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THERE MUST BE SOMETHING PRIMAL about big trucks, something that draws Riley to the noise and excitement. Work trucks are big, brightly colored, loud. They are stronger than anything in his daily life, and they probably volvohydraulicpistonpumpparts seem unpredictable in a wonderful way. They are rough, with a potential for destruction not unlike his own impulse to hit, kick, pinch, and bite when he is frustrated. He and I spend a lot of time in our car, too -- a much milder sort of machine -- so he knows all about piloting large metal vehicles down the road. If Mama seems powerful driving the car, think how omnipotent a boy must appear in his imagination, perched behind the wheel of a backhoe. In an earlier era, a toddler might have watched men with bows and arrows, or a brace of oxen, and would have been given his own, boy-size replicas to play with. But nowadays, diggers and dumpers are what introduce him to that important, yearned-for, grown-up world. When Riley first became interested in construction vehicles, I would sometimes shyly, casually approach moms of girl toddlers. "Does she ... like trucks?" I would ask, usually volvohydraulicpistonpumpparts earning a pitying look in reply. "Oh, sure, she likes them, but she''s not crazy about them." Well, volvohydraulicpistonpumpparts Riley is crazy. Absolutely nuts. Lately, as I try to keep him from stomping ants and bullying other kids, I''ve been wondering if maybe it really is a boy thing, as people say. Something to do with his biological makeup. volvohydraulicpistonpumpparts "A boy''s being vibrates to the rhythm of testosterone," say Don and Jeanne Elium in their sometimes infuriating but always interesting book Raising a Son: Parents and volvohydraulicpistonpumpparts the Making of a Healthy Man. This hormone, they say, drives boys and men through a repetitive cycle of emotional buildup and eventual, sometimes-violent release. More benignly, it makes them really like trucks, with these machines'' barely contained violence, power, glorious potency, and superior force. Trucks are, let''s face it, cool! In 1997, they put 2 men and 2 women in a 30-foot chamber for 91 days (Schreckenghost et al. 1998b). A physical-chemical air revitalization system recycled the air for 3 of the 4 people, and a wheat crop in the 10-foot chamber did the same for the fourth. The ALS team also experimented with a solid-waste incinerator. Our second ALS AI control system managed the transfer of O2 and CO2 among the gas reservoirs for this test to ensure crew and crop health and to recycle gases produced by waste incineration. These reservoirs included a crew habitat, a plant chamber, an airlock, and a number of pressurized tanks (figure 1). Operating 24 hours a day, 7 days a week, the AI system also used a generative planner that scheduled waste incinerations and crop planting and harvesting, coordinating these tasks with the day-to-day product gas transfer. For both these projects, we used a three-layer architecture (Gat 1998) to design, organize, and develop the control software. AR&SD had used a particular implementation of this architecture known as 3T (see The 3T Intelligent Control System) in a number of robot projects prior to 1995 (Bonasso et al. 1997), and because life support systems are a form of immobots (Williams and Nayak 1996), its application to ALS projects was straightforward.
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