GPS tracking down to the centimeter

[Jim__]

From phys.org:

...

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 autonomous vehicles.

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.

more ...

[longship]

1. Yup! But folks will still drive into oceans, lakes, and rivers.

http://gizmodo.com/5655527/man-drowns-after-gps-guides-him-into-a-lake

According to Spanish newspaper El Mundo, a 37-yo Senegalese man died when his car fell into a lake near the town of Capilla, Badajoz. According to his companion—who survived the accident—the driver was following the GPS directions when the car fell into the water, sinking in just a few minutes.

Apparently, it was a very dark night in a bad rural road. The man was a foreigner who didn't know the area. When he saw the end of the road, it was too late. He didn't have time to stop the car. Perhaps he was going too fast, perhaps it was a sudden turn into the cliff. Whatever it was, I have traveled through these roads and I know how treacherous and bad they are. I'm not surprised that a foreigner fell into such an apparently obvious—but not really—trap.

Some drowned because they absolutely trusted their GPS. Apparently they never opened their eyes and saw the water. Or were driving too fast.

[William Seger]

2. I'm not sure I get this for self-driving cars

To know where a car is in a lane from its GPS position, you would also need lane locations down to centimeter accuracy. I'm skeptical about that.

[Jim__]

3. I believe maps are being worked on as part of this.

Here's a link to a June 2015 article from GPS World that talks about it a little bit:

[center][/center]
[center]Figure 2. Renault outdoor test center at Aubevoye, France.[/center]

[hr]

Land-vehicle autonomous navigation requires centimeter-level qualification tools to enable confidence build-up for delivery to open-road traffic insertion. External positioning sensors over a dedicated road section can be replaced with an embedded high-accuracy, highly responsive epoch-by-epoch differential GNSS receiver coupled with an inertial navigation system. The demonstrated absolute accuracy and mobility extends the potential test area and minimizes cost for multi-environment validation.

Personal cars and commercial trucks are continuously improving the driver experience and safety thanks to integration of more significant and machine-assisted control systems. Advanced driver-assistance systems (ADAS) are now integrated in all luxury cars and moving into mainstream products. Technologies covered by ADAS are specific for each car integrator, but increasingly they include now involving more safety features, such as driver assistance and partial delegation to autonomous control for small maneuvers such as lane control. The generation of ADAS systems introduced in early 2015 on high-end models are engaging more intelligence from the control system such as:

• Lane departure warning system
  
• Speed assistance and control
  
• Driver assistance and control
  
• Autonomous emergency braking.

It is not only individual drivers who want this technology, but also governments that are getting involved to prevent accidents and minimize the economic impact associated with them. In the European Union, the general safety regulation 2009/661 was the first step to engage member-states to act as a regulator to mandate car safety improvements. The European Transport Safety Council, a non-profit private association, released in March 2015 a position paper titled “Revision of the General Safety Regulation 2009/661.” It promotes the introduction of lifesaving technologies like intelligent speed assistance, autonomous emergency technology including all speed and pedestrian detection, and lane-departure warning systems as the next step of regulation.

...

[Jim__]

4. Actually, this article talks more about the maps.

From wired:

...

Autonomous cars will require maps that differ in several important ways from the maps we use today for turn-by-turn directions. They need to be hi-def. Meter-resolution maps may be good enough for GPS-based navigation, but autonomous cars will need maps that can tell them where the curb is within a few centimeters. They also need to be live, updated second by second with information about accidents, traffic backups, and lane closures. Finally, and this was the point Skillman was trying to make with the 1720 road atlas, they’ll need to take human psychology into account and win the trust of their passengers. “The key to making autonomous driving work is to not forget about the driver,” Skillman said.

Fully autonomous cars will be ready to hit the road as soon as 2017 (according to Sergey Brin), or perhaps sometime in the 2020s (according to more conservative forecasts), or maybe never (according to naysayers). The timing may be uncertain, but cars are already becoming more autonomous, creeping across a spectrum from current models with adaptive cruise control and assisted parallel parking to future vehicles that can navigate from A to B while you take a nap or make a sandwich. Much of the attention has focused on the sensors and other technology inside the cars and on the legal questions they raise (if an autonomous car causes an accident, who’s to blame? what if the car was hacked?), but there’s another crucial element: maps.

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All told, HERE has driven 2 million kilometers (1.2 million miles) in 30 countries on 6 continents, all in the last 15 months. Google, HERE’s main competitor in the race to build maps for autonomous cars, has focused its efforts close to home, reportedly mapping 2,000 miles around its headquarters in Mountain View. (The US road network, for comparison, covers 4 million miles). A live map in HERE’s Berkeley office shows which cars are active. The afternoon I visited, a green tags indicated cars actively mapping roads on the west coast and a couple tags indicated that drivers in Australia were off to an early start. The tags in Europe and the east coast were grayed out, done driving for the day.

...

[BadgerKid]

5. I've heard of GPS-guided agriculture.

Not sure it was centimeter level accuracy, but it sure sounds useful.