Another unexplained acceleration

[AJB]

The Wookie said:

Of course it's not impossible that she could have had a temporary and unrepeatable brake failure simultaneously with either a multiple, temporary, unrepeatable throttle pedal/butterfly position sensor failure, or an obscure and unrepeatable total failure of the car's entire electronic control system...

Or maybe she just pushed the wrong pedal and is in total denial.

This. If a car suddenly accelerated hard towards something/someone, instinct would make sure you press the brake pedal very hard, and very quickly. Brakes beat engine, car stops. Unless you're not on the brake pedal... In which case your brain tells you you REALLY have to stop, and you've really got to push what your right leg thinks is the brake pedal right now...

I can do left foot braking in autos just fine (learnt on an old misfiring carb-engined auto on damp mornings...). I tried it in a manual once... All was good until I needed to change down a gear. My left foot (on the brake pedal) went into auto-pilot and thought it'd push the clutch down. The car slowed a lot, and that told my brain that I REALLY needed the clutch down right now, and seemed to tell my left foot to press harder even though I kind of knew it was the wrong pedal... I'm very glad nothing was behind me, as I ended up with a full ABS emergency stop to stationary, and a stalled engine as the clutch still wasn't down!

That was when I knew my left foot was on the wrong pedal, but I still couldn't control it in the confusion of something being out of the ordinary. I can imagine that if you 100% thought your right foot was on the brake but had the accelerator, it'd actually be pretty easy to muscle-memory it to the floor once panic set in.

[AJB]

MajorMantra said:

WokingWedger said:

Don't these cases of 'pushing the wrong pedal' (which it almost certainly is) only happen in Autos ?

Sounds obvious I know, but think about it.

You are creeping forward (or back) without touching any pedals, but 'covering' one of them, possibly the throttle because it often doesn't quite creep faster enough.

An emergency happens and you get it wrong (you had been 'covering' the throttle)but stamp on it thinking you were covering the brake.

Doesn't happen with manual cars as you have to know where your feet are to make it move.

As there are a lot more autos out there in the hands of older people (and young)we are bound to see more of it.

I've been thinking this too. My impression is that there are a lot of this type of accident (cars mounting pavements, smashing through shopfronts etc.) in the US and I don't think it's a coincidence that this is the case in a country where the vast majority drive autos. It's MUCH harder to have a 'sudden unplanned acceleration' in a car with a manual clutch.

I think WokingWedger is right about autos not needing either pedal pressed to creep, so making it easier to get wrong.

Also, in a manual, your instinctive panic emergency stop routine is to press the brake and the clutch down. If you had your right foot on the accelerator not the brake, you'd still press the clutch and just gently roll into whatever you're heading towards with the engine at max rpm. That's a lot less newsworthy, so we'd never hear about it happening.

[durbster]

98elise said:

durbster said:

98elise said:

Its very simple to design a fail safe. For example the pedal operates two potentiometers in opposite directions. This will give two pedal different position signals which can be checked against each other, yet don't behave the same in a failure. It is sudden unintended acceleration, but the cause is very very likely to be the driver.

Why add complexity?

It doesn't matter if the accelerator is flat to the floor - if you press the brake the car will stop. The problem is how the human mind can trick you into thinking your body is doing something it's not.

The only reliable solution is autonomous cars.

Its not complicated at all to add a fail safe like that, and it would prevent it happening in the first place. I'd be very surprised if drive by wire relied on a single sensor for throttle position. I can't see a car company admitting that full throttle can be induced by a single potentiometer short.

But it doesn't matter what causes a throttle to be wide open.

If the driver has the presence of mind to press the brake, the car will stop fine.

[saaby93]

Wills2 said:

The absence of any explanation as to how the car could leap forward with no driver input means it's going to be difficult to create a reasonable doubt in the mind of the jurors as to what actually happened.

She hasnt said it was with no driver input - do some people not read the article

She said she pressed the accelerator lightly when the car surged forward - already some indication of a possible failure mode there
then when she pressed the brake little happened - which may not be surprising if the car's in full pelt mode
Its not the braking shes arguing about - its the going into full acceleration mode when touching the throttle

Once that's happened it's going to take you some seconds to get on the brake anyway

article said:

Mrs Diggles, who was attempting to park, said: "I went into drive and I put my foot very gently on the accelerator to cross the road and then the car just took off. It surged forward.

"I can remember taking my foot off the accelerator quickly and I'm sure it went on to the brake and the brake didn't appear to be working.

Unless Nissan can demonstrate they have a better fault control system than the space shuttle with its 13 computers ( because they didnt trust any one of them) surely there is reasonable doubt?

Edited by saaby93 on Friday 3rd February 14:28

[Rude-boy]

Phil Dicky said:

t400ble said:

Shes pressed the wrong pedal, simple as that

This ^^^^^

There was an old lady who drove into a building near us a few years ago. She still tells anyone who will listen that she was hard on the brakes, despite the person who was first on the scene opening the door to her car, which was still trying to push the building over, having to pull her leg off the accelerator once they had turned the ignition off....

[Wills2]

saaby93 said:

Wills2 said:

The absence of any explanation as to how the car could leap forward with no driver input means it's going to be difficult to create a reasonable doubt in the mind of the jurors as to what actually happened.

She hasnt said it was with no driver input - do some people not read the article

She said she pressed the accelerator lightly when the car surged forward - already some indication of a possible failure mode there
then when she pressed the brake little happened - which may not be surprising if the car's in full pelt mode

article said:

Mrs Diggles, who was attempting to park, said: "I went into drive and I put my foot very gently on the accelerator to cross the road and then the car just took off. It surged forward.

"I can remember taking my foot off the accelerator quickly and I'm sure it went on to the brake and the brake didn't appear to be working.

Well that just sounds like a load of old bull....Take her down.

[CoolC]

She'll not be sentenced to prison in any case.

The 35 year old man who ran over and killed my father in law while simply not paying attention was sentenced to a two year suspended sentence, two year ban and a fine. We were told from the start by the family liason that this was the most likely outcome.

This lady will get similar as a worst case.

[GroundEffect]

saaby93 said:

GroundEffect said:

SirSquidalot said:

Still never understand why the cable throttle was replaced with drive by wire.

Because it allows a lot of extra control:

1) Different throttle maps for 'sport' modes etc
2) Different throttle maps per gear (very useful in auto trans)
3) Cruise control on gas engines much simpler

It also introduces almost an infinite number of ways to go wrong, once it's off in the new world outside the happy loop it normally enjoys.
When they went through the Toyota software didnt they discover that all the checking procedures had been based on a working system - they hadnt allowed for what happens when it had gone into lala mode

You should see the safety validation and FMEM handling with hardware redundancy it goes through. It boggles my mind, and I've been involved in it for years.

[AJB]

saaby93 said:

She hasnt said it was with no driver input - do some people not read the article

She said she pressed the accelerator lightly when the car surged forward - already some indication of a possible failure mode there
then when she pressed the brake little happened - which may not be surprising if the car's in full pelt mode

That would be VERY surprising. Instinct would mean she'd press the brake very hard, and brakes can easily resist the engine, even at full pelt. Indeed, testing torque converters can involve a stall-speed test where you floor the accelerator whilst standing hard on the brake pedal and see what revs are achieved. The car doesn't accelerate and crash when you do that.

[saaby93]

AJB said:

saaby93 said:

She hasnt said it was with no driver input - do some people not read the article

She said she pressed the accelerator lightly when the car surged forward - already some indication of a possible failure mode there
then when she pressed the brake little happened - which may not be surprising if the car's in full pelt mode

That would be VERY surprising. Instinct would mean she'd press the brake very hard, and brakes can easily resist the engine, even at full pelt. Indeed, testing torque converters can involve a stall-speed test where you floor the accelerator whilst standing hard on the brake pedal and see what revs are achieved. The car doesn't accelerate and crash when you do that.

Is it still a torque convertor?
Anyway as I said shes not arguing about the brakes - by the time youve thought about braking whatever it has already happened - its the accelerator surge. How would the engine know that was a fault rather than someone requesting max power?

Edited by saaby93 on Friday 3rd February 14:35

[Sten.]

I'd be quite happy to bet everything I own on it being driver error. This sort of thing is pretty common with old dears but thankfully it's usually just a garden fence or a wall they damage.

I don't believe she should go to jail but I do think she should never be allowed to drive a car again.

[SonicShadow]

Even if she didn't press the pedal to the limit, pretty much all modern cars have some form of Emergency Brake Assist - https://en.wikipedia.org/wiki/Emergency_brake_assi... - if she went onto the brakes quickly and with a reasonably amount of force, the car would have applied near enough full braking effort even if there was travel left on the pedal. Many of these systems will prioritise brake input over throttle input and cut throttle input as well. It would have stopped very quickly if she did press the brake.

[saaby93]

GroundEffect said:

You should see the safety validation and FMEM handling with hardware redundancy it goes through. It boggles my mind, and I've been involved in it for years.

I could ask the same here
How would the engine know the difference between a faulty input from a light throttle press and a normal request for max power?
Surely as its within normal operating parameters it would just give max power?

[AJB]

saaby93 said:

Is it still a torque convertor?

Doesn't matter if it's a torque convertor or not - my point was that the brakes can overcome the engine's full-throttle torque

saaby93 said:

Anyway as I said shes not arguing about the brakes - by the time youve thought about braking whatever it has already happened - its the accelerator surge

saaby93 said:

article said:

Mrs Diggles, who was attempting to park, said: "I went into drive and I put my foot very gently on the accelerator to cross the road and then the car just took off. It surged forward.

"I can remember taking my foot off the accelerator quickly and I'm sure it went on to the brake and the brake didn't appear to be working.

It seems incredibly unlikely to me that the car had an electrical or mechanical throttle fault and accelerated hard of its own accord, and simultaneously had a mechanical brake failure. Neither of which had happened to her before, and neither of which could be detected by examining the car afterwards...

Edited by AJB on Friday 3rd February 14:40

[TheInternet]

saaby93 said:

could ask the same here
How would the engine know the difference between a faulty input from a light throttle press and a normal request for max power?

I'm on a hiding to nothing, but how do you think this would come about?

[RobM77]

I had weird stuff happen several times with my E46 330ci BMW, the first drive by wire car they made. I had an early year 2000 car. It did the following:

• If the car thought you were about to stall, then it would put in a surge of power to prevent the stall. As if this wasn't scary enough, the computers on the car were very slow, so you'd get the power come through about a second after the judder that signified you were about to stall. It usually happened in car parks when driving round at very low revs in 2nd gear. Given the number of pedestrians in car parks I can well imagine how this could lead to an accident. I always park using the clutch, so can rescue any such situation immediately, but if you park in first gear with the clutch fully engaged this could be pretty dodgy, because as soon as you turn the front wheels and get that extra drag, if you don't put in the right amount of power to balance it and the car gets down near idle, then the car can surge forwards suddenly.

• Another scary thing that E46 did, that a lot of modern cars do too, is they have a lag from when you back off the throttle to the engine actually backing off, so if like me you avoid using the brakes and just plan ahead and back off, things can get quite scary, because you'll back off and the car just continues forwards. Again, this is most noticeable in car parks, if for example you're in second gear and you've lined up the exit ramp and give the car a quick spurt of power to get up the ramp and then back off, that spurt instead of lasting a second whilst you're on the throttle pedal, last two seconds, which at 15mph is just over 6.5 metres travelled with your foot off the throttle, but the car still surging forwards. If you've timed things to avoid pedestrians or other cars, again I can see why this would cause an accident.

• Finally, if my 330ci detected a tiny bit of rear slip, it would cut the power for about a second. I once had this happen crossing a dual carriageway, when my rear wheels crossed the dirt and gravel often at the edge of such a road. I drove across the road onto the other carriageway just fine, and then the car reacted to that gravel back at the start and killed all the power and gave me a dead right pedal, leaving me stranded. The problem then is that with a dead right pedal you can't judge how much power you should put in because you lose the feedback loop, and if you put in too much, it'll happen again. I had one very scary moment once trying to pull out quick when a lorry was coming - I straightened the steering and used momentum to coast out of the way, but it was quite scary.

Performance cars (Lotus, Porsche etc) or more expensive cars (Mercedes, BMW etc) tend not to do this these days, but I've experienced the above traits to some extent in a lot of cheaper cars that I've had as courtesy cars. For example, I had a Peugeot 208 a few years ago that had a massive lag when you backed off the throttle. I've never driven the car mentioned in the OP, so couldn't comment. Crazy st is possible with DBW though; personally I can't stand it.

[Roger Irrelevant]

saaby93 said:

Roger Irrelevant said:

Why don't we see Qashqais (or other similarly complex machinery) careering out of control for unknown reasons on a regular basis?

This doesnt have to be a regular basis failure mode (they'd have fixed that) - isn't more likely a very rare occurrence failure mode?

The problem there is that there isn't any indication whatsoever that there were any unusual circumstances in this case to give rise to the failure. It was a very common car performing a very common manoeuvre under normal conditions.

So we're back to was it A) an elderly lady making the type of mistake that elderly people (and other people besides), sometimes do, or B) a mystery software fault that for some reason only manifests itself in the extremely precise circumstances that were present in this case (and has apparently never happened to anybody else doing the same manoeuvre in the same car with the same code), that nobody has been able to recreate, and which nobody has been able to identify the root cause of?

I think A, you think B, let's call the whole thing off etc

[Josho]

I haven't read all the thread but the car has a hydraulic brake system.

If you push the pedal the car will stop. The servos are way over active on them Qashqais anyway.

I have once had a car "drive itself" forward. The mat was wedged under the throttle and a jab of the brake pedal killed the throttle anyway!

[TwistingMyMelon]

Was sat in a car park last week, lady parked next to me floored it in reverse hit the car behind at speed, not a car park knock, but propper high speed hit. Old dear then tried to drive off, we stopped her she gets out sees half the car behind demolished and before we said anything she goes "I didnt do that"

OK sample size of 1, but the denial and attitude was scary

My grandad was the same, watched him knock off a cyclist and not even realise

Various other anecdotes involving elderly drivers , normally pulling away/start/stopping and then not "realising" what theyve done

Im sure there are a few good drivers in their late 70s, but a large proportion shouldn't be on the road

[durbster]

saaby93 said:

Is it still a torque convertor?
Anyway as I said shes not arguing about the brakes - by the time youve thought about braking whatever it has already happened - its the accelerator surge. How would the engine know that was a fault rather than someone requesting max power?

Have you ever heard of a case of "unintended acceleration" where the driver has pressed the brakes?

That is the first thing a driver will do in an emergency and the only reason they would not hit the brakes is because they think they are already on the brakes.