BP神经网络在女性假人颈部标定试验中的应用

采用BP神经网络代替响应曲面法的多项式函数,建立了基于BP神经网络的女性假人颈部减速特性模型.该模型以摆锤冲击速度、标定温度、蜂窝铝孔数、蜂窝铝切割形式为输入,10ms时刻颈部减速度为输出,实现了颈部减速特性的拟合预测功能.两种方法的预测结果表明,基于BP神经网络法的预测误差最大值为0.04m/s,而响应曲面法的预测误差最大值为0.05 m/s.     

舰载天文经纬仪轴系误差分析及星校技术研究

标校是舰载天文经纬仪的一个重要环节,其标校的结果直接影响设备的精度。通过对天文经纬仪轴系的分析以及建立坐标系之间的线性变换关系,推导出天文经纬仪轴系误差模型。最后研究轴系误差的星校方法,对全天分布均匀的恒星进行观测,得到观测误差的实验数据,利用最小二乘法进行拟合解算出模型的参数。实验结果表明,通过星校技术进行轴系误差标校,可将指向精度提高10倍左右,满足设备总体要求。     

Analysis of the pencil of conics with double complex contact and its application to camera calibration

In this paper,we introduce a novel class of coplanar conies,the pencil of which can doubly contact to calibrate camera and estimate pose.We first analyze the properties of con-axes and con-eccentricity ellipses, which consist of a natural extending pattern of concentric circles.Then the general case that two ellipses have two repeated complex intersection points is presented.This degenerate configuration results in a one-parameter family of homographies which map the planar pattern to its image.Although it is unable to compute the complete homography,an indirect 3-degree polynomial or 5-degree polynomial constraint on intrinsic parameters from one image can also be used for camera calibration and pose estimation under the minimal conditions.Furthermore, this nonlinear problem can be treated as a polynomial optimization problem(POP) and the global optimization solution can be also obtained by using SparsePOP(a sparse semidefinite programming relaxation of POPs). Finally,the experiments with simulated data and real images are shown to verify the correctness and robustness of the proposed technique.     

发动机转速传感器测控平台设计

设计了一种新的发动机转速传感器测控平台。该平台主要包括DSP系统板、磁电式转速传感器、发动机转速工况模拟装置、汽车转速仪表以及上位机。介绍了器件选型及硬件设计过程,分析了汽车仪表转速系数修正与标定、转速信号频率测量及系统测控流程。测试结果表明:该平台人机界面友好,操作简单方便,转速传感器信号测量准确可靠,模拟工况控制快速平稳。     

基于激光摄影测量方法的地铁限界检测系统研究*

限界检测系统主要采用激光摄影测量方法快速实现地铁限界非接触式检测,检测系统采用激光摄像式传感器实时采集隧道断面图像,通过对激光摄像式传感器非线性模型进行标定从而建立空间物体与摄像机图像像素之间映射关系,实现隧道断面上待测目标点的距离测量。针对系统中激光光条图像的处理,先后采用图像预处理算法提高图像处理效率,Sobel算子提取激光光条边缘,利用 Sobel算子提供的光条梯度信息经脊线跟踪法实现光条中心亚像素提取,提高检测系统精度。利用研制出的地铁限界检测系统进行现场试验和精度验证。试验表明,地铁限界检测系统能够满足地铁限界高精度检测需求,能够为地铁安全运行发挥重要作用。     

Measuring the safety impact of road infrastructure systems on driver behavior: Vehicle instrumentation and real world driving experiment

Featured in this pilot experimental study is the construction and design of an instrumented vehicle that is able to capture vehicle trajectory data with an extremely high level of accuracy and time resolution. Once constructed and properly instrumented, the various data collection systems were integrated with one another and a driving experiment was conducted on northern Virginia roadways with 18 participants taking part in the study. Trajectory data were collected for each of the drivers as they traversed a predefined loop of four roadway segments with varying numbers of lanes and varying shoulder widths. Data collected from the experiment were then used to calibrate the parameters of the prospect theory car-following model through a genetic algorithm calibration procedure. Once all model parameters were successfully calibrated, significance testing was carried out to determine the impacts that the varying roadway infrastructure had on driving behavior. Results indicated that there were significant changes in behavior when comparing one lane roadways to their two lane counterparts—specifically in cases where the roadway featured a wide shoulder. Additional testing was conducted to ensure that there was no variation based on gender, as nine study participants were female and nine were male. The successfulness of this first study conducted with the newly constructed instrumented vehicle creates the opportunity for a variety of additional studies to be conducted in the future.     

Automatic calibration of fundamental diagram for first‐order macroscopic freeway traffic models

Despite its importance in macroscopic traffic flow modeling, comprehensive method for the calibration of fundamental diagram is very limited. Conventional empirical methods adopt a steady state analysis of the aggregate traffic data collected from measurement devices installed on a particular site without considering the traffic dynamics, which renders the simulation may not be adaptive to the variability of data. Nonetheless, determining the fundamental diagram for each detection site is often infeasible. To remedy these, this study presents an automatic calibration method to estimate the parameters of a fundamental diagram through a dynamic approach. Simulated flow from the cell transmission model is compared against the measured flow wherein an optimization merit is conducted to minimize the discrepancy between model‐generated data and real data. The empirical results prove that the proposed automatic calibration algorithm can significantly improve the accuracy of traffic state estimation by adapting to the variability of traffic data when compared with several existing methods under both recurrent and abnormal traffic conditions. Results also highlight the robustness of the proposed algorithm. The automatic calibration algorithm provides a powerful tool for model calibration when freeways are equipped with sparse detectors, new traffic surveillance systems lack of comprehensive traffic data, or the case that lots of detectors lose their effectiveness for aging systems. Furthermore, the proposed method is useful for off‐line model calibration under abnormal traffic conditions, for example, incident scenarios. Copyright © 2015 John Wiley & Sons, Ltd.     

船舶电气设计常见问题分析

船舶电气图纸是指导电气设备安装、保障船舶正常运行的基础。船舶电气设计图纸及设备工作资料的校核是船舶电气工程师的一项重要工作,文章从图纸校核等方面分析了船舶电气设计中常见问题及注意要点。     

宏观标定方法在Wiedemann驾驶行为阈值研究中的应用

基于流量速度图对Wiedemann74模型参数标定的宏观方法进行了研究,建立了集成VISSIM、Matlab、ExcelVBA的参数标定平台,以最小化流量速度图的实测值与仿真值的差异为优化目标,应用图像识别方法判剐图像的差异性,利用遗传算法优化参数值,实现了参数自动寻优的迭代过程.建立的参数标定平台能够利用流量、速度等宏观运行数据标定驾驶行为阈值参数,为利用检测器数据实现自动化标定提供了有效手段,为分析驾驶行为特点提供了方法,解决了VISSIM软件中默认参数不适合我国交通状况导致仿真精度不高的问题.利用路侧激光检测器采集长沙市南二环路断面交通数据,根据标定后的参数、实测数据对Wiedemann模型的驾驶行为阈值曲线进行了拟合,根据驾驶行为分区对长沙市南二环路的驾驶行为进行了分析.     

一种利用参考图象与路面信息的道路监控摄像机标定方法

鉴于基于视频处理技术的交通流检测系统需要进行摄像机的标定才能得到准确的车流速度信息,而传统的人工标定法无法满足道路监控摄像机发生人为转动时的这一要求,提出了一种基于参考图像与路面信息的的道路监控摄像机标定方法.该方法利用车道标线的宽度和间距以及一条垂直于车道标线的线段,即可估计出摄像机的焦距、俯角、水平偏角和距离地面的高度,同时,为了计算“病态条件”下的摄像机参数,提出了在焦距保持不变的情况下,通过旋转摄像机来获取一组合适的参考图像,再通过参考图像来实现标定.在摄像机发生人为转动的情况下,也能方便地通过参考图像和路面信息来实现重标定.仿真试验表明,该方法具有操作方便、计算简单精确的优点,且无需人工现场操作,大大减少了外业工程量.