Saturday, August 23, 2008, 03:48 PM - Flying ContraptionsFor several years, my friend and colleague Andrew Ng at Stanford has run an autonomous helicopter project in his lab, with two of his PhD students, Pieter Abbeel and Adam Coates. They have developed new reinforcement learning techniques to automatically learn how to stabilize and control the helicopter. They reached the point where they can pretty much get their heli to perform every aerobatic figure known under the sun. There is a bunch of videos on their website, as well as on their Youtube chanel.
Interesting implementation details: they have no on-board intelligence on the heli. They use a GPS and an IMU with serial outputs directly fed into Xbee Pro modules. The signals are received by a PC on the ground, which remotely controls the heli through the training port of a conventional R/C transmitter.
Saturday, August 23, 2008, 03:31 PM - Flying ContraptionsThere are a few YouTube videos of an interesting VTOL flying contraption that seems to be using contra-rotating propellers, most likely based on a Himax co-axial contra-rotating motor pair from MAXX Products. The plane appears to be very maneuverable (thanks to Bertrand for the pointer).
More videos are available here, here, here, and here.
UPDATE (2008-09-08): Chris Good, the builder of this nice flying contraption, pointed us to his rcgroups forum post describing the construction. The post has several pictures of the innards, and details of the channel mixing. Contrary to what I guessed, Chris used two separate motors (mounted in a push-pull fashion), rather than a co-axial double motor. The motors are geared brushless in-runners.
Tuesday, July 1, 2008, 12:11 AM - Flying ContraptionsDrone manufacturer Lite Machines Inc. has a video of their latest drone called the Voyeur.
It's a cigar-shaped drone, 686mm in length, 63.5mm in diameter, with two counter-rotating rotors, 762mm in diameter. It seems to be using bushless outrunner electric motors powered by a 3-cell LiPo battery.
The total mass is 1.4kg. The cruising speed is 30 knots and the autonomy 30 minutes.
There is a cool video on YouTube
This must be the same Lite Machines Inc. that got started by producing the first gas-powered micro-helicopter many years ago. It used a Cox 0.8 cubic cm motor and had a really clever mechanical system on the tail rotor to stabilize the yaw. This was a kind a mechanical gyro, before the days of cheap and light solid-state gyros.
Monday, June 16, 2008, 11:03 AM - Flying ContraptionsThe Rencontres Electriques de Crespiere, an annual electric flight meeting took place near Paris last week-end. A particularly interesting design was shown this year: the Verti4. It is the simplest and most successful electric VTOL design I have ever seen. It looks like a fairly conventional trainer-style airplane with four motors on each side of the wing (two in front of the wing, two aft of the wing). The motors can pivot 90 degrees (all together) from facing up to facing forward (V22 Osprey-style), allowing a transition from hovering to translational flight. Is with other quad-rotor contraptions, two rotors turn clockwise, and two counter-clockwise on a diagonal. From what I gather from Jean-Claude and Bertrand (my dad and brother) who attended Crespiere, the stabilization and control is not done with some sort of custom electronics, but with a combination of conventional gyros, and channel mixing.
There are a few videos on YouTube:
Others have built quad-rotor or quad-ducted fan electric VTOL planes before (like this F35 or this strange-looking quad-EDF contraption), but not with this simple way of transitioning to translational flight.
Monday, June 16, 2008, 12:48 AM - Flying ContraptionsKyosho has a series of ready-to-fly R/C airplanes called the Minium that come with a complete 2.4GHz radio set.
Until recently, the only Minium plane was a small Cessna (38cm wingspan, 18 grams). The plane has been available (and very successful) in Japan, Europe and Australia under the Kyosho/Minium name. In the US, a very similar plane (if not exactly identical) has been distributed by Horizon Hobby under the ParkZone brand. It sells for $120
Now Kyosho has announced a new Minium: the Piper Cherokee. The main difference is that the Cherokee has ailerons. The plane is advertised for pre-orders for $180 on Kyosho's US e-commerce web site, but the availability date is unspecified.
What's strange is that the same web site does not have the Cessna (probably because of some exclusive contract with Horizon Hobby).
Even stranger, Kyosho's Japanese website used to have a page on the Cherokee, but it has been taken down....
Monday, June 16, 2008, 12:38 AM - Flying ContraptionsAerovironment has apparently received 0.5e6 US$ to develop a nano-UAV that flaps it wings. I'm guessing Aerovironment's Matt Keenon (an micro R/C enthusiast and pioneer) must be involved in this project.
It looks like the plane could be designed to take off vertically.
The advantage of flapping wings for hovering is that you don't get a reaction torque, as with a helicopter rotor. The solutions are few: contra-rotating rotors, or oscillating blades (flapping wings).
The mechanical design, the control system, and the aerodynamic efficiency will all be challenging.
Monday, June 16, 2008, 12:28 AM - Misc TechnoToysThis French furniture store sells what looks like oversized LEGO blocks called LunaBlocks, with which one can build furniture. Cool concept.
Monday, June 16, 2008, 12:22 AM - Flying ContraptionsEagleTree Systems have introduced two new sensors to their telemetry and flight recording product line: an altimeter with 1 meter resolution, and an airspeed sensor (with Pitot tube).
They cost around $40 each, and include an 7-segment LED display.
They can run standalone and display the maximum value observed during a flight, or they can plug into one of EagleTree's flight recording systems.
Monday, June 16, 2008, 12:18 AM - ElectronicsThe Drum Master is a DIY "brain" for an electronic drum pad.
The web site has some data on how to process the output of piezo-electric sensors used in drum pads.
Monday, June 16, 2008, 12:11 AM - RoboticsThe arduino.cc forum has an entry describing a nice little robot that can solve mazes written on the ground with a black marker. There is a link to a YouTube video showing the robot in action.
The author used the Arduino IDE to program the ATmega-168 used on his robot. He mentions using a Pololu 3PI robot platform. This platform is not yet available from Pololu, but apparently will be soon.
Sunday, June 15, 2008, 11:59 PM - Flying ContraptionsPlantraco (also known as MicroFlight.com) sells a tiny disk-shape plane called MicroMAV that looks a lot like a smaller version of my PMAV: disk-shaped wing, rudder underneath the wing.
The MicroMAV has a 12cm wingspan (my PMAV is 32cm), and weighs a mere 4g. It was designed by Henry Pasquet and Robert Guillot. It uses a single cell 20mAh LiPo, and a magnetic actuator for the rudder (no elevator). You can have it for $90 (plane only) or packaged with a transmitter for $150.
Sunday, June 15, 2008, 06:49 PM - Flying ContraptionsScience Daily has a piece on a University of Florida professor of mechanical engineering Subrata Roy, who has proposed a design for a flying-saucer-shaped UAV that would be propelled using magneto-hydrodynamics. The basic idea is pretty old: ionize the air around a plane, apply a magnetic field, and inject a current through the ionized plasma. The Lorentz forces will accelerate the plasma. The principle works fine to propel model boats in salt water, but it's horribly inefficient because, although salt water conducts electricity, it has a high resistance. Much of the energy is wasted in the water. In air, the situation is worse.
The article in Science Daily merely mentions a patent, not an actual prototype. Don't hold your breath for a practical prototype...
Sunday, June 15, 2008, 06:42 PM - Electronicsat $40, the Wireless ARMmite micro-controller board from Coridium has a pretty high coolness/price ratio: a 60MHz ARM7 (LPC-2103), and a space for optional ZigBee (XBee), USB, or Bluetooth serial modules.
Sunday, June 15, 2008, 06:37 PM - Misc TechnoToysKorg-Japan has come up with three new USB music controllers that are the same width as a typical laptop: nanoKey (keyboard), nanoPad (drum pads), and nanoKontrol (control knobs).
Saturday, April 19, 2008, 06:33 PM - RoboticsOkay, I'm about to switch into total bragging mode here.
This is an uber-cool video of an autonomous mobile robot that can drive itself in outdoors environments (parks, fields, forests) solely from vision. The sensors are plain cameras (well, stereo cameras). There is no laser range finders, radars, or ultrasounds of any kind. Just cameras.
Best of all, this little guy actually learns to recognize obstacles and traversable areas by driving itself around. It also learns it own dynamics.
Why the statement about bragging mode, you may ask?
Well, this is my project: I lead the team that built the software for that robot. This is one of the things I do for a living (when I'm not TechnoToying).
For more details, videos, technical papers and the like about this project follow this link to my labs web site at NYU.
By the way, this video was put together by Pierre Sermanet using Blender on Linux.
Sunday, November 25, 2007, 03:38 AM - Flying ContraptionsThe latest trend in R/C flying is First Person Video. This consists in mounting a wireless camera in an R/C airplane, and flying the plane by looking at the video from the camera (generally using goggles).
The ultimate refinement is to mount a head tracking device on the goggles so as to control the pan and tilt of the camera.
A few on-line shops and web sites have popped up to cater to the new population of FPV pilots. One of these web sites is FPV Video.
Shops for FPV equipment include Hobby Wireless, and New Generation Hobbies.