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.
Saturday, November 24, 2007, 04:31 PM - RoboticsFor quite some time, a few of us have been toying with the idea of building an autonomous 3D aerobatic plane.
A [video] by Jonathan How and his students at MIT demonstrates an indoor 3D plane flown automatically. Technically, it is not autonomous because the plane is controlled remotely (automatically) from a ground-based computer.
The plane has no on-board intelligence: it is remotely controlled, and its position is accurately measured by a Vicon motion capture system. This eliminates the need, not only for on-bord intelligence, but also for any on-board sensors and telemetry.
The use of a mocap system is a bit of a cheat because it basically eliminates the problem of estimating the position and attitude of the plane (the Vicon Mocap system has mm accuracy at over 60 frames per second).
Still, the control is quite impressive.
A longer video showing Jonathan How research on swarm UAV (using quad-rotor DraganFlyers) is available on this page. The video was shown at the last ICRA.
Thursday, November 8, 2007, 04:26 PM - Flying ContraptionsThe Toki Corporation in Japan has a new type of micro servo for micro R/C flying contraption. The new servo doesn't use a motor or regular actuator (electromagnetic or piezo), it uses shape memory alloy wires that the company calls "biometal".
The SmartServo RC-1 has the following specs: dimensions: 38x9x3mm, weights (with wires): 1.03g, torque: 15 g.cm, consumption: 10 mA, 0.15 W, deviation angle +- 30 degrees, operating voltage: 3 to 5 V.
The good news is that the servo is available for sale at Air Midi Micros for $32. The AMM web site has a video showing the servo in action. The technical documentation for the servo is available from Aair Midi Micros and from Toki.
Technical data about the material is available in this PDF document.
The servo apparently measures the resistance of the wire to estimate the position of the horn. Hence, the wire serves not only as an actuator, but also as a sensor (the control circuit is shown here).
Many moons ago (circa 1994), I built a micro R/C airplane with Nitinol wires from RobotStore to control the rudder. It wasn't a success, because the Nitinol wires took way too long to cool down after "contracting". The cooling time was roughly 1/2 second. Toki seems to have solved the problem, though their documentation says that the servo slows down (and the max deflection angle is reduced) after a period of continuous use.
RobotStore sells Toki's helical BioMetal wires.
Saturday, November 3, 2007, 11:32 PM - Flying ContraptionsThe DelFly II is a radio-controled ornithopter with an on-board camera built by the University of Delft.
The specifications are quite impressive: 16 grams, 1.6g outrunner brushless motor, 130mAh single-cell LiPo battery, autonomy: 8 minute of hovering, or 15 minutes of horizontal flight, 15 m/s max speed, -0.5 m/s min speed,
30cm maximum dimension, electromagnetic actuators for elevator and rudder control. They also claim video-based trajectory stabilisation, target recognition, and such (see the second video).
There are photos, and movies
here, and here.
Monday, October 8, 2007, 01:46 AM - ElectronicsOver the last few months, I have become rather fond of the Arduino microcontroller board concept. I like its simplicity, its open design, and (last but not least), the fact that the development environment runs seamlessly on Linux.
One shortcoming of most Arduino boards is that they are rather bulky (not good for putting them onbard a small airplane). While the Arduino Mini has been available for a while, it is not as convenient as the new $17.50 Boarduino kit from Ada Fruit.
The Boarduino has everything a regular Arduino has, but it is much smaller and can plug into a breadboard.
Monday, October 8, 2007, 01:07 AM - ElectronicsSpeaking of Jeff Han: Jeff pointed me to this new device, recently announced by Analog Device. Many people were anxiously waiting for something like this to appear: single chip that contains 3 accelerometers and 3 gyroscopes that can be used to build a full, 6 degree of freedom inertial measerument unit (IMU).
The part is called the ADIS16355.
It uses an SPI interface, and even includes an auxillary 10-bit A/D converter, an auxillary D/A converter, and two digitial I/O
(see data sheet).
Now for the bad news: the price is $360 in 1000 quantity (ouch!).
It's still a lot cheaper to buy a 5 DoF break-out board for $110 from sparkfun (3 accelerometers, 2 gyros), plus another gyro, and a cheap micro-controller.
Monday, October 8, 2007, 12:51 AM - Misc TechnoToysMy friend and colleague Jeff Han has been getting a lot of attention in the last year or two with his amazing multi-touch display panel (see various videos here and here, and
his August 2006 TED talks)
Jeff has started a company in New York City called Perceptive Pixel.
The funny thing is that the upscale department store Neiman Marcus is offering Jeff's "online media wall" in the "fantasy" part of its Christmas catalog. The price is "starting at 100,000". If you have to ask.....
There is a nice video on the Neiman Marcus site too.
Monday, October 8, 2007, 12:18 AM - Flying ContraptionsBattery manufacturer A123 Racing is offering a new type of Lithium-Ion batteries for model cars and airplanes that can not only put out enormous amounts of current, but can also be charged in 15 minutes.
A123 Racing is a sub-brand of manufacturer A123 Systems, who has been producing the new type of battery for a while. They were so far mainly used in rechargeable cordless drills.
The so-called Hypersonic cell has the following characteristics: capacity: 2300 mAh; nominal voltage: 3.3V; internal impedance: 10 milliohms; max continuous discharge: 70A (30C); burst discharge (10 seconds): 120A (60C); fast charge current: 10A (4C), which translates into a charging time of 15 minutes; mass: 70 grams; price: $20.
A 3S1P pack costs $90, and the special charger is roughly $100.
The energy per gram is not as good as a LiPo, but you can't beat the charging time....
Monday, September 10, 2007, 06:31 PM - Misc TechnoToysStartup company EEstor claims to have produced ultra-capacitors with en energy density of 280 Watt-hour per Kilo. When you realize that your typical LiPo battery is around 140 Wh/kg your interest level goes up a notch. Given that ultra-capacitors can be charged extremely quickly (in seconds), and have a huuuuge maximum current, this might just be the miracle power source, not just for model ariplanes, but also for (full-scale) cars, which is EEstor's main target.
The main limitation of garden-variety ultra-capacitors (the ones you can get from DigiKey) is that they have a very low breakdown voltage (like 3V). The energy per unit mass sucks. It's enough for those e-charger toy airplanes from AirHog with a 10 second running time, but not for R/C planes. Since the energy stored in a capacitor is quadratic with the voltage (1/2.C.V^2) increasing the breakdown voltage can make a big difference. That's apparently what EEstor has done: they were able to raise the breakdown voltage to 1500V....
EEstor doesn't really have a web site, but there was a nice article on them at Technology Review back in January.
Monday, September 10, 2007, 06:29 PM - TechnoToysAfter a long hiatus, Yann's Techno Toys is back in business.
A large backlog of Techno Toys awaits us.
Friday, May 18, 2007, 01:49 AM - Flying ContraptionsPaparazzi is an open source hardware/software project whose goal is to provide a complete autopilot system for UAVs.
The Paparazzi project is hosted at the "Ecole Nationale de l'Aviation Civile" (ENAC) in France, and is the basis of ENAC's autonomous UAV project.
The hardware is built around a Philips LPC2148 ARM-7 chip. It includes a GPS and Pyro-electric infrared sensors for pitch and roll angle detection (no gyros).
Friday, May 18, 2007, 01:25 AM - Flying ContraptionsCrespiere 2007, an annual get-together of electric R/C airplanes in France, took place last week. I'm told the weather was sub-optimal (very high winds), and the turn out less than usual (because of the weather). Web magazine RC Pilot Online has a picture gallery of the event.
I was intrigued by this weird-looking plane that looks like a Calder scultpure.
There is also a picture of my dad's new CAP-10 . Unfortunately, bad weather prevented test flights before Crespiere, hence it didn't fly during the event.
Tuesday, April 3, 2007, 01:26 AM - Flying ContraptionsTrek Aerospace has demonstrated a small, electric powered UAV called the OVIWUN. It has two contra-rotating ducted fans on each side of a "fuselage". The ducted fans can be independently tilted forward or backward to control yaw and pitch (as well as forward/backward translation). Roll is apparently controlled by changing the relative speed of the rotors. Each rotor is powered by a 450 Watt electric motor. The UAV is 36cm tall, 65cm wide, 41cm long, and weighs 2520 grams (with batteries). They claim an endurance of 20 minutes, and maximum speed of 75km/h (which I find very hard to believe).
The $15,000 price is a bit steep for something many of us could probably build in our shop. However, the good news is that UAV is controlled by an Xscale-based single-board computer running Debian Linux, and comes with open source flight control software.
There is a nice video of the OVIWUN's indoors test flights
Monday, March 19, 2007, 01:00 AM - Flying ContraptionsThis page has a collection of papers by the participants of the 2006 student competition of Unmanned Air Vehicles. There is quite a lot of details about the hardware used in each of the participants' planes.
Monday, March 19, 2007, 12:47 AM - ElectronicsProcerus Technologies offer the Kestrel micro UAV auto-pilot. It weighs 16.5 grams and contains a 6 degree of freedom inertial measurement unit, a magnetometer, an absolute and differential altitude sensor, and an airspeed sensor. It's built around a Rabbit micro-controller. The only thing that's not light about it is its price: 5 kilodollars.