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3D Robotics

What does "Open Source Hardware" mean?

Posted by Chris Anderson on March 18, 2008 at 2:00pm
Here at DIY Drones, we adhere to open source principles wherever possible. That means we aim to share (that means post it, not make people ask for it) code, schematics, PCB files, parts lists, instructions, and algorithms for every project featured here. In practice, that's not always possible (not all project have PCB files; not all projects need schematics), but it's our philosophy. Is that "open source"? In spirit, yes. But in letter, it's more complicated, because hardware is more complicated than software. We can't GPL a parts list, and the license that we do use for this site, a Creative Commons "Attribution" license (use/modify what you want, but give credit), doesn't have the same viral characteristics of the GPL in the sense that people who use our intellectual property are free to keep closed their "derivative work" if they want. This is all a bit messy and complicated, but fortunately Phil Torrone of Make Magazine gave a great talk on Open Source Hardware at Etech that helps explains all this, and it's now available.
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3D Robotics

A clever approach to indoor beacons: ultrasound + IR = GPS

Posted by Chris Anderson on March 18, 2008 at 5:13am
A Luxembourg-based team has come up with a really clever indoor navigation system that combines ultrasonic beacons with IR to achieve absolute position ("synthetic GPS"), much like the NorthStar system we use but entirely DIY. As they describe it: "The infrared flash of a single beacon arrives instantaneously at the robot that is equipped with a combined infrared/ultrasonic receiver. But the ultrasonic signal only arrives with a certain delay, due to the "slow" sound velocity, in comparison to the speed of light. The receiver is able to measure the time lag between both signals and deduce the distance between the robot and the beacon." Features include: # participation of up to 7 beacons that may be placed at strategically interesting places # the beacons send out strong IR and ultrasonic signals that don't require reflectors on the receiver side # like RF-beacons, these beacons transmit their identification number, making localization easy # always one beacon acts as the master beacon, sending out a synchronization message to all other slave beacons The project is entirely open source and is in the proto-board stage (see below). It was designed to work with LEGO Mindstorms NXT and as such uses I2C output. But that, of course, is also readable by any microcontroller, so it could work as well with Arduino or Basic Stamp. Looks like a great opportunity for one of our PCB whiz's to make a small and light version for blimps!

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YARB 1.0 - added compass and ultrasonic sensors

Posted by Howard Gordon on March 16, 2008 at 5:01pm
I attached some additional sensors today - a pair of Maxbotics EZ0 ultrasonic ranging modules and a Honeywell HMC6532 I2C compass. Also, I added an extender to the camera module to point downward about 30-degrees and I finally adjusted the focus. I think the camera angle is pretty good now - the wide angle lens has a field-of-view of approx 120-degrees, so the bottom of the frame captures objects almost directly below.I haven't yet filtered the sensor data. The ultrasonic data is pretty solid - the forward looking readings bounce around a bit, but the download readings are fairly consistent. However, I am thinking about going with a narrower beam module - probably the EZ1. Also, I would like to add a couple of side-looking modules to enable some degree of mapping capability.The compass is less consistent, but I suspect the may be due to magnetic field interference from the motors. When I was recording, I wasn't paying attention to the readings, so I will have to run some tests to see if the compass reading change depending on whether or not the rotors are firing.Here's a snapshot of the gondola with the additional sensors -

I'll work on cleaning up the data a bit, and then will start to write a script (there's an onboard C interpreter) to let the blimp wander around on its own, perhaps following a course based on heading. After that, I will add some logic to use the camera to lock onto an object and follow it around while maintaining altitude and avoiding collision - that will be a bit more challenging.Here's a short video clip of the latest test -
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YARB 1.0 update - first untethered flight

Posted by Howard Gordon on March 13, 2008 at 4:26pm
Here's a video clip from YARB 1.0's first untethered flight. I captured the video while sitting in my office while the blimp explored the hallway and front room (the dogs completely ignored it). The camera is a bit out of focus, and the afternoon light washed out the picture somewhat, but you get the idea.You can see the modified console with buttons to vector the props and invert the video. I'm actually surprised with how easy it is to pilot YARB - it is very responsive. Next step is to add the ultrasonic sensors and compass.
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3D Robotics

Minimum Blimp UAV (Version 1) schematic and code

Posted by Chris Anderson on March 11, 2008 at 9:30pm

For those who want to reproduce what we did with the Minimum Blimp, the schematic is above. The Arduino code is here. We're now moving on the Minimum Blimp Version 2, which will be based on a custom PCB. Rather than use the flimsy and expensive BlubberBot kit as the starting point, we're probably going to mod a $15 RC toy blimp. We just rip out the RC unit, put in our Arduino processor board and sensors, and presto, instant UAV! And under $100...
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Prairie Predator Build

Posted by Ron Jacobs on March 10, 2008 at 4:43pm
I've been working on a Nitro Predator for about a month and ahalf now. I'm stalled trying to figure out some problems with an Airtronics radio system I have that doesn't want to work. Everything "seems" OK but when I hook up servos to the receiver and try to control with the TX, no luck. the servos jitter when I apply power at the receiver, but no response at all to TX commands.am playing with adding a controllable rudder to the Predator for no other reason than the real one has one. So, I'm making it more difficult, I know. I'll probably end up fixing the rudder, but its fun to play with.
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3D Robotics

Regulatory FAQ

Posted by Chris Anderson on March 9, 2008 at 8:30pm

[These are Frequently Asked Questions about the current state of UAV regulation in the US. Regulations elsewhere are different, but here is a similar post giving the rules for Canada.]

Q: Are UAVs legal in the United States?

A: Under certain conditions, they are. There are two ways to legally fly Unmanned Aerial Vehicles in the "National Airspace", which is to say all but certain restricted areas: 1) Get a Certificate of Authorization (COA) from the FAA, a process that can take months or more. 2) Fly under exemptions granted to non-commercial ("recreational") flyers who adhere to certain restrictions. More detail is here.

Q) What are those restrictions for non-commercial UAVs flying without a COA?

A: You MUST do the following: 1) Stay below 400ft. 2) Maintain a "pilot in control", which is to say that you must always be able to take manual control and fly the aircraft out of danger (in general, that means maintaining line-of-sight contact with the aircraft). 3) Stay away from built-up areas. More detail is here.

Q) Who can apply for a COA?

A: Typically only government agencies (Law enforcement, Civil government, etc). This is not an option for a private individual.

Q) I've heard that the FAA doesn't allow unmanned aircraft with cameras and/or GPS. True?

A) No. Commercial use of aircraft with cameras is regulated as above, but aircraft flying under the recreational exemption may use cameras and GPS.

Q) What countries have more relaxed UAV regulations?

A) Australia and New Zealand are famously progressive in their UAV policies. Other countries, such as Mexico, have been know to be relatively friendly, too.

Q) What are the prospects for FAA regulations that allow amateur UAVs more freedom?

A) There is currently a rulemaking proceeding that aims to improve the regulations on UAVs. It will take a while; indeed, you shouldn't hope for anything before 2010-2012. There may be a special category for UAVs under 4 pounds, which may be more lightly regulated. But then again there may not. It's all up in the air, so to speak, and the forces that oppose amateur or commercial UAVs in the National Airspace are many and powerful. Speak up!

Q) What about universities and other students. Any exemptions for them?

A) Not automatically. But they may be able to get COAs more easily if they are federally funded and go through that agency.

Q) What if I break the rules?

A) Well, for starters, we don't want to hear about it here! We realize, of course, that people break the rules all the time on the assumption that if they use good judgment and stay away from built-up areas, they won't be caught. That may indeed be the case, but it will only take one cowboy flying a UAV into an airport landing zone and endangering civil aviation to set our hobby back by decades. So please don't do it! (Plus you could go to jail)

Q) Okay, I'm obeying all the rules. Are there any other guidelines for safe and responsible UAV operations?

A) Yes. RCAPA (the RC aerial photography association) has some excellent guidelines that are a great place to start.

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3D Robotics

PicoPilot software updated

Posted by Chris Anderson on March 9, 2008 at 7:47pm
The good folks at UNAV have been listening to our complaints about the way their software handles communications errors if you don't have your Com ports set up just right when running the software (it basically barfed up a cascade of mystifying error messages, with no indication of what was really wrong and what to do about it). They've now created a new version of the main program (the waypoint editor) that handles Com port problems much better (see screenshot). You can download the new version here. (It will only work if you've already installed all the other software that comes with the PicoPilot). Thanks, UNAV!
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3D Robotics

Testing the real world range of the Pololu IR transcievers

Posted by Chris Anderson on March 8, 2008 at 8:00pm
As you know, we've had a lot of trouble with the short range of our Pololu IR transceivers that we use with our Blimp UAV. They're rated at up to 20 feet, but we can't seem to get more than 10 feet (and usually more like 5) in real world conditions, with the usual amount of IR noise and the two transceivers not being on the same horizontal plane. I know that the power of the transmitting LEDs should be roughly proportional to input voltage (they're rated from 6-16 volts), so I thought I'd test them at different voltages. Here are the results:

Note that this is on the same horizontal plane. If you're not on the same plane, as we usually aren't, you need to cut those figures in half. So basically it doesn't look like we're ever going to get more than about 7 ft of range reliably. That means it's time to make our own custom IR transceivers with high-power LEDs and a dome array (to handle 3D positions). We'll save weight and money in the process, so this is well worth doing.
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Yet Another Robotic Blimp (YARB)

Posted by Howard Gordon on March 8, 2008 at 2:42pm
Frustrated by difficulties in achieving adequate stability with my coaxial and quad flyers, and inspired by the efforts of Chris and Jordi with their BlimpBot project, I commenced yet another attempt to defeat gravity with a robotic entity.This new project employs a relatively inexpensive 66-inch helium blimp from RC Guys, modified for direct motor control using the H-bridge built into the radio board portion of the SRV-1 Blackfin board set. The build was pretty simple - the only real challenge was in mounting the vectoring servo in the gondola. I would guess that I have spent 2-3 hours total on the build.

I haven't yet mounted my other sensors, but wlll be adding two Maxbotics EZ0 ultrasonic ranging modules (forward and down views) and an HMC6352 compass. First, I need to work out flight controls and invert the video feed, so all testing thus far has been with the blimp tethered.

Here's the first captured (inverted) video from the tethered blimp - it's not very exciting to watch, but I am using the motors to rotate the blimp. Untethered flight should follow in the next 1-2 days.
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Wiring - First Experiements

Posted by Gareth Farrington on March 5, 2008 at 8:46pm
I finally got my Wiring board form Sparkfun! Wiring is a platform similar to the Arduino but using an AVR atmega128 chip. This chip is clocked at 16Mhz while the Arduino is clocked at 20Mhz. The advantage of the 128 is the increased RAM, ROM & Flash capacity over the Arduino. Both share the same development environment and code written for one can be made to run on the other. A 'mini' version of the board is due out on March 5th and should fit easily inside a Park Flyer sized UAV.I got the drivers, plugged it in and got it to accept some code. Then I did a little hello world program and I had it flash the on board LED. So far so good, this is pretty cool. Time to break out the RC gear for a more UAV related hello world.

This is a pic of the board and the gear. I have an AR6000, a little 10A Hyperion ESC and a 2S 300mAh lipoly battery. The funny gold thing bridging from the Rx to the board is a tree of female servo connectors. I'm going to make some test jumpers with those.I tried to read the input from a servo pulse pin and have the LED flash in time with it. First result was a bright glowing LED which didn't seam right. The signal should be off 95% of the time. Further experimentation seem to indicate that the Spektrum Rx I'm using holds the voltage on the signal pin "high" most of the time and only brings it low for the pulse. This is the exact opposite of what I expected! Is this also true of the Futaba gear?The board is pretty neat and its already teaching me things about my radio gear I didn't know. When I get more time I'll see if I can read the uSec time of a servo pulse using interrupts.
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3D Robotics

ETech BlimpBot demo report: Success!

Posted by Chris Anderson on March 5, 2008 at 4:00pm
Well, that went better. After last week's disaster, Jordi and I worked hard to make the Etech demo of the Minimum Blimp UAV go smoothly. It was almost a full hour, and the room was a bit smaller, so we were optimistic. But we weren't counting on optimism alone: Jordi had done a lot of work on the blimp since TED to help it handle air currents better, including:
  • Using the voltage regulators on the Pololu Motor Driver boards rather than a stand-alone voltage regulator.
  • Adding a separate battery for the motors so high current drains and voltage drops don't risk crashing our Arduino. (This is a short term hack while we get our power management properly fixed and switch to LiPos)
  • Upgrading the vertical motor to a low voltage N20, which has a better power to thrust ratio than the motor we'd been using
  • Tweaking the code to give full thrust when needed, which is allowed by the better power management
  • Other tweaks in the software to adapt to the inertial momentum and laggy physics of a blimp in a moving fluid

  • The result: success! The range of the IR transceiver is still less than ten feet in a noisy environment like a conference hall, but it nicely follows you around if you hold the beacon and walk around the room and otherwise does what it's supposed to do. Presentation went great, full room, people seemed to love it and video crews interviewed us afterwards. (Links to coverage when they go live)
    Next: Minimum Blimp UAV 2.0 with a custom PCB, single LiPo and integrated motor driver chips. And then a kit you can buy and build for less than $100. Stay tuned! [Photo of Jordi credit: Phil Windley]
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AUVSI - Conference

Posted by Cory on March 2, 2008 at 2:14pm
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.

Also, here is the SWIPER from Emman Aerospace

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3D Robotics

TED Report: Foiled by Air Conditioning!

Posted by Chris Anderson on March 1, 2008 at 7:00am
Yesterday Jordi and his wife drove up with the BlimpBot to Monterey, where I was attending the TED conference, so I could demo it. This was a pretty high-stakes demo, since not only would there be 2,000 of the most influential people in the technology, entertainment and design (TED) worlds watching, but they included Al Gore in the FRONT ROW, Google's Sergey Brin and Larry Page and movie stars such as John Cusack and Cameron Diaz. The bot worked great in the hotel room, and then we took it the the auditorium during a break to test it on the main stage. Yikes. We were getting IR interference from everything, from LCD screens to the bright stage lights, and our reception range dropped to something around three feet. Even worse, the air currents were overcoming the blimp's ability to fight them. So we gave up on the idea of a fixed IR beacon on the ground, and I decided to hold it in my hand to keep it near the blimp. Even then, the motors couldn't fight the currents well enough. So we rushed back to our staging area (my hotel room) and Jordi updated the firmware to give more power to the motors even at the cost of battery life (this demo only had to run three minutes) . We tested it again in the hotel room, it worked fine, and then it was time to go. When we got to auditorium and waited in the wings to go on, it was clear that something bad had happened in the firmware update. The vertical motor wasn't coming on at all sometimes and it wasn't clear why. Then Jordi realized that in changing the power settings, he'd also changed the timing of the loops, and we weren't resetting the motor controllers at the right time, which meant that the chance of them working when needed was random (and low). We'd just been lucky in the hotel room, but clearly weren't now. Still, I crossed my fingers and went on, carrying the blimp. Disaster! It turns out that one big thing had changed since our test run in the auditorium: 600 people had arrived. All that body heat had raised the temperature of the room, kicking in the air conditioning, which came out of huge ducts right over the stage. Basically I was under a raging waterfall of cold air, and the poor blimp sank right to the floor, its little vertical thruster completely overcome.
  • Lesson 1: Little blimps need still air
  • Lesson 2: If you can't find still air, you need WAY more powerful thrusters (which means more battery power, which means more weight, which probably means a bigger blimp)
  • Lesson 3: Don't update your firmware five minutes before you're going to fly an autonomous robot ten feet away from a former Vice President of the United States.
  • Lesson 4: Hey, it's a tech demo on stage, and they *always* go wrong--don't let it throw you. So I didn't. I just stood there holding the blimp, as you can see in the picture above, and went on with my talk and slides as planned. Points made, time limit met, applause gained. I looked a bit awkward, I'm sure (although hopefully not always as unhappy as I look above), but at least I got the sympathy vote! Now on to San Diego for Etech on Tuesday, where we get to do it again for an hour in front of the smartest geeks in the world. So much for the sympathy vote ;-) Jordi's hard at work fixing the firmware problems, so fingers crossed...
[Photo credit: Red Maxwell]
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Developer

ArduBlimp (minimum Blimp) V1

Posted by Jordi Muñoz on February 28, 2008 at 12:30pm
Finally we have the final version of the first prototype of ArduBlimp, wells know as the "Minimun Blimp".Capability's:* Hold altitude with PING))) sensor...* Fly around the infrared beacon...* Use Arduino Lilypad, for low power consumption ...
Some High res pictures:

CIMG0201.JPG

CIMG0203.JPG

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CIMG0206.JPG

CIMG0207.JPG

CIMG0209.JPG

CIMG0210.JPG

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Parts used:-The Blubberbot-The pololu motor controller x 2, used to control the motors of the blimp-The pololu infrared beacon, used for navigation-The Parallax Ping))) sensor, for hold altitude-And offcourse, the arduino LilyPad...Source code click here...
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3D Robotics

Getting ready to debut the Minimum Blimp UAV at TED

Posted by Chris Anderson on February 28, 2008 at 12:30pm
Tomorrow Jordi and I will give everyone at the TED conference in Monterey the first public preview of the Minimum Blimp UAV. I did the design and Jordi did all the work! Jordi has more detail in his post (apologies for the repetition!), but basically we took a BlubberBot, kept the envelope, two motors and the plastic motor mounts, and threw everything else out. We added IR position sensors, ultrasonic altitude sensors, an Arduino "Lilypad" and a third motor for vertical control. Our autopilot, sensor and thrust package looks like this:

And it works! Here's a video of it circling a ground-based beacon and maintaining altitude. Extending that to full-room autonomy is simply a matter of adding beacons as waypoint markers.
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