重型筑路机械虚拟设计可调节平台运动与机构分析

重型筑路机械的虚拟设计与制造技术可以减少设计过程中的错误、缩短开发周期。本文介绍了一种满足ISO6 6 82规范的工程机械可调节驾驶模拟平台的设计 ,将该模拟驾驶平台放到 CAVE中 ,与虚拟图形系统、输入输出系统组成虚拟驾驶系统。通过虚拟驾驶系统来对重型筑路机械的设计进行评价 ,如方向盘、油门、刹车踏板和其它操纵机构的设计是否满足人机工程的要求。在该平台的设计中我们使用了连杆机构 ,可使方向盘、操纵杆等在一定区域内非常方便地调节 ,这样不同类型的重型筑路机械均可使用该平台来组成虚拟驾驶系统。我们设计了专门的程序来对四杆机构的运动进行仿真 ,以便选择正确的连杆尺寸。最后 ,文章介绍了动感椅的集成。     

基于OpenGL的数控仿真三维图形的研究

在制造之前，通过数控仿真软件可以在计算机中模拟加工过程，发现可能出现的碰撞、干涉，零件的可加工性及工艺的合理性等。因此，以三维图形软件标准OpenGL为工具，探讨数控仿真系统中三维图形的处理方法。     

一种基于物理造型的球体弹性碰撞模拟算法

虚拟环境是一种逼真的视、听、觉一体化的计算机生成环境 ,虚物实化的目标是不仅要使虚拟环境下的虚拟物体在外观上有逼真感 ,而且在行为 (运动与变形 )上符合物理学规律。本文从较简单的弹性小球的平面碰撞入手 ,建立了一种解决纯弹性碰撞问题的实践方法 ,实现了虚物实化的目标。该算法对于物理造型的进一步研究有一定的理论价值和实用意义。     

A new type haptics-based virtual environment system for assembly training of complex products

Virtual reality (VR)-based assembly training has been an interesting topic for the last decades. Generally, there are two shortcomings for nowadays virtual assembly training systems. One is that the operators cannot move around the virtual environment in a natural way as people activity in the real world: they are constrained in a fixed position or can only move in a limited space. The other is that most of the virtual assembly training systems are based on geometry constraint modeling only, which lacks haptics feedback. A new type haptics-based virtual environment system for assembly training of complex products is described in this paper. A new low-cost motion simulator is designed and integrated with the virtual environment to realize free walking by human. An automatic data integration interface is developed to transfer geometry, topology, assembly, and physics information from a computer-aided design system to a VR application, and a hierarchical constraint-based data model is rebuilt to construct the virtual assembly environment. Physics-based modeling and haptics feedback are undertaken to simulate the realistic assembly operations. The application examples and evaluation experiments demonstrate that both motion simulator and haptics have great value for training of assembly processes.     

湿式离合器流场与作用力模型试验研究

轴向和周向作用力影响湿式离合器宽速域范围工作性能。针对湿式离合器对偶片间带排转矩与轴向力演变问题,根据湿式离合器简化结构,开发湿式离合器模型流场可视化与受力测试试验装置。通过试验测试分析流场演变过程,得到对偶片间带排转矩与轴向力参数影响规律。结果表明,流场包括全液相流和气液分层流两种基本流型,在纯液相和纯气相区之间可形成一个稳定的边界。随着转速的增大、流量的减小和间隙的增加,对偶片间流场中的油液体积分数减小,两相边界向内侧移动。流量和间隙对带排转矩的拐点有显著影响,减小流量和增大间隙都可降低拐点对应的转速。随着转速增大、流量减小和间隙增加,对偶片间轴向力呈现下降趋势。在带排转矩拐点附近,轴向力的作用方向发生改变,且最终轴向力几乎减小到零。     

汽车自适应巡航系统的多模式切换控制

在复杂交通环境下,由于前车运动状态和驾驶意图的不可预知性,使得传统的自适应巡航控制(Adaptive cruise system,ACC)的应用受到限制,因此提出一种多模式自适应巡航控制策略。在现有上、下位控制器的基础上增加模式切换层,通过将车辆纵向运动状态划分为八种工况,使得系统根据实际工况条件选择最优的控制模式,并采用加速度加权平均算法提高模式切换的准确性和输出连续性。分别设计定速巡航、稳态跟随、接近前车、强加速、强减速和避撞六种控制模式。基于每种模式侧重的控制目标,设计相应的上位控制器并对其控制参数进行整定,从而改善了系统整体的控制品质。最后通过实车试验验证了多模式切换算法的有效性和实用性。     

基于虚拟环境下的产品开发技术研究

虚拟产品开发技术不仅可真正实现设计与过程的集成,同时它还可促进异地分布式协同产品开发的实现。本文介绍了虚拟产品开发的技术内涵、研究内容,结合以往对虚拟产品开发领域的研究成果,对虚拟产品开发的体系结构进行了初步探索。     

Development of an Intelligent Vehicle Experiment System

Existing vehicle experiment systems tend to focus on the research of vehicle dynamics by conducting performance tests on every system or some parts of the vehicle so as to improve the entire performance of the vehicle.Virtual technology is widely utilized in various vehicle test-beds.These test-beds are mainly used to simulate the driving training,conduct the research on drivers' behaviors,or give virtual demonstrations of the transportation environment.However,the study on the active safety of the running vehicle in the virtual environment is still insufficient.A virtual scene including roads and vehicles is developed by using the software Creator and Vega,and radars and cameras are also simulated in the scene.Based on dSPACE's rapid prototyping simulation and its single board DS1103,a simulation model including vehicle control signals is set up in MATLAB/Simulink,the model is then built into C code,and the system defined file(SDF) is downloaded to the DS1103 board through the experiment debug software ControlDesk and is kept running.Programming is made by mixing Visual C++ 6.0,MATLAB API and Vega API.Control signals are read out by invoking library function MLIB/MTRACE of dSPACE.All the input,output,and system state values are acquired by arithmetic and are dynamically associated with the running status of the virtual vehicle.An intelligent vehicle experiment system is thus developed by virtue of program and integration.The system has not only the demonstration function,such as general driving,cruise control,active avoiding collision,but also the function of virtual experiment.Parameters of the system can be set according to needs,and the virtual test results can be analyzed and studied and used for the comparison with the existing models.The system reflects the running of the intelligent vehicle in the virtual traffic environment,at the same time,the system is a new attempt performed on the intelligent vehicle travel research and provides also a new research method for the development of intelligent vehicles.     

Development of a washout algorithm for a vehicle driving simulator using new tilt coordination and return mode

A vehicle driving simulator is a virtual reality device which makes a man feel as if he drove art actual vehicle Unlike actual vehicles, the simulator has limited kinematical workspace and bounded dynamic characteristics So it is difficult to simulate dynamic motions of a multi-body vehicle model In order to overcome these problems, a washout algorithm which controls the workspace of the simulator within the kinematical limitation is needed However, a classical washout algorithm contains several problems such as generation of wrong sensation of motions by filters in tilt coordination, requirement of trial and error method in selecting the proper cutoff frequencies and difficulty in returning the simulator to its origin using only high pass filters This paper proposes a washout algorithm with new tilt coordination method which gives more accurate sensations to drivers To reduce the time in returning the simulator to its ougin, an algonthrn that applies selectively onset mode from high pass filters and return mode from error functions is proposed As a result of this study, the results of the proposed algorithm are compared with the results of classical washout algorithm through the human perception models Also, the performance of the suggested algorithm is evaluated by using human perception and sensibility of some drivers through experiments     

Virtual prototyping simulation for a passenger vehicle

The primary goal of virtual prototyping is to eliminate the need for fabricating physical prototypes, and to reduce cost and time for developing new products. A virtual prototyping seeks to create a virtual environment where the development of a new model can be flexible as well as rapid, and experiments can be carried out effectively concerning kinematics, dynamics, and control aspects of the model. This paper addresses the virtual environment used for virtual prototyping of a passenger vehicle. It has been developed using the dVISE environment model including features, functions, and behaviors is constructed by employing an object-oriented paradigm and contains detailed information about a real-size vehicle. The human model is also implemented not only for visual and reach evaluations of the developed vehicle model, but also for behavioral visualization during a crash test. For the real time driving simulation, a neural network model is incorporated into the virtual environment. The cases of passing bumps with a vehicle are discussed in order to demonstrate the applicability of a set of developed models.     

传动件误差的计算机仿真与分析

以齿轮为例 ,运用机械动力学分析软件ADAMS等对传动件的误差及其对运动精度的影响进行计算机仿真和分析 ,可以直观地分析传动件误差对传动装置运动的影响 ,有助于传动系统的设计 ,也为在虚拟环境中对传动装置进行误差分析 ,提供了一条途径。     

Washout algorithm with fuzzy-based tuning for a motion simulator

In the virtual environment, reality can be enhanced by offering the motion based on a motion simulator in harmony with visual and auditory modalities. In this research the Stewart-Gough-platform-based motion simulator has been developed. Implementation of vehicle dynamics is necessary in the motion simulator for realistic sense of motion, so bicycle dynamics is adopted in this research. In order to compensate for the limited range of the motion simulator compared with the real vehicle motion, washout algorithm composed of high-pass filter, low-pass filter and tilt coordination is usually employed. Generally, the washout algorithm is used with fixed parameters. In this research a new approach is proposed to tune the filter parameters based on fuzzy logic in real-time. The cutoff frequencies of the filters are adjusted according to the workspace margins and driving conditions. It is shown that the washout filter with the fuzzy-based parameters presents better performance than that with the fixed ones.     

变电站巡检机器人虚拟样机系统开发及其研究

利用计算机虚拟环境,将复杂的巡检机器人研发模型真实地展现在设计者面前,并提供与实际情况十分接近的运动学仿真测试。使用软件可以真实地展示产品研发过程中每个环境遇到的问题,并能及时的提出解决方案,缩短产品的研发周期和生产成本,为部门的管理和决策提供了定量的分析依据。     

汽车安全车距的安全度评定系统研究

以汽车行驶过程中的理论安全间距为基础,定义一个安全度的概念。利用函数将汽车的安全度和汽车在各种运行条件下的参数联系起来,以建立一个评估汽车安全的模型,并提出了应用该安全度评估系统的汽车主动避撞系统,及对两种常见的行车状态下安全度变化进行实时仿真的结果。     

基于二分试探的平面冗余机械臂碰撞检测与避障

针对协作机械臂与未知环境安全交互问题,提出基于二分试探的平面冗余机械臂碰撞位置检测与虚拟碰撞空间估计方法,基本思想为碰撞臂杆绕选定二分点旋转微小角位移,期间根据关节电流信息判断是否发生进一步碰撞,从而确定碰撞位置所处二分区间,以此迭代试探缩小碰撞位置估计误差至可接受范围。建立冗余机械臂碰撞臂杆以选定二分点为不动点的逆运动学模型,解决机械臂二分试探运动控制问题;通过简化改进二阶前馈外力观测器,建立基于关节电流的快速碰撞检测算法;根据碰撞位置与碰撞臂杆位姿信息,建立基于包络法的虚拟碰撞空间模型,以近似表征障碍物空间信息。仿真与实验结果表明,所提出的基于二分试探的碰撞位置检测与虚拟碰撞空间估计方法,可为主从任务转化闭环控制避障算法提供有效的障碍物信息,实现平面冗余机械臂安全避障,提高协作机械臂与环境交互安全性。     

虚拟环境中产品动态物理模型构建方法的研究

在虚拟环境中，构建的产品模型是一个包含质量、位置、重量、表面变形、表面纹理、硬度、变形模式等多维物理信息的动态物理模型。动态物理模型以直观的物理方式动态、实时响应用户操作，具有物理特性与几何模型和行为模型相融合的特征。用离散虚拟对象方法构建了可变形的动态物理模型，研究了动态曲面描述、虚拟对象离散的方法，对影响物理模型的主要因素进行了讨论。针对雕塑曲面建立了可变形的动态物理模型，验证了模型的正确性。     

Robust adaptive fault-tolerant control for leader-follower flocking of uncertain multi-agent systems with actuator failure

In this work, we study the flocking problem of multi-agent systems with uncertain dynamics subject to actuator failure and external disturbances. By considering some standard assumptions, we propose a robust adaptive fault tolerant protocol for compensating of the actuator bias fault, the partial loss of actuator effectiveness fault, the model uncertainties, and external disturbances. Under the designed protocol, velocity convergence of agents to that of virtual leader is guaranteed while the connectivity preservation of network and collision avoidance among agents are ensured as well.     

多移动微小型机器人编队控制与协作避碰研究

针对多移动微小型机器人系统的协作避碰和队形保持,给出了一种分布式的编队控制方法。结合移动微小型机器人的运动控制模型,提出了一种路径规划方法,使其在运动中实时避免碰撞。在此基础上利用李雅普诺夫(Lyapunov)法设计了一种编队控制器。在有界误差范围内,该控制器能够保证多机器人的轨迹跟踪和协作避碰。通过将编队控制转化为跟踪整个队形质心的轨迹,降低了控制的复杂度,从而可以较好地应用到计算资源有限的多移动微小型机器人中。通过仿真、分析和对比,对以上控制方法的稳定性和可行性进行了验证,并进行了实际的编队和避碰控制实验。实验结果表明该方法可有效地应用于多移动微小型机器人的协作避碰和编队控制。     

基于Kirchhoff动力学比拟理论的柔性管件维修可视化

为逼真模拟柔性管件在虚拟维修过程中的变形过程,提出了基于横截面假设的软管模型构建方法。将软管的变形过程转换成截面中心受力后的响应过程,结合软管的物理特性,对其进行平衡状态下的受力分析;构建了软管Kirchhoff动力学平衡方程,为便于求解,使用欧拉四元参数法对动力平衡方程进行转换;构建了基于几何约束的圆截面运动微分方程,使用有限差分法对方程进行求解;基于软管模型假设,提出了基于节点间最短距离的碰撞检测方法。最后,以天然橡胶软管为仿真对象,结合其几何特征和物理特征,对其运动过程进行数值模拟,仿真结果证明,该方法可以有效模拟橡胶软管受力后的空间形态。     

基于Creator的塔式起重机建模技术研究

为提高塔式起重机模拟驾驶系统的逼真度,满足视景仿真系统的要求,利用虚拟现实建模软件Multi Gen Creator,结合塔式起重机自身的结构特点,研究了三维实体建模技术和技巧,建立了塔机三维实体模型,通过模型优化有效地减少了多边形的数量。仿真结果表明这一建模技术有效地减少场景驱动过程中系统资源的开支,增加了系统的实时性,并在仿真系统中取得了良好的仿真效果。