Unintended Acceleration analysis

I think the substitution of a traditional keyed ignition in the Prius is partially the cause for panic during a UA event. Pair that with a non traditional shifter layout. There's no clutch pedal, but neither is there any in an automatic.

Let's say you have UA or brake failure.

A key is basically a rotary switch. It's more tactile. It is easier to find and use than a button, you have to use fewer senses -- I would not argue this point.

If I ever experienced UA & unresponsive brakes, my reaction without thinking would be to reach for the key to turn off the ignition. Perhaps I would try to put the car into neutral first. But if I only had a split second to react, the key would be fastest.

Most people who drive the Prius normally hardly ever use "N" and would not immediately remember to hold the N position for 1/2 second to engage it. "N" is still a software setting, I believe.

Now in an emergency, in a Prius, the fastest way to disable the car is to hit the "P" button. At this point, I still have to look to find "P".

The other way is to hold the power button for 3 seconds, if I recall correctly.

 

Now that you mention it, I've had a couple of failed return springs, also a jammed throttle linkage that kept the throttle open on at least one occasion that I can remember. Neither on is somthing that should cause a competent driver a serious problem.

 

need one of those big paddle off sitches like on shop equipment.

 

How is a key easier to find and use than a button? If this is true, why do we use emergency shutoff buttons on machinery? Shouldn't we be using emergency shutoff keys?

You are making assumptions about the type of key and the type of button. Certainly the power and park buttons on a Prius are less than ideal for emergency use, but that doesn't condemn buttons as a whole. A real shutoff button is much easier to find and use than any rotating key.

Perhaps it is easier for you to find the key in a car because you learned to drive with a keyed ignition switch. This is an example of training or habitualization, not inherent utility. Consistency is important for user interfaces, but we also need room for innovation. I don't hear anyone suggest that we should have stayed with the floor controls of the Model T.

Tom

 

Oh great...
Here we go again!!!!

FWIW...a big red scram button will generate more lawsuits than it prevents the first time some latte queen or GPS jock hits it by accident on the freeway.

UI seems to be a mostly 'made in the USA' phenom, and whether it's caused by our pathetic driving standards or by the abundance of sniveling bed-wetting lawyers, it's probably not going to be solved by bolting the mats to the floor, using day-glow warning decals, or any other interlock or safety feature we can think of.

JMHO....

We now return you to our previously scheduled saga already in progress.......

 

I am not making assumptions nor am not condemning buttons. Perhaps you have misunderstood my previous thoughts. Let's analyze this carefully.

I think if the button's sole function and purpose is to turn something on or off something in an emergency, like a giant red button that you walk up to and hit quickly, then that is good design. In machinery, this would be great, provided it was clearly marked. Is this better than a lever or a toggle? Perhaps. But you could also argue that a lever or rotary toggle switch would work just as quickly, and it would not be as prone to accidentally being hit.

I don't think you can apply the ergonomics of machinery to that of an automobile. Things are more cramped, your eyes must watch the road, while your hands and feet do other things.

A key is a rotary toggle switch that physically projects outward in three dimensions. So this is the difference and inherent utility. The key is arguably easier to locate and grasp without the aid of sight. If you push the key, it doesn't do anything. If you turn the key, it will perform its function.

Have you read some of the threads on here about people accidentally hitting "P" when they want to turn off the A/C? One person even made a cover to prevent him from hitting the button.

Also, using the button, in order go to ACC mode from ready mode, you first have to go to off mode. Apparently this reboots some GPS and bluetooth accessories.

As safety against accidentally hitting the on/off button in the Prius while moving, you need to depress it for 3 seconds. With a key, you could switch off and more intuitively, in much less time.

 

This is a subjective analysis based on your version of ergonomics. I don't happen to agree.

I do agree with ETC that a prominent kill button would cause trouble. The cure would be worse than the disease. The real solution is for people to learn how to drive their cars. We allow too many bad drivers on our roads. Getting a driver's license should be like getting a pilot's license.

Tom

 

Actually, this is your subjective analysis based on your version of ergonomics. A key in the same location can be no less difficult to find than a button. Based on it's physical protrusion, I would conclusively argue that it is easier to find without sight, using touch alone, especially during an emergency.

Also because the key requires rotation instead of translation, it is by its very design less likely to be accidently engaged. Subjectively or objectively, I argue this has more "inherent utility" within the context of commanding a vehicle in an emergency situation.

Subjectively, therefore I would say that a key presents an excellent balance of ease of use against its likelihood of being accidentally engaged incorrectly. I would subjectively say more so than a button with a 3 second delay, because the key would not require a delay.

By your own words you refute your earlier position. You say a shutoff button is "easier to find and use" and you then agree it would "cause trouble".

You present machinery vs an automobile, which is apples to oranges. When you operate a machine, you can give it 100% of your attention with all your senses. You aren't distracted with whether you are hurtling headfirst into a Semi.

Please note I respect your opinions greatly. I agree to disagree, but your position is much more subjective than mine because I try to present my rationale behind my analysis.

 

Thanks for the link, interesting article.

Hopefully the National Academy of Sciences study coming out later this year will be more comprehensive than the NASA study.

 

the problem is having to hold the button for 3 seconds. i really don't see how you can hit the power button by accident, but if you can, than a rotary knob might be better. let's limit this discussion to the possibility mrntioned in the article. that since u/a cannot be ruled out in any modern car, there should be a consistant acroos the board emergency shutdown method.

 

i would guess that in emergency, the best would be to hit brakes, and not gas pedal.

that solves 100% of the issues.

why in the world would you ever turn off moving car?

 

it's better than hitting a bridge abutment at 90 mph.

 

I agree on the whole more training idea for driving. Sometimes I think people really take driving in general for granted watching someone whip a minivan around the corner in a parking garage and then look sheepishly at me in my little prius and realizing they were not thinking about how big their van was. Honestly I don't think it should be as strict as a pilots license but have some of the ideals behind it like knowing the system and it's functions and how to properly work it. Not by guessing you know how to do it and "winging it" (sorry bad aviation joke ) but knowing it, also some consideration of emergency procedures would be beneficial.

 

As I stated before, I understand your arguments, I just don't happen to agree. A rotating device such as a key requires you to find it and also know which direction to turn. Generally rotating switches or keys are used as failsafe devices, where you want to make them harder to operate, or for multi-step operation. The only reason car keys seem natural is that we are all well trained.

One of the frustrating things about ergonomics is that you can't prove merit with a logical argument. You can put forth ideas and do a lot of hand waving, but in the end it's up to the user. Sometimes they just don't want to play along with our well reasoned arguments.

Tom

 

I agree with your second point, but as your first point, you try to bring other contexts into this discussion. The only context we should be talking about is that of an automobile.

Of course if you are talking about buttons, switches, dials, knobs, etc. in a machine, the design requirements would be completely different.

Going back to your earlier point. Ideally, a person would be trained and certified to operate the item in question. People just don't care to learn about how to properly operate their vehicles. This is a fact of life. Is it right we have to dumb things down to the lowest common denominator? Is it right if we don't?

Especially the CHP officer and his family who unfortunately lost their lives in the Lexus ES 350 with the Smart Access ignition. It was a loaner, and I can only speculate, but if he been given a car with a traditional ignition, he could have killed the vehicle, instead of getting killed. His brother in law had time to call 911 and provide much detail until the unfortunate final moments. It's hard to imagine how the brakes, parking brake, shifter and power button all failed, especially with 3 adults on board. Apparently the brakes were used and heavily worn during the episode, but proved useless to slow down the vehicle. He apparently didn't press the power button down for 3 seconds. I don't know why he didn't go into neutral or jam into reverse or park. I can understand why he didn't use the foot operated parking brake in that moment.

Whether by habituation or whether it's actually easier to use, it's likely a keyed ignition would have made a difference. That's not a condemnation of push button starters with a 3-second delay kill function. It's just reality.

 

Agreed. This is why we have standards.

Standards do change, which is where it gets tricky, especially when they relate to controlling dangerous devices. Our laissez faire free enterprise system tends to encourage change, as manufactures try to differentiate their products from the competition. In the long run, this encourages innovation. In the short haul people get killed. Generally safety standards come about only after enough people die.

Keyless ignitions are the future. Eventually the industry will get together and come up with a standard. If they don't, the government will step in after a few more spectacular deaths.

Tom

 

I guess my arguement in the debate between "Key" vs. "Button" would be simplier. Divorcing it from a personally subjective debate about ergonomics and safety, I'd say we need to work for solutions that don't involve a key...because keyless entry and push button starts are the present and the future.

More and more cars outside of The Prius are featuring push button starts and keyless entry and ignition.

Yeah, anyone not just getting their driving permit, probably learned to drive an automobile when the almost all of them had "keys". I love keys. Keys good.

But people like convience, they like the idea of not having to reach into purses, or pockets. Remote Keyless Entry and Push Button starts simply are not going away. So I can't advocate that any "solution" would involve taking steps backwards.

Other threads have had lengthy debate about Keys, Push Buttons and how to react if a vehicle starts to accelerate, debates I have taken part in. It's a debate in scope that nobody is ever going to win.

In general? I think the OP's article reveals to me that the NHTSA and Toyota have done a relatively thorough job of evaluating the ETC...but no testing model is 100% fool proof. This admission doesn't worry me, it's simply a truth about Code, Software and Testing...it's also everyone covering their own butts...

Nothing has really changed for me. Even at the height of Toyota Hysteria last summer, my feeling was that Toyota's were designed to stop...designed to accelerate safely...

Toyota has made huge moves to minimize the risk of floormats becoming intangled with pedals...and the recall for the pedals was huge.

Evaluation should never quit. Improvement in systems and evaluation of interface between user and machine should also never quit. But bottom line? Key, Button, or Anchor Thrown out the back hatch...

I think Toyota builds a safe product that meets todays safety standards.

 

Unanticipated software bugs can happen anywhere, no matter the industry. Even the F-22 raptors were released to active service with a significant software bug that locked the computers when they flew across the international dateline.

F-22 Squadron Shot Down by the International Date Line

We face this issue in my industry too. The usual mitigation is to have independent redundant interlocks. For instance, if you have an industrial compressor (by industrial I mean 100,000+ hp), getting liquid into the suction is a very bad thing to do. So there's a drum to catch liquid before it gets into the suction line.

Of course, that only works if you drain the liquid. So there's a continuous level instrument that reads out in the control room. That signal has a high alarm and a high-high second alarm. Then there's a float level switch above. That flashes a light sets off a buzzer using a circuit completely separate from the continuous readout and the control computer. Above that, there's another float switch that shuts down the compressor...again, separate from the other indicators and their electronics.

Your backup to the throttle control does not have to be mechanical, it can be electronic, as long as it's fully independent. Redundant <> independent.