Energy for Biomimetic Robots: Challenges and Solutions

Abstract

Animals and autonomous robots need to carry their own fuel (unlike plants, they do not generate usable energy from their surroundings). Animals typically exceed the normal endurance and range of all our current untethered robots. As an obvious example, humans have tremendous burst speed (less than 10 seconds to run 100 meters) and endurance (running a 26-mile marathon), and they can continue to do everyday activities without refueling (eating) for several days. The typical cost of transport for humans is about 0.2. In comparison, most robots operate for less than 1 hour on their carried fuel; the cost of transport is 15 or 20 times more than that for animals. An intriguing insight is that passive dynamic walkers can approach the human cost of transport (the Cornell Ranger can walk nonstop for 65 km), but this is a single optimized task (walking) with none of the versatility of an animal that can step over objects and operate on varied terrain. What it does illustrate is that structures (and by extension, material properties) can be exploited to ‘‘get the most’’ out of a given fuel source. Surely, this is what animals do on a continuous basis. What do we need to do to give our robots similar capabilities? In particular, what are the special demands, advantages, and limitations of fuel storage and usage in soft robots? To begin exploring some of these issues and to also stimulate a larger dialog in the robot community, the following discussion has been compiled from a series of questions posed to the participants.