Minoru stereo webcam now works under Linux 
Tuesday, February 17, 2009, 02:53 AM - Robotics
Thanks to Laurent Pinchart, maintainer of the uvcvideo driver, the Minoru stereo webcam now works on Linux.

If you are in a hurry to get it to work, here is the installation process under Ubuntu (or any Linux distro with kernel version 2.6.27-xx):
0. make sure you have installed the linux-headers package, probably called linux-headers-generic.
1. download Laurent's latest driver from linuxtv.org (click on the .gz link near the top of the page).
2. do "tar xvf <the-file-you-just-downloaded>". This will make a directory named "uvcvideo-XXXXXXX" in the current directory. cd to that directory.
3. do "make", and "sudo make install".
4. plug in the Minoru webcam.

The left and right webcams will appear as /dev/video0 and /dev/video1 (unless you already have a video device plugged in). You can grab from both cameras simultaneously at 640x480 at 15 frames per second, or 320x240 at 30 frames per second.

Thanks to Laurent for the quick fix, to Jan Ciger for testing the patches, and to Steve Jamieson and David Holder from Minoru for being supportive.

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Universal Robot: Play at the Manhattan Theater Source + Panel Discussion (with yours truly) 
Friday, February 6, 2009, 11:06 AM - Robotics
The Manhattan Theater Source in Greenwich Village, just north of Washington Square Park (and two blocks away from my lab at NYU) will host the play Universal Robots, a liberal adapation by Mac Rogers of Karel Capek's classic play R.U.R. ("Rossum Universal Robots", this is where the word "robot" comes from). The play will run from Feb 12 to Mar 7.

A Panel discussion will take place on Feb 21st from 3:00 to 4:00 PM entitled Resistance is Futile: Exploring our Evolving Relationship to Robots in Todayĺs Wired World. Panel participants will include my friend Michael Littman (from Rutgers), and yours truly, as well as artists and scifi writers.

Sounds like fun.
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Using the Minoru stereo webcam under Linux 
Saturday, January 31, 2009, 04:29 PM - Misc TechnoToys
I just received one these brand new Minoru stereo webcam, which I bought at Amazon from 90 bucks (a steal considering the price of the closest competitor).

Naturally, I'd like to use it under Linux for robot vision, so I was crossing my fingers that one of the webcam drivers on Linux would recognize it.

As soon as I received the camera, I plugged it into my laptop running Ubuntu 8.10 Interpid. There are good news and bads news.

Good news: the device is detected by the uvcvideo driver, and the left and right cameras appear as /dev/video0 and /dev/video1. My video grabbing software was able to grab frames from both camera separately. I tried my own video grabbing test program written in Lush for v4l2.

Now for the bad news: it seems impossible to grab video from the left and right cameras at the same time :-(

It looks like uvcvideo assigns more than half the USB port bandwidth to the first camera, and there is not enough left for the second. I've posted a question about the problem on the uvcvideo developer mailing list. Stay tuned.

UPDATE: Laurent Pinchart, maintainer of the UVC driver is looking into the problem. It looks like the camera reports a higher bandwidth than it needs (at least, that's what how the driver interprets the data). The Minoru people are interested in making their camera work with Linux and are helping out Laurent (sending him a free camera and such).


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MIDI library for the Arduino 
Tuesday, January 27, 2009, 11:15 PM - Electronics
Title says it all. Get it here.

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Neural Net in JavaScript 
Sunday, January 25, 2009, 11:06 PM - Misc TechnoToys
[via Hack A Day] Shaun Friedle has written a simple neural net code in JavaScript (forward prop only, no learning) and uses it as an OCR engine to break badly designed CAPTCHAs from within the browser. The script is here, and the demo home page here.

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cheap video gear from ChinaVasion 
Sunday, January 25, 2009, 12:10 PM - Misc TechnoToys
China Vasion (not China Vision, oddly enough) has a slew of cheap video gear such as wireless cameras and receivers for $25, and quad-camera systems for $100.

They also have rather unusual widgets, such as this underwater remote camera which comes with an MPEG recorder and costs $250.

The also have this radio-controlled car with a built-in wireless camera and a transmitter-mounted LCD screen. Things like this have been available for some time, but not for $90!

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Arduino-based MIDI -> control voltage converter 
Monday, January 12, 2009, 07:22 PM - Electronics
This page (with an interesting domain name) describes a simple MIDI->control voltage converter that can be used to control analog synths from MIDI controllers. The contraption contains an arduino and an Analog Device AD5668 16-bit digital to analog converter chip. this chip has 8 independent analog outputs with 16 bit resolution, and uses an SPI (serial) interface. The chip can be had for $25 from DigiKey.

The most complicated part is to figure out how to talk to DAC chip, but the Arduino sketch source code says it all.
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Amazing automatic book scanner made from Legos 
Monday, January 12, 2009, 12:38 AM - Robotics
The Make Magazine blog has a link to this amazing DIY automatic book scanner from Japan. It's made out of Lego Technics and turns the pages of the book automatically. Very nice indeed.

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Fry your retina for $50 
Monday, January 12, 2009, 12:22 AM - Misc TechnoToys
Steve Crandall from Tingilinde pointed me to this 150mW blue laser diode available for $50. An ideal way to fry your retina in the blink of an eye (actually *before* the blink of an eye, and way faster than it).
With proper precaution it might be used to build a CNC laser cutting machine to cut foam (Depron) and such.

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ArduPilot (quasi-)available from Sparkfun 
Tuesday, January 6, 2009, 11:29 PM - Robotics
ArduPilot is a small Arduino-compatible board designed to be the centerpiece of a UAV autopilot. It has servo outputs, a receiver input, a GPS input, and an input for a PIR-based stabilization sensor (such as FMA's Copilot).

Sparkfun has the kit for $25, except that they seem to be out of stock right now. The SMD components are pre-soldered on the PC board.

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G-Dog: impressive robot dog kit from Japan 
Monday, December 29, 2008, 04:24 PM - Robotics
The G-Dog is a new robot dog kit from Japanese company HPI Robots, a division of HPI Racing, which sells R/C models and techno-toys of various kinds.

The G-Dog sells for about 70,000 Yens (about US$800).

This YouTube video shows the speed and agility of the G-Dog. It's much faster than the Aibo ever was. Then again, unlike the Aibo, it doesn't have a nice-looking shell, and has a rather simple on-board computer and few sensors.

It uses 9 custom servos, dubbed RS304MD, which seem to be controled through a TTL-level serial port. The CPU is based on an Atmel AtMega128, and includes a 3-axis accelerometer. It has interfaces for 2 gyros, and a wireless receiver.

The G-Dog weighs 570g, which is quite light, but could be made lighter with the use of LiPo batteries instead of NiMH.

If only this things became available outside of Japan....

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Akai EWI USB: a quick review 
Friday, December 26, 2008, 08:06 PM - Misc Music
I've been playing with my new Akai's new EWI USB for a couple of weeks now. I have to say, it's a mixed bag. Compared to the more expensive EWI 4000-S, there are pros and cons.
Let's start with the pros: it's a lot cheaper than the EWI 4000-S ($300 versus about $600), it's lighter (no built-in battery, no built-in synth), it's powered through the USB cable, and the breath, lip, pitch-bend, and key sensors are essentially identical to the 4000's, except that they are self-calibrating. Now for the cons: my main gripe is the absence of portamento sensor. The 4000 has a slider on the right side of the octave rollers that, when touched with the left thumb, turns on the portamento (or glissando). I love that feature, but it's absent from the EWI USB.
Second, since the EWI USB doesn't have a built-in synth, it comes with a software synth that runs on PC/Mac. The sounds provided with the soft synth are few and not so great. Many of them do not even react to the EWI sensors (like the pitch bend or breadth control). So, you will need another soft synth if you want decent sounds. I tried to install the soft synth on Linux under wine. The good news is that it runs. The bad runs is that the latency is so high that it's unusable. I'm not sure where the latency comes from, or whether it's fixable.

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Akai EWI USB available 
Saturday, December 6, 2008, 01:02 AM - Misc Music
Akai has announced the availability of the EWI USB, the latest product in their long line of Electronic Wind Instruments. The EWI USB sells for about $300 at Sam Ash, Sweetwater, and other online music instrument stores. It look similar to the EWI 4000S, but has a USB port instead of a MIDI port, and has no built-in sound module. Instead, the EWI USB relies on software synths on PC or Mac to produce sounds. Getting rid of the built-in analog emulation synth allows Akai to bring down the street price from $700 for the EWI 4000S to $300 for the EWI USB.

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CNC router table for $600 
Monday, December 1, 2008, 12:26 AM - Robotics
The Probotix Fireball V90 CNC router goes for $600. Okay, for $600 you only get the mechanical part, not the stepper motors nor the controller boards. Still, it's pretty cheap. Add $300 to $400 for a 3 axis kit, and you are all set.


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Pixhawk: Beagleboard-based UAV autopilot at ETHZ 
Sunday, November 30, 2008, 01:22 PM - Robotics
While we are on the topic of the Beagleboard, it is worth mentioning that a group at ETH in Zurich is working on a micro-UAV autopilot project based on the Beagleboard called the Pixhawk. The main difference with most other open source autopilot projects is that this one will include a camera and a vision system. The beagleboard OMAP processor is powerful enough for simple vision algorithms (the alternative being the Blackfin processor).
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Make Magazine's definitive guide to open source hardware 
Sunday, November 30, 2008, 01:11 PM - Electronics
Make Magazine's blog has a great list of opne source hardware projects for 2008. The list includes most flavors of Arduinos (although not the stickduino, that we mentioned before), as well as various UAV autopilots, synths, and other projects.

Perhaps it is worth reminding our esteemed readers of the existence of the Beagleboard, a $150 board available from Digikey with a super-powerful OMAP3530 chip from Texas Instruments. The OMAP contains a super-scalar 600MHz ARM Cortex-A8 core and a 430MHz TMS320C64x+ DSP. The Beagleboard can run Linux.

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