Low cost two dimension navigation using an augmented Kalman filter/Fast Orthogonal Search module for the integration of reduced inertial sensor system and Global Positioning System

Due to their complementary characteristics, Global Positioning System (GPS) is integrated with standalone navigation devices like odometers and inertial measurement units (IMU). Recently, intensive research has focused on utilizing Micro-Electro-Mechanical-System (MEMS) grade inertial sensors in the integration because of their low-cost. In this study, a low cost reduced inertial sensor system (RISS) is considered. It consists of a MEMS-grade gyroscope and the vehicle built-in odometer. The system works together with GPS to provide 2D navigation for land vehicles. With adequate accuracy, Kalman filter (KF) is the commonly used estimation technique to achieve the data fusion of GPS and inertial sensors in case of high-end IMUs. However, due to the inherent error characteristics of MEMS grade devices, MEMS-based RISS suffers from the non-stationary stochastic sensor errors and nonlinear inertial errors, which cannot be handled by KF and its linear error models. To overcome the problem, Fast Orthogonal Search (FOS), a nonlinear system identification technique, is suggested for modeling the higher order RISS errors. As a general-purpose numerical method, FOS algorithm has the ability to figure out the system nonlinearity efficiently with a tolerance of arbitrary stochastic system noise. Even using online short-term training data, this method is still able to build an accurate nonlinear model that predicts the system dynamics. Motivated by the above merits, an augmented KF/FOS module is proposed by cascading FOS algorithm to a traditional KF structure. By estimating and reducing both linear and nonlinear RISS errors, the proposed method is supposed to offer substantial enhancement on the positioning accuracy of MEMS-based RISS during GPS outages. In order to examine the effectiveness of the proposed technique, the KF/FOS module is applied on the low cost RISS together with GPS in a land vehicle for several road test trajectories. The performance of the proposed method is compared to KF-only solution, both assessed with respect to a reference offered by a high-end solution. The experimental results confirm that KF/FOS module outperforms KF-only method. The results also show the applicability of the proposed method for real-time vehicle applications.     

锦屏二级水电站交叉隧洞模型试验研究

多洞室交叉处围岩力学状况目前国内外研究相对较少。文章以锦屏二级水电站3#引水隧洞三洞交叉段为工程背景,为了解交叉洞室对围岩的影响,进行了三维地质力学模型试验;通过两组试验,有效地揭露了交叉洞室间的相互影响,以及开挖与支护方法对围岩稳定性的影响。最后通过超载试验,确定了交叉洞室的破坏模式及其破坏过程;试验结果为指导施工提供了依据。     

驱动桥壳有限元分析模型的改进

针对目前常用的驱动桥壳有限元分析模型中由于边界条件定义造成结果不准确的问题,在分析模型中引入了板簧的弹性特征,并按不同的边界条件对桥壳应力分布进行了计算。结果表明,按照传统约束方式计算,板簧座外侧桥壳应力高,板簧座内侧桥壳应力位于低;按新建立的边界条件计算,则高应力区将向板簧座内侧的桥壳扩展。测得弯曲及扭转工况下桥壳的应力结果表明,采用常用边界条件所得位于板簧座内侧的桥壳应力计算结果与实际相差接近50%;引入板簧元件后桥壳应力的计算结果则与试验结果相近。     

A Finite Element Analysis on the Engine Block of a Horizontal Diesel Engine

建立了某卧式双缸柴油机机体组件的有限元模型,在通过多体动力学软件得到的力边界条件下,分别计算了预紧工况和最大转矩工况下1、2缸爆发时的机体强度,确定了机体的最大应力和变形部位.结果表明,采用有限元分析较真实地反映了机体的实际工作情况.     

柴油机连杆大头轴承润滑特性影响因素的研究

构建了连杆大头轴承仿真模型和试验设计与CAE技术相结合的仿真流程,选定了轴承相对平均间隙、曲柄销油孔直径和轴瓦宽度作为连杆大头轴承润滑特性分析的3个因素.仿真结果表明,影响最小油膜厚度、最大油膜压力和平均摩擦损耗因素的主次顺序为轴承相对平均间隙、曲柄销油孔直径和轴瓦宽度.     

甲醇汽油对汽车橡胶元件溶胀作用的力学分析

为研究甲醇汽油对汽车橡胶零部件的腐蚀和力学性能的影响,通过对几种现有车辆正在使用的橡胶元件进行甲醇汽油浸泡试验,观察橡胶元件形变随作用力的变化关系,并深入分析橡胶元件经过浸泡后变化的原因.结果表明,浸泡橡胶管的溶液析出的黑色沉淀物包含有增强剂碳黑.由丁腈橡胶(NBR)+氯丁橡胶(CR)材料组成的橡胶管,和由三元氟橡胶(FKM)+编织层+氯醇橡胶(ECO)组成的橡胶管,受甲醇汽油中甲醇浓度影响较大,力学性能显著下降;多层PA12受掺入甲醇的影响较大,但对其掺入甲醇比例变化不敏感;甲醇汽油对气门油封无明显影响.     

弧形底宽箱梁横向预应力空间作用效应分析

以上海市中环线工程为工程背景 ,讨论了宽跨比较大的弧形底单箱多室箱梁在横向预应力作用下的受力特性。建立空间有限元模型分析横向预应力的空间效应 ,分别讨论了横梁和顶板中横向预应力对结构的影响 ,得出箱梁横向应力沿结构纵向和横向的分布规律。     

PLC系统的抗干扰设计

1干扰的来源(1)空间的电磁干扰。置于电网、大功率电气设备、雷电、无线电波、雷达、高频感应加热设备等产生的电磁场中的PLC系统会受到辐射干扰,它主要是通过电源和信号线引入的。例如,由于电网覆盖范围广,它将受到空间电磁辐射干扰,并在线路中产生感应电动势,从而影响PLC电源     

起重机风灾事故的防范

介绍了影响港口大型起重机安全的风害种类,以及目前在大型起重机上配备的各种防风防台设施,强调了防风防台工作的重要意义及其现实意义。     

上海市轨道交通2号线系统总体建设目标的思考

上海市轨道交通2号线是规划网络中4条市域级快速线之一。通过对该线功能定位、线路走向、所经重要活动中心和对外交通枢纽、线路功能与作用、客流特征以及既有和在建工程技术特征等的分析和认识,提出了系统建设目标要求、技术对策、系统客运模式和系统功能目标特征。该线应分解为两个独立的运营系统:高速铁路客站(虹桥机场)以东区段利用既有2号线及其西延伸段,采用贯通运营方案;青浦段(朱家角至高速铁路客站)独立运营。