Lost on a New Hampshire back road? I can help. Keep heading downhill and try to find and follow a river. Before long you will come to a town where you can either ask directions to Tennessee or consult your maps. Lost in Cubicle City? You're on your own. Or maybe the SWAN could guide you.
I have perhaps 1/10,000th a migrating butterfly's sense of direction if I'm indoors with no reference to either the Sun or the terrain. I will never truly understand how the blind navigate with their dogs or canes. I am in awe of those with "facial vision," an unexplained ability to detect air currents that advise of walls or open doors. Except in movies, the sightless don't move about with outstretched arms and groping hands.
Right now we should be thinking about two sensor-based navigational technologies: GPS and a form of dead reckoning to use when you can't get a good satellite signal. The former is approaching maturity, with many excellent consumer products now on the market. They, and cell phones, have saved many a smokejumper and hiker. The latter technology has lagged behind, perhaps because the devices are in a sense far more complex. (Remember that up until the twentieth century, sailors would far rather shoot the Sun or another star with a sextant than use dead reckoning to determine their vessels' position.)
Augmenting the Dog and Cane
At Georgia Tech (and a good many other research institutions as well), work is going forward to develop systems that will help the blind navigate indoors. Georgia Tech calls its system SWAN, for System for Wearable Audio Navigation. This system assembles a wearable GPS receiver in the form of a neck pendant, a light sensor, and thermometers designed to help the user distinguish between being indoors and out. There are cameras too, which gauge distance to objects, a compass for magnetic direction, and an inertial sensor that tracks and corrects for the pitch, roll, and yaw of the user's head. (Think Stevie Wonder.)
The sensor data are crunched by a PC carried in a backpack and reported as audible signals resembling sonar's twings. The more frequent the signal, the closer the obstacle. The user hears the twings through head phones positioned behind the ear so as to conduct it through bone. The consumer version is expected to indicate passage through or past a door, along with other valuable information such as the location of restaurants, stores, and restrooms.
A Growth Industry
As I said, many researchers in labs and in commercial R&D enterprises, are busily working on one form or another of substitutes for vision. But perhaps not busily enough. Contending with blindness is a true growth industry. Think about it—and I'm simply being realistic—1)the U.S. population is aging and the elderly often become blind from glaucoma or cataracts they cannot afford to have treated or corrected; and 2)we have a national epidemic of obesity, which can bring on Type 2 diabetes and its concomitant retinal problems that quietly destroy eyesight.
So as we grow older and fatter, we're going to need more personal navigation aids. Ditto for those who can't find their way through a particularly large structure or one stuffed with tiny cubicles. Especially in a hurry, as when firefighters are trying to find their way through smoky conflagrations or miners are doing their best to escape the results of an explosion.
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