I show that at the physical limits of technology, crude robots on the size scale of 10--100 (mu)m may be possible. An interesting aspect of such miniscule vehicles is the means by which they might move about. I address this question with a number of detailed calculations for microrobots traveling by air, land, and sea. The Reynolds number for airborne robots is close to unity -- the viscous forces dominate the inertial forces. I show that there is no sense to using a lifting airfoil, a microrobotic helicopter could fly by simply gripping the viscous air around it. Swimming robots encounter a higher Reynolds number and I explore a variety of propulsion mechanisms. The best propulsion appears to be a fan propeller using blades of rather unusual design. Surprisingly, the corkscrew-flagellum propulsion of the motile form of Escherichia coli is a good deal less efficient than this fan propulsion. Nature is known for her parsimonious use of energy: perhaps she uses the flagellum because it is easy to fabricate from protein. Hopping seems to be the most effective mode of transport for earth-bound robots. It is stealthy, predator-evading, and energy-efficient and provides mobility over many types of terrain. I calculate optimum hopping strategies as a function of weight and atmospheric viscosity. It would be interesting to see how these equations apply to insects. Finally, I show various ways adhesion and electric fields can be used for walking on walls. The research is avant-garde, but may be useful when micromechanical technology reaches the projected level of competence. 5 figs.
Motility of military microrobots
1991
28 pages
Report
Keine Angabe
Englisch
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