GPS tracking down to the centimeter

February 11, 2016 by Sarah Nightingale
The new technology will enable users to access centimeter-level accuracy location data through their mobile phones and wearable technologies, without increasing the demand for processing power.

Researchers at the University of California, Riverside have developed a new, more computationally efficient way to process data from the Global Positioning System (GPS), to enhance location accuracy from the meter-level down to a few centimeters.

The optimization will be used in the development of autonomous vehicles, improved aviation and naval navigation systems, and precision technologies. It will also enable users to access centimeter-level accuracy location data through their mobile phones and wearable technologies, without increasing the demand for processing power.

The research, led by Jay Farrell, professor and chair of electrical and computer engineering in UCR's Bourns College of Engineering, was published recently in IEEE's Transactions on Control Systems Technology. The approach involves reformulating a series of equations that are used to determine a GPS receiver's position, resulting in reduced computational effort being required to attain centimeter accuracy.

First conceptualized in the early 1960s, GPS is a space-based navigation system that allows a receiver to compute its location and velocity by measuring the time it takes to receive radio signals from four or more overhead satellites. Due to various error sources, standard GPS yields position measurements accurate to approximately 10 meters.

Differential GPS (DGPS), which enhances the system through a network of fixed, ground-based reference stations, has improved accuracy to about one meter. But meter-level accuracy isn't sufficient to support emerging technologies like autonomous vehicles, precision farming, and related applications.

"To fulfill both the automation and safety needs of driverless cars, some applications need to know not only which lane a car is in, but also where it is in that lane—and need to know it continuously at high rates and high bandwidth for the duration of the trip," said Farrell, whose research focuses on developing advanced navigation and control methods for .

Farrell said these requirements can be achieved by combining GPS measurements with data from an inertial measurement unit (IMU) through an internal navigation system (INS). In the combined system, the GPS provides data to achieve high accuracy, while the IMU provides data to achieve high sample rates and high bandwidth continuously.

Achieving centimeter accuracy requires "GPS carrier phase integer ambiguity resolution." Until now, combining GPS and IMU data to solve for the integers has been computationally expensive, limiting its use in real-world applications. The UCR team has changed that, developing a new approach that results in highly accurate positioning information with several orders of magnitude fewer computations.

"Achieving this level of with computational loads that are suitable for real-time applications on low-power processors will not only advance the capabilities of highly specialized navigation systems, like those used in and precision agriculture, but it will also improve location services accessed through mobile phones and other personal devices, without increasing their cost," Farrell said.

Explore further: New centimeter-accurate GPS system could transform virtual reality and mobile devices

More information: Yiming Chen et al. Computationally Efficient Carrier Integer Ambiguity Resolution in Multiepoch GPS/INS: A Common-Position-Shift Approach, IEEE Transactions on Control Systems Technology (2015). DOI: 10.1109/TCST.2015.2501352

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antialias_physorg
4.3 / 5 (6) Feb 11, 2016
Neat. If I understand this correctly then phawse measurement could also make GPS spoofing quite a bit harder (or at least it will make it easier to detect when someone is spoofing an area).

On the downside: Geocaching will become far too easy.
promile
Feb 11, 2016
This comment has been removed by a moderator.
antialias_physorg
5 / 5 (5) Feb 11, 2016
Such a GPS could watch & count your steps without requirement of accelerometer.

Did you even read the article?

"Farrell said these requirements can be achieved by combining GPS measurements with data from an inertial measurement unit (IMU) through an internal navigation system (INS). I"

Notice the 'inertial measurement unit'? Read: accelerometer

pntaylor
3 / 5 (2) Feb 11, 2016
Such a GPS could watch & count your steps without requirement of accelerometer.

Did you even read the article?


Possibly, he just misread the word, as did I. Dyslexia is a widespread bitch.

antigoracle
3.4 / 5 (5) Feb 11, 2016
Didn't the US military intentionally handicapped the GPS signal for civilian use to prevent such accuracy? I wonder what their response would be?
Max5000
5 / 5 (2) Feb 11, 2016
Interesting. While GPS delivers the free service with an accuracy within 10 meters the new European Galileo positioning system (using extreme new atomic clocks) should deliver the free service with an accuracy below 1 meter. Using this new process that would mean free accuracy down to even millimeters. That is just mind blowing accuracy for small mobile systems using signals coming from space. A lot of new possibilities will certainly emerge.
Pooua
5 / 5 (4) Feb 11, 2016
The US military used to add a signal to degrade the accuracy of civilian GPS, until some hackers demonstrated that they could compensate. That was a long time ago (a few decades).

When I took GIS classes, my professor talked about bringing in a professional GPS unit, with accuracy to centimeters. Those cost thousands of dollars and are the size of a small suitcase.
Darren_GNSS
5 / 5 (3) Feb 12, 2016
Poorly written article. RTK technology, that's been around for well over a decade, is easily capable of sub-centimetre accuracy, not 1 metre and has been used in precision agriculture and autonomous vehicles for years.

The downside of RTK is that the GNSS boards (now the size of a credit card, but quite power-hungry) are generally quite expensive (think $10k+) and you need either to have RTK base stations in the vicinity or access to a web-based RTK correction service (costing up to $3k per year).

These solutions use the commercial (L1) and encrypted (L2) signals from the GNSS Satellites. They don't de-crypt the military code, but use them to remove some of the error induced by the atmosphere on the L1 signal.

If, however, they have managed to work out how to get cm level positioning from a L1 only chipset-based Rx, then they are really onto something. The advantage of GNSS/INS is usually to give a high update rate and to cover GNSS outages due to high building etc..
antialias_physorg
5 / 5 (4) Feb 12, 2016
the new European Galileo positioning system (using extreme new atomic clocks) should deliver the free service with an accuracy below 1 meter. Using this new process that would mean free accuracy down to even millimeters.

I'm not sure the gain in precision scales that linearly. At some point it becomes noise dependent on your inertial measuring unit. Milimeter accuracy would be awesome, however.
Darren_GNSS
5 / 5 (1) Feb 12, 2016
Didn't the US military intentionally handicapped the GPS signal for civilian use to prevent such accuracy? I wonder what their response would be?


The dithering on the clock was removed years ago as a response to Europe announcing its own GNSS System (Galileo). The original publication of the signal spec was a response to the South Korean airliner being short down over Korea and the conflict of not knowing where it was...
gkam
2 / 5 (4) Feb 13, 2016
For once, antigore is right: The Guvmunt keeps us dumb civilians in a mode with less accuracy than the military gets, and I can see this upsetting the hell out of them.

EyeNStein
5 / 5 (1) Feb 18, 2016
It also needs to allow for indoor position locator extensions where available.
So your wearable can find the store and the item on the shelf.
(Or tell you not to bother as the previous wearable found the special offer is out of stock.)
TechnoCreed
3 / 5 (2) Feb 18, 2016
Didn't the US military intentionally handicapped the GPS signal for civilian use to prevent such accuracy? I wonder what their response would be?

The dithering on the clock was removed years ago as a response to Europe announcing its own GNSS System (Galileo). The original publication of the signal spec was a response to the South Korean airliner being short down over Korea and the conflict of not knowing where it was...

For once, antigore is right: The Guvmunt keeps us dumb civilians in a mode with less accuracy than the military gets, and I can see this upsetting the hell out of them.

There is no more dithering since May 1st 2000. Antigore was asking the question mister G, and you answered it wrong.
For Darren; it was more than a decade before Galileo. I don't think that it had much weight in the decision. http://www.navigo...GPS.html

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