[Technology Report]
Four-Wheeled Supercomputers
Automotive safety equipment turns vehicles into the largest collection of mobile computing and sensing equipment you'll own.
SAFE SOFTWARE, LEGALLY LIABLE All of these sensors and redundant processing bring up the issue of software. The analysis and complexity challenges are large, but they will be trivial compared to the standardization and legal hurdles associated with active safety.
A few standards are popular but not universally adopted, such as AUTOSAR (AUTomotive Open System ARchitecture). Likewise, protocols for networks like CAN are standardized, at least at a low level, though vendor exceptions abound.
Wireless sensors like Freescale’s MPX8300 are embedded in a tire with the receiver in the body of a car (see “Tires Put Pressure On RF” at www.electronicdesign.com, ED Online 16497). Unfortunately, dissimilar radios and protocols can make it difficult to go to the nearby auto parts store for a replacement. The plethora of wiper blades and headlights is just a fraction of what will occur with the inevitable increase in sensors and associated processing systems.
In the longer term, cooperation between the vehicle and other cars or fixed wireless information sources will provide details that can be incorporated into the safety system. This is already done, albeit on a limited basis, with some GPS navigation systems that receive traffic information via radio.
One alternative that’s been tossed around would have cars talking to cars and sharing their environmental sensor data with each other. This would reduce the reporting requirements and related delays of the radio-based GPS navigation systems in place while significantly increasing the accuracy and timeliness of the data.
Unfortunately, this approach opens a can of legal and standardization worms. How do you prevent invalid information from being inserted from a third party? What happens if an accident arises due to the exchange of bad or insufficient data? What cars will talk to each other? The list goes on.
Other interesting ideas hovering on the radar include heads-up displays (HUDs) and verbal interaction. The cost and effectiveness of these technologies aren’t right for mass markets yet, but the same once was true for vision systems, automatic stability control, and a host of other features, including airbags. A HUD allows overlays from the vision systems, enabling direct driver feedback—and that’s only one possible use. Overlaying building and terrain information is another.
Voice-activated command systems are already common for multimedia device and climate control. Advances in voice recognition and the ability to bring more computing power to bear will allow this interface methodology to improve. In turn, it will reduce the need for drivers to interact with the car via manual controls, thereby improving overall automotive safety.
ELECTRIC SAFETY Hybrid and electric vehicles are becoming more prevalent, but they add their own safety issues to the equation. The primary concerns deal with high voltage and the batteries required by the system.
Most systems employ a multicell battery pack. For example, Tesla Motors’ Roadster has a battery pack that incorporates more than 6000 lithium-ion (Li-ion) cells in the 18650 form factor, weighing almost 900 pounds (Fig. 7).
The system uses multiple microprocessors and sensors to monitor each cell as well as the battery cooling system’s temperature. Additional sensors track the environment and initiate a shutdown when an accident occurs or when maintenance is required.
Popular hybrids such as the Honda Civic and the Toyota Prius have less ambitious power systems, but their battery sensor and control systems are no less important (Fig. 8). Improvements in sensor technology and price reductions in microcontrollers will allow even safer systems to be constructed, including the cabling and connection points.
It should be interesting to see what kinds of safety systems next year’s car models have in store.
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