Mark Tilden might be UW's best recycler, collecting and putting to good use obsolete or worn out electronic and mechanical equipment. By day Tilden is a design engineer in the math faculty computing facility, where he looks after, builds, creates, and modifies electronic mechanisms for the math labs, from sophisticated mainframe computers to computer-controlled train systems and hand-held test equipment. But by night he's a robot designer. He recycles some of the electromechanical castoffs in the Computer Science 452 lab, some for MFCF use, and some into the small robots he builds, most of which can fit in the palm of your hand. He's such a good recycler that there are only three cabinets of new material in the "supply room" sandwiched between his office (on the third floor of the Math and Computer building) and the CS 452 lab. For example, he's collected the balls out of roll-on deodorant packages for use in a $70,000 robot that teaches students how to write real-time programs in CS 452. He also uses discarded cells that powered pocket calculators, gears that drove printer spools, and small motors. Not content with his windowless office, he fashioned a "window substitute" from "four dead lap-top computers. . . . It's solar powered. It will never repeat the pattern in 56 years," he says. His "window" flashes in different designs and colours and becomes brighter when the light source is stronger. Besides his window substitute, Tilden says, he's built "about thirty" robots. There's something novel about his creations: no processor. Most people assume you need a massive computer in a robot, he says. But even with a massive computer, "you can't make the robot as smart as an ant." So he based his robots on biological and mathematical concepts instead of engineering. He refers to his robots as "simply controlled and reaction based." His robots include Zax, a floor-cleaning robot, a dust- bunny blaster, a window cleaner and a pyramid clock. Now he's trying to build a small spider-like creature. Tilden and his creatures are so well-known that journalist A. K. Dewdney wrote an article about them for Scientific American last year. In his opening paragraph Dewdney said that "when the lights turn on in Mark Tilden's office . . . visitors are sometimes startled: a roller edges forward here, and a hopper springs into the air over there." That doesn't happen any more. The robot-builder has cleaned up his office because some visitors found the special effects distracting. But he still does have a few sitting passively on the shelves in his office waiting for a visitor to ask questions about them. Then he proudly demonstrates the features of several of his robots. Said the Scientific American article: "Tilden made these light-craving robots based on what he calls BEAM principles (for biology, electronics, aesthetics and mechanics). Lovingly polished brass and stainless steel frames embrace motors that once ran Vanilla Ice tapes, solar cells that powered pocket calculators and gears that drove printer spools." Tilden's fame started when he took the scientific community by storm at an artificial life conference held in Santa Fe, New Mexico, last June. He took a case of his small robots with him and they soon became a hit. He would tell the other participants, "Here it is. Play with it. Make your own conclusions." The crowd favoured the turbot, a light-seeking robot -- what he calls "a photovore". In strong light the robot remains virtually in a confined space, but in dim light the tetrahedral turbot moves around by frequently balancing on its edges and chaotically moving to find more light. "I was a nobody," Tilden says, before the Santa Fe conference. There he gave a paper and presented a video. They were so impressive that he won three of the five awards -- best innovation concept, best presentation and the environmental conscious award. Now he is encouraging other "closet mad scientists" to come out of their closets and submit their inventions to the second international BEAM Robot Olympics and Micromouse Competition, which will be held in the Ontario Sci- ence Centre April 22 to 25. The robot olympics encourages imagination. Tilden wants to "wake up students' creativity . . . (and) encourage people to build again instead of program". He considers the robot olympics to be "the most politically correct games" because age, physical conditioning, religion, political philosophy and race don't matter. Just the idea is important. A seven-year-old girl won a silver medal at the first olympics. "The idea of doing robotics for fun is not new," he says, who founded BEAM Robotics, which oversaw the first olympics, held in the fall of 1991. A form of computer olympics had been held in Europe but it turned out to be more of a trade show so it was disbanded, Tilden says. He then took the idea and turned into a competition for robots. Now an international robot games committee has been set up based at the Turing Institute in Scotland. There are many robot games around the world, but the olympics will be an international competition. BEAM principles certainly make it more possible for anyone interested in creating their own creatures to do so, he says. He will be operating about 22 devices of his own at the Olympics -- for demonstration purposes only. Competitors are supposed to take the "BEAM" principles into account in designing their entries. "The BEAM Robot Olympics is not so much a series of technological competitions as a chance for robot enthusiasts to present their designs to each other, the press and the public," he says. "It is also an open forum for anyone who wants to get started in the field to compete and compare. "Any and every robot will be considered so long as it doesn't come exclusively from a kit or store. Robots of similar ability will be pitted against each other in simple competitions, but generally robots will be judged on sophistication of behaviour, novelty of design, efficiency of power source and quality of hardware innovation. . . . "Basically, if you built it, we'd like to see it." No commercial, store bought or kit robots will be allowed without heavy physical changes, he warns. Modified or improved software isn't sufficient. All robotic entries should be self-contained or have an option where they can execute behaviour without human intervention. Eleven formal competitions, ranging in difficulty from simple to complex, include solaroller, a self-starting robot dragster race; photovore, robots face a closed world and each other; high jump, robot creatures leap and land on their feet; robot sumo-wrestlers, opponents push each other out of the ring; and micromouse, where metal mice race through a maze for aluminum cheese. Entries can range from simple mechanical devices, built with a soldering iron and discarded electronic parts, to more elaborate contraptions. "I can't promise big prizes," Tilden warns. Competitors' guides cost $10 each and contain detailed competition rules, get-started instructions and a discussion into what's dubbed the new science of artificial life (Alife). For more information on the BEAM Robot Olympics, other robotic competitions and weird robotics in general, contact Tilden at ext. 2454. Registration cost is $40 per competitor, and Tilden must receive applications by April 5 to be included in the show dossier. He says that about 100 people from around the world will compete, but he would like to see more UW competitors. Eventually Tilden hopes to build a separate lab at UW for research on the robots. He considers his creations "creatures, not toys. You can observe them over a period of time and then improve them. They can evolve much like calculators have."