Computation Austringer on 14 Jul 2010
Toyota, WSJ, and Computers
I heard a segment on NPR this evening about the Toyota sudden uncontrolled acceleration problem (I’ll just call it SUAP). They were following the lead of the Wall Street Journal, who said:
The U.S. Department of Transportation has analyzed dozens of data recorders from Toyota Motor Corp. vehicles involved in accidents blamed on sudden acceleration and found that at the time of the crashes, throttles were wide open and the brakes were not engaged, people familiar with the findings said.
The results suggest that some drivers who said their Toyota and Lexus vehicles surged out of control were mistakenly flooring the accelerator when they intended to jam on the brakes. But the findings don’t exonerate Toyota from two known issues blamed for sudden acceleration in its vehicles: sticky accelerator pedals and floor mats that can trap accelerator pedals to the floor.
What the WSJ reported, though, doesn’t exonerate Toyota of anything.
NPR had a commentator on who said something to the effect that 100% of the cases examined showed the same thing, and that one would be hard pressed to argue that the computers got it wrong every time. Not at all, Mr. Non-programmer dude on the radio; all it shows is that the fault is upstream of the black-box recorder and not downstream of it. And it isn’t just the driver who is upstream; there is a lot of Toyota software and hardware there, too. If the Toyotas have an intermittent fault that causes the brake to be recognized as if it were the accelerator, it would explain the data far better than the “all those drivers forgot which pedal is the brake pedal, some of them for minutes at a time” conjecture. That’s just one way in which the problem might occur. In any case, it appears that the data recorders do tell us what the computer controlling the car operated upon, which is full-throttle acceleration and no attention to brakes whatsoever, which corresponds neatly with the survivors’ reports of what happened to them.
I’m thinking when all is said and done, this is going to be discovered to be a software fault in Toyota’s control program. I’m hoping the commentator on NPR gets 30 seconds of airtime to make an abject apology to the survivors when that happens.
Update: I found the NPR All Things Considered transcript, and the fellow whose name I didn’t recall is Mike Ramsey of the Wall Street Journal.
NORRIS: How many data recorders were analyzed? And of those, how many of these accidents were found to have been caused by driver error?
Mr. RAMSEY: Well, we have been saying several dozen, all of them that were -fit the criteria, were found to have the brake not depressed and the accelerator wide open. So 100 percent of the incidents where it fit that criteria, that’s what was found.
NORRIS: One hundred percent?
Mr. RAMSEY: Yes.
NORRIS: It sounds like, upon hearing that, that the government might be on its way toward exonerating Toyota.
Mr. RAMSEY: Well, when it comes to incidents where people are claiming electronic throttle control, the government has already said they have no evidence of it. This set of data, what it does is it completes the other side of it, which is if it’s not that, then what is it, right? It’s probably driver error. So the government has been hesitant to say that so far.
[...]
I totally understand the position of these people. And if you hear many of these anecdotes, it’s incredibly compelling to hear them and all of their evidence. That said, when you have dozens of incidents that are similar where people say they were stepping on the brake and the car accelerated anyway and hit and that all of these incidents show virtually the same findings, that’s difficult to believe that the computer was wrong and, you know, they had a special instance.
(Emphasis added.)
Mike, the data recorder can say what it says and the survivors still be right. Try doing some embedded programming sometime. You haven’t come up with anything that in the least puts their accounts in a bad light, at least not to those who know something about computer control systems.
And be scripting your apology.
Update 2: I’ve marked in bold a particularly interesting piece of information from Ramsey. We have dozens of incidents that show exactly the same thing: no depression of brakes ever, and full depression of the accelerator throughout. This pattern is not what one would expect of humans behaving either in panic, where accidental touching of the brake would be likely, or in Mr. Ramsey’s alternative of confusion of pedals. Pumping the brake is common, so if people were confusing the accelerator with the brake, we’d expect to see some fraction of those incidents showing variation in the accelerator control, and according to Mr. Ramsey, we never see that. That’s pretty damning for Toyota, I think. Having absolutely the same data pattern across dozens of drivers when some of those incidents went on for a significant amount of time doesn’t speak to mass confusion of drivers; it says “computer screw-up” to me.
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