The bane of every Lego Mindstorms enthusiast is to be accused of plotting to take over the world with an army of robots. As you might have noticed, the world still seems to be relatively free of killer Lego robots. In fact, my little minions barely made it to the front door before grinding to a halt against the two-inch doorjamb. To tell the truth, even if they did manage to get outside, they wouldn't know what to do. Austin Powers' nemesis, Dr. Evil, would be very disappointed in me. But I thought it might be interesting to see what other hobbyists have created since the release of Mindstorms.
For starters, almost every type of locomotion has been attempted with Lego Mindstorms. There are plenty of wheeled robots on the scene because most new users start with them for their simplicity. Most use differential steering, a system in which direction is changed by making one wheel rotate forward, and the other backward. There have also been some models that use power steering, just like a car. I have yet to see a two-wheeled motorcycle that maintains balance, though there has been a motorcycle with a sidecar (the RCX computer brick). Synchro-drive has been accomplishedan impressive form of steering in which all four tires point in the same direction, and all turn at the same time (see Figure 1). This causes the robot platform to face the same direction, no matter which way the robot is moving. There are also many tank robots that can cross uneven terrain using the rubber treads that come in the kit.
Figure 1 Synchro Drive (Photo courtesy of Mario Ferrari).
Users have added other peripherals to their robots to make them even more interesting. One user made a Spycam robot that uses an Xcam2 wireless camera to send images and sound to his television. The robot drives around outside his house while he watches the images from inside. This seems like the perfect sort of robot for those wishing to do a little covert espionage.
The RCX computer brick is considered a great addition for people who own Lego Train sets. It is ideal for controlling the switches for Lego trains, allowing trains to run many different circuits and alter their schedule according to the time of day, the path of other trains, or other factors the RCX sensors can detect.
Walking robots have always been a favorite; two-, four-, or even six-legged creatures are common (see Figures 2 and 3). These types of robots are interesting because of their similarity to animals, rather than being able to accomplish anything above and beyond their wheeled cousins. What would really take the biped creations beyond the toy stage is if they would change their walking style depending on the terrain. Most of the biped walkers trudge forward like a windup toy, repeating the same motion over and over, no matter what the situation. Even fewer are able to make a controlled turn, though some (including a NASA engineer) have designed their walkers to turn within their own footprint.
Figure 2 Biped II (Photo courtesy of JP Brown).
Figure 3 Hexapod I (Photo courtesy of JP Brown).
So, have Mindstorms hobbyists covered every form of locomotion? Not even close. Users are always searching for new concepts, and no form of locomotion is safe. There have been snake robots that extend and contract to move. Lego itself released plans for a wall-climbing robot that ascends a metal racka little bit like a sloth. Someone has even created a jumping robot, but this isn't nearly as impressive as it sounds. The main goal of the robot is to "commit robot-suicide" by jumping off a table (I suppose the landing wasn't so great, which is why it simply jumps once). One type of locomotion most people didn't think possible with Mindstorms was climbing a smooth surface using suction cups, much like a cat burglar. Rob Stehlik of Canada proved them wrong by designing a suction cup climber that goes straight up plate glass using the Lego pneumatics system (see Figure 4). Another entry in the robot burgler category is a robot that crawls along a cable while hanging upside down.
Figure 4 Window Walker (Photo courtesy of Rob Stehlik).
Strangely, I haven't seen many water dwelling robots yetperhaps because of the fear of ruining the RCX computer brick. I know a university undergraduate who used the RCX to simulate a swimming bacterium that remains under water and enclosed in a margarine tub, but there haven't really been any high-powered water vehicles. The best I've seen is a robot that rows a little Lego boat around a pond (see Figure 5). It's a start.
Figure 5 Boatman (Photo courtesy of JP Brown).
Wind has been used a few times as the source of locomotion, with the motors actively working to harness the wind. Mario Ferrari created a land-sailing robot that harnesses the wind in a large plastic sail. According to Mario, it was less than 100% successful, but "with a strong wind, going downwind or broad reach...it moves!" It is a neat contraption, though; it can steer with a rudder, and raise or lower the sail (see Figure 6). JP Brown was brave enough to strap his RCX brick to a large cloth kite for a hang glider. His goal was to release the glider and then have the RCX control the flight down through a spiral, and landing. Though the wind often got the better of the small glider, it did manage to exert some control.
Figure 6 Duna Rossa, the land sailing vehicle (Photo courtesy of Mario Ferrari).
So has Lego conquered all types of locomotion? While writing this article, I thought the only terrain no one had challenged was snow. Only later did I learn that Mario Ferrari had in fact put his mind to conquering snow while in Italy. He built a skiing robot. Apparently he and his brother scraped enough frost out of their freezer to simulate a mini-snowfield!
I have yet to see powered flying robots, but the possibilities are obvious here, too. Recently, I read an article about an attempt to send the first unmanned model plane (under five kilograms) across the Atlantic from Newfoundland to Ireland. This feat, if accomplished, will be amazing for a number of reasons. First, the man behind this mission is 75 years old and legally blind! Second, the technology is accessible to pretty much anyone. On less than a gallon of fuel, it will navigate using its own onboard computer and GPS system across the Atlantic directly to a landing strip in Ireland. What is outstanding is that impressive technology is available for a reasonable cost. Mr. Hill and his team have created a piece of technology with roughly the same abilities as a cruise missile, but on a shoestring budget.
After reading about Mr. Hill, it occurred to me that the RCX is light enough to go along for a ride on most radio-controlled, fuel-powered model planes, helicopters, or possibly even larger helium-filled airships. Gyroscopes for detecting orientation and GPS receivers would need to be interfaced with the RCX, but this is usually not very hard to do. And, of course, the RCX would need an interface to control servo motors (the motors used to control plane flaps), but these are available for ordering online. The possibility is definitely there for anyone to be the "Charles Lindbergh" of the Mindstorms world.