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1、 UNIT 14 ELECTRIC AND AUTONOMOUS VEHICLESTEXT B Autonomous Ground VehiclesConcepts and a Path to the FuturePROFESSIONAL ENGLISHTEXT B Autonomous Ground VehiclesConcepts and a Path to the Future本次课学习内容本次课学习目标l掌握Autonomous Ground Vehicles的英文专业词汇l训练快速阅读能力,提高阅读速度NEW WORDSautonomoustnmsadj.自治的;有自治权的;自主的;
2、有自主权的augment ment v.增加;提高;扩大 n.增加;补充物trigger tr(r)n.起因,诱因;触发器;引爆器 v.发动;引起;触发;开动;起动scenario snri n.设想;方案;预测;(电影或戏剧的)剧情梗概antenna ntenn.天线;触角;触须high-definition ha defnnadj.高清晰度的;高分辨率的longitudinalltjudnl adj.纵的;纵向的;纵观的;经度的lane departure warnings(LDW)车道偏离预警(车道偏离预警(LDW)lane keeping assist systems(LKAS)车道保
3、持辅助系统(车道保持辅助系统(LKAS),),LKA包括车道包括车道偏离预警偏离预警LDW、车道偏离预防、车道偏离预防LDP(Lane Departure Prevention)和车道居中控制)和车道居中控制LCC(lane centering control)adaptive cruise control systems(ACC)自适应巡航控制系统(自适应巡航控制系统(ACC)point cloud点云点云;三维点云三维点云;点云数据点云数据;点群点群;云点云点odometry 测距(程)法测距(程)法real-time(计算机处理过程计算机处理过程)实时的实时的image-based se
4、nsors基于图像的传感器基于图像的传感器PHRASES AND EXPRESSIONStimestamp时间戳时间戳,通常是一个字符序列,唯一地标识某一刻的时间。通常是一个字符序列,唯一地标识某一刻的时间。数字时间戳是数字签名技术一种变种的应用,戳是指数字时间戳是数字签名技术一种变种的应用,戳是指格林威治时间格林威治时间1970年年01月月01日日00时时00分分00秒秒(北京时北京时间间1970年年01月月01日日08时时00分分00秒秒)起至现在的总秒数。起至现在的总秒数。PHRASES AND EXPRESSIONS Autonomous driving started in the
5、1980s.Today,some aspects of these early achievements have reached series production in the form of driver assistance systems for cars.Lane detection is used to facilitate lane departure warnings(LDWs)for the driver and to augment the drivers heading control in lane keeping assist systems(LKAS).The d
6、etection and tracking of vehicles driving ahead is used in adaptive cruise control systems(ACC)to keep a safe and comfortable distance.More recently,pre-crash systems emerged that trigger full braking power to lessen damage if a driver reacts too slowly.Autonomous Ground VehiclesConcepts and a Path
7、to the Future Meanwhile,the attention of research in autonomous vehicles has switched its focus from the well-structured environments encountered on highways as studied in the beginning to more unstructured environments,like urban traffic or off-road scenarios.Three elements are common to all autono
8、mous ground vehicles:sensors to perceive the environment and the own movement,on-board computers,and actuators for vehicle control.Fig.14.7 shows the LIDARs,cameras and Global Positioning System(GPS)antennas used on three vehicles of the DARPA Urban Challenge teams.Autonomous Ground VehiclesConcepts
9、 and a Path to the FutureAutonomous Ground VehiclesConcepts and a Path to the FutureFig.14-7 three vehicles of the DARPA Urban Challenge teamsFor environment perception,both image-based sensors like monocular and stereo cameras(monochrome and color),and range sensing devices like RADAR and LIDAR are
10、 used.The high-definition Velodyne LIDAR with a 360,3-D view and rich point cloud was designed especially for autonomous vehicles and is used in many systems.RADAR sensors are additionally able to determine the objects relative velocity directly.To estimate the vehicles motion,measurements from odom
11、etry and inertial sensors are incorporated,supported mainly by global position measurements from GPS.Autonomous Ground VehiclesConcepts and a Path to the FutureAll distributed or centralized processing on board the vehicle has to be real-time capable.This is an important prerequisite for vehicle con
12、trol algorithms and system safety checks.Actuators are necessary for closing the control loop,e.g.,for steering wheel,brake,or throttle control.The ability to perceive the vehicles local environment is one of the main challenges in the field of autonomous ground vehicles.Environmental conditions lik
13、e lighting or colors are permanently changing,and there are a lot of static as well as dynamic objects in the scene to be taken into account.Autonomous Ground VehiclesConcepts and a Path to the FutureAs a prerequisite for the perception and control modules,a good estimation of the vehicles motion is
14、 necessary.Especially when the vehicle is moving fast or on nonflat terrain,relevant rotation along the longitudinal and lateral axes occurs.Working with measurements which are not taken at one unique timestamp,it becomes important to compensate for the vehicles ego-motion in all measurements.A reli
15、able position estimation is also essential for trajectory control.For a good estimation of the motion,all measurements regarding the own vehicle are incorporated.Typical measurements are velocity and steering angle from odometry and accelerations,angular rates,and attitude from inertial sensors.The
16、Velodyne LIDAR is ideally suited for detecting and tracking objects participating in urban traffic.Autonomous Ground VehiclesConcepts and a Path to the FutureAn imprecise localization of an autonomous vehicle might result in catastrophic behavior.The vehicle could drive on the wrong side of the road,it could believe a goal position to be inside a large obstacle,or it might even expect pedestrians crossing the road to be on the sidewalk.It is well known that GPS signals get weak or corrupted in d