Portable unit kicks in when GPS fades
(Credit:
Seer Technology)
Ahoy, GPS-stranded motorist. Stop banging the dashboard, and consider this timely reincarnation of dead reckoning to help you find your way out of "GPS-denied environments," or at least alert others to where you can be found.
Seer Technology is offering a miniature, self-contained, electronic navigation unit called NaviSeer that mixes GPS and DR in a complex gumbo of hardware and proprietary algorithms to deliver user location in real time.
It does this by blending the output from three gyros, three accelerometers (one at each axis,) a magnetometer, and a baro altimeter, and then running it through a Kalman filter.
The result: coordinates accurate to within less than a yard, according to Seer. And no, it "does not require sensors to be worn on the legs or feet."
"The NaviSeer product fills a giant void in the market for personal navigation products," said Fred Gallander, CEO of Seer. "We are seeing tremendous interest in this product from Fire, Police, SWAT, and military applications, where lives are in danger if personnel are "off the radar screen," inside buildings or other GPS-denied areas."
DR is a tried-and-true method for keeping track of where you are, using a fix (starting point), course, speed, and time traveled; it's how old-timey mariners navigated when they couldn't see the stars. It's also how ants find their way home. A Kalman filter is a powerful set of mathematical equations, which, when fed a sequence of observations, can provide a flow of estimates on past, present, and even future positions.
NaviSeer uses GPS to continually update its DR function, which, in turn, stands ready to take over, should GPS be denied. When that happens, "motion classification algorithms analyze movement and compensate when the user is moving backward, sideways, running, crawling, or just moving in place," according to Seer.
An "automatic compass orientation algorithm" gives the azimuth when the user is upright or prone. The result is a continuously updated feed of digital latitude, longitude, and elevation positions triggered by body movement.
If that doesn't work, there's always the stick-and-shadow method.
Mark Rutherford is a West Coast-based freelance writer. He is a member of the CNET Blog Network, and is not an employee of CNET. Email him at markr@milapp.com. Disclosure. 
GPS denied positioning is a huge advance, one that has been in the GPSWorld and other publications for the past 2-3 years. The Stratonovich-Kalman-Bucy filter method is brilliant, and effectively reduces 'position-walk' and deviations in narrow "urban canyons", reducing position errors significantly.
GPS denied positioning allows Soldiers to enter very dangerous IRAQ or AFGHANISTAN interior threat sites, and assess where not to shoot (i.e. through a wall) and avoid 'friendly fire' accidents. Although the topic is related to privacy, personal positioning when locating a Child in an Amusement Park , even in GPS-denied locations/indoors, would be a future asset to Parents. I speculate that there are applications we have not yet dreamed of.
Recent advances in Electronic Chips MEMS-micro-electro-mechanical devices, have allowed sensors such as accelerometers to be constructed right on the wafer, creating these magically devices. When I started in Electronics 31 years ago, accelerometers and barometers and other sensor devices were large and "resolution-challenged". Hey, I can recall using a-static conductive foam, copper tape and a A/D convertor as a robotic arm squeeze-feedback sensor, based on resistance as kind of leading edge in 1983; now we can obtain IC pressure sensors [for $3.99 per qty 1000] that put my early pragmatic efforts to shame.
Sometimes the perspective on how far we have "tech-advanced" is lost on those too young to recall the early efforts.
Its an excellent article, and describes what will be the leading edge of something that may be woven into our clothing in a decade or two. I have been following Mark's postings and Articles for sometime now. I am involved in Military projects and can say that He writes with great accuracy of the topics discussed.