won't get too rusty.I am planning to rebuild my little ground robot, and I am going to give it a 6 DOF IMU. I found that Pololu(also available from sparkfun for similar price) sells a triple axis accelerometer for only $18 and 300deg/s gyros for only $29. So I can build a full 6 DOF IMU for only $110. So I have ordered 3 of the gyros and the accelerometer, and I am planning to build the IMU and run it on my little ground robot for a while until I have the IMU figured out. I am planning to use an arduino to process the IMU data.
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I think for the hobbyist, the only real choice is an open source autopilot. Unfortunately with a closed source solution, you are stuck with the feature set that the developer wants you to have. Another major advantage of open source autopilots is that reading the source code is a valuable learning, and troubleshooting tool. Even if you never intend to modify the code, just being able to look at it can be enough to resolve a problem.In my personal opinion, the Paparazzi project is the best hobby autopilot. At the hobby level, no closed source(or open source) project can match the coding resources the Paparazzi project has. The Paparazzi project has a long list of features which are only matched by expensive proprietary autopilots. Want a camera, multiple UAVs, video, full featured ground station(with integrated real time video if you want), telemetry, powerful flight plans, to control a quadcopter? You can do all of this and more with Paparazzi.What are the technical requirements?I added a technical requirements post for UAVs in general here. The only thing you need to add to that list is some decent Ubuntu Linux ability. If you are halfway competent with windows you will be just fine. My father has been using Ubuntu exclusively for months now, and he is doing fine. He can barely even delete folders, and his first successful download in the short time he had Vista was spyware pretending to be antivirus.How long does it typically take to get it working?It took me a few months working off and on. It takes a while to fully get a handle on all the parts. You ARE going to bang your head on the wall a bit. I also spent about two days building the wiring harness. The molex picoblade connectors are a pain. Tip from me: buy the precrimped wires.What are the real costs, all included?Expect to spend around $600 for autopilot with telemetry. excluding RC Plane and laptopYou will need:The autopilot: Tiny V2.11 Comes with integratedGPS(Get the LEA-4P model, since the GPS is easier to deal with)Vertical IR SensorHorizontal IR SensorSee the Get Hardware page on the wiki for parts sources. Do not buy any parts from Halfbase.com, or you will most likely lose your money.I recommend using the Xbee Pro modems, it is pretty easy to get them working.For airborne, part number: XBP24-AWI-001 ← OEM module with whip antennaFor ground, part number: XBP24-PKC-001-UA ← This one has a nice aluminum enclosure for your ground station which will keep your modem alive longer.These are the 2.4ghz modems, if you have 2.4ghz video on your plane you can get xbee in 900mhz.Start with a slow and stable plane, and you will have an easier time and will not need to add a rate gyro on the roll axis.Where's the best place to get started?The best place to get started is on the Paparazzi wiki. The wiki can be hard to understand at times, but bear with it. If you find a problem, make some edits please.Go to the site map link on the wiki, and read EVERY page on the site map. It is a pain to read the whole thing, but it will help you a lot.Next download and install the paparazzi software, and simulate some flights, and play with the flight plans.Once you have done that, then I would purchase the hardware.What's the best place to turn to for help?1.The wiki2.The mailing list (don't forget to search the list archives)3.This big nasty thread on rcgroups (don't forget the thread search tool)The normal rules for getting help online apply: Show what you have tried to solve your problem, and use a descriptive title.Whew! You still with me? Paparazzi is not easy, but it is rewarding. Anyhow if you wanted easy, you would not be wanting to build your own UAV. It is a lot of hard work no matter what autopilot you choose, but it is extremely rewarding when you are standing in a field watching your plane fly around with no input from you.
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I made this non exhaustive list of skills which are nice to have if you want to build your own UAV.I think a basic handle on all of these skills will greatly help anyone who wants to build a UAV. If you want to build a UAV, and lack a lot of these skills, don't take this to mean you cannot do it, just understand the magnitude of the difficulty, and be prepared to press on in the face of adversity and to teach yourself a lot. When I decided to build a UAV, I had never even flown an RC plane or even been to a flying field. I had to learn all of the RC skills first. So, you can do it too, if you don't give up.Programming>Experience with C>Able to compile software>Can program embedded systems>Know how to find the appropriate resources for support (forums, mailing lists, wikis, etc.)Radio Control Aircraft>Be able to take off and land with confidence>Be able to fly simple patterns>Understand model aircraft setup>Be able to make simple repairs to model aircraft>Be familiar with tools and techniques used for model aircraft>Understand the care and usage of lithium polymer batteries>Be a member of the Academy of Model Aeronautics (For access to certain flying fields)Electronic>Familiar with embedded systems>Know how to interface electronic components to micro controllers>Be able to locate, read, and understand data sheets>Know how to troubleshoot electronic systems>Understand signal timing>Be able to solder small components and wires>Be able to fabricate wiring harness>Be able to read schematicsControl Theory>Understand PID controlGeneral>Able to learn without guidance>Strong ability to troubleshoot systems
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I am happy to report that I have installed the paparazzi autopilot in one of my airframes and have done some ground testing. So far the results are positive. The telemetry works well (at short range at least), and the aircraft reports proper position and attitude. When the aircraft is held at an angle, the control surfaces move to compensate, and the behavior of the control surfaces looks correct.In the picture below, all of the autopilot system except for the radio modem can be seen.
In this view of the fuselage interior, the radio modem is visble.
This is a detail shot of the installation of the horizontal infrared sensor.
This is a detail shot of the installed vertical IR sensor.
And finally, a shot of the interior of an RC reciever that has been hacked to output the PPM signal on the channel 8 PWM pin. The cut trace to channel 8 is hidden by the capacitor.
I have a bit more ground testing and configuration to complete, and this plane will be ready to fly.
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Lithium Polymer batteries are an attractive power source for electric flight due to their high energy density. The combination of lithium polymer batteries and brushless motors now rivals glow power in terms of power and duration.The main difficulty when using lithium polymer batteries is choosing what batteries and charger to use. Batteries are specified in terms of voltage, capacity, and discharge rating.Voltage is generally listed as 1S - 6S. The S number refers to the number of cells connected in series that the pack uses. You can calculate the nominal (mostly discharged) voltage by multiplying the S number by 3.7 volts, so a 3S pack has a nominal voltage rating of 11.1 volts. Fully charged, each lipoly cell will measure 4.2 volts, so a fully charged 3S pack will have measure 12.6 volts.Capacity is measured in Milliamp Hours (mAh). So for example a 2000 mAh 1S pack can be expected to provide a voltage of 3.7 volts at a current of 2000 mA (2 amps) for 1 hour. In a nutshell, more mAh is better (and heavier).One of the more confusing specifications is the C rating. The C rating refers to the maximum sustained discharge rate that the battery can tolerate. The formula is 1/C hours. In the example above where we discharge our 2000mAh 1S pack using a 2amp load for one hour, we are discharging it at 1C. If that pack is rated for 20C, we could discharge it in 3 minutes (1 hour / 20C = 60 min / 20 = 3 minutes) with a load of 40amps (20C * 2000mAh = 20 * 2A = 40A). As I understand it, lipo packs should be charged at a maximum of 1C; so 2 amps maximum charge current for the pack in the example above.The main drawbacks to lipoly batteries are cost and sensitivity to abuse. Now your pack may not burst into tears if you insult its paternal lineage, but it may explosively combust if charged improperly or if it becomes damaged. See here, and here for examples of lipo combustion.I personally use, and recommend using a balance charger, and battery packs that have a balance connector. I would not use any batteries that did not have a balance connector. I use the IMAX B5 charger, which can balance charge up to a 5S pack, and will refuse to charge unless it determines that the battery is connected properly and is of the correct type.
I also use 20C rated packs with JST style connectors(see photo below).
I have found that HobbyCity.com has excellent prices and quick shipping(from Hong Kong).Also PLEASE READ the sticky post about Lithium Polymer batteries on rcgroups for much more in depth (and accurate?) information about the care and feeding of Lipo batteries.Happy flying!
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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 InfoRead more…
This is a mini review of the Hobbico NexStarEP RTF. It currently costs $399 from tower hobbies There is a much more detailed review of the model here at rcgroups.com. That review is from a pure RC perspective. I am writing this to highlight the UAV friendly features of the NexStar.I took the plane for her maiden flight last Sunday at a local field. I had an instructor to help me fly since I am new to RC(keep this in mind as you read this review). This is the only RC plane I have ever flown.The features that make this plane a good platform for a UAV are the following:Size: The plane has a 68" wingspan, and weighs about 7lbs, so the plane is less affected by the wind. The size and weight were beneficial during the maiden flight since the winds were about 10mph with 15mph gusts. The experienced RC pilots were impressed by the stability of the plane in the wind.Stability control: The plane includes speed brake flaps, and airfoil extensions at the wingtips. It also features the Futaba PA-2 stability control system, so a simple GPS and rudder control only UAV can be built..
The PA-2 sensor is visible on the bottom right of the picture.Interior: The plane has ample space inside the fuselage for mounting electronics. It should be no problem to mount a flight computer and sensors inside the fuselage.
Complete package: The plane comes with everything needed to fly except batteries and a charger.Flight duration: The plane will easily fly for 15 minutes with a 5s 5000mAh lipo pack.The package also includes a stripped down version of the RealFlight RC flight simulator, so you can practice flying at home using the actual transmitter. The simulator practice was particularly helpful for me, since once the instructor got the plane into the air, I was able to fly it with ease even with the strong wind(we flew with the PA-2 disabled).Total cost for a flight ready plane with batteries and charger was approximately $650. So with $350 for electronics, you can build a sub $1k UAV with this plane.I am very pleased with this airframe, and I feel that it will make a fine UAV platform.Cory
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I am working on using flight gear to simulate and test my UAV code. The screen shot shows flight gear and the C# application that is receiving the data. the way I see it, the first step is to read some data out of flight gear. I am using a TCP socket to read the data. I have achieved display of the raw string of data. My next step will be to parse the data into meaningful bits. I have been looking all over the net for information on using flight gear for UAV simulation. I haven't found anything I can use, so I am trying the roll your own approach. The idea is to be able to run my own control algorithms on live flight gear data.Let me know in the comments if you know of any prior work that I could use to facilitate this.
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here are two notes below that describe the fantastic video demonstration of the MIT Autonomous Airplane Indoor Flying test. Keep your eye on this page for more info in the future."In these flight tests, a fixed vertical landing platform was designed and attached to a concrete pole in the middle of the RAVEN flight space to allow the fixed-wing aircraft to land and perch on the pole. This test is similar to the test performed on January 28th, 2007 except in this test the platform was attached to the wall. This test was repeated number of times and a video shows repeating the vehicle take-off, hover and land sequence twice. In this flight test, the aircraft took off from the vertical landing apparatus and autonomously moved to a location in the northeastern area of the room in the hover configuration. Once the vehicle reached this location, the vehicle was commanded to transition to level flight mode and flew 3 laps around the room. These three laps were completed in about 10 secs (since the vehicle was flying at approx. 6 m/s during the flight). Following the laps, the system commanded the vehicle to transition back to the hover mode and once it stablized itself began its decent to attempt a landing on the vertical landing apparatus. Note that room is approx 8 meters wide."I found this post on DailyDiy.comThe site is fantastic. It is impressive work.
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I went to the AUVSI (Association for Unmanned Vehicle Systems International) conference In Washington DC from Febraury 27-29. Each day focused on a different type of unmanned system. The first day was exclusively ground systems, the second day was maritime systems and the third day was air systems.For the most part, the presentations were military related. One point that was repeated again and again during all three days was the need for integration and interoperability. The military wants systems that can work easily with other systems, and they are pushing for the development of standards. They want standard controls, interfaces, and procedures for unmanned systems, so that soldiers do not need to be retrained for each system.
The picture above is BAI Aerosystems EVOLUTION_XTS. It is an ~8lb aircraft. It has a modular design, the nose and wings detach quickly. It fits in a large backpack, and can be launched by hand, bungee cord, or with a rifle style pneumatic launcher.
These are commercial automated pilot systems made by Athena Controls. The small orange object on the bottom left is a starburst candy included for scale.
