Green Car 101: How to "Fail Gracefully"

Photo courtesy of Tesla MotorsIn the move from gas powered cars to hybrids, plug-in hybrids and battery electric vehicles, our cars will become more like overgrown consumer electronics than ever before. That trend brings with it potential for a new breed of errors in our vehicles — a fact brought to the forefront by Toyota’s recent recall of millions of vehicles, some of them because of a glitch in the anti-lock brake system software. As electric car startup Tesla Motors explains in the risk section of its most recent regulatory filing:

“[O]ur vehicles use a substantial amount of software code to operate. Software products are inherently complex and often contain defects and errors when first introduced. While we have performed extensive internal testing, we currently have a very limited frame of reference by which to evaluate the performance of our Tesla Roadster in the hands of our customers and currently have no frame of reference by which to evaluate the performance of our Tesla Roadster after several years of customer driving.”

Bottom line, despite standards and testing procedures for chips and software in vehicles, errors should be expected — especially as new technologies are brought onto the market. But according to Steve Nelson, manager of global automotive marketing for Freescale Semiconductor, what’s important is “not that you have a glitch, [but] how the system responds to it.” The goal is to design a system that will “fail gracefully,” having enough redundancy that the car will “continue to run and take you home,” he told us in an interview for GigaOM Pro (subscription required).

Following the rash of complaints of unintended acceleration in Toyota models, several automakers have moved to boost consumers’ confidence in their ability to “fail gracefully” in the event of an error. General Motors announced on Monday that by 2012 it will equip all of its models with a brake override system that basically recognizes when the brake and accelerator pedals are both being depressed, and then reduces engine power. Earlier this year, Toyota said it will do the same for its models by the end of 2011. Tesla updated its IPO registration last week to say it has implemented algorithms in its control software that are meant to make unintended less likely “in the event of either a mechanical or electronic malfunction.”

So how does the system respond to an error in this case? By stopping the flow of electricity to the motor when the car is shifted into neutral, when the key is rotated out of the “on” position, or “when the brake pedal is depressed for more than two seconds after the accelerator has been depressed.” In addition, Tesla says it has “a dedicated processor that monitors the ratio of accelerator position and torque delivered to our motor and will stop the flow of electricity to our motor if the ratio diverges from set parameters.”

In a typical mid-range vehicle sold in the U.S., electronics currently make up 20-30 percent of the car’s cost, Nelson said. They serve functions from “bumper to bumper,” including stability control, navigation, transmission and engine management and many systems in between. According to Frost & Sullivan, hybrid vehicles, with their regenerative braking and start-stop systems designed to reduce fuel consumption, “have substantially higher semiconductor content compared to regular passenger cars.”

All-electric vehicles, in turn, have even more chips in them, relying on computerized systems to extend their range and manage complex battery packs made up of hundreds of lithium-ion cells, each of which needs monitoring, Nelson explained. Thermal controls and other management systems help ensure efficient charging and longer life (more charge and discharge cycles).

All of these systems spell an opportunity for chipmakers as the nascent plug-in vehicle market grows (we’ve elaborated more on that opportunity over on GigaOM Pro). For car companies, they also mean a critical area of innovation and intellectual property is increasingly shifting from the brawn of the internal combustion engine, to the brains — potentially opening a window of opportunity for startups that may not have the resources to compete with legacy manufacturers.

Photo courtesy of Tesla Motors

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