Toyota details its Automated Highway Driving Assist system


October 21, 2013

Toyota's advanced active safety research vehicle

Toyota's advanced active safety research vehicle

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The race to the car that drives itself continues to heat up. Automakers around the world are eager to tease their latest autonomous capabilities. Most recently, we've seen a self-parking system from Volvo and a glimpse at Nissan's plans. Last week, Toyota became the latest automaker to show its hand, providing a look at its Automated Highway Driving Assist, a feature that should be available within the next two or three years.

Toyota's Automated Highway Driving Assistant is a two-part system that takes over acceleration, deceleration and lane maintenance on highways. The AHDA system represents a more capable, next generation version of features that are available today. It is the latest marketable technology to come from Toyota's advanced active safety research vehicle.

The first part of the system is the Cooperative-adaptive cruise control, essentially a next-gen automated cruise control. The system uses 700-MHz band vehicle-to-vehicle ITS communications to gather acceleration/deceleration data from the vehicles ahead and maintain a safe, uniform following distance. Toyota says that this cuts down on unnecessary acceleration and deceleration, improving fuel efficiency and reducing traffic congestion.

The second part of AHDA is Lane Trace Control, which Toyota described to us as a more advanced form of its Lane Keeping Assist system. Current-generation lane systems simply provide a warning or minimal amount of steering feedback when the vehicle begins to stray from the lane, but Toyota's Lane Trace adjusts the steering angle, torque and braking in order to maintain a driving line within the lane. It uses a combination of high-performance cameras, millimeter-wave radar and control software. When compared to Lane Keeping Assist, Lane Trace Control can operate at higher speeds and work within a wider range of driving conditions, including sharper road curves.

Toyota is trialling the AHDA system on the Shuto Expressway near the greater Tokyo area. It says that it will market the technology by the mid-2010s.

Source: Toyota

About the Author
C.C. Weiss Upon graduating college with a poli sci degree, Chris toiled in the political world for several years. Realizing he was better off making cynical comments from afar than actually getting involved in all that mess, he turned away from matters of government and news to cover the things that really matter: outdoor recreation, cool cars, technology, wild gadgets and all forms of other toys. He's happily following the wisdom of his father who told him that if you find something you love to do, it won't really be work. All articles by C.C. Weiss

All that junk on the car must really mess with the gas mileage.


I can't wait until these systems lower the risk of crashes for millions of people.

Matthew Adams

Ed, actually Toyota is more famous for building reliable automobiles then for unintended acceleration. That was a bad time for them but it's foolish to say its their legacy. Anyway if cars ever do drive themselves its going to require development and cooperation between all brands.

Joe F

Chris, I am thrilled to see that Toyota will be taking a step toward car-to-car communication finally. I advocated this in a piece I wrote for my local paper: and started a Facebook blog in early 2012 called, where I quoted your piece today.

One question -- with this first step toward car-2-car comms, it is obvious that Toyotas will only be able to communicate with other new Toyotas that also have this feature at first. How did Toyota make the economic decisions to move forward? Will it be an option? How much would it cost, and who would pay that at first? I'm hoping Toyota will start having all their new cars broadcast automatically as standard equipment. They can then claim the mantle of being the safest car on the planet.

I have a 2014 Subaru Forester with Eyesight. I use adpative cruise on the higway every morning on my commute -- I like that invisible pillow in front of my car virtually guaranteeing I can never hit the car in front of me. But there are many instances where i have to hit cancel to let another car merge in -- as a courtesty. Car-to-car coms would allow this automatically, and would make adpative cruise smoother, since my car would not have to wait to react until a car ahead actually slowed. It could get a message that the brake was descending and brake lights are on before the car physically slows.

Also, any chance stoplights will be made soon that communicate with Toyotas? That would have an immediate benefit, since the car could time transit throught the light to avoid stopping if it knew the time to the next light change.

Gary Kreie

Funny, I've been driving for almost forty years and never needed my car to drive itself.

"The first part of the system is the Cooperative-adaptive cruise control, essentially a next-gen automated cruise control. The system uses 700-MHz band vehicle-to-vehicle ITS communications to gather acceleration/deceleration data from the vehicles ahead and maintain a safe, uniform following distance. Toyota says that this cuts down on unnecessary acceleration and deceleration, improving fuel efficiency and reducing traffic congestion."

I've already got that. It's called the "gas pedal". Couple that with another amazing invention called "paying attention" and I can get over 30 mpg out of my 255,000 mile '01 Monte Carlo SS. And I commute 1000 miles a week.

Dave Mikulec

Autopilots in cars will do nothing to stop global gridlock caused by the extra 2 billion population increase in the next 20 years. The automated cars will prevent traffic fatalities but not gridlock. Their will be one giant parking lot full of automated cars. The automated Verticraft (vertical takeoff and landing aircraft) will prevent gridlock and fatalities by traveling on non intersecting flight paths to the desired location.

Stan Sanders

Should be required penalty for those that have been busted for texting and driving.

Jay Finke

Stan Sanders, I would rather spend my 2 hour commute in an isolated bubble reading or watching some form of entertainment or even finding some way to be productive while trapped in bumper to bumper traffic than staring at the back end of someone elses car. I'm interested in self driving cars for the return on quality of life. Even if cars could fly, it would be better if they could do it themselves without our input, from a "lost personal time" perspective.

Dave Mikulec, we can't all have the luck to have never been struck by someone who doesn't possess your superior driving skills. It's unrealistic to expect everyone to simply "be better". We can make better technology, but we cannot make better people. People are what they are. Cars are what we make them to be.

Sean Roper we REALLY want to entrust automated driving to a company that is most famous for previous "unintended acceleration" issues that they won't talk about? Toyota is rife with issues involving their "drive-by-wire" system. In one famous issue years ago in Tokyo, a drive-by-wire bus was being test driven along an existing bus route when it suddenly went wild and no longer responded to the driver applying the brakes. The bus crashed into a bus stop luckily no injuries were reported...but the issue was that the bus did not stop when the driver applied the brakes. Toyota later found out that it was an illegal CB radio caused interference between the main computer and the braking computer and the braking computer never got the signal to apply the brakes. Up until the latest Lexus "unintended acceleration" problem, this article was available on the web...after the Lexus fiasco, it mysteriously disappeared...Then there was the Prius issue of not responding to driver controls...steering, braking or switching gears...nothing worked. Toyota claims user error, but as we know, if something as simple as a CB radio can cause a bus to crash, who knows what other kinds of interference can cause other problems? And with a history like Toyota's, do we really want THEM to be at the forefront of this technology?


Car-to-car com is a great idea--except for the bad guys who would send jamming/deceiving signals and cause huge accidents. Better to let each car be autonomous and monitor the other cars itself.


Have to agree with Danock about V2V abuse by hackers.

Stephen Russell

From a simple web search, the Toyota unintended acceleration was deemed to be user error after all.

When I was 17, I was driving a Saab 9000 with a heavy winter floor mat (from a Volvo, not the Saab mat) and the foot pedal got stuck all the way to the floor. My family was in the used car business, thus explains both the kid driving a Saab and the goofy mat. Luckily it was manual transmission and thinking quickly, I pushed the clutch in, which redlined the engine for another couple seconds until I shut it off, but not all the way to steering lock. Lucky for me all this happened on a quiet residential street with no other cars or people around.


@ Gary, Most modern cars already have a common output port standard ODBII I think it is. Most of the information required can already be read from this, and Bluetooth transmitters are available to send this info to smartphones etc. I imagine all that is required is to send this information to the car-2-car communications module so the surrounding vehicles can be aware of what is happening...

Ian McIntosh
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