Robot Redux

Photo: Randi Silberman

A Grabber: The updated Lego Mindstorms kit features improved motors, new sensors, and a much more powerful processor. It can communicate using USB and Bluetooth. $250 Lego Mindstorms NXT

When the Danish Lego Group debuted the first version of its Mindstorms robot-building kit in 1998, the company aimed the product at the children’s and educational markets. However, to Lego’s surprise, a huge number of adults embraced Mindstorms as a way to build small homemade robots of every possible stripe, including automated Rubik’s Cube ­solvers and toilet-bowl cleaners [see “Mindstorms, Not Just a Kid’s Toy,” IEEE Spectrum, September 2001].

Before long, hackers began replacing the simple graphical user environment that Lego provided for controlling Mindstorms robots with advanced software based on the Forth and C languages to gain greater programming power and flexibility. Others got busy selling ­custom-built sensors to supplement those provided by Lego.

Now Lego has released a long-awaited overhaul of the Mindstorms system, dubbed Mindstorms NXT, which sells for US $250. The bad news is that the core elements of the original Mindstorms—the motors, sensors, and the “programmable brick” that houses the microcomputer used to control Lego robots—are not compatible with the new system, although Lego says a converter cable will soon be available to allow the old motors and sensors to be used with the new system. The good news is that the new core elements are so superior to their predecessors that no one is likely to mind.

Let’s start with the heart of the system: the new programmable brick. About the same size and weight as the old brick, the NXT’s unit has a 32-bit microprocessor, with 256 kilobytes of flash memory available for storing software and data and 64 KB of RAM available for running programs. Compare this kind of power with the original brick’s single 8-bit micro­controller, which had 32 KB of storage space and just 512 bytes of RAM. In addition, input/output functions on the new brick are handled by a second microcontroller that allows the NXT to connect to a PC or Mac via a USB cable or wirelessly via Bluetooth. The new Bluetooth capability also allows the NXT brick to communicate with other bricks or, in a neat trick, to be controlled by a Bluetooth-enabled phone.

Another big change is the new motor design. The original motors were basically cubes about 3 centi­meters on a side. Although there was some internal gearing in these motors, many Mindstorms robot builders constructed elaborate gear trains over and over again in their projects to get better torque. The new motors are elongated and feature a built-in gear train—which means that many projects can now be considerably simplified.

What’s more, the motors have a built-in rotation sensor, which greatly improves the ability to make precise movements or to use dead reckoning as a navigation technique. The new motors also can be automatically synchronized, so that a robot using, say, left and right tank tracks—each driven by a separate motor—will travel in a straight line instead of drifting to one side.

The NXT sensors have been upgraded with the addition of a sound-level sensor and a much-anticipated ultrasonic ­ranging sensor, which can measure distances to about 2.5 meters with 3-cm accuracy. I found that the sensor usually refused to register any distance less than about 3 to 5 cm, even when brushing up against a surface. But by mounting the sensor toward the back of your creations, you can mitigate this problem, so your robot doesn’t smash into a wall that it’s convinced is a few centi­meters away. (To see the new system in action, watch http://spectrum.ieee.org/nov06/nxtrobot.)

The new programming environment is another big improvement. It features a system—based on National Instrument’s LabVIEW software—that provides support for manipulating variables, easily passing data between different control blocks, and controlling the NXT brick’s display and built-in speaker.

Although more ports for sensor inputs and motor control (the new brick sports four and three, respectively) would have been nice, the NXT system successfully strikes a balance between providing features that die-hard adult enthusiasts will love and still making the system simple enough for children to be able to pick up and play with immediately. That said, I can’t wait to see what surprises the diehards will have in store for Lego this time!

http://mindstorms.lego.com

The Wheel, 2.0

IMAGE: Logitech

A Better Mouse: Cunning design makes navigating complex documents and Web pages a breeze with the Logitech MX Revolution. $99 Logitech MX Revolution

A confession: when representatives from Logitech contacted IEEE Spectrum to see if we’d be interested in a demo of their latest mouse, my initial reaction was lukewarm. Lots of mice come on the market every year, and honestly, most of their new features are either bells and whistles in the form of extra buttons and other things that are soon sidelined in day-to-day use or are small improvements in pointing accuracy that most users would be hard-pressed to notice. But demos are always fun, so we invited the Logitech people from their headquarters in Fremont, Calif., to Spectrum’s offices to show off their prototype of the MX Revolution. And boy, am I glad we did.

While the Revolution looks cool, with a form-fitting curvilinear shape, and is wireless, it still didn’t appear to be groundbreaking to our eyes: a thumb-operated jog switch, some buttons, and a scroll wheel. But once I held it my hand, I was instantly hooked. Now, having tested a production unit for several weeks, I can’t imagine not using one.

Moving the Revolution’s scroll wheel back and forth at low speeds results in familiar scroll wheel behavior: the wheel rotates forward or backward through a short arc, before being held in position by a ratchet. That’s ideal when scrolling over short stretches of material, because you don’t want the wheel freely rotating with every twitch of your finger so that the text you’re trying to read is constantly moving up and down. But when you’re scrolling through a long document, the ratcheting action means you have to keep running your finger over and over the scroll wheel—which gets tiring fast.

The Revolution’s scroll wheel is different because once it detects that you’re spinning the scroll wheel over a certain (user-adjustable) speed, it disengages the ratchet. Now the scroll wheel can spin freely, and thanks to its solid-brass core, it usually has enough momentum to scroll all the way down to the end of most long documents on its own steam. See something that you’re interested in as you’re whizzing past? Tap the spinning wheel with your finger, and the ratchet re-engages for more precise scrolling. The scroll wheel can also be tilted to the left and the right to provide horizontal scrolling (for the full story on how Logitech packed the mechanical and electronic components into the MX Revolution to pull this off, see http://spectrum.ieee.org/oct06/4668.

All this maneuvering would be handy enough in itself, but it’s when the scroll wheel is used in conjunction with the thumb-­operated jog switch that the Revolution really earns its stripes. The jog switch acts as a zoom control by default: press your thumb forward, and things on screen get bigger; pull back on your thumb to reduce them again. As a result, the Revolution is indispensable when dealing with complicated documents, spreadsheets, or drawings.

Normally, when working on part of such a document, you’d scroll around, using a combination of the mouse scroll wheel and the onscreen scroll buttons. You’d lift your hand off the mouse, perform the appropriate key stroke to zoom in or out, and then return your hand to the mouse to put the pointer in the right spot to start work. But the Revolution lets you do that entire operation without lifting your hand from the mouse, something that all of us who’ve had those warning twinges in our mousing arms can appreciate.

Logitech’s configuration software allows you to customize the behavior of the Revolution at global and ­application-specific levels. For instance, I’ve set the button on top of the mouse to Google any text that I highlight in any application, while the two side buttons above the jog wheel act as “forward” and “back” controls when I use my Web browser.

If you find yourself doing a lot of Web browsing, or if you have to work on large and complex documents, take the Revolution for a spin. I think you’ll find that it actually deserves its name, and that’s why we made it this year’s Editor’s Pick. It’s in stores now for US $99.

http://www.logitech.com