大学英语综合教程 第四册 Unit 2B

[04:49.23]used by the vehicle's control computer to determine its exact position of the vehicle.
[04:56.57]Other researchers have used computer vision systems to observe the road.These are vulnerable to weather problems
[05:05.37]and provide less accurate measurements,but they do not require special roadway installations.
[05:12.66]other than well-maintained lane markings.
[05:16.84]Observing preceding vehicles
[05:20.39]The distances and closing rates to preceding vehicles can be measured by a radar or a laser rangefinder.
[05:29.14]Both technologies have already been implemented in commercially available systems in Japan and Europe
[05:36.82]The laser systems are currently less expensive,
[05:40.27]but the radar systems are more effective at detecting dirty vehicles and operating in adverse weather conditions
[05:49.41]As productins volumes increase and unit costs decrease, the radars are likely to find increasing favor.
[05:57.77]Steering,accelerating and brading
[06:02.03]The equivalents of these driver muscle functions are electromechanical devices installed in the automated vihicle
[06:10.42]They receive electronic commands from the onboard control computer
[06:14.91]and then apply the appropriate steering angle,throttle angle,and brakd
[06:21.10]pressure by means of small electricmotorsEarly versions of these devices are alresdy being introduced int production vehicles
[06:32.62]where they receive their commans directly from the driver's inputs to the steering whessl and pedals.
[06:39.54]These decisions ate being made for reasons largely unrelated to automation.
[06:44.66]Rather they are associated with reduced energy consumption,
[06:49.99]simplification of vehicle design,enhanced ease of vehicle assembly,
[06:55.32]improved ability to nadjust performance to match driver perferences,
[07:00.96]and cost savings compatred to traditional direct mechanical comtrol devies.
[07:07.68]Deciding when and where to change course
[07:11.83]Computers in the vehicles and those at the roadside have different functions.
[07:17.13]Roadside computer are computers are better suited for traffic management,
[07:22.02]setting the target speed for each segment and lane of roadway,
[07:26.09]and allocating vehicles to different lanes of a multilane automated facility.
[07:32.18]The aim is to maintain balanced flow among the lanes and to avvoed obstacles or incidents tha might block alane.
[07:40.70]The vihicle's onboard computers are better suited to handling decisions about exactly
[07:47.72]when and where to change lanes to avoed inerference with other vehicles.
[07:54.23]Remaining challenges
[07:57.15]There remain a number of difficulties t be over come.These are mainly technical,
[08:03.32]but there are in addition a number of nontechnical challenges that need to be addressed.
[08:09.87]These involve issues of liability,costs,and perceptions.
[08:15.28]Automated control of vehicles shifts liability for most crashes from the individual driver(and his or her insurance company
[08:25.03]to the designer,developer,and vendor of the vehicle and roadway control systems.Provided the system is indeed safer
[08:34.25]than today's driver-vehicle-highway system,overall exposure should be reduced .But its costs will be shifted
[08:44.51]from automovile insurance premiums to the purchase or lease price of the automated vehicle
[08:51.59]and toll for use of the automated highway facility.
[08:56.27]All new techologies tend to be costly when they first become available in small quntities,
[09:02.98]then their costs decline as production volumes increase and the technologies mature.
[09:09.12]We should expect vehicle automation technologies to follow the same pattern.
[09:14.92]They may initially be economically viable only for heavy vehicles(transit buses,commercial trucks)and highend passenger cars
[09:24.64](2)However,it should not take long for the costs to become affordable to a wide range of vehicle owners and operators,
[09:33.34]especially with many of the enabling technologies already being commercialized for volume production today.
[09:41.59](3)The largest impediment to introduction of electronic chauffeuring may turn out be the general perception that
[09:49.77]it's more difficult and expensive to implement than it really is.
[09:54.55]If political and imdustrial decision maders perceive automated driving to be too futuristec,
[10:01.91]they will not pay it the attention it deserves and will not invest their resources toward acceleerating its deployment.
[10:10.48]The perception could thus become a self-fulfilling prophecy.
[10:15.24]It is important to recognize that automated vehicles are already carrying millions of passengers every day.
[10:23.07]Most major airports have automated people movers that transfer passengers among terminal buildings.
[10:30.49]Urban transit lines in Paris,London,Vancouver,
[10:35.98]Lyon,and Lille,among others,are operating with completely automated,driverless vehicles;
[10:43.16]some have been doing so for more than a decade.
[10:46.97]Modern commercial aircraft operate on autopilot for much of the time,
[10:52.85]and they also land under automatic comtrol at suitably equipped airports on regular basis.
[11:00.40](4)Given all of this experience in implemaenting safe automated transportation systemsm,it is not such a large leap
[11:09.10]to develop road vehicles that can operate under automatic control.That should be a realistic goal for the next decade.
[11:18.14]The transportation system will thus gain substantial benefits from the revolution in information techonlogy.