

Woz says there's an acceleration problem with his Toyota Prius - siculars
http://news.cnet.com/8301-13924_3-10445564-64.html?tag=newsLatestHeadlinesArea.0

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AngryParsley
I've driven a Prius a couple of times, and I concur that they have an
acceleration problem. I step on the gas pedal and the car has problems
accelerating. (rim shot)

OK, back on topic. There's all this talk of cars accelerating out of control.
Almost any car with disc brakes is able to overpower its own engine... for a
little while. The biggest problem is that a wide open throttle means there is
no manifold vacuum, so the brake hydraulics will be unassisted after pumping
the brake pedal a couple of times. If the car is still at speed and the
throttle is wide open, it will to be a lot harder to stop.

The problem of uncontrolled acceleration is due to a failure of multiple
systems in ways that car designers didn't predict. All of the following are
required for a car to accelerate uncontrollably:

1\. An automatic transmission. In a manual the driver will hit the clutch and
brake pedals to decelerate.

2\. Hydraulic brakes powered by manifold vacuum. Electronic-assisted brakes
are less reliable overall, but they will work reliably if the car's throttle
is wide open.

3\. Keyless ignition and lack of a BIG RED KILL SWITCH in a standardized
location. Industrial equipment has them. Motorcycles have them. Why don't cars
have them?

Each of these things alone seems like a sound decision. Automatic
transmissions let drivers focus on driving instead of shifting. Hydraulic
brakes are usually reliable, and they use manifold vacuum that would otherwise
be wasted. Keyless ignition is convenient. But together these systems (coupled
with a panicked driver) can fail in unexpected ways. I'm not trying to excuse
Toyota, just pointing out that this sort of thing could have happened to any
car company.

~~~
Frazzydee
I haven't driven one of these cars...is there anything stopping the driver
from nudging the gear selector up to neutral?

I also don't agree with your point about point #3 being a sound decision on
its own. Keyless ignition is convenient, but there's no reason not to have a
kill switch besides aesthetics. And they probably could have designed an
aesthetically-pleasing, small kill switch.

Moving up a level of abstraction is only great when it works the way it's
supposed to, and there should always be some sort of manual override for the
rare, untested cases when it doesn't.

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AngryParsley
How often do you shift into neutral with an automatic transmission? A panicked
driver probably wouldn't think to take unfamiliar actions.

I agree that cars should have kill switches, but I forgot to mention a
disadvantage of them: killing the engine kills power steering. If a driver
accidentally hits the kill switch they could have trouble avoiding obstacles
or making a turn. Motorcycles don't have power steering and riders are
familiar with the kill switch.

~~~
Frazzydee
You're right, and I guess this shows how driver education can save lives,
especially now that drivers really don't need to understand how cars work (I
sure don't). Years later, I still distinctly remember my instructor describing
what you could do if your brakes fail.

Are you sure that power steering requires the main engine, or does it use a
different power source? Perhaps the kill switch could disable everything
except power steering, unless it's held down? I've read that turning the car
off using the key doesn't disable power steering unless it's turned all the
way, so that would provide similar functionality.

~~~
AngryParsley
Usually steering is powered by a hydraulic pump driven by the engine's
serpentine belt. Automatic transmissions have torque converters, which are
one-way (the engine can turn the wheels, but the wheels can't turn the
engine). As soon as the engine dies, the serpentine belt stops, hydraulic
pressure drops, and steering gets hard.

Some newer models (usually hybrids) power the hydraulic pump with an electric
motor, and a few cars have purely electric power steering (just an electric
motor, no hydraulics). In these types, a kill switch could be set up to stop
only the engine, not the electrics. The battery could power the car long
enough to stop safely.

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siculars
If the Woz says there is some sort of software malfunction I think those
talking Toyota puppets blitzing the airwaves should take a moment, pick up the
phone and ask Woz for his input.

What happened to the good 'ol days of harikiri
(<http://en.wikipedia.org/wiki/Seppuku>)? I'm not really suggesting that
Toyota top brass should start sharpening their knives ;) But if anyone
following this story over the last year or two can say that there isn't a
coverup afoot here, I'll eat crow. The proverbial heads should be rolling at
Toyota.

[edit] typos

~~~
bdfh42
There does not have to be a conspiracy here (even of silence) but you are
correct - if the Woz says there is a software glitch then a software glitch
there is.

If the Toyota guys can't find it then - yes - they should ask someone who can
find it.

~~~
GrandMasterBirt
Woz != god. Woz != says so therefore it most likely is so.

However if he can reproduce this quite easily then there is probably a
software bug. And Toyota can't afford a recall. Honestly this just has to be
taken to courts, its the driving force of our economy.

~~~
acangiano
> _Woz != god. Woz != says so therefore it most likely is so._

It doesn't mean that he is necessarily right, but he is definitely worth
paying attention to.

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ams6110
Gives one second thoughts about the idea of self-driving cars zipping down the
highway like a fluid in a pipe, never colliding or bunching up in traffic
jams.

~~~
metajack
Self-driving cars don't have to be safe in an absolute sense, just safer than
human drivers. I think in some ways that is not a very high bar.

~~~
ams6110
True, but if a human driver causes an accident it's treated as a one-off
thing. If a software bug causes your auto-driver to veer into the oncoming
lane under certain conditions, the manufacturer will be pilloried even if the
raw number of accidents is less than what human drivers cause. Irrational,
yes, but that's the way it is.

~~~
bad_user
Actually it's more like ... one drunk driver can cause one isolated accident
(assuming his license is revoked, he learns his lesson or he's dead
afterwards). One software bug can cause 10000.

~~~
ugh
Now, that’s definitely the wrong analogy. Drinking and driving is the bug, not
any individual. Societies with access to alcohol and cars have that bug.
Punishing the individual is sort of like telling your user who just reported a
bug “Oh, the program crashed when you clicked on that button? Yeah, don’t do
that.“ It’s like putting huge red warning labels next to that button or make
the mouse move slower when it comes close to that button. It’s like taking the
program away from that and only that one user. Cute, but won’t fix the bug.

We are limited in our ability to fix bugs of that kind. Banning alcohol would
probably the wrong thing to do and probably no work. What might work is
automating transportation. We can at least fix the bugs there.

~~~
bad_user
> _Drinking and driving is the bug, not any individual. Societies with access
> to alcohol and cars have that bug._

That's rich. That's another way of saying ... societies with people in them
have bugs.

Yeah, my wife last night had a bug ... she kept wining that I work too much.
If this escalates we'll probably end-up like other people getting divorced ...
which could lead me into getting drunk and into a car crash. If people only
automated those cars, I wouldn't have to worry about it.

Problem is, that's not a bug I can fix ... next time I'll get some automated
robot that doesn't mind me working so much ... hope she doesn't BSOD on me
though.

> _We are limited in our ability to fix bugs of that kind. Banning alcohol
> would probably the wrong thing to do and probably no work. What might work
> is automating transportation. We can at least fix the bugs there._

No, it would only give those people with God-syndrome some sense of control.

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ynniv
A similar situation devastated Audi in the '80s. Hopefully Toyota will learn
from history. The Audi problem was more severe because acceleration happened
during the transition from park to drive, which is a far more dangerous
situation.

[
[http://www.multinationalmonitor.org/hyper/issues/1987/05/wat...](http://www.multinationalmonitor.org/hyper/issues/1987/05/wathen.html)
]

~~~
__david__
That's an interesting link. Do you know if they ever figured out the root
cause? Wikipedia makes it sound like it was only ever considered driver error.

Also, why is accelerating during the park->drive transition more dangerous
than sudden acceleration at speed? Seems to me like the really high speed case
would be deadlier to car occupants and those around them.

~~~
wundie
Going from Park -> Drive indicates that you are just getting going and
possibly not fully prepared for such a surprising situation. If, like today’s
Toyota problem, I'm driving and my car starts to speed up I’m likely to be
fully engaged in driving and able to correct the situation more naturally.

~~~
__david__
True, it would be more surprising, but on the other hand I was thinking you're
probably nearer to obstacles such that you don't have enough time to
accelerate to lethal speeds before crashing into something.

