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Is Woz's Prius Acceleration Just Toyota's Wacky Adaptive Cruise?

 
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2010 Toyota Prius

2010 Toyota Prius

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UPDATE, February 8, 2009: Speaking in a sort-of-webchat on Digg, Toyota president Jim Lentz said of the Woz complaint, "We are working with him on the operation of the cruise control." Please forgive us while we quietly smirk.

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It's obviously pile-on-Toyota week. Transportation Secretary Ray LaHood and Toyota PR are trading barely-polite disagreements, and Japan is making Toyota investigate a new Prius braking problem.

Equally bad, on Monday a celebrity came forward to claim he'd experienced sudden acceleration in his new 2010 Toyota Prius while using the cruise control.

Since he's Apple co-founder and Silicon Valley luminary Steve Wozniak, universally known as "Woz," he got attention. Lots of it.

In fact, Toyota asked Jalopnik to send Woz the personal number of Toyota president Jim Lentz. (If only all owners got such treatment ....)

2010 Toyota Prius

2010 Toyota Prius

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2010 Toyota Prius combination meter

2010 Toyota Prius combination meter

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2010 Toyota Prius - showing round Touch Tracer controls that drivers operate with their thumbs

2010 Toyota Prius - showing round Touch Tracer controls that drivers operate with their thumbs

Enlarge Photo

2010 Toyota Prius

2010 Toyota Prius

Enlarge Photo

2010 Toyota Prius

2010 Toyota Prius

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15 10 prius

15 10 prius

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NOT sudden acceleration

But we think we know what's causing Woz's problem. It's not a sudden acceleration issue. It's Toyota's electronic cruise control, which behaves differently than most other carmakers' systems.

Speaking at Discovery Forum 2010, Woz said, "This new model has an accelerator that goes wild, but only under certain conditions of cruise control,"

"And I can repeat it over and over and over again--safely," he continued. "This is software. It's not a bad accelerator pedal. It's very scary, but luckily for me, I can hit the brakes."

Repeating it over and over

And that's what tipped us off. Not only is the 2010 Prius not subject to the accelerator pedal recall, but every report of accelerator behavior has essentially said that it was a random occurrence.

Instead, we think Woz didn't understand how Toyota's adaptive cruise system worked. Because we didn't either, when we first tested the car. Neither did an auto-industry friend of ours who asked to remain anonymous. Here's what he wrote [edited slightly for clarity]:

Ohhhhh, this happened to ME!

It's the way the cruise control in their hybrid cars works.  I was driving the Lexus HS250h we tested, and I set the laser distance cruise control.

Accelerating in 5-mph increments 

In every other car I've driven that has cruise control, when you press "ACCEL," it accelerates your vehicle for as long as you hold the button down. And it stops when you reach the speed you want and let go of the button or paddle.

But not so, this Toyota system. As you hold the button down, a tiny little electronic counter in the gauge cluster is SETTING YOUR SPEED.  With each click up or down, it sets it 1 mph faster or slower. 

But if you hold it down, it changes to increasing your speed in 5-MPH INCREMENTS.  So as you hold it down at 55 mph, thinking you'll let go at 70 mph when you're at the speed you want, the system is in fact rapidly increasing your target speed.

From 70 to 115 mph

By the time you're at 70 mph and you let go of the button, the computer has set your cruise control speed at 115 mph. And it's now rapidly accelerating you to that speed!

I had to have my passenger look in the owners manual while I was driving to see what I was doing wrong.  I tried it a couple times before I realized what it was doing.  I mentioned this later to [a Toyota executive]. He just quietly nodded, and looked perturbed... 




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Comments (16)
  1. Ahhh...let's tell Woz it's not a bug--it's a feature. He'll love that.
     
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  2. Soooo... WOZ is a MAC, and his PRIUS is a PC!!!!
     
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  3. my acura does 1mpg each time i hit the button
     
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  4. Who designs a cruise-control to increase in 5-MPH INCREMENTS!? Idiots!
     
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  5. Can you imagine the reaction if Ford/Chrysler/GM had this system?
     
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  6. By the time you're at 70 mph and you let go of the button, the computer has set your cruise control speed at 115 mph. And it's now rapidly accelerating you to that speed!
    I have never heard of such a stupid way to build something that has a hair trigger. I hope that Woz and any other electrical engineer including Dr. Antony Anderson be notified of this story. I would imagine that fire works and all sorts of stuff goes on at the point of rocketing on the highway.
    But I will say that you have at least finally come to an agreement as to where the problem originates. HOORAY. And still there is a major issue with the hair trigger toyota has made.
     
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  7. You're at 70 mph,let go of the button,the computer has set your cruise control speed at 115mph rapidly accelerating you to that speed! "And I can repeat it over and over again,safely" "This is software not a bad accelerator pedal.I was able to repeat what was going on with my cruise control as well UNTIL my accident. Now my cruise works differently. Toyota tell me WHY? And still you say it is not an ELECTRICAL issue. I would like to see what Woz's owners manual has to say in regards to using the cruise unit. In particular about holding the cruise to reach desired speed and then letting go that SHOULD set the cruise at the MPH desired, not the speed that the computer calculated. In a case that you have given, setting the speed at 70 mph and the computer spitting out 115 mph is criminal. There should be some NEON LIGHT that goes off saying WARNING,Prepare yourself,launching pad ready for launch. The action should be cancelled because of the massive acceleration boost trying to go from 70mph to 115 mph.Post the section on cruise control use from Woz's owners manual or same from Toyota. All of this needs to be brought to the outside, as well as Toyota's engineers. Possibly Dr. Anderson, Safety Research & strategies Inc, and Woz could sit down and truly diagnose the problem and come up with a resolution.Again! I say ELECTRONICS! Don't be shy Toyota, step up and do the right thing, not only by me but every one of your surviving, loyal to the brand customers.
     
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  8. Did not the whining commenters not read the article? Each button push changes the set speed by 1 MPH, while holding the button down goes to 5 MPH increments. This is clearly visible on the dashboard display. While it is different from what are, at root, mechanical cruise control systems, it works just fine.
     
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  9. It is not the best user interface design. A driver should be able to operate a cars controls entirely by touch while keeping the eyes on the road. While this design works fine when adjusting the volume of a TV (Hold down and quickly ramp the target value up) it unintuitive when the user might expect kinesthetic feedback to be sufficient (which for every control in a car is true, brakes, gas, steering wheel, all work kinesthetically) I think this may in fact be the first time ever in automotive history that a control system has worked by advancing a control loop setpoint rather than in real time.
    -Aurelio
     
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  10. It's a stupid design or design flaw. Think, speed of car is volume to music player. If the same design is incorporated in iPod or any mp3 player, people's ears will blow up. In a court of law, Toyota will blame people for not reading the manual, the people who lost their hearing will say "we pressed the - (down) button but the volume kept going up."
     
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  11. Whatever we say or do, we can't stop our cars transforming from our "mechanical slaves" to "electronic masters". May be it's time Toyota fires their software engineers who are used to writing software for the home PC and hire those who write software for aircrafts and spaceshuttles.
     
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  12. 1) Because "it's in the manual" doesn't make it OK or even make it rise to a level necessarily higher than criminal negligence.
    2) Because it seems like a cool idea to an engineer not only fails to ensure it's a practical idea, it militates against it. The best and most brilliant engineers love making toys--and shortcuts--only they and their friend Charlie can use.
    3) Requiring a driver to stare at a display located at a different focal distance than the road ahead in order to use an optional feature is beyond irresponsible.
    Everyone above the engineers who designed this accelleration short-cut should be fired; it's their job to prevent the engineers from shipping this kind of stuff. And don't expect the poor Hertz renter assigned a Prius to spend two hours reading the manual before driving off the lot.
     
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  13. Nice personal attack on Wozniak. Classy. Whether you've sussed the problem with your "5 mph increments" or not (which is, IMHO as a programmer for +35 years, _INCREDIBLY STUPID_) or not, it is still a problem to have a "feature" like that in shipping vehicles for, what, 10 years now?
    He found a real problem. You're treating it like it's his fault. And blaming him for bringing it to people's attention.
    You might be a self-titled "Car Expert," but your knowledge of UI is lacking. Futhermore, when you get taken to the woodshed by "asktog" (do you have any idea who HE is?) it proves you're only firing on two cylinders.
     
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  14. Only wimps use cruise control anyway. I bet there would be very few problems if people used manual transmissions and didn't use cruise control.
     
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  15. "There should be some NEON LIGHT that goes off saying WARNING,Prepare yourself,launching pad ready for launch. The action should be cancelled because of the massive acceleration boost trying to go from 70mph to 115 mph."....
    I'm sorry, but obviously you have never driven anything more powerful than a lackluster 4 banger, with a battery charge... WHEW lots-o-power there! Cranking out an astounding 134 hp, yeah, It'll feel like your braking the sound barrier as you blaze past the 70 mph mark. Now im Canadian and 70 mph converts to 110 km/h for me, hardly a speed trademark.
    With that kind of power I would expect a prius would take more than 45 seconds to accelerate from 70 mph to short of 115 mph (184 km/h) as a powerplant of that prowress would probably tip the scales at slightly over 100 mph.
     
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  16. As for the previous Sikes runaway prius escapade, If you can't comprehend the operation of a shift lever in an automatic, and belive your car might flip if you play with it while driving, you need your license revoked! Its scary to think that myself being a young male driver, authorities and licensing agencies (don't even get me started about my insurance premiums!) are more worried about me as a danger to society because I am alledgedly unsafe as I am plastered with the stereotype of a wreckless and careless driver due to my age. It's quite apparent that many experienced drivers are not able to safely operate a low powered and low risk vehicle (the Prius, and many other underpowered toyotas for that matter) while I have been driving my Volkswagen GTI VR6 disaster free for 4 years.
     
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