Complaints of sudden unintended acceleration afflict all car makers and, as Toyota advised Congress recently, the cause is "very, very hard to identify." This reality, forensically and politically, is coming into collision with the growing reliance on computers and software in the vehicles we drive, which can now account for 40% of the value of a new car. And, yes, "feature wars" play a role, but we're here to tell you the biggest reason is government regulation requiring cleaner emissions.Government mandated environmental requirements are one driver to the complexification of automotive software. As the intentions of those pushing environmental policy comes under greater scrutiny because of the loss of credibility associated with climategate, glaciergate, and the rest, we can expect a pull back from environmental regulation. As voters begin to understand that environmental legislation may harm them because their car's accelerator is more likely to fail and its breaks may not work, they'll vote for new legislators. Again, like other green issues, this is not going to help Russ Carnahan (D-MO) in this election cycle.
A decade ago, what were single-purpose computers, each with its own software, began to merge into systems with many millions of lines of code...
But implementing so many vital and not-so-vital control features as a network system also creates complexity and multiplies the opportunity for unpredictable software bugs and circuitry mishaps.
Take Toyota's latest troubles with its marquee car, the Prius. Even amid its runaway-acceleration traumas, the company was hit this week with Japanese and U.S. government investigations of brake failures in the 2010 version of its iconic hybrid.
A bit of history: Brakes were first introduced to computers and software for the relatively simple purpose of anti-lock braking. Then came stability control, giving brakes an additional computer-and-software controlled duty to perform.
In the Prius, brakes have now acquired a third function, "regenerative braking," or generating electricity to recharge the batteries for fuel-saving purposes.
That's a lot of software that has to cooperate to decide how the brakes should behave from one nanosecond to the next. Toyota has yet to offer a detailed diagnosis of the latest Prius misbehavior, but it sure sounds like the trouble arises from some unexpected interaction of these systems—on slippery or uneven roads, at low speeds, the brakes reportedly refuse to respond to a driver's foot on the pedal.
Friday, February 5, 2010
Holman Jenkins writes in the WSJ about Toyota and the Curse of Software [emphasis added]: