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The Case for WiFi in Drones

Posted by Adam Conway on June 11, 2013 at 9:00am

In full disclosure I work at a company that builds WiFi Access Points, routers etc for enterprises and I just put a hotspot on a drone for fun

It is hard to imagine now, but Ethernet as we know it today (802.3) was not the obvious choice for wired performant connections in 1996, many competing technologies like ATM, Token Ring, RS485, 802.4 etc seemed like more reliable choices, but because Ethernet was fast and cheap (among other reasons) it won out - since then it is hard to imagine a new technology displacing it.

Like Ethernet, WiFi is in the process of subsuming all adjacent technologies (802.15.4, Bluetooth, etc) and for all connections beyond the WAN (which will likely be LTE) it has the ability to be lower power, have better range (within reason) and perform better. This is not because WiFi is necessarily better spec'd - in fact it is unnecessarily complicated - it is because the R&D dollars are focused on it rather than competing technologies. A modern 3x3:3 802.11n chip has massive DSP resource and with .11ac we are seeing double the compute inside the mac/baseband. In addition we are seeing huge improvements in frame detection, phased antenna arrays and RF front ends which has the consequence of increasing link budget (link budget is roughly analogous to signal strength).

Okay, so where am I going with this: as a community we should be looking to use WiFi to consolidate our communication paths with our drones rather than 900MHz telemetry, 2.4GHz remote, 5.8GHz analog. Only fully integrated products like the Parrot AR drone use WiFi and I think that is a mistake. Here are a few reasons why WiFi makes sense:

We put a digital RX with -95 db sensitivity inches away from a video transmitter transmitting at 23 dBm (in my case, or if you go illegal 36dBm) - this desensitizes our RX significantly reducing link budget. While this is one example, putting a high power transmitter next to a high sensitivity receiver is a bad idea always and we do it 3 times on drones.
We need to deal with varying ranges and qualities of TX/RX pairs, complicated antenna and ground station setups.
Analog video is incredibly susceptible to multi-path, limiting quality and antenna types. Don't we all want HD?
Wouldn't it be convenient to just have one communication path? with maybe a remote as a backup.

Because there are naysayers (correctly so) out there, I thought I would point out common arguments against WiFi:

WiFi requires a much higher SNR than 802.15.4 - this is true, but the quality of receivers and transmitters along with techniques MRC overcomes much of this and gives you a link that has a much lower duty cycle making it less susceptible to interference and provides superior error checking. A distance of 2-4km is totally practical with WiFi assuming good radios and modest antennas (we do a lot further at my company without too much issue)
Using WiFi requires IP - yup… but does anybody think this isn't inevitable for us?
WiFi is unreliable - okay, this needs a 2 part answer - WiFi is actually extremely reliable… it offers very good error checking (CRC) and will do 9 retries before dropping a frame at which point the higher level protocol will also send retries. On the flip side, we are often used to the crappy WiFi found in an Acer laptop (not picking on Acer, just mentioning a random pc vendor) where the radio is placed poorly, the analog front end is poorly designed and the antennas are in odd positions - remove those limitations and buy a $20 card from a reputable manufacturer and you will find superior performance.
WiFi is really hard to integrate, especially when you need connections beyond serial speeds - I actually dont have an argument here. Most WiFi cards today use a soft MAC which means that most of the radio runs in software - replicating that in Arduino is infeasible. This is why the Arduino Yun uses a linux and a SoC to deliver WiFi. The obvious fix would be to put Autopilot on a linux based platform like OpenWRT, Android or Raspberry Pi

I don't think that it is a question of whether WiFi will become prevalent on drones, it is only a question of when. In the meantime I am working on my WiFi drone, I have 4G and WiFi on mine, Telemetry and Video are the next pieces to get working. I will update as I progress.

Control high power LEDs (1W, 3W) from the APM 2.5 LED output

Posted by Stefan Gofferje on June 11, 2013 at 9:00am

I was looking for a way to make the ARM and GPS LED signals more visible for quite a while. Ideally, I thought, I could drive high-power LEDs somehow from that outputs. A short question in the comments of my blog post with the LED poles didn't yield any results except the reflex-like pointing to the jDrones JDIO board.

Well, I do have a JDIO board and it's not usable for that purpose at all.

Reasons:

The JDIO board is not a LED driver. It's basically just a switch with an Arduino attached. Primary function of a LED driver is to supply a constant current, not to switch stuff on and off
The JDIO board has a current limit of 500mA per channel. That works for 1W LEDs but nor for 3W LEDs.
The JDIO board does decode MAVlink but the (IMHO) most interesting and important infos, i.e. ARM and GPS status, are not evaluated.

So, I started googling and scanning eBay. On eBay I found an interesting assortment of LED drivers from a German supplier - KT-Electronic. I ordered a few drivers and a bunch of other stuff and sent the seller a question about how the driver likes being dimmed by PWM on the supply side. Within a couple of hours I received an email, pointing me to another driver. The email described the circuitry and included the datasheet for the IC that's used on those driver. Actually, the seller has 2 drivers with this chip, one configured to drive 1-3x 1W LED in series and one configured to drive 1x 3W LED.It turned out, that those ICs have a combined analog/PWM input to control the LED output. Analog/PWM combined? Yeah! You can either apply between 0.2 and 5.0V to the ADJ input, which will result to proportional dimming of the output, or send a PWM signal with 0 and 5V amplitude.

This is the module before the modification:

The SN3350 is easily accessible (latter photo, bottom right). All that needs to be done is to solder a servo cable to ADJ (bottom right pin) and GND (bottom center pin) and replace the MR16 pins with some cables. Soldering the cables to the IC requires somewhat of a steady hand but it's totally doable.

This is the module after the modification:

Now you only have to connect the supply line to the battery and the control line to the APM and you have the APM controlling up to (3) 1W high-power LEDs. Don't forget the cooling for the LEDs!

According to the seller, the boards are tested up to 24V supply voltage. The IC can do up to 40 volts but the capacitors are only 25V types. The eBay auction does say 12V for one and 6-16V for the other but that is the normal operating voltage or (in the latter case) the minimum voltage (16V for 3 LEDs). I already tested the modules with a 4S LiPo a couple of hours constant operation and they didn't get noticably hot.

A view behind the scenes at TED Global, quadrotor “athletes” demo

Posted by IKE on June 11, 2013 at 9:00am

Raffaello D’Andrea, and the ETH Flying Machine Arena will perform a demo on TED Global. Take a look at the preparation behind the scenes exclusively on Robohub:

http://robohub.org/ted-global-raffaello-dandrea-and-his-quadrocopters-machine-athleticism/

There'll be more in-depth coverage, you can find all TED Global 2013 articles on Robohub here: http://robohub.org/tag/tedglobal2013/

Flying Hamburger? Right ...

Posted by Oliver on June 11, 2013 at 7:30am

So an insufferably "upscale" fishmonger/burger joint in the UK has posted a video on YouTube claiming to show a tray of food being flown to a customer's table on the back of a quad. The quad appears to be a Parrot (or close to one) and it seems that these folks have discovered some secret to carrying massive weight that has eluded all of us here! Either that or someone was real busy hollowing out blocks of Styrofoam, or maybe just real handy with video trickery. Well, at least they don't have this little quad listening to everyone's phone calls ...

First Autonomous Flight Results on PX4 / Waypoints

Posted by PX4 on June 10, 2013 at 2:00pm

Just some very early results, but here we go with our first autonomous onboard video. This is the PX4 native stack flying a stock Bormatec Camflyer Q (estimation and control used in the video contributed by James Goppert). PX4FMU + PX4io fits fine, but we are already working with Bormatec on a wider heavy-duty version (photos of the first prototype). Always keep in mind that the design goal of PX4 is to provide a modular autopilot platform not only for our own purposes, but also to allow others to build on. While working closely with the APM dev team making sure that APM runs fine on it, this allows us to experiment and push the state of the art (certainly on the platform, just starting on flight control), offering a flight control app on the same hardware for every purpose. For those who noted: Yes, QGroundControl has some cool new features coming, the AHRS display was contributed by Soren Kuula, and much more (not shown in the video) is coming from Michael Carpenter, with some really important design guidance by Michael Oborne and Craig Elders experience going in as well.

Thirty Days (#26): Two Y6 copters in carry-on

Posted by Joshua Ott on June 10, 2013 at 9:30am

Joe was able to fit two of the new folding Y6 birds plus RC transmitters in his carry on bag. TSA did ask a few questions, but let them through.

Virtual Sparkfun AVC Fly Around

Posted by Falcon UAV on June 9, 2013 at 10:26pm

After watching a spectacular showing by the DIY community at the Sparkfun AVC 2013 we let a Falcon take to the air. We took a few photos and put together this quick fly around using 123DCatch of the AVC layout. Enjoy, Chris

http://youtu.be/LkoosZPMnYc

Flying the Phantom indoors...

Posted by Mark on June 9, 2013 at 10:20pm

I just finished my first actual useful flight trying to do something productive with my DJI Phantom. Very impressed with how it works, although I've done a fair number of modifications to it. Everything you see in the video was shot with a GoPro Hero 3 Black, 1080p30. All the flying was done in ATTI mode, except the exterior shot which was in GPS most. Wind was at about 4-5 knots.

I'm running the ARRIS CM2000 Brushless Gimbal from Hobby-Wing.com, must say that I'm really impressed with it - after a few hiccups getting it going, it works flawlessly. I did drill out the vertical alignment screws a bit so I could balance the camera better, which helped quite a bit. Power is tapped from the built-in battery using the cable they have stashed in it from the factory.

I also replaced the built in TX/RX with a Futaba T8FG Super setup - I wanted the extra range and flexibility it gives, plus being able to continue to use S.BUS is a nice plus. I use the servo mirroring that the RX automatically does for the gimbal control (pitch and roll) instead of enabling it in the NAZA as I've seen other do.

Running the stock plastic blades - I have CF blades, but I crash on a regular enough basis I haven't the courage (or fool heartiness) to run them yet.

APM 2.6 + GPS with compass

Posted by Szilard on June 9, 2013 at 10:06pm

Is it something new or I missed the announcement?

Falcon UAV and APM Go To Africa (Thanks to the 3DR Dev Team)

Posted by Falcon UAV on June 9, 2013 at 10:00pm

http://youtu.be/E3dRpcB38pQ

http://www.falcon-uav.com/falcon-uav-news/2013/6/9/-falcon-uav-completes-wildlife-conservation-field-trials-in.html

Falcon UAV was fortunate to have recently completed field trials in South Africa for anti-poaching, wildlife conservation, and wildlife research missions. Given that the event was in Africa it was critical that we use a non-ITAR autopilot. What few may realize is that Falcon UAV was originally tuned with the help of Doug Weibel on the APM 1.x hardware because we didn't want to risk the few high dollar autopilots we had. After initial tuning and proving the airframe design we had to switch to a commercial autopilot option as our first customers desired that autopilot. While we continued to dabble with APM in the little free time we had it was hard to find time to finalize integration. That brings us to about 3-4 months ago when our trip to Africa was finalized. This put a date on our trip and a requirement to complete integration with APM and support of Falcons somewhat unique capabilities.

Through a very aggressive flight test program and the amazing support of the 3DR Dev Team we were able to really show the world what unmanned aircraft can do for the conservation community and also prove that APM and Mission Planner are by far the best value for an autopilot system on the market.

While I am proud in what Falcon has done I realize that we would have never have done this without the 3DR Dev Team. Special thanks to Doug Weibel for introducing me to the APM and helping me out in numerous flight tests, Craig Elder for coordinating efforts, Michael Oborne for making some great changes to MP to support Falcon's functionality, and last but not least to Tridge for his amazing knowledge, hours of skype calls, tlog reviews, up to the minute (literally) firmware updates.

This is an amazing community with amazing products that WILL revolutionize the UAV market and Falcon UAV is proud to be using 3DR APM products!!!!

Thank you,

Chris Miser

Owner, Falcon UAV

You say its your birthday? Its my birthday too, yeah! OR: How I abused a bee with a quad.

Posted by HeliStorm on June 9, 2013 at 9:06pm

Yes indeed, I put one more year behind, and one less year ahead of me today. For my birthday morning, the family packed up and walked down the street to our lovely park, where I was able to do some trail flying. In short, I keep a line of site on the quad and hike behind as I fly it down the trails. This is the first time I have accomplished this feat with an HD camera attached, and I am quite happy with the results. Stick around to the end, because there is a definite surprise as to what I caught on camera.

Hi! I have uploaded a set of three new videos explaining 3 basic principles of the quadrotor. In this case I'm using my own board, theFLCv2.0 ( but the concept may apply for other quadrotors and autop

Posted by Alan Kharsansky on June 9, 2013 at 8:30pm

Hi! I have uploaded a set of three new videos explaining 3 basic principles of the quadrotor. In this case I'm using my own board, theFLCv2.0 ( but the concept may apply for other quadrotors and autopilot systems too).

First of all: why do we need controllers on the quadrotor and the effect of the different modes of flying:

Then two different ways of reference tracking:

And the coolest part: perturbation effects and rejection

3D Robotics

NPR: "The Green Side of Drones: Science and Environmental Apps Abound"

Posted by Chris Anderson on June 9, 2013 at 8:00pm

John Cherbini and Joshua Ott of 3D Robotics, setting up a thermal imaging camera for infrared shots of a field at the Berkeley Marina. Photo by Aarti Shahani

From a NPR radio program airing tomorrow morning:

It appears that “drones” are here to stay. And Silicon Valley drone makers are going beyond military and spy applications, creating new environmental uses for unmanned aerial vehicles.

On Friday afternoons, you’ll usually find Chris Anderson out by the Berkeley Marina, tinkering with his squadron of drones. Looking up at the sky as one of his creations buzzes about, he can’t help blurting out, "So that’s just freakin’ cool, right?"

For Anderson, this is serious stuff. He quit his job as editor-in-chief of Wired Magazine to build 3D Robotics. The do-it-yourself drone company based in San Diego, won’t do military projects. That's part of a compact it has with about 40 thousand developers in its online community.

A few of them are here today, testing a 2-pound fixed-wing airplane that’s carrying a pocket-sized near-infrared camera, which is nothing more than a regular point-and-shoot model, with the plastic filter popped off.

"Our eyes are like the worst eyes in the animal kingdom,” Anderson says. “The cameras have been sort of crippled, to resemble the human eye. So we ‘un-cripple’ these cameras, to see the world the way an insect would see it."

This mini-airplane with a 2-and-half foot wingspan is different from conventional remote-controlled planes because it’s flying without a human operator. It’s following GPS coordinates plugged in before take-off. Other drones track moving objects on the ground using sensors.

"The more autonomous, the more drone-like they are," Anderson says.

The drone darts back and forth in a lawnmower pattern, 150 feet above the grass. It’s reporting its position to a laptop, and snapping pictures to stitch together a high-resolution map of the marina.

That image may not be something the world desperately needs but Anderson says farmers could use this kind of data gathering and image processing for crop surveys, to figure out what plants need water.

"A healthy plant will absorb the red light, but reflect the infrared,” he explains. “But as chlorophyll is damaged, it'll start to reflect the red as well. So the ratio of the infrared and the red tells you the health of the plant."

Yet An Other Quadcopter, or Maybe not.... Project Colossus

Posted by Synesthesia on June 9, 2013 at 6:30am

I am creating this blog to document the design and development of my quadcopter. This is going to be my first attempt at designing a quadcopter and I am really excited about it.

"Is this Yet An Other Quadcopter? Is there anything interesting, new, different about this quacopter? What is he doing differently that has not been done before?" All these questions are valid, after all there are thousand of blogs about quadcopters not just in this community but all over the net... So what I am bringing to the table that is new?

Well what I am trying to do differently is to use an FPGA rather than a microcontroller as the core of the quadcopter. I am sure this has been done before but it is my belief that there is a lot less material and support out there for people who want to take this approach. And I want to share my efforts with this community.

Well some might ask, Why FPGAs, after all, microcontrollers work perfectly fine. They are good enough to get all kinds of flying machines airborne and they are dirt cheap, easy to program and they work well... So why bother with FPGAs?

Well the honest answer for me is that, it will be more fun. Of course, FPGAs have a number of advantages over the microcontroller, (flexibility in logic implementation, parallelism....) but whether these advantages are really useful and help an airborne machine fly better is a question I really cannot answer at this stage, but it is something that I will really enjoy exploring.

Additionally, some FPGAs are reasonably cheap nowadays, and in my opinion, comparably as cheap as some of the microcontrollers out there, so it makes sense to me to try and use them in some of the applications that microcontrollers are used for in the RC community, maybe some advantages can be gained from down that route. And I want to share my experience with this community.

So why DIYDrones? Well to be honest, I think it is one of the best communities out there for hobbyist and RC geeks :p I have been doing some research for quite sometime around this area and I have always found DIYDrones to be a great source of information and support. The people in this community seem to be really enthusiastic and really knowledgeable. Also it seem to have a lot of members from the UK as well which is a plus for me.

As I am developing this project, I am willing to share EVERYTHING with anyone that is vaguely interested. If anyone has any questions, interests and ideas for collaboration, feel free to get in touch with me.

I am really looking forward to sharing my work with this group.

P.S. I chose the project name Colossus not because the quadcopter is going to be a huge machine, but because I realise how big the task ahead of me is. It should be a fun journey though.

Drone build progress.... Will it fly?

Posted by Phil P on June 9, 2013 at 4:00am

Well it's been a few months since my last blog post, so here is an update and some photos.

The ground control trailer is going well. I have finished putting on the steel cladding, and insulated with 10mm foamboard. In my last blog post, I referred to a generator which I was thinking of including.....I have decided to leave it out of the build, as I have decided to use two car batteries, 100W solar panel, and the tow car's alternator as a last resort to run the 2KW inverter. Should be plenty of power. The generator would be very loud if I incorporated it into the build, though it would allow me to have air conditioning, which would be nice!

And a vid never goes astray, subscribe for more :-)

Now the plane is taking shape too. See previous blog for the solidworks drawing. Basically it's an aluminium skeleton made from box section, and hot wire cut foam wings. The wings are 3m tip to tip. and there are two 16mm tubes joining the tail plane to the wings. The fuselage is a work in progress, but it will probably be made from water jet cut 3mm aluminium, then bent into a box.

The wings are cut from "medium density" insulation foam. The local insulation shop had offcuts of a suitable size, which they parted with for $30. Nice!

This is my first build of this size, so I really am not sure if it will be strong enough. Time will tell!

That's a two car garage, so the build is getting bigger and bigger!

That's a CRRCPro 50cc two stroke gas engine. It's a low cost Chinese engine. Reliability? Yet to be proven, but I can only find great reviews online, and only one unhappy review from someone that didn't like the BOX it came in?!?!?!

Landing gear, and motor mount fitted. Servo compartments cut...

Now for the fun part (NOT) ... fiberglassing!

I purchased some fiberglass cloth from ebay. It was the remains of some stock used for building wind turbines. So I thought it would be perfect...... Well, this stuff is strong, but it is VERRRRY heavy... The tail plane alone, after the fiberglass treatment, is 4KG! So the entire aeroplane will weigh around 20Kg before I add a payload, electronics and fuel. Too heavy? Again time will tell!

Moderator

AVC 2013

Posted by Gary Mortimer on June 8, 2013 at 8:00am

Starting very shortly, 0900 Mountain AVC 2013.

Chris Anderson and co are there to be covered in glory having flown an autonomous take off then out over water to drop a tennis ball on a spit of land, fly under a hoop and finally land all without the aid of a net.

What could possibly go wrong.

Live stream here http://www.ustream.tv/channel/autonomous-vehicle-competition

I'm hanging out as sUASNews on twitter there.

Skywalker X8 hand injury

Posted by Tommy Larsen on June 8, 2013 at 12:38am

Everytime i launch my X8 it's never any problems. That was until i mounted a bigger propeller. I went from 13x6 to 14x9.5 and my plane "suddenly" went out of my hand much faster than before! The result is a painful hand and a lot of thinking :) Maybe some of you guys should think twice before you hand launch your new X8 or similar...