Vehicles That Talk to Each Other Know What Lanes They're In

December 18, 2007 By Lisa Zyga, feature
Vehicles That Talk to Each Other Know What Lanes They're In
Vehicles with GPS receivers communicating with each other can increase the positioning accuracy to a level that enables them to determine what lane they’re in. Credit: Thanh-Son Dao, et al. ©2007 IEEE.

A standard GPS receiver has an average 2D-positioning accuracy of about 13 meters. While this precision is high enough to direct you to your hotel, it’s quite a bit lower than the accuracy required to determine which lane your car is in while driving down the highway.

A group of scientists from the University of Waterloo and California Polytechnic State University are currently working on an Auto21 project called Dynamic Collaborative Driving. Within this project, the scientists have developed an intelligent lane detection system that uses communication among GPS-equipped vehicles to achieve significantly greater accuracy than with a single GPS device. Because the new system uses only low-cost GPS receivers, a filter, and an algorithm, it has the potential to be much less expensive – as well as more robust – compared to other lane detection systems.

“The lowest accuracy GPS we used is the LocSense 40-CM, which has an accuracy of 5 meters CEP (Circular Error Portable),” Dao explained to “The 5m CEP accuracy means that half of the data points fall within a circle of a 5-meter radius, half lie outside this circle. This accuracy is equivalent to 13 meters in 2dRMS, where 95% of the data points occur within a 13-meter radius. Therefore, any GPS receivers better or the same as the LocSense 40-CM can be used for lane positioning.”

As the researchers explain in their study, GPS errors from multiple sources are common. Errors can occur due to the geometry of visible satellites, atmospheric effects, clock errors, and many other causes.

However, the scientists note that GPS receivers that are relatively close to one another experience many of the same errors. This means that, even though absolute vehicle positions may have a large error, the relative position between vehicles has a smaller error, and can provide a more accurate location than a single GPS receiver can.

By communicating GPS data among vehicles traveling within about 300 meters of each other, the precise lane of each vehicle can be determined. Emergency vehicles might even be equipped with systems that have a communication range of up to 1 km.

In addition to GPS, the other two components of the system are a filter and a Markov localization algorithm. The filter minimizes the measurement noise from different GPS receivers, enhancing the system’s overall quality.

“The most challenging part is designing a filter to effectively reject the receiver noise that can influence the prediction phase of the lane positioning system,” Dao explained. “We did this by using a combination of a low-pass Butterworth filter and a particle filter to eliminate this high-pitched noise.”

Then, the Markov algorithm transforms the GPS data into a lane estimate, without the need for prior knowledge. The algorithm is probabilistic: rather than making a single hypothesis for which lane a vehicle is in, the Markov algorithm maintains a probability distribution over all possible lanes for a vehicle.

To determine if a vehicle has changed lanes, the system calculates the shortest distance between the vehicle’s current position estimate and the predicted vehicle path calculated using two previous position estimates. If the distance is close to zero, there is a low probability that the vehicle has changed lanes.

If the distance is large, then either the vehicle is switching lanes, or there’s a curve in the road. The lane-finding algorithm can distinguish between these two possibilities by estimating the arc of the road, where a lane change would not form a large arc. Further, if a vehicle changes lanes on a curved road, the system can tell because the vehicle’s previous position will not lie on the estimated arc.

The researchers tested the device both in simulations and in real road tests, where they demonstrated an accuracy of between 92 and 99%. They also noted that the algorithm could sometimes anticipate when a vehicle would change lanes before the vehicle had completed the change. They even tested the system’s ability at low speeds by calculating the lanes of two individuals walking down the street holding GPS-equipped laptops, and achieving high accuracy.

“The limitation of the system lies in the fact that it only uses GPS data to estimate lane positions,” Dao said. “This might be challenging where GPS data are not available or the GPS signal is completely blocked by large obstacles, like in a long tunnel. One possible solution to this problem is to fuse the GPS with another type of sensor, such as an IMU [Intertial Measurement Unit], until the GPS data is again available.”

A lane detection system could have many benefits as a component of an intelligent transportation system. For example, a lane-level navigation system could advise drivers which lane to use to reach a destination without having to make a last-minute lane change. The system could also measure lane-specific traffic conditions, and advise drivers to choose a certain lane to reduce traffic congestion. Safety could be another possibility, with the system warning the driver when swerving within a lane, and even autonomously taking control of the vehicle if needed.

More information: Dao, Thanh-Son; Leung, Keith Yu Kit; Clark, Christopher Michael; and Huissoon, Jan Paul. “Markov-Based Lane Positioning Using Intervehicle Communication.” IEEE Transactions on Intelligent Transportation Systems, Vol. 8, No. 4, December 2007.

Copyright 2007
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of

Explore further: Tracking fear-causing spaces in the city

Related Stories

Tracking fear-causing spaces in the city

October 9, 2018

Cyclists feel the cold sweat of fear when trucks come too close. Pedestrians feel uncomfortable in the subway, but just around the street corner they enjoy their relaxing strolls. Spatial and social structures of a city cause ...

GM: Self-driving vehicles could be ready by end of decade

October 17, 2011

Vehicles that partially drive themselves will be available by the middle of the decade with more sophisticated self-driving systems by the end of the decade, General Motors Vice President of Global Research and Development ...

Nokia HERE prepares maps for autonomous cars

December 17, 2014

Autonomous cars will need a new kind of map, a crucial element that until now has been given a back seat to the more popularly discussed issues of sensors and legal questions. Senior Writer Greg Miller in Wired put maps back ...

Jaguar Land Rover explores placing drivers on pothole alert

June 12, 2015

Jaguar Land Rover is doing its connected-car technology homework. (The company actually has someone with the job title of Global Connected Car Director.) They believe they are on to something important: a new system to detect, ...

How an autonomous Ford hybrid manages to drive in the snow

March 11, 2016

Ford motor company, along with all the other major car manufacturers, has been working on self-driving cars, but unlike others, such as Google, Ford has begun demonstrating an autonomous vehicle that is capable of driving ...

Recommended for you

Understanding dynamic stall at high speeds

December 18, 2018

When a bird in flight lands, it performs a rapid pitch-up maneuver during the perching process to keep from overshooting the branch or telephone wire. In aerodynamics, that action produces a complex phenomenon known as dynamic ...

Pushing lithium ion batteries to the next performance level

December 13, 2018

Conventional lithium ion batteries, such as those widely used in smartphones and notebooks, have reached performance limits. Materials chemist Freddy Kleitz from the Faculty of Chemistry of the University of Vienna and international ...

Uber filed paperwork for IPO: report

December 8, 2018

Ride-share company Uber quietly filed paperwork this week for its initial public offering, the Wall Street Journal reported late Friday.


Adjust slider to filter visible comments by rank

Display comments: newest first

3.3 / 5 (4) Dec 18, 2007
I've been waiting for this quite a while. Bravo.
1 / 5 (1) Dec 19, 2007
While this is potentially exciting new piece to the autonomous vehicle puzzle, the reality is that it will take many pieces, like DARPA's off road challenge, and faster imaging and AI to get most of us to trust technology with our children's lives... but every step counts, this is a good one.
1 / 5 (1) Dec 19, 2007
How easy will it be for someone to hack this system and cause cars to crash? A person with a laptop sitting near an interstate hijacking the cars navigation system is a real possibility.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.