How Sleeping Ducks Can Teach Us a Thing or Two

Sleep. We do it. Most forms of life do it. And yet, it's poorly understood. Thanks to functional Magnetic Resonance Imaging (fMRI), modern medicine can explain some of what happens during sleep, such as moving short-term into long-term memory. Still, we can't explain the basics, such as why individual cells have their own internal clocks.

While science is plodding along on defining the basic principles of sleep, as roboticists, we can leverage the observable phenomena associated with sleep. As in other forms of Biomimetics — the imitation of biological systems — sleep behavior has potential applications in robotics. For example, consider that most "lower" forms of life have the ability to shut down part of the brain while keeping other parts of the brain fully awake. Shutting down only one hemisphere of the brain at a time allows a dolphin — a warm-blooded, air-breathing mammal — to sleep without drowning. Although it seems as though some people operate on only half a brain, humans are unique in that we've lost the ability to consciously control the alertness of parts of our brain.

If you're a deep sleeper, you can probably sleep through a meteorite crashing through your roof. However, have you ever tried sneaking up on a group of "sleeping" mallards? It's virtually impossible because they sleep in teams. For example, let's say we have four ducks in a row. The two ducks in the middle will be in full sleep, meaning both hemispheres of their brains are asleep. The two ducks on the end will each have one eye open for predators, and the hemisphere connected to that eye will be fully awake. Because one eye is mapped to each hemisphere, one hemisphere of the brain can be asleep while the other is vigilant. After a while, the two end ducks rotate 180 degrees, allowing the other “rested” hemisphere of the brain to take over the watch. Human eyes, in contrast, are each connected to both hemispheres.

So, how can these sleeping behaviors be useful in robotics? Well, power management is one area. If your robot isn't expected to be needed for several hours, why not shut down all processors not absolutely necessary? Similarly, if you have a swarm of robots, why waste battery or solar power keeping every robot fully energized? Mimic the sleeping duck behavior and basically shut down the robots in the center of a group and partially energize the "watcher" robots on the periphery so that certain sensors are active.

The bottom line is that it's natural to anthropomorphize robots, but often so-called lower life forms can provide a more useful model for robot behavior. We've lost the ability to keep half a brain active, but that shouldn't limit your robot designs. SV