Saturday, January 31, 2009, 04:29 PM - Misc TechnoToysI 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).
Sunday, January 25, 2009, 12:10 PM - Misc TechnoToysChina 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!
Monday, January 12, 2009, 07:22 PM - ElectronicsThis 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.
Monday, January 12, 2009, 12:38 AM - RoboticsThe 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.
Monday, January 12, 2009, 12:22 AM - Misc TechnoToysSteve 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.
Tuesday, January 6, 2009, 11:29 PM - RoboticsArduPilot 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.
Monday, December 29, 2008, 04:24 PM - RoboticsThe 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....
Friday, December 26, 2008, 08:06 PM - Misc MusicI'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.
Saturday, December 6, 2008, 01:02 AM - Misc MusicAkai 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.
Monday, December 1, 2008, 12:26 AM - RoboticsThe 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.
Sunday, November 30, 2008, 01:22 PM - RoboticsWhile 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).
Sunday, November 30, 2008, 01:11 PM - ElectronicsMake 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.
Sunday, November 9, 2008, 09:15 AM - ElectronicsLady Ada from Adafruit Industries has a nicely detailed tutorial on configuring a pair of Xbee wireless modules to talk wirelessly to an Arduino. It is an expanded version of another tutorial by Rob Faludi, a researcher in the Interactive Telecommunication Program at NYU
Adafruit conveniently sells (for $10) an Xbee carrier board which contains the level shifters, voltage regulator, and pin headers required to easily talk to an Xbee.
Saturday, November 8, 2008, 11:33 PM - ElectronicsEffet de Bord is a French blog (written in English) that talks about using an Xbee module as the basis of an R/C system. Xbee Pro modules establish a bidirectional serial communication link with a range of roughly 1.5 km.
The blog is connected to the O24RCP project whose purpose is to build an open design for a 2.4GHz R/C system out of off-the-shelf components (such as the Xbee).