GPS中频信号仿真及软件接收机设计

提出一种中频信号的软件仿真方法,通过对GPS L1C/A码信号的研究,分析GPS中频信号的数学模型。设计实现GPS中频信号仿真器,并以多普勒频率仿真、多径干扰仿真和噪声仿真为例对GPS中频信号进行仿真实验,为GPS软件接收机的设计与验证提供高效平台。在介绍GPS软件接收机原理的基础上,研究信号捕获、信号跟踪及导航电文解算的实现过程。将设计的GPS接收机的定位解算结果与NovAtel接收机实际测量结果进行比较。结果表明:软件接收机各功能模块算法正确,可以满足使用要求,具有良好的灵活性和可扩展性。     

Validation of railway vehicle dynamic models in training simulators

Training simulators play an important role for sustaining safety, efficiency and cost effective railway transportation. Dynamic modelling of train systems is one of the main modules of training simulators. Validation of the dynamic models with collected real data ensures the fidelity of the simulator utilising the respective models. In this study, a validation process (Dynamic Modelling Validation Process (DyMVaP)) which is developed to support the validation of railway dynamic models is introduced. However, the proposed process can also be used in validating other dynamic models as well. The developed process is based on five steps including the preparation of validation scenarios, sensor deployment, real data collection, data preparation, and comparison of simulated and measured data. Note that the proposed DyMVaP was used for the validation of a full-mission training simulator so called TRENSIM, which was developed for Turkish State Railways. During the study it is realised that the current speed, travelled distance, acceleration (in x, y, z directions), rotation angles (around x, y, z axes), air pressure, in-train pressure/tension forces, traction motor currents, catenary voltage, positions of controllers must be collected synchronously by using proper sensors in order to ensure simulation validation. The required data was collected from locomotive body, bogies, wheel sets and connection of railway cars. The data (～200?GB) collected from the field by applying 27 different scenarios and transformed into appropriate data for utilising the generated dynamic models within the simulator. The measured and simulated data were also compared visually using graphical representation of the parameters as well as performing computations regarding the magnitude, phase and comprehensive error factors.     

Motion cueing in high-performance vehicle simulators

The majority of motion cueing algorithms have been developed for passenger car applications, with correspondingly less research dedicated to race-car and high-performance vehicle simulators. In the high-performance context, the focus is on cueing the vehicle's behavioural and handling characteristics, particularly when driving near the limits of performance. In race-car simulators the cueing requirements are therefore quite different, with the problem made all the more challenging by the presence of large accelerations. To understand the drivers' cueing needs, the vehicle's stability and handling response characteristics must be examined near the performance boundary. Frozen-time eigenvalue analyses are used to determine stability and response characteristics across all vehicle operating conditions, including accelerating and braking under cornering, with the results used to determine motion cueing algorithm requirements. Lateral acceleration and yaw cueing filters are designed in order to retain information critical to understanding the vehicle's behaviour on its performance boundary. Cueing filters are then tested, with the help of a professional race-car driver, and are found to provide the cues necessary for the driver to control the vehicle on the limit of performance.     

船舶动力定位模拟器自动定位功能研究与实现

为了自主研发功能完备、扩展性好的船舶动力定位模拟器,分析船舶动力定位模拟器中各个模块的功能,对现有航海模拟器的系统架构进行改进,提出适用于多单元协同仿真的船舶动力定位模拟器系统架构。根据动力定位系统自动定位模式的原理,设计动力定位控制器和推力分配算法,提出使用 Direct2D图形技术来设计动力定位人机交互界面。最后在所设计的动力定位模拟器系统架构下,以1艘动力定位供给船为仿真对象实现在不同海况条件下的自动定位功能和系统信息显示,并验证算法的有效性。     

Driver's braking behavior approaching pedestrian crossings: a parametric duration model of the speed reduction times

The driver's braking behavior while approaching zebra crossings under different safety measures (curb extensions, parking restrictions, and advance yield markings) and without treatment (baseline condition) was examined. The speed reduction time was the variable used to describe the driver's behavior. Forty‐two drivers drove a driving simulator on an urban scenario in which the baseline condition and the safety measures were implemented. The speed reduction time was modeled with a parametric duration model to compare the effects on driver's braking behavior of vehicle dynamic variables and different countermeasures. The parametric accelerated failure time duration model with a Weibull distribution identified that the vehicle dynamic variables and only the countermeasure curb extensions affected, in a statistically significant way, the driver's speed reduction time in response to a pedestrian crossing. This result shows that the driver, because of the improved visibility of the pedestrian allowed by the curb extensions, was able to receive a clear information and better to adapt his approaching speed to yield to the pedestrian, avoiding abrupt maneuvers. This also means a reduction of likelihood of rear‐end collision due to less aggressive braking. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of intersection field of view on emergent collision avoidance performance at unsignalized intersections: analysis based on driving simulator experiments

Proper intersection sight distance can effectively lower the possibility of intersection accidents. American Association of State Highway and Transportation Officials (2011) provide a series of recommended dimensions of intersection sight triangles for uncontrolled and stop/yield‐controlled intersections. However, in reality, although the actual intersection design for unsignalized intersections satisfies the requirements of sight distance and clear sight triangle in American Association of State Highway and Transportation Officials' guideline, there are still a large number of crashes occurring at unsignalized intersections for drivers running stop/yield signs or failing to slow down. This paper presents a driving simulator study on pre‐crash at intersections under three intersection field of view (IFOV) conditions. The aim was to explore whether better IFOVs at unsignalized intersections improve their emergent collision avoidance performance under an assumption of valid intersection sight distance design. The experimental results show drivers' ability to identify potential hazards to be significantly affected by their IFOVs. As drivers' IFOV improved, drivers were more likely to choose braking actions to avoid collisions. Better IFOVs were also associated with significant increases in brake time to intersection and significant reductions in deceleration rate and crash rate, thus leading to a lower risk of traffic crash involvement. The results indicate that providing a better IFOV for drivers at intersections should be encouraged in practical applications in order to improve drivers' crash avoidance capabilities. Copyright © 2016 John Wiley & Sons, Ltd.     

2H-4000型轮机仿真训练器的研究与开发

文章介绍了轮机仿真训练器的设计目的和原则,并以2H-4000型轮机仿真训练器为例对其结构组成和应用特点进行了系统的分析,文章最后对轮机仿真训练器技术发展作出了展望。     

对航海专业认识实习的探析

分析现阶段海上认识实习的资源和各自的优势，得出模拟器训练可以成为在船实习的辅助手段，但不能完全替代的结论，认为学院只有合理利用现有资源并安排合适的实习内容才能确保高质量地完成认识实习任务。     

雷暴低空风切变引起的长周期飞行振动

典型尺度的雷暴低空风切变以长周期振动频率激励飞机,使其偏离预计下滑航迹.在正弦风切变假定下,利用计算机计算和飞行模拟器模拟研究了长周期振动频率上下的正弦波风切变对飞机着陆航迹的影响.结果表明,计算机计算与飞行模拟器模拟得到的飞行航迹并不完全一致,说明用现有模拟飞行器模拟模式训练飞行员处置雷暴低空风切变是不全面的.     

绿灯倒计时影响下机动车微观驾驶行为分析与决策建模

机动车在交叉口信号相位切换期间的驾驶行为对于城市道路交通安全至为重要,本文对绿灯倒计时影响下的机动车微观驾驶行为与“通过/停止”决策进行研究.首先,利用驾驶模拟器进行1组单盲实验来提取车辆的接近速度、反应时间、减速度等参数.其次,详细地刻画了车辆进入交叉口范围至行驶至停止线全过程的微观驾驶行为.再次,综合交通因素及驾驶员个体特征等解释变量,建立了随机效应Logistic模型以描述车辆的“通过/停止”决策行为.结果表明：车辆进入交叉口范围后会“先减速,再加速,再减速”,加速通常出现在距停止线30~ 40 m的范围内,且绿灯倒计时与黄灯启亮前期对驾驶员具有催促作用;速度、距离、年龄、性别对车辆的“通过/停止”决策行为具有显著影响;随机效应Logistic模型比Logistic模型更能表征其他未纳入模型的因素及反映不同交叉口与驾驶员的异质性.