Automatic Steering Based on Roadway Markers: From Highway Driving to Precision Docking

Bus Rapid Transit (BRT) is an effective alternative for providing rail-like corridor transit service. An advanced BRT concept involves the use of automated buses to provide functions of a rail transit system. A vehicle under automatic steering control following a prescribed trajectory is operated like a train on a rail. A lateral position sensing that uses roadway markers, such as magnetic markers embedded under the roadway, as lateral reference is one of the promising approaches for a reliable sensing system. The BRT concept requires the steering control system to consistently perform all necessary steering functions from high speed driving to low speed precision docking. This paper describes a single steering controller that achieves all performance objectives. Various data collected during several public demonstrations are presented in this paper to illustrate the effectiveness of the approach. These data include the following automatic steering control scenarios: over 100 mph high-speed driving, high-g maneuvers, sharp curve following, and low speed precision docking.     

Analysis of Automatic Steering Control for Highway Vehicles with Look-down Lateral Reference Systems

In this paper, steering control for passenger cars on automated highways is analyzed, concentrating on look-down reference systems. Extension of earlier experimental results for low speed to highway speed is shown to be non-trivial. The limitations of pure output-feedback of lateral vehicle displacement from the road reference are examined under practical constraints and performance requirements like robustness, maximum lateral error and comfort. The in-depth system analysis directly leads to a new alternative design direction which allows to preserve look-ahead reference systems for highway speed automatic driving.     

常州市快速公交的实践与探索

快速公交具有速度快、容量大、建设周期短、造价低等优点,国内许多城市已经建成,或正在考虑建设快速公交。回顾了常州市快速公交系统的发展历程,探讨了快速公交在城市公共交通体系中的功能与定位,指出快速公交与轨道交通是相互补充的,快速公交可以作为轨道交通的延伸、补充和过渡。分析了快速公交系统的运营效果,快速公交在支持城市发展、优化居民出行方式结构、改善居民出行环境等方面有着重要的积极作用。最后,总结了快速公交系统规划设计和运营过程中的经验与教训,并指出一个成功的快速公交系统需要系统化的思路,从规划设计、选线到运营组织与运行保障体系。     

Analysis of Automatic Steering Control for Highway Vehicles with Look-down Lateral Reference Systems

SUMMARY

In this paper, steering control for passenger cars on automated highways is analyzed, concentrating on look-down reference systems. Extension of earlier experimental results for low speed to highway speed is shown to be non-trivial. The limitations of pure output-feedback of lateral vehicle displacement from the road reference are examined under practical constraints and performance requirements like robustness, maximum lateral error and comfort. The in-depth system analysis directly leads to a new alternative design direction which allows to preserve look-ahead reference systems for highway speed automatic driving.     

汽车电子转向技术发展与展望

汽车电子转向系统是一种全新概念的转向系统，其取消了转向盘和转向车之间的机械连接，通过软件协调它们之间的运动关系，可以实现一系列传统转向系统无法实现的特殊功能。它可以实现传动比的任意设置，并对随车速变化的参数进行补偿。并且可以和ABS、汽车动力学控制、防碰撞、单个车轮转向、轨道跟踪、自动侧向导航等功能相结合，实现对汽车的整体控制。综述了国外汽车电子转向技术的研究现状，介绍了电子转向系统的结构及性能特点，阐述了电子转向系统的关键技术、主要问题及解决方法，并展望了电子转向系统的发展趋势。     

分心对驾驶人交通冲突反应时间的影响(双语出版)

为了研究分心对交通冲突状态下驾驶人反应时间的影响,采用驾驶模拟器构建城市道路交通环境下2种典型冲突形态：侧向行人冲突和纵向追尾冲突,设计认知、视觉以及发短信（认知+视觉复合分心）3种分心任务,在不同行驶车速、跟车时距、前车减速度等紧迫度条件下,采集30名驾驶人应对交通冲突的制动反应时间,分别采用重复测量一般线性模型及线性混合模型进行统计分析。研究结果表明：认知分心使驾驶人应对侧向行人冲突的制动反应时间增加0.09 s,但未观察到其对纵向追尾冲突反应时间的显著性影响;视觉分心与发短信都会延缓驾驶人应对侧向行人（分别增加0.31 s和0.27 s）以及纵向追尾冲突（分别增加0.47 s和0.38 s）的制动反应时间;此外,在纵向追尾冲突中,随着冲突紧迫度提高（前车减速度增大、车头时距减小以及自车速度增大）,驾驶人制动反应时间显著减小。表明驾驶分心延长了驾驶人应对交通冲突的反应时间,容易导致事故的发生,具体而言,认知分心主要延长驾驶人应对侧向冲突的反应时间,涉及视觉的分心同时延长驾驶人应对侧向及纵向冲突的反应时间;视觉分心对驾驶人反应时间的延长显著性高于认知分心,说明视觉分心对行车安全影响更大。     

Snowplow Steering Guidance with Gain Stabilization

Acquisition and utilization of lateral guidance information is crucial for steering a vehicle. With practice, drivers can successfully perform the steering function using visual perception and hand-eye coordination. However, this seemingly simple task becomes difficult when the visual information loses its clarity. Driving a snowplow during whiteout conditions is one such example. In order to improve the safety and efficiency of snow removal operations, a supplemental guidance display was proposed and successfully implemented in a California Department of Transportation (Caltrans) snowplow. The guidance information was calculated based on the magnetic markers embedded in the roadway. The crucial step to this success is a transformation of the guidance display problem into a robust driver-in-the-loop control problem. This transformation considers the ‘display’ law as part of the overall driver-steering-control algorithm. Two key ‘assumptions’ for this design are (1) the ‘display’ law should be designed in such a way that drivers can use ‘proportional’ control gain alone to satisfy the performance and stability requirements of the steering tasks, and (2) the driver steering model can be described as a combination of gain and dynamic delay under the display law in (1). This paper describes the validation process for the ‘gain’ stabilization design concept as well as the associated driver steering model using the initial snowplow test data.     

解决N车型外后视镜调节失效问题

车辆后视系统由车外反射镜和广角透镜组成,在车辆安全系统中起着重要的作用。现有的汽车后视镜系统还存在许多问题亟待解决,如汽车转向过程中的盲区等。本文提出了一种新型的智能车辆后视系统的设计方案,该系统能够在不同的行驶条件下自动调节车辆外部镜头的角度。影响因素包括车辆转向角、行驶速度和车辆尺寸参数。本设计以AT90C516RD+单片机为核心控制单元。该系统增加了一个新的自动模式与现有的手动功能保留。通过理论仿真和模型试验,证明该设计完全可行,并已被具有工业潜力的客户调查所接受。     

Snowplow Steering Guidance with Gain Stabilization

Acquisition and utilization of lateral guidance information is crucial for steering a vehicle. With practice, drivers can successfully perform the steering function using visual perception and hand-eye coordination. However, this seemingly simple task becomes difficult when the visual information loses its clarity. Driving a snowplow during whiteout conditions is one such example. In order to improve the safety and efficiency of snow removal operations, a supplemental guidance display was proposed and successfully implemented in a California Department of Transportation (Caltrans) snowplow. The guidance information was calculated based on the magnetic markers embedded in the roadway. The crucial step to this success is a transformation of the guidance display problem into a robust driver-in-the-loop control problem. This transformation considers the 'display' law as part of the overall driver-steering-control algorithm. Two key 'assumptions' for this design are (1) the 'display' law should be designed in such a way that drivers can use 'proportional' control gain alone to satisfy the performance and stability requirements of the steering tasks, and (2) the driver steering model can be described as a combination of gain and dynamic delay under the display law in (1). This paper describes the validation process for the 'gain' stabilization design concept as well as the associated driver steering model using the initial snowplow test data.     

Simulation of curving at low speed under high traction for passive steering hauling locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.     

分布式驱动电动汽车转向工况转矩分配控制研究

针对分布式驱动车辆转向工况在低速下期望提高转向机动性能,高速下期望保证行驶稳定性的需求,充分考虑转向行驶内外侧车轮的转向关系以及车辆动力学,制定了适应车速变化的四轮转矩分配策略,建立了四轮轮毂电机驱动模型以及二自由度参考模型。为了改善分布式驱动转向机动性能,建立自抗扰控制器调整内外侧车轮转矩,形成合理的转速差,减小转向半径,以提高转向机动性;对于高速转向行驶稳定性的需求,通过二次规划方法优化分配各车轮驱动力矩,分析轮胎纵横向附着裕度建立目标函数,并加入附加横摆力矩和路面附着力的限制,进行车轮驱动转矩的在线优化分配,提高车辆转向行驶的稳定性;另外为避免2种控制模式转换时驱动转矩突变,根据车速和稳定性参数制定模糊规则决策2种模式的协调系数,保证2种控制模式的平滑过渡。基于CarSim和MATLAB/Simulink进行联合仿真,并搭建硬件在环平台进行试验,对所提出的方法进行验证。结果表明：在低速转向工况下,提出的分配策略能够调节内外侧车轮产生差速效果,与转矩平均分配的策略相比,转向半径有所减小,提高车辆机动性;高速转向工况下,分配策略能够保证车辆稳定转向,与未考虑稳定性控制的分配策略相比,能更好地跟踪目标轨迹,且横摆角速度控制在参考横摆角速度附近,证明了所提控制策略的有效性。     

车道线保持自校正滑模控制

为实现复杂工况下的车道线保持控制,建立了包含转向机构动态的车辆横向动力学模型,在此基础上研究了车辆在直道与弯道工况下的车道保持控制问题并提出一种自校正滑模控制方法.该方法引入sigmoid函数代替滑模控制中的符号函数并根据Lyapunov稳定性理论设计了自校正律,在自校正律的作用下sigmoid函数的边界层厚度以及切换...     

A Snowplow Steering Guidance System Using Roadway Markers - Problem Formulation and Solution Concept

Acquisition and utilization of lateral guidance information is crucial for steering a vehicle. With practice, human drivers have performed this function quite successfully using visual perception and hand -eye coordination. However, this seemingly simple task becomes difficult when the visual information loses its clarity. Driving a snowplow during whiteout conditions is one such example. In order to improve the safety and efficiency of the snow removal operation, a supplemental guidance display was proposed and instrumented in a Caltrans (California Department of Transportation) snowplow. The guidance information was calculated based on the magnetic markers embedded in the roadway. Operations for the steering guidance system were successfully conducted on a 6.25 km freeway over Donner Summit on Interstate 80 in California during the 1998–1999 winter season. The key to this success was a transformation of the guidance display problem into a control problem. This paper describes the problem formulation and the solution concept for this steering guidance system.     

Forced Steering of Rail Vehicles: Stability and Curving Mechanics

A forced steering rail vehicle employs linkages between.the carbody and wheelsets to force a more radial wheelset alignment. It is shown that the curve negotiation capability of forced steering trucks is significantly improved over conventional and self steering radial trucks. Parametric curves are presented showing angle-of-attack and lateral flange force as a function of steering gain parameters and truck bending stiffness. It is also shown that the forced steering concept can produce kinematic instability and severely reduced critical speeds for low conicities and creep coefficients. Analytic expressions are derived that illustrate how these kinematic instabilities can be avoided.     

A Snowplow Steering Guidance System Using Roadway Markers - Problem Formulation and Solution Concept

Acquisition and utilization of lateral guidance information is crucial for steering a vehicle. With practice, human drivers have performed this function quite successfully using visual perception and hand -eye coordination. However, this seemingly simple task becomes difficult when the visual information loses its clarity. Driving a snowplow during whiteout conditions is one such example. In order to improve the safety and efficiency of the snow removal operation, a supplemental guidance display was proposed and instrumented in a Caltrans (California Department of Transportation) snowplow. The guidance information was calculated based on the magnetic markers embedded in the roadway. Operations for the steering guidance system were successfully conducted on a 6.25 km freeway over Donner Summit on Interstate 80 in California during the 1998-1999 winter season. The key to this success was a transformation of the guidance display problem into a control problem. This paper describes the problem formulation and the solution concept for this steering guidance system.     

Forced Steering of Rail Vehicles: Stability and Curving Mechanics

SUMMARY

A forced steering rail vehicle employs linkages between.the carbody and wheelsets to force a more radial wheelset alignment. It is shown that the curve negotiation capability of forced steering trucks is significantly improved over conventional and self steering radial trucks. Parametric curves are presented showing angle-of-attack and lateral flange force as a function of steering gain parameters and truck bending stiffness. It is also shown that the forced steering concept can produce kinematic instability and severely reduced critical speeds for low conicities and creep coefficients. Analytic expressions are derived that illustrate how these kinematic instabilities can be avoided.     

认知分心对车辆跟驰过程操控安全性的影响

为了研究车辆跟驰过程中驾驶人认知分心与驾驶安全的关系,采用驾驶模拟器构建城市道路车辆跟驰场景,并设计3种难度等级的认知分心次任务,采集35名被试驾驶人在试验过程中的方向盘转角、油门开度、制动踏板力等操作参数,以及车辆位置、速度、加速度等车辆运动参数。采用重复测量一般线性模型,分析不同等级认知分心对上述参数的影响。研究结果表明：在横向操控方面,随着认知分心程度增高,方向盘回转率增大,但车辆横向位置标准差减小,表明驾驶人处于认知分心时,采取频繁修正方向盘的补偿方式,降低车辆横向位置波动,过度补偿车辆横向安全性,且该补偿行为与认知分心程度正相关;在纵向操控方面,认知分心时,油门开度、制动踏板位置方差增大,且制动踏板位置均值增大,同时车头间距及时距未观察到显著性变化,表明认知分心时驾驶人采取频繁操作油门、制动踏板,增大制动幅度等方式进行补偿,使车头间距及车头时距等表征车辆纵向跟车安全性参数处于正常驾驶水平,但加速度标准差增大,表明跟车稳定性降低。研究结果为涉及分心的人车交互装置优化设计及考虑分心状态的驾驶人状态管理系统开发提供了一定的理论依据。     

轨道交通站点综合开发模式探讨

为推动旧城改造与新城发展,解决目前地铁高投入低回报的公益性给建设方带来的巨大资金压力问题。通过总结已运营的地铁线对城市发展的影响,探讨以轨道交通建设为契机、在TOD理念指导下的综合开发模式,并提出轨道交通站点与周边地块综合开发理念、综合开发类型,以其良好的收益来减少地铁建设的资金压力。     

矿用货车自动驾驶条件下侧翻安全分析与极限参数研究

为防止自动驾驶条件下矿用货车发生侧翻,对依靠规划控制层实现侧翻事故的主动预防方法进行研究.针对该问题先建立矿用货车侧倾数学模型,推导静态稳定因子(Static Stability Factor,SSF)与车辆侧倾稳定极限(Roll Stability Limit,RSL)公式.利用TruckSim仿真软件完成水平路面1...     

光纤感测技术在轨道交通运营线路中的应用

为解决城市轨道交通工程在施工和后期运营过程中隧道差异沉降、结构变形、基坑渗水与失稳及周边建筑物变形等安全问题。依托宁波市轨道交通运1 号运营线,采用分布式光纤传感技术实现长距离隧道的管片变形和差异沉降监测,利用布拉格光纤光栅技术实现了隧道断面和结构变形自动化监测,结果显示监测段隧道变形较小,较为稳定。项目的成功实施,证明了光纤传感技术在轨道交通工程结构监测中的有效性,具有广泛的应用和推广价值。