Wednesday, February 9, 2011
SAN DIEGO Toyotas have been accused of accelerating out of control, and the U.S. Department of Transportation has investigated. But it had to enlist the help of NASA engineers to examine the vehicles. To this you might say, It’s not rocket science! But then UCSD electrical and computer engineer Mohan Trivedi might respond by saying, No… it’s a lot more complicated than that.
“Today’s vehicle has 100 million lines of software code,” said Trivedi. “Today’s Boeing 787 has about 7 million lines of software code. So you can see that these (cars) are very complex electro-mechanical computer units.”
In case you hadn’t heard, U.S. transportation secretary Ray LaHood announced Tuesday the government’s investigation found there was no evidence that reports of unexplained acceleration in Toyotas were due to electrical malfunctions. They were caused by either mechanical problems, faulty floor mats or “pedal misapplication…” i.e. human error.
This development is of particular interest to San Diego, where two events led to recalls of millions of Toyota cars and many months of investigation. One event happened last year when James Sikes claimed his blue Prius zoomed out of control on I-8. The other happened two years ago when an off-duty CHP officer named Mark Saylor lost control of his car on Hwy 125, leading to a crash that killed him and three family members.
Investigations indicate Saylor’s crash was caused by an ill-fitting floor mat that snagged the accelerator.
The news that electronic demons were not to blame for Sikes’ journey or several other similar events came as no surprise to either Mohan Trivedi or to another expert in automotive computers, Ingolf Krueger, also of UCSD. But while Krueger wasn’t skeptical of the finding, he said we can never be sure a computer snafu didn’t cause an accident.
“There’s a lot of fleeting information that simply goes away when you unplug the vehicle or when you turn off the power. So this information is notoriously difficult to reconstruct,” he said.
This may come as a surprise to people who imagine some “black box” aboard the suspect Toyotas that could be extracted and studied to determine which systems worked and which did not. But Krueger says while a car’s integrated computer systems process a huge amount of information, they don’t store much of it.
Trivedi adds that a computer is not the most complex or problematic operating system in a car.
“There are not just computers and software or mechanical devices,” he said. “There is also a human in the loop.”
And the dude behind the wheel can space out, screw up or get drunk. Information storage in humans is also less that perfect, subject as it is to lies and forgetfulness and faulty impressions.
Car electronics have made cars much more complex but Krueger said they have also made them much safer. He says for instance that electronic stability controls, which manipulate the a car’s braking system to prevent rollovers, have reduced fatal accidents dramatically.
Advances in automotive technology could someday make drivers entirely passive. Their cars, equipped with all manner of sensors, could drive for them in a way that keeps them safe, mitigates traffic jams and assures that fuel is used as efficiently as possible. But Trivedi, who is director of UCSD’s Laboratory for Intelligent and Safe Automobiles (LISA), said there will always be a “human in the loop.”
There is, after all, a limit to the amount of trust we can bestow on a machine that flings us down the freeway at 70 mph.