Sensitivity of a vehicle ride to the suspension bushing characteristics

The sensitivity of the ride characteristics of a road vehicle to the mechanical characteristics of the bushings used in its suspension is discussed here. First, the development and computational implementation, on a multibody dynamics environment, of a constitutive relation to model bushing elements associated with mechanical joints is presented. Bushings are made of a rubber type of material, which presents a nonlinear and viscoelastic relationship between the forces and moments and their corresponding displacements and rotations. Suitable bushing models for vehicle multibody models must be accurate and computationally efficient, leading to more reliable models. The bushing is modeled in a multibody code as an arrangement of springs that penalize the motion between the bodies connected. In the methodology proposed here, a finite element model of the bushing is developed in the framework of a finite element (FE) code to obtain the curves of displacement/rotation versus force/moment for different loading cases. The basic ingredients of the multibody model are the same vectors and points relations used to define kinematic constraints in any multibody formulation. Spherical, cylindrical and revolute bushing joints are developed and implemented in this work, since the methodology is demonstrated through the ride over bumps, at different speeds, of two multibody models of a road vehicle: one with perfect kinematic joints, for the suspension sub-systems; the other with bushing joints, riding. Then, sensitivities of different vehicle kinematic responses to the characteristics of the bushings used in the suspension are evaluated, by using numerical sensitivities. Based on the sensitivity analysis, indications on how to modify the vehicle response by modifying the bushing characteristics are drawn. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Jorge A.C. Ambrósio received his Ph.D. degree from the University of Arizona in 1991, being currently Professor at the Mechanical Engineering Department of Instituto Superior Técnico at the Technical University of Lisbon, Portugal. He is the author of several books and a large number of papers in international journals in the areas of multibody dynamics, vehicle Dynamics, crashworthiness and biomechanics. He has been responsible for several international projects in railway dynamics, biomechanics and passive safety. Currently he is the Editor-in-Chief of Multibody System Dynamics and member of the editorial boards of several international journals.     

Driving Performance Analysis of the Adaptive Cruise Controlled Vehicle with a Virtual Reality Simulation System

Nowadays, with the advancement of computers, computer simulation linked with VR (Virtual Reality) technology has become a useful method for designing the automotive driving system. In this paper, the VR simulation system was developed to investigate the driving performances of the ASV (Advanced Safety Vehicle) equipped with an ACC (Adaptive Cruise Control) system. For this purpose, VR environment which generates visual and sound information of the vehicle, road, facilities, and terrain was organized for the realistic driving situation. Mathematical models of vehicle dynamic analysis, which includes the ACC algorithm, have been constructed for computer simulation. The ACC algorithm modulates the throttle and the brake functions of vehicles to regulate their speeds so that the vehicles can keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamics simulation with VR rendering. With the developed VR simulation system, several scenarios are applied to evaluate the adaptive cruise controlled vehicle for various driving situations.     

Development of a motion simulator for testing a mobile surveillance robot

A 6-axis motion simulator has been developed, in order to regenerate UGV (unmanned ground vehicle) motion and to test the stabilization system of the mobile surveillance robot that is mounted on the UGV. For developing the 6-axis motion simulator, a simulation-based design procedure was introduced. The 3D geometric model of the motion simulator was created by using 3D CAD modeler ProE. The multibody dynamics model of the motion simulator has also been created by using the general purpose dynamic analysis program ADAMS to validate the design of the motion simulator. Dynamics and control co-simulation model for the motion simulator has been also established for control performance analyses. Actual hardware of the motion simulator has been fabricated based on the proposed simulation based design. Hardware test of the motion simulator has been tried to validate the design. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Oskar Wallrapp was awarded a Ph.D. degree in Mechanical Engineering at the Technical University of Berlin, Germany in 1989. Dr. Wallrapp is currently a Professor in the Department of Precision and Micro Engineering, Muenchen University of Applied Science, Munich, Germany. His research interests are mechanism analysis and design, robotics, and bio-mechanics. Sung-Soo Kim received a Ph.D. degree in Mechanical Engineering from the University of Iowa in 1988. Dr. Kim is currently a Professor in the Department of Mechatronics Engineering at Chungnam National University in Daejeon, Korea. His research interests are real-time multibody formulation and its application to the automotive systems and military robot systems.     

基于MATLAB/RTWEC自动代码生成技术整车控制器快速原型开发

介绍了整车控制器快速原型的系统架构。在Simulink的软件平台上搭建了整车控制器仿真模型,利用仿真数据对算法原理进行错误检查和修正。介绍了利用MATLAB/RTWEC实现了基于模型的自动代码生成机制,并将应用层代码与控制器硬件TTC-90底层代码进行了集成,用于整车实验。整车实验结果证明了快速原型的正确性和MATLAB自动生成代码的可靠性、快速性。     

利用组合铰建立汽车多体运动学模型

为了满足HIL技术对适时仿真环境的要求 ,提高仿真速度 ,本文利用多体理论提出了组合铰的思想 ,建立了双作用臂悬架组合铰的运动学模型 ,并利用所建立的组合铰得到一个简化的汽车模型 ,该模型的运动学方程和约束方程的规模大大降低。本文对简化前后的两种汽车模型在同一个环境下进行了仿真计算 ,仿真结果表明 :利用组合铰建立的模型在不降低仿真精度的前提下节约了约 2 / 3的CPU计算时间 ,该模型能够应用于HIL技术。     

柔性多体系统动力学的递推建模与算法

基于将２种变量的耦合运算降低到最少的数学模型的建立,是解决柔性多体系统动力学数值病态的关键。提出一种柔性多体系动力学的单向递推建模方法。在此基础上提出了一种新的违约校正方法,在数值计算上给予保证,最后,通过对一个闭环柔性多体系统的动力学与控制仿真计算的实现,表明上述方法的可行性。     

Application of modified local parametrization method for the constrained multibody dynamic systems

This paper presents a corrector method for analyzing the dynamic behaviour of constrained multibody systems. For correcting the state variables this method uses Lagrange-Newton method, which is a nonlinear programming technique. The Lagrange-Newton method uses the Lagrangian function that is a combined form of state variables with constraints, and the iteration formulation for convergence can be derived by the Newton-Raphson method. This algorithm does not update the Lagrange multipliers in the iteration formulation, for correcting the state variables, and is to project the state variables on the constraint manifold, in contrast to the previous local parametrization method. The validity of the algorithm and numerical solutions is verified through the convergence theorem denoting the convergence order of numerical solutions and the dynamic analysis of the full vehicle 3D model. The numerical solutions are compared with the ADAMS solutions     

Vehicle dynamics analysis of a heavy-duty commercial vehicle by using multibody simulation methods

In this paper, the computer-aided vehicle dynamics analysis of a 6?×?2 heavy-duty commercial vehicle is examined. For the analysis, Mechanical Simulation Corporation's TruckSim multibody dynamics simulation and SuspensionSim multibody statics simulation softwares are used. The aim of this study is to design and model the front suspension and tandem rear axle suspensions, compose the full-vehicle model representing the real-life vehicle, and examine the dynamic behavior of this model. The models related to the front and rear suspensions are prepared and solved in SuspensionSim and the solutions are imported thereafter to TruckSim. The full-vehicle model excluding the suspension system is formed by using TruckSim. The simulation scenarios, runs of which are made to observe the effects of different parameters concerning the dynamic behavior of the full-vehicle model, are also prepared in TruckSim environment.     

Influence of blank profile on the V-die bending camber process of sheet metal

The finite element simulation is now widely used in the design of stamping tools. A trial and error procedure has been replaced by a simulation in which defects associated with sheet forming processes are predicted and evaluated. This paper aims to clarify the process conditions of the V-die bending of a sheet metal. It provides a model that predicts not only the correct punch load for bending, but also the precise final shape of the products after unloading. An incremental elastic-plastic finite element computer code, based on an updated Lagrangian formulation, was developed to simulate the V-die bending of sheet metal. In particular, the assumed strain field (ASF) element was used to formulate the stiffness matrix. The r-minimum technique was used to deal with the elastic-plastic state and solve contact problems at the tool-metal interface. A series of experiments were performed to validate the formulation in the theory, leading to the development of the computer codes. The predicted punch load in the finite element model agrees closely with the experimental results. The whole history of deformation and the distribution of stress and strain during the forming process were obtained by carefully considering the moving boundary condition in the finite element method .A unique feature of this V-die bending process is the camber after unloading. The computer code successfully simulates this camber. The simulation was performed to evaluate the effects of the size of the blank on the camber process. The results in this study clearly demonstrate that the computer code efficiently simulated the camber process .     

单电机式强混合动力车辆控制策略

提出了基于一种新型的单电机、双离合器式强混合动力结构的车辆分层控制系统方案,制定了整车能量管理策略,并研究了车辆行进中启动发动机过程的动态协调控制方法。通过自行开发的前向仿真系统对能量管理策略进行了验证,在NEDC循环工况下等效百公里油耗降低了34%。同时通过动态台架试验,对车辆行进中启动发动机的动态协调控制策略进行了验证。     

An improved model-based predictive control of vehicle trajectory by using nonlinear function

A new model-based predictive control algorithm for vehicle trajectory control is proposed by using vehicle velocity and sideslip angle. Based on the error function combined with vehicle velocity and side slip of a bicycle model, a predictive control method has been proven to be useful on low velocity. Thus, it could be applied for an autonomous vehicle without a driver. Although an autonomous robot is not necessary to be driven with a high velocity, a commercial vehicle has to be driven at high velocity. Thus the previous predictive control formulation is not enough for a commercial driving system. This study is proposed to enhance the capacity of the predictive controller for rather high speed vehicles. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Mr. Jeong-Han Lee is pursuing a Ph.D. degree in Mechanical Engineering at Pusan National University under the supervision of professor Wan-Suk Yoo. His research interests are focused on the area of adaptive control using multibody dynamics. Dr. Wan-Suk Yoo received his Ph.D. degree in 1985 from the University of Iowa. In 1994, he became a full professor at the Pusan National University, and he was selected an ASME fellow. He is serving as a vicepresident of the KSME.     

Study on the dynamic model and simulation of a flexible mechanical arm considering its random parameters

Randomness exists in engineering Tolerance, assemble-error, environment temperature and wear make the parameters of a mechanical system uncertain So the behavior or response of the mechanical system is uncertain In this paper, the uncertain parameters are treated as random variables So if the probability distribution of a random parameter is known, the simulation of mechanical multibody dynamics can be made by Monte-Carlo method Thus multibody dynamics simulation results can be obtained in statistics A new concept called functional reliability is put forward in this paper, which can be defined as the probability of the dynamic parameters (such as position, orientation, velocity, acceleration etc) of the key parts of a mechanical multibody system belong to their tolerance values A flexible mechanical arm with random parameters is studied in this paper The length, width, thickness and density of the flexible arm are treated as random variables and Gaussian distribution is used with given mean and variance Computer code is developed based on the dynamic model and Monte-Carlo method to simulate the dynamic behavior of the flexible arm At the same time the end effector’s locating reliability is calculated with cncular tolerance area The theory and method presented in this paper are applicable on the dynamics modeling of general multibody systems     

基于并行计算的新型并联机床动力学解析模型

基于运动学分析、凯恩动力学方程和数字-符号方法,建立了新型并联机床的动力学解析模型。将动力学模型矩阵的推导问题转化为特定条件下运用运动学和动力学计算公式求解驱动力的问题,由计算机自动生成了动力学模型矩阵的各矩阵元素的实时代码,并提出了实时代码的多项式结构优化方法。还构造了动力学解析模型的并行算法。由于动力学模型是离线建立和优化的加上采用了并行计算结构,大大减少了在线计算量,节省了计算时间。给出了动力学模型矩阵元素实时代码生成和仿真计算的数值实例。     

基于解析模型法的机器人动力学建模自动生成软件系统

基于改进的机器人动力学解析（数字-符号）模型算法,研制出用于机器人动力学自动建模的计算机辅助生成软件。在计算机上自动生成机器人的动力学模型元素与运动方程,并产生动力学模型的实时代码。采用的解析模型算法改进了动力模型多项式结构矩阵的优化算法,还简化了代码输出程序,大大减少了中间变量与赋值语句。提高了运算速度及导致最少的浮点乘/加数。该软件还带有图形接口,用于仿真时具有动画显示功能。     

Joint coordinate method for analysis and design of multibody systems: Part 2. System topology

In Part 1 of this paper, the method of joint coordinate formulation for multibody dynamics was reviewed. The application of this method to forward and inverse dynamics, static equilibrium, and design sensitivity analyses was studied. In Part 2 of the paper, systematic procedures for constructing the necessary matrices for the joint coordinate formulation are discussed in detail. These matrices are; the primary and the secondary path matrices describing the topology of the system, the velocity transformation matrix, and the generalized inertia matrix. The procedures for constructing these matrices and other necessary elements for the joint coordinate formulation can easily be implemented in a computer program for analysis and design process.     

履带行动系统动力学建模方法及性能仿真

提出了履带行动系统的动力学建模方法,分析了履带板与机构内各部件之间的接触碰撞力模型;对于履带板与软质地面之间的作用力模型,开发了履带板地面作用力子程序,分析得到以三维矢量力表达的履带地面作用力,实现了在软质地面下的履带行动系统的性能仿真.该工作提高了履带行动系统样机设计及性能分析的准确性和效率.     

汽车起重机振动模态研究

汽车起重机在起吊工作过程中,激励频率应远离固有频率,以免因产生共振而发生危险。因此在汽车起重机设计与应用过程中对其进行振动模态分析是十分必要和重要的工作。将汽车起重机处理为由多个刚体、集中质量、弹性梁、扭簧以及弹簧按一定方式铰接而成的刚柔耦合多体系统,建立了汽车起重机的动力学模型,用多体系统传递矩阵法计算了其振动固有频率及对应的主振型,解决了同时含有多个刚体和弹性体的复杂多体系统的振动模态计算问题。     

Multidisciplinary simulation for driving performance analysis of an escalator system

An electric motor coupled with a gear train generates driving torque to move step band and handrail band together with passenger load for operation. Therefore, understanding of electric motor dynamics and its influence on escalator system in transient and steady state is very important for both product development and service operation in compliance with safety code requirement. A multidisciplinary escalator simulation model in complete system-level is introduced based on multibody dynamics technology including 3-phase induction motor, gear train inside of machine gearbox, step band, handrail band and all other drive chain bands. Torque from 3-phase induction motor is considered in the system model by the flux linkages equations derived from d-q axis equivalent circuit. The verified simulation model compared with Thévenin’s equivalent circuit model is used to investigate driving performance of an escalator system in different passenger load condition.     

某型轨道巡检车导向系统的强度分析

介绍一种用于轨道巡检作业车辆的结构特征，并详细介绍其采用的导向系统，这是保证车辆在轨道上安全行驶的重要部件。然后建立整车动力学模型，并利用多体动力学软件（ADAMS）对其进行动力学分析，由安装在滑动基座内部的可伸缩弹簧的弹簧力变化得出巡检车在通过曲线轨道时导向系统的动态极限载荷。最后利用有限元软件（ANSYS）对连接导向轮系和车身的关键部件——导向架进行应力强度分析。结果表明，导向系统的强度设计满足要求。