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When I first started planning a robot for the recent LVBots dead reckoning competition, it was more or less a conventional design—a flat chassis with motors and circuit boards attached to the top and bottom—and I lost interest in it quickly because it felt like I was just reinventing the 3pi. I looked for a way to make the shape of the robot unique, and I noticed that the three-legged shape of R2-D2, the famous astromech droid from Star Wars, might be a good fit for a typical undercarriage composed of a ball caster and two wheels. The result of continuing along this line of investigation is my dead reckoning robot, R2-DR (you can probably guess what DR stands for). Continued…
We’ve released an updated version of our dual VNH5019 motor driver shield for Arduino. The VNH5019 is a great solution for driving high-power motors, with each chip able to supply up to 12 A continuously at 5.5 V to 24 V. However, the original version of our dual VNH5019 shield was designed before the Arduino Uno R3 was released, so it lacked pass-throughs for the four new pins (SCL, SDA, IOREF, and an unused pin) introduced by the R3 and present on all newer Arduinos. This makes it harder to stack other shields with it, especially ones that make use of the new I²C pin location. The latest board revision adds these pass-throughs to make the shield fully compatible with the Uno R3 pinout.
On March 6, LVBots held another competition at Pololu. This time, it was a dead reckoning contest: each robot had to find a line course and follow it to its end while keeping track of its position, then try to return to its starting position without any external navigational aids. Scoring was based on how close to the starting position the robot ended up, as well as how quickly it got there. The complete rules are available here (23k pdf). You can see a selection of the entries in this video compilation from the contest.
David has already posted about his entry. My robot was R2-DR, the miniature astromech droid, and I’ll be writing a post about it soon, too.
Are you in the Las Vegas area? Check out the LVBots Meetup page and drop by this Thursday, March 20, to see the robots in person!
Updates: You can read more about each of our robots in these blog posts:
When we designed the first version of the Pololu USB-to-serial adapter way back in 2004, using a USB Mini-B receptacle was an obvious choice: it was much smaller than the standard B-type connector, allowing us to keep the board compact, and it was readily available in surface-mount configurations that facilitate automated printed circuit board assembly.
We went on to use the Mini-B connector in lots of products, like our Maestro servo controllers and Wixel. Although the even smaller Micro-B connector became part of the USB specification in 2007, it didn’t seem to offer enough of an advantage over the Mini-B connector for us to immediately switch over. Continued…
We’ve started selling USB versions of these two RoboClaw motor controllers from Orion Robotics:
These new RoboClaws add a USB serial interface to the other three control interfaces available (TTL serial, RC, and analog inputs), but are otherwise identical to the V4 RoboClaw 2×15A and 2×30A controllers that we previously offered. Like their predecessors, they can drive a pair of brushed DC motors with up to 15 A or 30 A, respectively, at voltages from 6 V to 34 V. Integrated dual quadrature decoders make it easy to create a closed-loop speed control system; analog feedback is also supported for closed-loop position control.
This data logger shield from Adafruit provides an easy way for your Arduino to save data so you can process and analyze it later. It accepts any SD card formatted with a FAT16 or FAT32 file system, and it includes a real-time clock (RTC) for accurate timestamping of your data. Lots of documentation and resources are available from Adafruit to help you get started with the shield.
For more information, see the Adafruit Data Logging Shield for Arduino product page.
Get a FREE copy of Elektor magazine’s January/February issue with your order while supplies last. To get your free issue, enter the coupon code ELEKTOR0114 into your shopping cart. The magazine will add 8 ounces to the package weight when calculating your shipping options.
For other issues and more information, see our Free Elektor Magazine Offers page. All issues are now available for shipping worldwide!
We’re now selling an I²C long distance differential extender from SJTbits. When you connect one of these boards to each I²C device in your system, they transparently convert all I²C communications to differential signaling and back, allowing the range of your I²C bus to be significantly increased (they have been tested at ranges of over a hundred feet).
For more information, see the I²C Long Distance Differential Extender product page.
If you’re looking for an inexpensive motor driver that works with higher voltages, but our DRV8801 carrier’s single channel isn’t enough, we now offer another option: a carrier board featuring Allegro’s A4990 dual motor driver.
The A4990 can deliver a continuous current of up to 0.7 A per channel at voltages from 6 to 32 V, making it a good choice for small, low-current motors that run on relatively high voltages. Onboard sense resistors enable the A4990 to actively limit the peak motor current to about 0.9 A per channel, and the carrier board adds a reverse-voltage protection circuit in addition to the robust IC’s built-in protection against under-voltage, over-voltage, over-temperature, and short circuits.
For more information, see the A4990 carrier product page.
As smartphones and tablets become more popular and more advanced, they drive the rapid development of progressively better and cheaper inertial sensors, and we’ve come to expect a new 3D compass/accelerometer chip from ST every year or so. We’re catching up again with their latest technology (for the time being) with the release of our LSM303D 3D compass and accelerometer carrier.
The LSM303D offers a number of improvements over its predecessors, including a wider maximum magnetic sensing range (up to ±12 gauss). It also features a more unified I²C interface and adds support for SPI communication. Our carrier board includes a 3.3 V voltage regulator and level shifters that make it easy to use with 5 V systems. For more information, see the product page.