Powered flight, child´s play, silly wheels and walking machines

Recent theoretical and experimental studies of biped walking machines are reviewed. The author summarizes results in passive and pumped walking, and discuss issues arising for robot design. The fundamental idea is that a pair or pendula will walk just as naturally as a wheel will roll. It is shown that, as far as dynamics and control are concerned, use of the passive walking effect can substantially simplify biped design. In particular, it tidily resolves the problems of trajectory selection, generation, and stabilization which become the focus of attention in devising active means of walking. Methods of modulating and pumping the passive cycle emerge naturally from dynamics analysis and the cycle makes inherently efficient use of energy without being sensitive to how the energy is supplied. The walking mode persists across a wide range of variations on the coupled-pendula theme, and so allows the designer generous latitude