Build a Webcam Robot With Latest Lego Kit
Vision Command adds new dimension to Lego Mindstorms Robotics Invention System.Dennis O'Reilly, PCWorld.com
Legos have come a long way from the bright, interlocking plastic blocks I remember using to build houses and pyramids back in the 1960s. These days, in addition to houses and pyramids, you can build your very own robot with the $199 Lego Robotics Invention System 1.5, and you can give your creations sight by adding the company's $99 Vision Command system. Ideal for budding engineers (and programmers) 12 and older, these "toys" promise many hours of discovery and creative expression.
Instructions are included for building three basic robots, but the idea is to create your own variations on those basic themes. It took my 10- and 14-year-old assistants and me about 2 hours to build our S'Cargobot motorized Web camera bot, but we had the advantage of previous Lego experience. (Lego beginners will probably require a little extra time to become accustomed to the standard Lego components.) My assistants started the project with me, but they wanted to take a break before completion and left me to finish the robot. Their interest returned once our creation started to move.
Lego Engineering
When you're ready to begin building, you can either follow the manual's instructions or let your imagination be your guide. Finding the right pieces is challenging, but putting them together is easy. Pictures in the instructions show not only which components are required for each stage of the construction, but also what the robot will look like when each stage is completed.
The heart of the robot is the programmable Robotics Command System, also known as RCX, a yellow brick about the size of a personal cassette player that snaps into place like the other Lego pieces. Based on an 8-bit microprocessor with 16KB of ROM, 512KB of internal SRAM, and 32KB of external SRAM, the RCX contains sensors to control your robot's actions and drive its two motors. It uses four AA batteries; I didn't test the robot's battery life.
After you've assembled your robot, it's time to make it move. That's where the Lego RCX Code programming language comes in. You do the programming work on your PC using the software included with the robot. It's very simple to use: You just choose actions from a scroll-down list of green blocks on the right of the screen. When you double-click a block, you open a window that allows you to change that action's properties. You can change the attributes of an action--such as how long the robot waits before backing up when a touch-sensor is activated--by double-clicking the green block and entering a new setting via up/down buttons or the keyboard. Once you've set the actions, you click and drag the blocks into a column running down the middle of the screen to create a program.
Programming your robot is much easier than building it, thanks in large part to the "Training Missions" you're forced to go through before you strike out on your own. While the Training Missions are certainly helpful, making them obligatory for all new users is a bear.
When you finish your program, you upload it to your robot through an infrared transmitter that connects to one of your PC's serial ports. (The transmitter must be 4 to 6 inches from the robot.) Although this upload method is not as easy to use as a Universal Serial Bus connection is (if you have one, and if you have the right operating system), I had no problems transmitting programs to my test robot.
Robotic Sight
How about making a robot that shoots soft-tipped darts at a target? Or maybe you'd rather check on your kids in the next room? With the Vision Command system, you not only give your robot sight, but you also make the robot suitable for completing a variety of activities. Using your PC and the camera's built-in microphone, for example, you can eavesdrop (although I don't want to give the kids in my house any ideas).
With the same RCX Code language, you can program your Vision Command system to react to motion and lights, or you can use it as a Webcam or for sending video e-mail. You can also take still shots with the camera and focus its lens manually. The only limiting factor is the camera's USB cable, which has a range of only 15 feet. The Vision Command product is a bit pricey and doesn't compare that well to other Webcam products, but trying to use other Webcams with your robot would be awfully clunky. The software is designed for kids, though, so it has big buttons, bright colors, and clear instructions.
While either toy--the Robotics Invention System or the Vision Command system-- will alone brighten the eyes of budding engineers and programmers, the devices really come to life when you use them together. Overall, $300 is a lot to spend for a toy that may be shelved after a few days or weeks, but for the most serious geeks in training the two products could be the start of something big.