Wednesday, March 10, 2010

Unintended Acceleration

Back in the era of the muscle car and 25 cent per gallon leaded gasoline I decided that I wanted to be an automobile mechanic.  One thing that influenced my decision was my neighbor across the street owned a race car which he built himself.  I'd watch quietly while he put the engine together, adjusted the valve lash and set the points in the dual point distributor.  The end result is that by the time I was 21 I knew enough about auto mechanics to be a tolerable shade tree mechanic and to avoid being ripped off by the occasional scam artist who told me I needed a new muffler bearing.  So when the unintended acceleration problems with Toyota surfaced I had some idea of what might be going on.

When I first began my career of choice computers where huge things that read paper tape and required a climate control system that would rival the royal palace in Saudi Arabia.  The electronic calculator cost over $75 for a basic model.  Still, a good friend of mine worked for a branch of General Motors concerned with R&D, and one night over six drinks he finally broke down and told me that GM was working on a computer controlled engine.  I realized that the mechanic's shade tree was slated to become part of a new development and resolved to find a different career, one that didn't involve jump starting cars in sub-zero temperatures.  I did so, and surprisingly the auto industry progressed without me.

In the old days, cars had a mechanical linkage between the accelerator pedal and the carburetor.  Not so anymore.  Today we have a sensor in the accelerator pedal which sends an electronic signal to a computer, which decides how best to control the engine.  What this amounts to is that when the driver is trying to accelerate at, for instance, full throttle, as the gas pedal is mashed to the floor the throttle is not immediately opened.  Instead, the pedal sensor signals the computer and requests an open throttle.  The computer decides just how to proceed, meaning that your request may not be granted right away or may not be granted in full, so to speak.  When the driver takes his size nine off the pedal, the same process occurs.  The computer decides, based on the state of the car, just how to proceed.  Not the driver; the computer.  Therein lies the rub.

My car has a standard (or manual) transmission, otherwise known as a stick shift.  I don't need some gear head in Detroit or Tokyo to tell me when to shift; I'll decide that for myself, thanks.   Not everyone feels this way.  For the uninitiated, which encompasses everyone under 30 (I'm being generous here) and most people over thirty, this means I have an extra pedal on the floor of my car.  It's called the clutch pedal, because when the electronics in your Toyota screw up and your car heads for a viaduct at 120 mph, you can duck down in the floorboards and 'clutch' this pedal as you wait to meet your maker.  All police vehicles have a built in clutch sensor unit which will inform the police of your plight and they will come and rescue you.  Okay, I'm kidding.  The clutch pedal controls the clutch and is connected to the clutch by a mechanical linkage.  When you press the clutch pedal to the floor, your engine is disconnected from the wheels of your car and you coast.  The car's computer system knows this, but can't do a thing about it.  To drive the car, the driver evaluates the state of the car, depresses the clutch pedal, selects the proper gear using the stick shift, then releases the clutch pedal.  The driver must do this constantly around town, less so on the freeway.  There is a skill that must be developed to drive a stick successfully.  Advanced drivers know how to double clutch, and really advanced drivers can drive an unsynchronized transmission, a thing you're not likely to find these days.  New drivers take a good deal of pride in being able to drive a stick shift without stalling the car out in first gear, and shifting without grinding the gears.  If you've never driven a stick shift, I recommend you try it sometime.

Compare this to the automatic transmission, which is what most yo-yos have in their vehicles.  With the automatic transmission the driver puts the shift lever into 'D' and promptly forgets about it until the car is parked.  Then the shift lever must be moved to 'P'.  How easy!  How convenient!  Anyone can do it as it requires no skill.  I think it's worth noting that the automatic transmission was originally marketed towards women – Hey guys!  Now the little lady can drive and not burn out the clutch or grind the gears – just look at our new Dynaflow transmission.  The Dynaflow was a Rube Goldberg meets Dr. Frankenstein design and we don't have it today.  Note that on most cars there is no mechanical linkage for the automatic transmission.  Again, it's two electronic sensors routed through the computer.  This means that if you demand that the transmission cycle from reverse into drive, you may not get an immediate response from the transmission.

The unintended acceleration problem with automobiles is thought to be a wide open throttle which refuses to close.  I think that it's safe to say that in such a situation seconds matter.  Some application of grade school math reveals that at 55 miles per hour your car is actually traveling 80.67 feet per second (do the math yourself if you don't believe me, and you shouldn't.  I'm not credible.).  At normal highway speeds of 75 mph, you're going 110 feet per second, and at Detroit speeds of 110 mph you're moving right along at 161.33 feet per second.  Now then, if this unintended acceleration problem happened to me I have to realize that my throttle is stuck open, about 2 seconds.  I curse to myself and depress the clutch and brake pedals simultaneously, about 1 second.  My worst case scenario is that I've covered 322 feet (2 seconds at 110 mph) instead of 220 feet I expected, or about 100 feet more than usual.  Still plenty of time to have a major accident, but not as bad as it might be.  Compare this with the fool driving the automatic transmission.  Leave the time it takes to realize what is happening as a constant, even though it isn't.  Why?  Because people who drive a stick have to drive the car constantly.  They can't just forget about it.

Since the engine overpowers the brakes, stopping requires shutting the engine off or disconnecting the engine from the wheels.  In this case the driver will practice their normal stopping or slowing routine; they take their foot off the gas and stomp the brake pedal, and when that doesn't work they stomp harder.  The car continues to accelerate.  If the driver keeps their head about them, and most do not, they'll put the car into neutral.  This should be a fool proof way to stop the car, and it would be were it not for the fools in Tokyo.  You see, the linkage between the shift lever and the transmission is electronic, not manual.  The computer, now suffering some kind of electronic indigestion, decides if and when the transmission will shift into neutral, and since the throttle is wide open this is clearly not the time to switch gears.  The driver might try switching the engine off, but again this is not a mechanical linkage.  It's electronic and it routes through the computer.

I'm not the only one who sees this as an unreasonable design.  In the January edition of Business Week a few details on a class action suite Toyota Speed-Up Suits Say Problem Goes Deeper Than Gas Pedal are revealed and a retired retired US Army Colonel is suing due to personal injury.

The federal government didn't learn much from the Volstead Act of 1920 and it should have learned that US citizens do not like being told what to do.  Likewise, our elected officials were too busy to learn much from the Ford Pinto gas tank fiasco back in the 1970s, when it became evident to anyone who could watch TV that big business cares nothing for its clients.  I don't expect anything will happen here, either, and this is one area where the general populace could be protected. 

I think I'll hold off buying a new car until they gets the bugs worked out of the voice recognition system.

Shades of HAL 9000.
Mad Jack: What the - ? The fucking brakes don't work!  Brakes!!!
HAL: I'm sorry, Jack. I'm afraid I can't do that.
Mad Jack: You junkyard refugee!  I'll turn you into a toaster!

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