Sudden Unintended Acceleration in Runaway Cars:
Is Electro-Magnetic Interference Causing It?
London, UK - 26th February 2010, 09:35 GMT
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Could sudden unintended acceleration in cars be caused by electro-magnetic interference and other computer glitches given the sophisticated drive-by-wire systems in modern cars? At the US Congress hearings, the American National Highway Traffic Safety Administration (NHTSA) has admitted that it is investigating electro-magnetic interference (EMI) and other computer glitches as a cause of serious malfunction in cars. Toyota's top American executive, James Lentz, told the US Congress inquiry that the company's recent safety recalls may not totally solve sudden unintended acceleration in its cars, as the transportation secretary said he would expand a federal probe to other auto makers.
Electromagnetic Waves within the Spectrum
How can cars, computers and cell phones inexplicably malfunction? EMI induced malfunction of electronics equipment is a common occurrence. We have all noted that:
. If a cell phone is put next to a computer, a loud static can often be heard on the computer's speakers;
. The car's CD player can produce a loud static whenever a call is made or received via the cell phone;
. When a number is dialled on a cordless phone, one can hear the number being dialled through a baby monitor;
. When a truck goes by, its CB -- Citizen's Band -- radio system can overwhelm the FM radio station tuned in the car; and
. Most of us have come across motors that cause radio or TV static.
None of these electro-magnetic interferences (EMIs), technically, should be happening. A truck's CB radio is not transmitting on the FM radio bands, so a car radio should never hear the truck's radio signals. However, all transmitters have some tendency to transmit at lower power on harmonic side bands, and this is how the car radio picks up the truck's radio. The same principle holds true for the wireless phone crossing over to the baby monitor. In the case of the cell phone affecting the computer's speakers, the wire to each speaker is acting like an antenna, and it picks up side bands in the audible range. These are not dire problems. But notice how common they are. In an aeroplane, hospital or in a highly sophisticated modern car, with hundreds of microprocessors and microchips, the same phenomena can be responsible for malfunction and safety hazards. Electromagnetism suggests that electronic signals — from sources as diverse as cellphones, airport radar and even a car's own systems — briefly and unpredictably wreak havoc with sensitive electronic controls in vehicles. In a 2008 report after testing a 2007 Lexus ES-350, manufactured by Toyota, NHTSA stated, “Magnetic fields were introduced in proximity to the throttle body and accelerator pedal potentiometers and did result in an increase in engine revolutions per minute (RPM) of up to approximately 1,000 RPM, similar to a cold-idle engine RPM level.”
Onboard EMI sources
Automakers' move to electronic engine controls, including throttles, has been driven by the need to meet tighter US federal fuel and emissions regulations. They allow far more precise control of the engine operation and fuel use. Recent years have seen drive-by-wire systems replacing mechanical control of other critical functions, such as steering assist. While EMI from external sources, such as traffic lights or radar, is possible, it is unlikely because it would require an unusually strong signal. More likely sources of EMI are onboard components, because even very low-power electromagnetic radiation from the car's electronics can cause a problem. For example, EMI from poorly designed ignition wiring disrupts signals in the electronic throttle or engine controls. Internal EMI has been linked to high-voltage spikes when current in a wire or coil is switched, such as when the headlights or brake lights go off.
Automakers EMI Concerns
At least 14 Sudden Unintended Acceleration (SUA) lawsuits specifically alleging EMI are pending, including the ones against Toyota. Testing for potential EMI is a closely guarded subject within automakers. They contend that vehicle systems are designed with sufficient shielding and redundancy to prevent malfunctions of electronics and computerised equipment including accelerators. However, lawsuits over the years have uncovered documents citing internal concern. Auto experts interviewed by NHTSA defect investigators say automakers almost never publicly acknowledge EMI problems. Why would automakers spend millions of dollars on sophisticated EMC (Electro-Magnetic compatibility) test facilities, and place EMC test requirements on all their electronics suppliers, if it wasn't necessary?
GM: Walter Gelon, then an employee at General Motors-owned Hughes Aircraft, warned in early 1987 that he thought EMI was behind reported sudden unintended acceleration in GM vehicles, according to an internal memo. "It seems very clear to me that (GM) vehicles have serious EMI problems which are triggering ... unwanted acceleration," Gelon wrote to Hughes colleagues.
Ford: In the 1980s, as use of electronics in cars expanded fast, EMI was on the minds of Ford engineers as well. The minutes of an October 1986 Ford Technical Affairs Committee meeting, show Ford looked into whether "electromagnetic influences" were behind an increase in unexplainable electronic component failures.
Toyota: Engineers say floor mat interference and sticky gas pedals are the cause of sudden unintended acceleration in more than 8.5 million vehicles Toyota has recalled. It commissioned an outside company, Exponent, in December to look at the electronic throttle controls, which have replaced mechanical gas pedal and throttle systems in most vehicles of all makes since the 1990s. According to a draft report, Exponent says it could not induce sudden unintended acceleration through "electrical disturbances." But EMI experts argue that tests weren't comprehensive enough to find whether EMI could be to blame; and two experts consulted by the House Energy & Commerce Committee of the US Congress were similarly critical. To help protect against surges in acceleration, Toyota is also installing a brake override system on new cars and updating some models dating back to 2007. Several automakers, including Chrysler and Nissan, already offer a form of smart-brake technology that enables drivers to cancel sudden acceleration by pressing on the brake.
Carwash and SUA
Some evidence suggests that carwashes may be a susceptible environment for Sudden Unintended Acceleration (SUA) incidents because of moisture and electronic signals from equipment. Independent safety experts note that a disproportionate number of sudden unintended acceleration events occur in or around car washes. The data suggests the car wash causes electromagnetic interference with the vehicle electronics, which either initiates or replicates errant signals to the electronic throttle controls. This interference is likely caused by moisture penetrating the electronics and acting as a conductor for electromagnetic interference from the car wash machinery. Carwash operators for years have complained about SUA incidents involving several auto brands and models.
Although the root cause for Sudden Unintended Acceleration (SUA) remains unknown, including incidents involving recalled Toyotas, some engineers believe electromagnetic interference from cell phones, satellite radio and even microwaves may be contributing to the problem. Electromagnetic interference may disrupt the electronic signals to the throttle system, which controls the acceleration. The basic problem is that electronic malfunctions do not necessarily leave a trail of evidence. It is a classic case of dead men tell no tales. There is no imprint due to electronic failure. As an example of electronic interference, a voltage spike can generate electromagnetic flux and interfere with the signal sent to the accelerator pedal. In one incident, a cell phone signal has caused a German-made bus to shift into gear. Several sudden unintended acceleration (SUA) lawsuits filed against Toyota claim some type of EMI link. However, if the US Congressional hearings probe deeply enough, they may discover that the global car industry has known for a long time that one of the plausible causes of SUA is internal electro-magnetic interference (EMI).
Members of the US Congress blasted Toyota this week for what they said was its resistance to the idea that electromagnetic interference can cause car systems to go haywire. Bart Stupak, a Democrat from Michigan, said Toyota “misled the American public by saying that they and other independent sources had thoroughly analysed the electronics systems and eliminated electronics as a possible cause of sudden unintended acceleration when, in fact, the only such review was a flawed study conducted by a company retained by Toyota's lawyers.”
This week's hearings in Washington, DC, have shown that many Congressmen are deeply sceptical about traditional mechanical explanations for sudden unintended acceleration (SUA) in vehicles. Given the detailed evidence presented by the victims, the sombre mood of the public and wall-to-wall coverage of this critical issue, there is likely to be extra pressure on automakers to renew their efforts in identifying the real cause of the SUA. Especially if the proposed fixes do not solve the identified problems in recalled cars. In essence, this means that US lawmakers will seek to ensure that going forwards, electromagnetic interference and computer glitches cannot and should not be ignored by the global car industry.
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