Development of a long-range untethered frictional microcrawler

This paper examines the development and performance of a new type of microcrawler. The frictional microcrawler is distinguished from previous microcrawling robots in that it operates by taking advantage of the friction/stiction present between its segments and the surface upon which it travels. It is driven by conventional thermal actuators that create a sequence of horizontal forces that push the microcrawler forward against friction forces one segment at a time. It can be precisely positioned by accumulating micron sized steps. It is capable of long- range reversible motion which is limited only by the length of the tracks along which it travels. The microcrawler requires less than 3 V to operate and it can travel at velocities exceeding 700 mu m s(-1). It can develop a horizontal force greater than 130 mu N and it continues to operate reliably while carrying a load of over 100 times its own weight of 1 mu N. Experiments have shown that it can even climb a vertical wall. The effect of input frequency, actuation voltage and size of contact area on the measured crawling velocity and force are presented and discussed.