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Toyota recalls: Deeper engineering implications

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DH123
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re: Toyota recalls: Deeper engineering implications
DH123   2/10/2010 4:53:25 PM
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The brake should always override the throttle for reasons too obvious to state. For brake failures a secondary system could be the hand brake taking into account hand brake pressure and wheel speed. When stopped the handbrake will function as usual, however above a set speed, e.g., 3mph, the main brakes will operate. Finally the last resort is cutting the engine electrics & fuel supply which works well on stick shift cars. It can seem daunting at first try since normally the ignition key is only turned when the car is stopped, however the car continues to behave as expected, the main difference being that one cannot now of course accelerate. Power steering continues to function well until speed has dropped to about 4 mph & even then steering is still possible. A stick shift car can be brought complete halt down a relatively steep hill using the gears alone. Practice is important, and any practice is better than no practice.

bobzz0
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re: Toyota recalls: Deeper engineering implications
bobzz0   2/10/2010 3:41:48 AM
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I am sorry, but the failure is not that complex and within the realm of expected. Stuck throttle was a common problem in auto racing and back in the bad old days before brakes were well engineered it could end quite badly. The failure appears to be a problem in the throttle by wire or cruise control which applies full throttle. Consumerreports and others have already done the test of applying full throttle and brakes at the same time. Some but not all other car makers with fly by wire have included a throttle cut under braking, either as software or separate hardware. In most of the cases the brakes were barely able to overcome the engine if the car was at speed. So the brakes are too small and the modern throttle did cope with an old problem. And don't even start on the fact that the keyless push button start needs a big red kill switch as covered by the yestertech in NASCAR. Easy to do, easy to predict. Generally Toyota appears to build well solid if boring cars, but this is a Ford class failure, e.g. Pinto gas tank, Explorer exploding tires. I find it hard to believe that someone at Toyota had not noticed the problem prior to the recall and they are guilty unless they can prove their innocence.

Rubberman
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re: Toyota recalls: Deeper engineering implications
Rubberman   2/10/2010 1:56:17 AM
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FWIW, that comment about "rational markets" was applied to the failure of Long Term Capital Management a few years ago, sort of the harbinger of the mortage and capital market meltdown of the past couple of years.

Rubberman
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re: Toyota recalls: Deeper engineering implications
Rubberman   2/10/2010 1:52:54 AM
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I've been designing and developing high reliability systems for almost 30 years and I have to agree with Mapou for the most part. Systems in these sort of real-time systems have to be designed with parallelism as part of the model, not as an afterthought. They also have to be designed for failure. All systems will fail. Its what they do when that happens that is important. Most of these automotive systems are designed to not fail, which is contrary to reality. As one really bright economist once said (quote not necessarily accurate), "Normally rational markets can behave irrationally longer than any investor can stay solvent". That sentiment applies to these systems as well. Any model that does not accommodate "irrational behavior" of the system is doomed to catastrophic failure!

Mapou
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re: Toyota recalls: Deeper engineering implications
Mapou   2/9/2010 11:32:48 PM
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Also, the parallel programming crisis is a direct result of our infatuation with the Turing Machine and multithreading. We must switch to a new software model that is inherently parallel and does not use threads. Threads are evil. * How to Solve the Parallel Programming Crisis: http://rebelscience.blogspot.com/2008/07/how-to-solve-parallel-programming.html

Mapou
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re: Toyota recalls: Deeper engineering implications
Mapou   2/9/2010 11:27:27 PM
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Excellent points. However, I think you are underestimating the software reliability problem. I believe that software is almost always to blame, even in situations like the Toyota sticky brake pedal where the hardware is defective. If the software was properly written, the problem would have been discovered much earlier and accidents would have been prevented. * The problem with current safety-critical software systems is that manufacturers are reluctant to deploy sophisticated software because they know that reliability is inversely proportional with complexity. And the the reason for that is that the basic software paradigm used by the industry has not changed since the days of Charles Babbage and Lady Ada. * The Turing Computing Model is inadequate for modern applications because 1) it does not address parallelism and 2) timing is not an inherent part of the model. What is needed is a new model that makes it easy to determine whether any two operations in a program are simultaneous or sequential. In other words, software needs to be more like logic circuits and less like algorithms. I've been calling for a deterministic, non-algorithmic, synchronous, reactive software model for ages. Nobody is really listening because computer science is still controlled by the same baby boomer generation who got us into this mess. It's time for a change. Go to the link below if you're interested in the future of safety-critical software. * Why Software Is Bad and What We Can Do to Fix It: http://www.rebelscience.org/Cosas/Reliability.htm

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