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junko.yoshida
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Re: The "Task X" failure testing
junko.yoshida   10/29/2013 4:11:43 PM
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Thanks, Bert. Well explained, as usual.

And as you wrote:

I have to agree that monitoring functions, especially in safety-critical systems, should be done independent of the control functions. A totally separate loop, software and also hardware.


And why Toyota didn't make that as a totally seprate loop, software and also hardware -- as you pointed out -- is mystery to me. 

Bert22306
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CEO
Re: The "Task X" failure testing
Bert22306   10/29/2013 4:02:29 PM
Actually, what this throttle position algorithm does is translate the pedal position (which is apparently determined by an unregulated analog voltage, corrected by the program, according to a separate article) into fuel and air delivery to the fuel injection system. When the car is not in cruise control. In cruise control, presumably the throttle angle is not examined at all, and the fuel/air command is supplied as a function of vehicle speed vs requested speed.

Worrisomely, brake application did not override these control signals if that control algorithm app died. *That's* the crux of the issue here, I think.

I have to agree that monitoring functions, especially in safety-critical systems, should be done independent of the control functions. A totally separate loop, software and also hardware.

junko.yoshida
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Re: The "Task X" failure testing
junko.yoshida   10/29/2013 3:45:21 PM
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What caused the so-called "stuck pedal" wasn't the issue in this case. At issue was the software controlling the electronic throttle control system.

As the expert witness explained, the software in electronic throttle control is responsible for performing the sparking and the throttle control.

But there is another part of the software that is looking at the driver controls-- looking at the accelerator pedal and cruise control. So there is a part of the software looking at what the accelerator pedal position is, is it down, is it up, how much down. Then that is translating that into a calculatedthrottle angle.

That malfunction was the crux of the issue that was argued in this trial.

 

rick merritt
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Author
Re: The "Task X" failure testing
rick merritt   10/29/2013 3:20:10 PM
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Do we know what's the relationship between task X and the stuck accelerator in the OK case?

junko.yoshida
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Re: The "Task X" failure testing
junko.yoshida   10/29/2013 3:13:45 PM
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The Toyota trial in Oklahoma is over. But Toyota still faces hundreds of other sudden acceleration lawsuits, many of which will probably make similar arguments.

The next trial, involving a Georgia woman who accelerated into a schoolyard, is set to begin in federal court in Santa Ana early Nov.

So, in light of that, nobody is publishing any results, even if the throttle function in the worst case scenario is being tested again.

Kinnar
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CEO
The "Task X" failure testing
Kinnar   10/29/2013 3:02:48 PM
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It is true that the throttle function will be affected by the software malfunction, but why the throttle function is not being tested again in the worst case scenario again to justify the findings after Toyota Trial?

junko.yoshida
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Blogger
Kitchen Sink
junko.yoshida   10/29/2013 3:00:29 PM
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The expert witness aptly describes the Task X as "kitchen-sink" task. It is designed to do just so many thing. So what happens when the Task X does? So many things could go wrong, and one of which is a loss of throttle control. Talk about a bad design.

 

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