Vertical dynamics of the Maglev vehicle Transrapid

The Maglev vehicle Transrapid is levitated by magnetic forces which pull the vehicles levitation frames toward the guideway from below. The magnets possess poles with alternating fluxes which are part of the synchronous long stator linear motor. Although the Transrapid glides along its guideway without mechanical contact, this alternation as well as the loading and unloading of the guideway girders excite vibrations of the ground. In order to calculate the time behavior of the vibrational emissions, a simulation of the transfer of a Transrapid vehicle over several guideway girders is proposed. The equations of motion for the vehicle and the girders are calculated separately by the MBS software NEWEUL and assembled and numerically integrated in MATLAB/SIMULINK. The control law for the magnet forces is simplified by the characteristics of linear spring-damper elements. The controlled magnet forces travel along the guideway continuously and include the dynamic component due to the alternating fluxes and the geometry of the poles and stator. Results of a complete vehicle moving along a guideway consisting of several girders can be obtained within a few minutes of computation time. Therefore, the mechanism of excitations can be analyzed by numerical time integration in the full state space. The results are validated by measurements of the forces in the joints of the guideway girders. The vibrational emission along the Transrapid guideway differs from the vibrations of contact-afflicted vehicles as no impacts and fewer stochastic effects occur.     

GPS-based Clock Synchronization in a Mobile,Distributed Real-Time System

In a vehicle tracking system computers aboard moving vehicles determine periodically their geographical position and transmit it to a control center. This paper presents a commercial vehicle tracking system as an example of a distributed real-time system with mobile components and focuses on the issue of clock synchronization. The mobile components of the system obtain highly accurate timing information from the Global Positioning System which is used to synchronize their local clocks to UTC world time. Thus a tight clock synchronization is achieved without imposing additional load on the communication channels of the system.     

Modeling and robust adaptive iterative learning control of a vehicle‐based flexible manipulator with uncertainties

In this brief, this paper deals with a robust adaptive iterative learning control (ILC) problem for a flexible manipulator attached to a moving vehicle with uncertainties. To begin with, considering the infinite dimensionality of the flexible distributed parameter system, a coupled ordinary differential equation and partial differential equation model is established without any discretization. Then, it is followed by a presentation of an adaptive ILC strategy, which can drive the vehicle and joint to the desired positions based on a proportional‐derivative feedback structure with unmodeled dynamics and external disturbances. The deformation of the flexible manipulator can also be suppressed simultaneously under the proposed control laws. By using Lyapunov's direct method, the stability of the closed‐loop system is demonstrated. The simulation results are provided to illustrate the effectiveness of the proposed control laws.     

Control aspects of a tracked magnetic levitation high speed test vehicle

The paper deals with the control system of the high speed test vehicle KOMET. The control hardware configuration consisting of digital computer, interface, sensors, magnet drivers and magnets is described. Control system synthesis is performed based on the state space approach and the classical approach of the z-transform. It leads to various control concepts, which are evaluated with regard to their responses to guideway irregularities, external forces and their sensitivity to plant parameter variations. The measurements used to reconstruct the state vector are magnet gaps, vehicle accelerations and/or magnet currents. To be efficient, the magnets have to be operated on small magnet gaps. This demands a fast system response to external disturbances and guideway inputs. This in turn may lead to the excitation of the elastic modes of the system. The higher order modes of vehicle and guideway are therefore included in the control synthesis. The speed range of the KOMET extends to 400 km/hr. Results from high speed testing are evaluated with regard to system responses, power requirements, and loss in magnetic force due to eddycurrents.     

用图像处理技术提取交通车辆移动轨迹

交通仿真的不断发展要求能为其提供现实中的车辆运动过程,从而使得模拟更加逼真,同时交通仿真模型评估也需要用到现实的车辆运动轨迹来比对仿真模型模拟出来的车辆运动轨迹。该文提出了一种用图像处理技术提取交通车辆移动轨迹的方法。该文介绍的这一方法采用了动态目标区域检测的技术来追踪运动车辆,所谓动态目标区域检测就是指被检测区域是动态更新的,是随着被检测对象位置的变化而改变的。这样一种思路有效地提高了系统运行的速度和系统检测的精度。避免了采用全局扫描思路所引起的系统复杂、运算量大以及精度不高的缺点。同时又有别于静态的重点区域检测的思路,使得系统更加灵活,运算更加快捷。通过实验验证,该系统可以快速准确地提取交通车辆的移动轨迹。     

磁浮列车悬浮系统的串级控制

为了消除磁浮列车的轨道共振,必须设计鲁棒性较强的悬浮控制系统.将悬浮控制 系统分解为电流环和悬浮子控制系统两个串行、解耦的子系统来考虑,并应用H∞控制理论 设计了电流环控制器,用时域法设计了悬浮子系统的控制器,给出了所设计的控制器在一个 单转向架磁浮列车上的悬浮试验结果.     

某型SUV乘用车冷却系统性能仿真与优化

为解决某型SUV乘用车在中、低速爬坡和高速行驶工况下发动机水温过高的问题,利用一维和三维联合仿真工具建立整车冷却系统的仿真模型,采用试验与仿真相结合的方法,分析单回路和双回路冷却系统、不同冷却管路布置、不同散热器选型,以及不同前端冷却模块结构等对冷却系统热平衡性能的影响.结果 表明:变速箱和发动机相互独立的双回路冷却系...     

A real time particle system for display of ship wakes

The particle-system technique is used to model `fuzzy objects', i.e. objects not bounded by well-defined, easily visible surfaces. the technique is used to depict, in real time, ship wakes in an air/sea simulation using a high-speed workstation for graphics calculation and display. The system consists of a graphics workstation tied to a compute server (typically a minicomputer, mainframe, or parallel processor, depending on the simulation complexity). The compute server executes the dynamic models associated with the vehicles in the simulation. The position and attitude of each vehicle are periodically transmitted to the graphics workstation, where a rendering of the situation is produced and displayed. Such a system normally runs at a frame redraw rate of 10 frames per second or greater to sustain an illusion of smooth movement. The ship wake phenomenon and its modeling, including some simplifications, are described     

基于模糊PID对AGV的纠偏控制

针对自动导引车辆AGV沿着既定路线行走时,由于外界不确定因素的影响而偏离既定路线的问题,提出了基于视觉CCD引导方式对AGV的行驶路径进行数据采集,以位置偏差和方向偏差作为纠偏控制系统的输入,同时基于模糊推理和PID控制策略对AGV行走进行纠偏。利用该控制策略,提高控制系统的鲁棒性、智能性、快速性、准确性。在Simulink仿真环境中进行了动态仿真,与常规的PID控制器相比,该控制系统能够更精确地对AGV的行驶过程进行实时纠偏。     

Mobility analysis in vehicular ad hoc network (VANET)

This paper focuses on vehicle mobility analysis in VANET. The performance of vehicle mobility in terms of average inter-vehicle link available time and the average number of inter-vehicle link changes for maintaining an active link in VANET is analyzed using both handover model and random moving model, respectively. The theoretical analysis is verified by simulation experiments. The numerical results indicate that the analytical random moving model is able to appropriately present the behavior of vehicle moving under different conditions, especially when mobile vehicle is moving relatively fast. On the other hand, the effect of traffic conditions on the accuracy of theoretical analysis is also investigated.     

Dynamic Modeling and Analysis of a Robot Manipulator Intercepting and Capturing a Moving Object,with the Consideration of Structural Flexibility

In this paper we investigate the dynamics of robotic interception and capture of a moving object. This problem, i.e., the interception and capture of a moving object by a robot, is called dynamic mass capture. The effects of structural flexibility of the robot is taken into consideration. In terms of time, the analysis is divided into three phases: before capture (finite motion), at the vicinity of interception and capture (impulsive motion), and after capture (finite motion). Special attention is paid to the modeling of the second phase when the robot captures the target and it becomes part of the end effector, thus, the system's degrees of freedom suddenly change. To decribe this event, a novel approach is proposed. This is based on the use of a class of impulsive constraints, the so-called inert constraints. Jourdain's principle is employed to derive the dynamic equations for both finite and impulsive motions. Simulation results are presented for two examples: a single flexible link and a two-link manipulator capturing moving objects. In the example of the single link, the results are compared with the observations of an experiment, and good agreement is found between experimental and simulation results.     

磁耦合共振双发单收系统特性仿真分析

针对电动汽车行驶过程中出现的多个能量发射端向一个能量接收端非接触供能的情形,基于磁耦合共振无线电能传输原理,建立“双发单收”式磁耦合共振理论模型,求解得到“双发单收”系统负载总功率数学表达式.选取3个典型位置,利用ANSYS仿真软件得到发射、接收线圈的磁感应强度云图和电流波形图,分析比较3个位置的电流传输特性与磁场特性.逐渐改变接收线圈与发射线圈的横向相对位置,模拟得到一个能量接收系统在两个能量发射系统之间运动时的充电过程,发现接收线圈运动时系统具有较为稳定的充电电流与充电功率,验证了“双发单收”系统的正确性.     

Attitude control of a spinning flexible spacecraft

The dynamics of rotational motion of a spinning orbiting spacecraft consisting of two rigid bodies connected by a flexible joint and arbitrary number of flexible appendages (two of which are flexible massless booms having masses on their tips) is analyzed. Active attitude control is provided by momentum exchange devices (e.g. control moment gyroscopes) or a mass expulsion system. The linearized equations of motion describing the vehicle are presented, and a large scale digital simulation that has been developed at the Marshall Space Flight Center is presented. A simplified model of the geometrically complex vehicle is selected to make it analytically tractable. The simplified model consists of a single rigid core body with two attached flexible massless booms having tip masses. The states of the vehicle are defined as small perturbations about its steady-state spin. An analysis is performed to determine the domain of stability.     

Dynamic modelling and stabilization of a new configuration of two-wheeled machines

This paper presents a novel design of two-wheeled vehicles and an associated stabilization approach. The proposed design provides the vehicle with more flexibility in terms of increased degrees of freedom which enable the vehicle to enlarge its working space. The additional translational degree of freedom (DOF), offered by the linear actuator, assists an attached payload to reach different levels of height as and when required. The model of the system mimics the scenario of the double inverted pendulum on a moving base, with the added DOF. Lagrangian dynamic formulation is used to derive the system dynamics. Joints frictions based on the Coulomb friction model are considered so as to retain nonlinear characteristics of the system. A PD-PID robust control approach is derived for the stabilization of the system. An investigation of the impact of damping associated with joints on the stability of the system is carried out. Simulation results validating the model and the control approach are presented and discussed.     

Synthesis of a high-speed tracked vehicle suspension system--Part I: Problem statement, suspension structure, and decomposition

This two-part paper is concerned with the problem of synthesizing a high-speed vehicle suspension system. Using a new decomposition technique, it is shown that there exists an optimal structure which a high-speed suspension must have in order to fulfill the requirements of vehicle body vibration isolation within given displacement constraints, external force cancellation, vehicle body tilting and guideway tracking while maintaining primary gaps or contact forces within given limits, and assuring maintenance of nominal mass and inertia parameters of the vehicle body. The suspension structure derived in this part is such that the incompatibility of vibration isolation and guideway tracking under the influence of external forces which is present for all suspensions synthesized heretofore-whether optimal control approaches have been used or not-has been removed. The new suspension structure features three independent parts: the nonlinear and time-varying preload-and-mass control operating on external forces and vehicle body accelerations, the linear time-invariant tracking control operating on the means of certain vehicle states, and the linear time-invariant vibrating control which operates on the difference between the actual vehicle state vector and its mean.     

车联网中beacon消息传输频率研究

车联网(VANETs)提供车与车之间的车间通信(V2V)和车与路旁设施(V2I)间的通信.VANETs中存在两类消息:beacon消息和安全消息.车辆周期地交互车辆的beacon消息,仅在紧急情况下才广播安全消息;而beacon消息的传输频率受多个因素影响.为此,提出基于模糊逻辑的自适应beacon传输频率方案,利用模...     

The simulation of 3D unsteady incompressible flows with moving boundaries on unstructured meshes

The development of a computational model for the simulation of three-dimensional unsteady incompressible viscous fluid flows with moving boundaries is presented. The numerical model is based upon the solution of the Navier–Stokes equations on unstructured meshes using the artificial compressibility approach. An ALE formulation is adopted and the equations are discretized using a cell vertex finite volume method. The formulation ensures the satisfaction of the geometric conservation law when the mesh is allowed to move. An implicit time discretization is adopted and a dual time approach is employed. Explicit relaxation is used for the sub-iterations, with multigrid acceleration. For moving geometries, the mesh is deformed by adopting a spring analogy, combined with a wall distance function approach. The numerical procedure is validated on a standard problem and is then used for the simulation of flow over a flexible fish-like body.     

Simultaneous control of vehicle routing and inventory for dynamic inbound supply chain

This paper investigates inbound logistics for an OEM (Original Equipment Manufacturing) manufacturer, who aims at short production time and JIT policy. In such a case, it can be argued that the inbound vehicle routing schedule should be combined with incoming parts inventory control. In this paper, we propose a simultaneous control method of combining vehicle scheduling and inventory control for such dynamic inbound logistics. For the transportation control, a vehicle routing system, in which delivery jobs are made with shipments of one supplier, is proposed to generate a vehicle routes plan by considering production start time, travel time, waiting time, and loading/unloading time. To evaluate the performance of the generated vehicle routing plan, a goal model is also developed by considering vehicle operating cost, stock level exceeding penalty, and transportation efficiency. A generated vehicle routing plan can be rejected when the stock level is over the capacity and an appropriate number of vehicles for its manufacturing environment can be determined. Using real data from an LCD firm, a simulation study is conducted. The simulation results indicate that the simultaneous control approach requires fewer vehicles than the existing system and shows better efficiency of transportation. This method can also be used to determine the appropriate incoming part inventory level or the number of vehicles required in dynamic inbound logistics.     

Synthesis of a high-speed tracked vehicle suspension system--Part II: Definition and solution of the control problem

This two-part paper is concerned with the problem of synthesizing a high-speed vehicle suspension system. In part I [13] a new suspension structure was developed which features three independent parts. All three parts are calculated for a vehicle which travels along a rigid guideway with arbitrary vertical and lateral curves and grades. In this part in developing the system control the use of instantaneous state feedback and the presence of inaccessible states demand the use of Itô-calculus and the Athans matrix minimum principle in order to solve the problems of vibration control synthesis. It is concluded that the application of the principles and methods of advanced dynamics, deterministic and stochastic optimal control theory, and applied mathematics to the problem of synthesizing a high-speed vehicle suspension is successful and results in the identification of a new suspension structure which is proposed as a starting point in the development and design of a high-speed vehicle suspension system. Augmented by a thorough system simulation and hardward tests for verification of all assumptions made and by implementation of the sensor-and actuator-dynamics, the described synthesis procedure will lead to an effective suspension system.     

Computer simulation and field measurement of dynamic pavement loading

Two methods, i.e. computer simulation and field measurement, are used in this paper to investigate dynamic pavement loading (DPL) generated by vehicle–pavement interaction. A profilometer is used for measuring road surface roughness. Based on the power spectral density of the measured surface roughness, a computer simulation program is developed using quarter vehicle model. In field measurement methods, an experiment is designed to gain the time history of DPL. An IVECO vehicle is taken as a test vehicle and eight vibration cells were used to pick up vertical accelerations of vehicle body and axle. The test data are collected and recorded while the test vehicle is moving along 11 different pavement sections of highway and bridge at six different speeds. Statistical characteristics of vertical accelerations and DPL of the test vehicle are obtained and analyzed by means of random process theory. The result of computer simulation matches the result of field measurement very well. It is found that DPL is primarily concentrated between 1.8 and 14.8 Hz and coefficient of variation of DPL falls into the range of 5–35% of static vehicle load. An approximate relationship between coefficient of variation of DPL and vehicle speed and road surface roughness is established.