Feb. 5 (Bloomberg) -- Toyota Motor Corp.’s U.S. recall of 5.6 million vehicles for possible unintended acceleration may spur regulators to require braking technology that prevents such sudden bursts of speed in all future vehicles.
So-called brake override systems, which disengage the engine when the brake and throttle are both depressed, are now on many newer autos that use computers instead of cables to control acceleration. Toyota said last month it is adding the equipment on most models, in response to a Sept. 29 recall.
“There’s no question,” said Joan Claybrook, a safety advocate and former director of the National Highway Traffic Safety Administration. “We are going to see a brake override system requirement in response to this.”
New regulations would build on the government’s history of expanding its safety rules in response to accidents that expose dangerous vehicle defects. Upgrades such as improved fuel tanks, new gearshift designs and air-bag warnings all flowed from federal mandates to automakers since the 1970s.
“The most likely outcome of this will be a regulatory catharsis,” said Brian Johnson, a Barclays Plc analyst based in Chicago. “There will probably be some sort of fail-safe system against unintended acceleration.”
http://www.businessweek.com/news/2010-02-04/toyota-pedal-recall-may-spur-u-s-to-require-new-brake-systems.htmlToyota's latest woes may be hard-wired
On top of mounting criticism of mechanical glitches in its cars, Toyota faces a much more complex set of issues related to car electronics, based on consumer complaints and analysis by an electronics engineer familiar with Toyota's history of throttle control.
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The birth of drive-by-wire
At the center of the alleged incidents is the electronic throttle control, or what is more generally referred to as "drive by wire." This was seen as a significant leap in automotive technology for car makers like Toyota, replacing the traditional mechanical and hydraulic control systems with electronic control systems.
Drive by wire allows for a more refined, computer-controlled acceleration and, somewhat ironically--at least to some owners with problem-plagued cars--is thought to boost safety. But it also introduced a new set of hard-to-trace problems, according to Antony Anderson, an engineer and electrical engineering consultant who is familiar with Ziprin's case.
"These are intermittent failure modes. The moment you switch off the (car's) computer, they go away. The problem is that when they look for the errors afterward, there's nothing to be seen," Anderson said. And indeed this is what often happens; the car accelerates and slams into something, disabling the car and leaving no evidence of what caused the electronic glitch, he said.
One of the most disturbing aspects of these hard-to-detect glitches is that the driver and other victims often provide the only evidence that something has gone wrong. "What happens today is that the driver is made the fail safe for the electronics," Anderson said.
More technology, more complexity
Today, cars can have as many as 70 electronic control units, or ECUs, based on microcontrollers (sometimes generically referred to as microprocessors). ECUs manage engines, doors, transmissions, seats, and entertainment, and climate systems.
Electronic throttle systems use an array of sensors, microcontrollers, and electric motors to control how the car is accelerated. Gone are the old steel cables to connect the driver's foot to the engine
Because of all of this added complexity and the need for chips to talk to each other, a bus system was introduced--not unlike the Peripheral Component Interconnect, or PCI bus used in virtually all PCs today. Called the Controller-area network, or CAN-bus, it is designed to allow microcontrollers and devices to communicate with each other within a vehicle
http://news.cnet.com/8301-13924_3-10446502-64.html
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