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[English][收藏]LAN-Cruising |
本文转载自W3CHINA.ORG讨论区(BBS.W3CHINA.ORG) 原文链接以下为原文:LAN-Cruising
The wheel hasn’t changed much over time apart from the addition of a tyre, and it’s this that most seriously affects its efficiency: a 10 per cent drop in optimum tyre pressure can easily add 10 per cent to the fuel consumption of the engine driving them.
So critical is tyre performance to road transport costs that engineers at Volvo Truck have developed an RF transmitter for each tyre on its massive trucks to send constant information to an in-dash display to warn drivers when any of up to 50 tyres are at anything other than perfect pressure.
A quarter of truck breakdowns are caused by tyre failure, starting as slow leaks and sometimes ending in explosion but certainly adding to rolling resistance and reduced life of expensive rubber.
The matchbox-sized transmitters are fixed next to the valve and connected by a tiny tube to send a burst of eight readings every 15 minutes to a receiver and processor bolted to the chassis.
The processor sifts reports from each wheel to find the most accurate average, signalling an errant tyre on a schematic of the wheel configuration on an LCD screen in the dash.
The system’s CPU is one of 25 in the vehicle, together providing far more computing firepower than for the Apollo 13 landings.
They control pretty well every function in the vehicle other than driving it: engine performance, brake pressure, gear changes and transmission management, air conditioning, and GPS-enabled locators.
While on-board computers have been increasingly gaining new tasks in trucks for nearly a decade, wireless networking has steadily replaced complex wiring looms to get information to the driver’s cab and beyond.
Already 30 per cent of the cost of a new car is in the electronics: the chips, wires and networks that support features ranging from automatic door locks to anti-lock brakes to airbag deployment.
As automotive electronics become more complex, car manufacturers are borrowing a page from the network industry, relying on shared networks and standard protocols to support internal communications between control systems. They’re also turning to industry standards such as Bluetooth and Wi-Fi to support links to external systems that provide traffic, weather, entertainment and other information.
Today’s cars have half a dozen different proprietary networks that carry messages from control systems to the devices being operated. Until recently, each car manufacturer and car model had its own network parts. These are hardened, automotive-specific networks with ultra-reliable electronic components that can withstand vibration and operate in extreme heat and cold.
The latest trend is toward standardisation so car manufacturers can save money on components and software development.
Companies are converging on several standards for internal networks that address different speed requirements. At the same time carmakers are looking to extend the use of those networks to replace the spaghetti of wire used to support functions such as turning on the engine and operating lights.
More carmakers are going wireless to support a host of new navigation and safety services.
Bluetooth is the technology of choice to support mobile phones. The car industry is developing a special profile of the Bluetooth standard - dubbed Bluetooth Handsfree 2.0 - that will link a built-in microphone in the car to any mobile phone without requiring a docking station, allowing for hands-free calling.
Longer term, car manufacturers plan to use Bluetooth to support services such as remote vehicle diagnostics, advanced safety features and vehicle-to-vehicle communications.
But Bluetooth is only one of the technologies that are emerging to connect the computer-based car to the outside world. The rising demand for in-vehicle entertainment services has carmakers looking at everything from satellite links to Dedicated Short Range Communications (DSRC) and Wi-Fi.
On the horizon are real-time news, information and entertainment services that are integrated with in-vehicle entertainment systems. The most promising way to deliver these services is digital satellite radio. With improvements in compression techniques and smaller antennas, digital satellite also could deliver streaming video.
Another technology that could bring high-speed, two-way communications to automobiles is DSRC. DSRC was designed specifically for the transportation industry to complement cellular communications, supporting 6 to 54Mbit/sec wireless data transfer rates. Mercedes-Benz has started shipping cars with DSRC support in Germany.
Further out on the horizon is in-vehicle support for Wi-Fi technology. By around 2006, some car manufacturers will be looking to install self-contained Wi-Fi to allow users to load music and files into the car. Users could download files and other content to the car such as traffic reports or news.
But use of Wi-Fi for Internet access while cars are in motion is still just a pipe dream today. You’d need to have Wi-Fi hot spots along the highway. That won’t happen anytime soon. <完>参与讨论本主题
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