Blogs

Sounds good, price good, specs good but not much interaction from the designer, who doesn't seem to correspond well.

Actually I'm not even sure it is legitimate, correct me if I'm wrong?

http://www.rcgroups.com/forums/showthread.php?t=1455433

I've modified Phillip Anthony Smith's Mavlink Ardustation to support an inexpensive tilt/pan antenna platform. RAM is very tight in the software so this is not a laptop/ground station replacement and the original software was oriented towards APM. However, I've been flying many flights with Arducopter 2.0.x and this antenna and have gotten pretty good video performance with much less multipath interference. I still use a second Xbee on a notebook with the Mission Planner and that seems to work pretty well with the Ardustation. This link gives some more details, a demo video of the software with some explanation of the added screens, and the software itself for others to play with. The software is a little rough since it was developed quickly before the 4th of July weekend, but it is fun to watch the antenna follow the quad and I wanted to give a little back to the Arducopter community.

The stock skyfun platform is pretty good, but as a lot of people have pointed out, the power system is barely enough for our needs by the time you add a few goodies on.
There is lots of info on the web about motor upgrades for the Skyfun but most of the motor upgrades published on the net are all about speed. I wanted my Skyfun to have enough power to lift all the extra weight, but then to be able to settle down to a slow and efficient cruise speed to maximise the amount of time in the air. That means means going for a slow turning large prop. Finding info on this sort of upgrade is next to impossible. 

Lets start with the airframe:

I took a stock RTF Skyfun, removed all those hideous decals and then set about applying Gaffa tape to all of the vulnerable surfaces. This has already proven its worth during my initial testing as I had a high speed collision with a power poll with practically no damage. Gaffa is quite heavy, but it is incredibly strong and prevents the foam from tearing. Applying it to any part of the airframe where torn foam is possible reduces damage considerably. The tape can then be removed and easily replaced after an 'incident'..

After multiple failed canopy gluing attemps, I have also applied a thin strip of Gaffa tape around the edge of the canopy to keep the plastic on, which has proven effective. The canopy now feels very sturdy.

I'm using the stock servos, they seem fine for the task as it is not going to be a high speed machine.
RC equipment was upgraded to a 9ch JR PCM system.

Mounted just behind the receiver is a keyring video camera, I set it into a hole in the fuse at a 45 degree angle. This gives a great view and has the advantage of being closer to the CG for maximum stability and does not result in any part of the aircraft obscuring the picture.
I chose to mount the camera upside down so that the USB cable can be inserted into the camera (from the bottom) without needing to dismount the camera, it also allows easy access to the camera controls. The downside is that the image is upside down, but this can easily be flipped on a PC later.

I spent a lot of time on motor research and determined I needed the biggest prop I could spin at the slowest speed possible in order to gain maximum thrust and low speed efficiency. I settled on a Rimfire 400. Specs are below..

Model: RimFire 400 (GPMG4560)
Diameter: 28mm (1.1in)
Length: 30mm (1.2in)
kV 950
Constant Watts: 160w
Burst Watts: 220w
Weight: 54g (1.9oz)
Shaft: 3mm (0.12in)
Voltage: 2-3S LiPo
Airframe: Up to 1kg
ESC: 25 Amp
Prop: 8x6 to 10x4.5(slow fly)

I decided to run with a 10x4.5 slow fly prop, however a prop this big is wider than the distance between the two vertical stabilizers. This requires reversing the motor, pushing the shaft through to the opposite end and drilling some holes in the motor mount in order to attach the motor to the back of the mount. Doing so clears the back of the stabilisers by 8mm.

Next came the battery, I wanted to be able to cruise for at least 30 minutes and my rough calculations indicated this would require at least a 3000mAh battery. I settled on a DN 3300 30C pack. In my first few flights with this I have achieved 35 minutes and 37 minutes respectively without much consideration for efficiency. I think this can be extended further by reducing airspeed.

A battery pack this large would normally have to be seated well towards the back of the cockpit, this would have meant mounting the APM in front of the battery, something I really wasn't too keen to do. A battery this big in a crash would completely destroy anything in front of it (APM). My camera, receiver and APM were already consuming most of the back of the cockpit and putting a battery this large at the front of the plane shifted the CG too far forward.

I opted for belly mounting the battery, bomb style. This proved to be very useful as it allowed the CG to be easily shifted by quite large amounts without running into any obstacles. It also keeps the CG very low which has improved stability noticeably. It now flies more like a high wing trainer.

At the moment it is being held by industrial Velcro, however my next upgrade is to install a Velcro strap through the fuse for additional safety.

The only downside is that it exposes the battery, particularly on hard landings. I couldn't see an easy way around this that would maintain CG flexibility and didn't add a lot more weight, so I opted for sponge foam with gaffa tape over it along the bottom of the battery. I will review this after a few more flights to see how it goes but so far if I'm careful with landings its fine. If it looks like the battery is wearing too hard, then I will add some more rigid protection. Long term I will probably build some form of capsule underneath for at least the front of the battery to slot into. Most of my landings are in long grass so isn't an issue. 

Total weight including the battery is now 900 grams which is under my target of 1kg. I have yet to measure the thrust from the motor, but at full throttle it achieves a slow vertical climb so it must be slightly higher than 900 grams.

The next step is establishing the slowest speed I can possibly fly so I can figure out how long I can stay in the air for. I would be very happy if I could get it closer to a 45 minute flight.

OK, OK, technically this is the second  flight..  First flight is here: http://youtu.be/0yKjbtFW-u4  ; I just like the second video better.

The vertical instability was caused by me not having the throttle curve set right on the Transmitter; by default it is just a straight line from 0 to 100. Setting the throttle curve to something more curvy makes it much more stable up and down.

Took me a while to get back to this, mostly because I was waiting for a  replacement motor installed after a brief but terminal "magic smoke event".

Thought I also needed a new ESC, but found a post here (http://diydrones.com/profiles/blogs/one-esc-is-not-like-the-others) which set me straight.

Spent a bunch of time at the workbench running through things, including

• pretty much all of the RC inputs need to be reversed for me (JR790)
• you really do need to arm the motors before anything happens; it is amazing how much time you will spend trying to figure why nothing is going on (but see previous point as to why I may have been having difficulty.
• taping and wrapping connections, I'm toying with the idea of heat-shrinking the motor wires to the end of the arm:

Next steps:

• Wrap the remaining motor wires
• Replace nylon screws with metal ones 
• Add XBee modules to airframe
• lots and lots of flying

Anyway, that's enough for now -- I'm off to fly some more...

The PPM Encoder team has been working on a new servo input to ppm firmware for the PhoneDrone board and any future boards using the ATmega32u2 chip.

Since there has been reports of problems with the old APM firmware (PPM encoder problem, loosing CH3 again with new APM board) when used together with receivers that has synchronous changes on multiple servo channels. So Olivier ADLER and me decided to back port the new atmega32u2 firmware to the ATmega328p chip used in APM boards.

We now feel that the new and hopefully improved firmware is ready for public beta testing. Source code and compiled firmware are available in the official APM repository (Unified ArduCoder). Please read the readme.txt carefully before usage and report any problems.

Future updates for the new firmware will have PPM pass-trough for receivers with PPM output and also possibly native support for Spektrum satellite receivers.

Happy flying!

For those of you with 3D printers, here's a file on Thingiverse that will let you print out a tricopter tail motor mount. The description is in Japanese so I can't tell you much more than that!

All working great. Thanks to Alpo Hassinen for help  camera stabilization

The CanberraUAV team has submitted its deliverable 1 report for the outback challenge, so we are back to doing development and testing of our test platforms again.

The main platform we have been using lately is a Senior Telemaster, which I got 2nd hand from another club member at CMAC. It has been a great test plane, and I'd highly recommend it for doing UAV development.

I was initially concerned it may be a bit too big for my car, but I found that it did fit (just!), although it is also a fairly tight fit in my study at home when I put the wings on to do a CoG test.

The plane came without a motor, so the first thing to do was work out what motor/prop/ESC/battery combination would work. I knew I'd be loading it up with a lot of electronics, so I aimed for enough thrust to handle well over 6kg flight weight (its total flight weight with all the electronics ended up at 6.5kg). Because it is a front-prop plane, it had to be electric as otherwise we'd get too much gunk on the cameras. After playing with a prop calculator for a while, I worked out what a E-flite 32 would do the job nicely, with 2x5Ah 4S LiPos in parallel to drive it and a 13x6.5 prop. I got a 100A ESC and isolated it from the rest of the electronics by cutting the +ve wire on the throttle lead, and the plane was setup for power. Now that we've flown it a bit the E-flite 32 turned out to be a great choice. It takes off in just a few meters and has plenty of power, and gives us flight times of about 35 minutes, despite the heavy load. I wanted a sedate slow flying plane as a camera platform, and this turned out to be ideal. The watt meter shows it pulls a little over 60A at full throttle, which should be just under the 60A limit of the motor once its through the ESC. It cruises at below 1/3 throttle.

Making room for the electronics

The next step was to get the fuselage ready for a pile of electronics. The rudder and elevator servos were right under the wing where the fuselage is largest, which was also where we wanted to put all the electronics, so Jack moved then back to behind the wing for me. It's handy having someone on the team who is good with balsa!

After that we just needed to fit the electronics in. This aim for this plane is to be a scaled down test version of the Mugin we are using for the OBC competition, so we put in as many of the same electronics as we will be using in the competition as possible. That means a pandaboard, a 32G SSD, a Ubiquity bullet TDMA radio, a PoE injector for the radio, and a couple of cameras on the bottom. We also added a pitot tube for airspeed, a mixer for flaperons (for really slow easy landings!), a UBLOX GPS and of course a UBEC to power all the electronics (a castle creations 10A).

The cameras take still images, one in IR grey-scale, the other IR-filtered colour. The IR camera is a ptgrey chameleon machine vision camera. We'll probably use a 2nd ptgey chameleon colour camera for the competition, but for now we're using a Philips webcam for the colour images (a SPC 900NC). The idea behind the dual camera system is to give us better rejection of false positives in the IR search for 'Outback Joe' by looking for places with a high IR signature but low on the IR filtered camera. The colour camera also looks for the distinctive coloured clothing that Joe should be wearing.

Software setup

The pandaboard runs the Ubuntu Natty Linux distribution, and on top of that it runs the mission control software, which is mostly python scripts using pymavlink, in particular MAVProxy, which proxies the MAVLink stream from the APM to the ground control station (which runs another copy of MAVProxy). It also runs the camera capture software, which does the gain and exposure control to keep the images at a reasonable level for finding the IR lamp. The ptgrey chameleon camera really shines at that, with most of our exposures taken at around a 100us exposure or so, which means no blurry images! That is pretty good given we have a IR-pass filter in front of the lens blocking all the visible parts of the spectrum.

Radio Link

We link from the plane to the ground using an ethernet bridge radio, a Ubiquity Bullet which is a 300mW radio at 5.8GHz. On the plane we currently had a 5dBi omni antenna, although we will probably switch to a higher gain antenna soon and start using servos and the APM attitude values to keep it pointing straight down. We did some range testing on the radios yesterday with a 20dBi phased array antenna on the ground station, and got a good link at 5.2km. We're aiming for a high quality link at over 10km, with about 5Mbit of bandwidth or better (we want to send a H.264 video stream from an IP camera on the plane).

We also have an XbeePro900 straight from the APM to the GCS, and we're planning on having a DroneCell as well for a GSM link. We will probably also upgrade the 900MHz link from an Xbee to something with a bit more power. The idea is for the ground station to monitor all the links in parallel, and auto-switch between the links according to a priority order, so if we lose the main 5.8GHz link we still have full telemetry and control via the secondary links.

Ground setup

While on the ground we have a ground power lead, so we can do all our electronics setup without running the avionics battery out. We also use our sunlight readable laptop to ensure we can use the GCS easily at the field. The GCS also reads out key data using a text to speech package, so we know if (for example) we're running low on power in the batteries on the plane. All of that info is transmitted via MAVLink from the plane.

All up this plane has turned out to be pretty much perfect for us to prepare for the outback challenge. Once we've perfected it we'll move onto the larger Mugin, but for now, the Telemaster is great!

This is cool! Now to think about what we might do with it.

Digi International (NASDAQ: DGII) today introduced the XBee® Wi-Fi, an embedded module that enables industry leading low power, serial-to-Wi-Fi networking in the popular XBee form factor.  Because of the XBee’s common footprint and application programming interface (API), customers can now create a single board design for wireless products that supports 802.15.4, ZigBee, ZigBee Smart Energy, 2.4 GHz, 900 and 868 MHz, Wi-Fi and proprietary DigiMesh protocols.  

“XBee modules offer developers tremendous flexibility and are extremely easy to use,” said Larry Kraft, senior vice president of global sales and marketing, Digi International.  “By adding a low-power Wi-Fi module to the XBee product family we give customers the fastest and most flexible way to get Wi-Fi up and running on their systems.”

Ideal for energy management, wireless sensor networks and intelligent asset management, the XBee Wi-Fi offers 802.11 b/g/n networking and flexible SPI and UART serial interfaces. Because the module includes the 802.11 b/g/n physical layer, baseband MAC and TCP/IP stack, developers can add Wi-Fi to their products simply by connecting to the XBee Wi-Fi’s serial port.  The XBee Wi-Fi is fully tested at manufacture and comes with modular certification for the U.S., E.U., Canada and a number of other countries, further reducing the time to market, development expense and design complexity.

Via Adafruit

UPDATE:

Please note that the initialization of Gyros was requested to move to the Arming function. This had the unintended consequence of making the Ground Station report erroneous attitude until the unit is armed at least once. This is changed already in the next version 2.0.39 which is still in development. Thanks.

This is a nice update and is recommended for everyone. I've gotten a half dozen flight in with it and have had good success. I'll be incorporating some of the ideas mentioned in the suggestions post over the next few versions. 

What's new:

I reworked the startup so it's much faster. Also, a feature a lot of folks wanted, calibrating the IMU at first Arming is in there. If you hand launch, please do your first arming of the motors on the ground.

I enabled a mode filter for sonar. Not too thoroughly tested performance wise, but it does work. (note, if you rely on the rangefinder class, you must rework your code to be compatible.)

RTL bugs are squashed and it's flying really well now.

Added a special filter in the PID for the derivative term to get rid of the alt hold and loiter issues from noisy sensors. 

Added a completely experimental mode called circle. It will by default spin the copter in a 10m circle from the point at which it was engaged. And it will Yaw towards that point at all times.

Yaw while navigating happens at quarter speed, which was problematic before.

Roll and Pitch Imax are higher 5° than before (.5°)

Logging seems to work now. Please erase the log after installing.

Everything else is mentioned on the SVN.

This week I made improvements to the MTP2 and took it for some general flight maneuvers to get a better feel for its abilities, its turning into quite the platform! Don't forget, my end goal is to FPV and then drone this airplane to fly across the United States.

It's flight path was much more stable and direct, the control inputs were not as sensitive, and overall performance was improved.

I made the following improvements this week:
-Leveled (set to neutral) the ailerons and elevator
-Reduced the control surfaces themselves by 50%
-Redesigned the motor mount to allow for better landings
-Placed the motor closer to the center of drag (placed it on the top of the motor mount) 

The belly landings are still destroying the motor mount due to the prop coming into contact with the ground during landing. I've ordered a folding prop in hopes that it will not sacrifice performance and allow belly landings without damaging the motor or airframe.

Have had this flying as a prototype for a while using open pilots copter control, now using APM.
She weighs 3.8 kg, with a bit over 10 kg thrust
Control is done with 5 motor channels , the front motors are operated as one, and control pitch, the left and right middles motors are controlled as left and right pairs, so that two more channels, and control roll, and finally the rear motors are operated individually (channels 4 and 5) for pitch and yaw control.
Size wise, motor to motor shes 700 wide and 800 long.

Now what i need to learn is how to enable camera contol on APM 2, and how to do the motor mixing (will modify a hexacopter profile)

https://www.youtube.com/watch?v=dwmYk7MKxi8

Can anyone give me a quick guide on how to do the mix and enable camera compensation ?

A new home for hackers and makers in Oklahoma City.

The space has been cleaned and the walls have been painted. Soon the doors will open on a new makers space. OHM Space is an Oklahoma nonprofit corporation that seeks to create a safe, entertaining space in Oklahoma City where everyone can learn, create and share. OHM supports the Hacker, Maker and Local Art communities, which include just about anyone who likes to create and modify things in ways.

It’s at 1700 W. Main St Oklahoma City, OK 73106. We’re calling it “Beta Space”. We have 5,000 sqft at the moment and should have another 5,000 sqft soon, for a grand total of 10,000 sqft of pure potential!

We’d like to give you a chance to become a co-founder. By paying for a full year of membership now, you’ll be guaranteed to have 24/7 access to an amazing community, voting rights, a neat certificate, access to a free parts wall and the honor of being an “OHM Space Founding Member”.

Jim St Leger from Intel's embeded group in Arizona gave a speech to the Intel staff about why the Maker movement is so important and why it's so unfortunate that Intel isn't participating. DIY Drones gets a nice callout.

This is a 1/10th scale model of what is eventually intended to be a 90m autonomous airship that can generate its own hydrogen (for buoyancy and fuel) from rainwater. It's mostly an art project now, but the vision is inspiring. Arduino-powered, of course. That reminds me that we have to design Blimpduino 2 later this year. I miss blimps!

Good interview and write-up here.

Here it is flying:

(via Makezine)

Forbes reports on the latest from this team, who uses the original Ardupilot as an autopilot:

At the Black Hat and Defcon security conferences in Las Vegas next week, Mike Tassey and Richard Perkins plan to show the crowd of hackers a year’s worth of progress on their Wireless Aerial Surveillace Platform, or WASP, the second year Tassey and Perkins have displayed the 14-pound, six-foot long, six-foot wingspan unmanned aerial vehicle. The WASP, built from a retired Army target drone converted from a gasoline engine to electric batteries, is equipped with an HD camera, a cigarette-pack sized on-board Linux computer packed with network-hacking tools including the BackTrack testing toolset and a custom-built 340 million word dictionary for brute-force guessing of passwords, and eleven antennae.

“This is like Black Hat’s greatest hits,” Tassey says. “And it flies.”

On top of cracking wifi networks, the upgraded WASP now also performs a new trick: impersonating the GSM cell phone towers used by AT&T and T-Mobile to trick phones into connecting to the plane’s antenna rather than their carrier, allowing the drone to record conversations and text messages on a 32 gigs of storage. A 4G T-mobile card routes the communications through voice-over-Internet or traditional phone connections to avoid dropping the call. “Ideally, the target won’t even know he’s being spied on,” says Tassey.

That GSM hack is based on a demonstration that security researcher Chris Paget performed at Defcon last year, showing that with a powerful enough antenna placed close enough to target phones, the victims’ handsets can be tricked into connecting to Paget’s setup instead of the carrier’s tower. Perkins and Tassey have implemented the same tools in their airborne hacking machine, and like Paget, used a portion of the radio frequency band set aside for Ham radios to avoid violating FCC regulations. They don’t plan to demonstrate the phone-hacking trick at the conference, and tested it only in isolated conditions to ensure their flying contraption wasn’t illegally eavesdropping on random strangers’ phones. “We want to make sure we’re not stepping on any cell providers’ toes,” says Tassey.

And why build a digital spy drone? Perkins, an Air Force contractor focused on cybersecurity who once owned a airplane hobby shop, and Tassey, an ex-Air Force consultant with Engineering Systems Solutions, say they wanted to demonstrate the vulnerability of government and corporate facilities to a nimble eavesdropping machine that can cover large distances and circle above a target. Though it requires remote control to take off and land, WASP can be set to fly a pre-programmed course once airborne and loiter around any chosen area. “We wanted to bring to light how far the consumer industry has progressed, to the point where public has access to technologies that put companies, and even governments at risk from this new threat vector that they’re not aware of,” says Perkins.

(via SUAS News)

UNITE a group of leading HALE vendors in the UAV pantheon including AeroVironment, Aurora Flight Sciences, Boeing, General Atomics, Lockheed Martin, and Northrop Grumman.

These guys had a booth at EAA and were trying to get the word out to allow civil UAV use. They are coming from the background of trying to get FAA permission to have UAV use in the civilian market. They are not so much after the "small ones" that we tend to work with but they do have an AR Drone and took it over to the FAA and said the FAA would not fly it, and the FAA said that is not approved.

I think this is a group to keep an eye on. They have some dollars behind them to push their use of UAVs but they also don't have a problem with the idea of the FAA requiring a medical and license to operate a UAV.

I've created an I2C digital signal sonar module to avoid the noise problems I have been having with the current analog signal sonar module.

Why?

Seeing all the problems we are having with noisy sonar data got me thinking

Where does the noise come from? Is it:

• RF noise from the ESCs affecting the sonar module directly ?
• RF noise from the ESCs affecting the analog signal line between the sonar and APM?
• Noise on the DC power supply affecting the Sonar module?
• Something else?

The current popular solution of remote mounting the sonar has probably eliminated DC power as the primary source of our noise. In other words - if noisy DC power was the ource of the noise problem then no matter where you mount the sonar you would still have the noise. Regardless if DC noise were still an issue Maxbotics has a solution to DC noise in their FAQ.

Personally I've found that remote mounting the sonar module has only partially solved my noise problems. This is probably due to the Sonar power and signal cable passing within 10mm of one of the ESCs near where it plugs in to the APM on my arducopter.

(This photo shows how close my ESC is to the analog port on the IMU Shield)

So I wondered if I could get rid of the analog signal path and see how the sonar noise changed. This has led me to put together a I2C sonar module. This communicates digitally between the sonar and APM using the I2C port on the APM IMU shield. It also allows you to use the PWM output from the sonar which Maxbotics recommends as "the most accurate"

Hardware

All that is needed is an Arduino, an I2C cable and some software.

Arduino mini

DIY Drones GPS Cable

The GPS cable supplies power and connects data lines between the Arduino and APM IMU Shield (you need to cut one end off the cable)

APM IC2 Function Arduino Mini

PIN1 <-----> GND <-----> GND

PIN2 <-----> 5V <-----> VCC

PIN3 <-----> SDA <-----> A4

PIN4 <-----> SCL <-----> A5

Three Wires connect the Arduino to the Sonar

Arduino Function Sonar

GND <-----> GND <-----> GND

VCC <-----> 5V <-----> V+

D5 <-----> PWM <-----> PIN2

Here is what it looks like mounted on the sonar - with double sided tape

The sonar is on a standard jdrones sonar mount

Software

The Arduino then needs to be programmed as an I2C slave.

Here is my code Sonar_I2C_Sender_v005.zip

You must use an FTDI cable to program an Arduino Mini

The code continuously reads and stores the sonar distance as a PWM signal from the module.

It responds to any I2C request for data with a two byte integer representing the current sonar range in cm.

Additionally it has the ability to return noise filtered sonar data.

Note the MaxBotix experts strongly recommend a mode or median filter not averaging filter.

Currently the code can be requested to return spike filtered, median or mode filtered data.

I have modified the Arducopter code to use this I2C sonar and started testing

Here is my sonar library APM_I2CSonar.zip

If the testing all works OK I'll see if Chris or Jason want to put it in the code repository

Results

To put it simply the results so far are great!

Indoor and outdoor tethered tests show no noise and no data problems

Here is a graph showing Sonar data in red and baro in green.

first segment is with motors running second with motors off

Its too windy to fly here today (in the Aussie vernacular: It's strong enough to blow ya dog off its chain!)

Stay tuned!

Andrew

Maybe we should start strapping chickens onto quadcopters... Hmmmm.