PSA: Beware of cosmic rays
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As if rollovers, suicidal deer, and thieves who break in with laptop computers weren't enough to worry about, now there's a new menace on the roadways - high-energy neutrons from cosmic rays.
Let's back up a moment. The increasing complexities and decreased time-to-market demands for automotive electronics has caused some manufacturers to migrate from microcontrollers and ASICs to field-programmable logic arrays (FPGAs). Devices based on volatile SRAM are the most common and also the most economical, but they rely on successfully loading and maintaining the device configuration into RAM upon each power-up.
Corruption of SRAM - where a stray cosmic ray disrupts the electron charge of a memory cell - has been a known phenomenon in the PC world for quite some time, but typically does not put the user at risk of a safety-critical failure. The story isn't the same in an automobile, where SRAM corruption can potentially cause a malfunction, or even the complete shut-down of a powertrain or safety system device. As annoying as PC crashes may be, it figures that a similar event in an ECM, ESP, or airbag module would be far worse.
It's highly unlikely that we'll ever see a recall that advises owners to minimize exposing their vehicles to cosmic radiation, but this issue does provide a sliver of insight into the challenges faced by those who design today's ever-more-complex vehicles.
[Source: Automotive Design Line via EE Times]
Reader Comments (Page 1 of 1)
Jim 6:27PM (6/01/2006)
I've been having an ongoing problem with the Intelligent Cruise Control on my 4 month old Infinti FX that can't seem to get fixed (even after 8 days of repairs on several trips to service). I wonder if this is causing my problem. On my car, something goes wrong randomly that knocks out the Intelligent Cruise Control and other feaures (like Lane Depature Warning system). The car starts going crazy, trying to either hit other cars or slams on the brakes with no cars around and comes to a stop on the freeway. I've questioned Infiniti if the problem could be related to some type of interference (there are certain areas where my car goes wacky more often).
Jim
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not important 6:50PM (6/01/2006)
jim that sounds dangerous. if its happeing frequently i doubt its a random cosmic ray. if my car slammed on the brakes on the freeway for no reason and it caused an accident i would want someone in debters prision.
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Fabulo 7:14PM (6/01/2006)
Jim, you're lucky that it's not triggering the airbag in your face when you're stopped at a redlight :)
Or maybe your intelligent cruise control is sick and turned into a bipolar cruise control.
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gbh 12:01AM (6/02/2006)
Cosmic rays are a PITA. Almost impossible to shield against, because when you do 'stop' them, you really don't.
Simplest analogy I can think of at the moment...
Kinda like a rifle round into a thinnish concrete wall-the bullet doesn't penetrate, but concrete chunks come out the other side. Can be just as bad, if not worse.
Historical footnote. In the early stages of processor-type chips, Motorola (and others IIRC) used ceramics, since they thought it to me more stable and better able to shed heat than an all plastic chip.
They ran into the same problems as described above with the cosmic rays. Occasional, random bytes dropping out. Even back in the day, scientist types get overspecialized - nobody remembered (or thought it mattered if they did) that ceramics are mildly radioactive. Fortunately, one man at Moto was a more of a generalist...
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DaveBro 2:53PM (6/02/2006)
Um, thing is, microcontrollers and ASICs also use internal SRAM (for storing programs and data). So there is little difference between FPGAs (in which the underlying logic function is stored in SRAM) and microcontrollers/ASICs (in which the program and data are stored in SRAM) -- a corruption of either will cause the system to fail.
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