Extreme reaches and reachable workspace analysis of general parallel robotic manipulators

This article presents a systematic numerical method for analyzing the extreme reaches and the reachable workspace of general parallel robotic manipulators. In this method, finding the extreme reach is formulated as an optimization problem. The closed loops of the robot are virtually disconnected into open kinematic chains. Violations of the loop closure constraints and the position error of the end-effector are included in the objective function as penalty terms. This formulation not only is conceptually straightforward, but also can effectively reduce the problem size. The problem is solved by using a two-stage sequential unconstrained minimization algorithm. A procedure for determining the boundary surfaces of the reachable workspace is also presented. © 1998 John Wiley & Sons, Inc. 15: 145–159, 1998     

高速列车空气动力学CAE分析技术的任务和方向

针对中国高速列车运营时速已接近380km／h,高速列车技术已完成消化吸收并进入国产原创阶段的状况,综述高速铁路设计中CAE分析技术的应用、高速列车计算流体力学（Computational Fluid Dynamics,CFD）分析的3大任务以及高速列车空气动力学CAE分析技术的方向等,总结CAE在高速列车气动分析方面的任务和方向．阐明CAE分析已成为新一代高速列车设计和结构分析的核心技术,空气动力学CAE分析技术则占据设计分析的核心地位．     

采用FPGA的高速CCD相机的时钟发生器

采用IL－E2 TDI CCD做为传感器，与计算机构成了成像系统，并在计算机CRT上显示出图像。主要介绍高速CCD相机的工作时钟产生电路的设计，采用大规模集成电路FPGA实现了该工作时钟驱动电路，采用AHDL语言对工作时钟驱动电路进行了硬件描述，并利用Max Plus2软件对所设计的工作时钟驱动电路进行了仿真，最后对FPGA器件进行了编程和硬件电路调试，进而实现了整个CCD相机的控制。     

基于空气流体动力学的高速列车制动盘散热性能模拟

基于CFD法分析高速列车制动盘的散热情况,得到制动盘各个区域的平均对流换热系数.在此散热条件下,用顺序耦合法模拟制动盘的温度场,实现复杂六边形热载荷的加载,并将二次制动温度场的模拟结果与试验数据进行对比分析.结果表明：模拟结果与试验数据在冷却阶段吻合度较高,且在制动阶段中最高温度值误差不超过5%.     

Comparison of surface roughness quality obtained by high speed CNC trimming and high speed robotic trimming for CFRP laminate

This paper proposes an experimental approach for evaluating the surface roughness of the CFRP parts produced by high speed CNC trimming and high speed robotic trimming under various cutting conditions. A comparison is made between the surface roughnesses obtained by the two processes. The results obtained show that, the measured profiles obtained from high speed robotic trimming are dominated by a large trajectory deviation, as compared to machine tool trimming results. After the trajectory deviation effect is discounted, the results show that for the +45° ply orientation, the surface quality obtained through high speed robotic trimming is similar to what is obtained with the CNC machine. Furthermore, a significant relationship was observed between the surface quality and the ply orientation, whatever the machining process and the cutting conditions employed. The −45° ply orientation represents the worst case in terms of surface roughness, whatever the machining process. It is 4 times higher compared with that of +45° ply orientations,The results also show that the effect of cutting conditions on surface quality is significant for both machining processes tested.     

高速球形摄像机PTZ跟踪策略设计及实现

针对智能监控中基于高速球形摄像机的PTZ跟踪功能模块,设计了一种PTZ跟踪控制策略。该策略在球机机械参数未知的情况下,一方面能控制球机实时地跟踪目标使目标始终处于视野中央,另一方面可自动进行变倍动作来放大拍摄目标的局部细节。针对球机Zoom控制中跟踪窗口大小自适应调整的问题,利用SIFT算法设计了一种计算球机变倍率的方法。利用VS2005和OpenCV软件平台实现了PTZ跟踪的整体流程。实验表明,该策略能有效、稳定地进行PTZ跟踪。     

基于FPGA的高速工业相机的设计与实现

介绍了一种基于FPGA的高速工业相机的实现,其中包含了CCD、AD驱动,数据预处理,UART接口以及Cameralink接口的设计,并给出了设计实际运行的结果。此相机可稳定可靠高速地完成大分辨率图像采集工作。     

Analysis of trajectory deviation during high speed robotic trimming of carbon-fiber reinforced polymers

Although carbon-fiber reinforced polymers (CFRPs) are used extensively in the aerospace industry, trimming of CFRPs in high speed robotic end milling has however not yet received its due attention within the research community. For such an application, the robot should be very stiff for the machining operation to be generated. If the robot is not sufficiently stiff, deviations in shape and position of the workpieces will occur.     

Spindle configuration analysis and optimization considering the deformation in robotic machining applications

Robotic machining is an increasing application due to various advantages of robots such as flexibility, maneuverability and competitive cost. For robotic machining, the machining accuracy is the major concern of current researches. And particular attention is paid to the proper modeling of manipulator stiffness properties, the cutting force estimation and the robot posture optimization. However, through our research, the results demonstrate the spindle configuration largely affects the deformation of the robot end-effector (EE). And it may even account for approximately half of the total deformation for machining applications with the force acting perpendicular to the tool. Furthermore, the closer distance between the tool tip and the EE does not mean that the deformation tends to be smaller. Thus, it is reasonable to consider optimizing the spindle configuration based on the optimal robot posture, thereby exhausting advantages of the robot and further reducing machining errors. In this paper, a spindle configuration analysis and optimization method is presented, aiming at confirming the great influence of the spindle configuration on the deformation of the robot EE and minimizing it. First, a deformation model based on the spindle configuration (SC-based deformation model) is presented, which establishes a mapping between the spindle configuration and the deformation of the robot EE. And it confirms the large effect of the spindle configuration on the deformation of the EE. Then, a complementary stiffness evaluation index (CSEI) is proposed. And it adopts matrix norms to evaluate the influence of the spindle configuration on the complementary stiffness matrix in the SC-based deformation model. Using this index, the proposed SC-based deformation model is simplified for the ODG-JLRB20 robot adopted in this paper. Finally, a spindle configuration optimization model is derived to minimize the simplified SC-based deformation model using an iterative procedure. With this model, the optimal spindle configuration with respect to the EE can be obtained for a specific machining trajectory. Experimental results conducted on the ODG-JLRB20 robot demonstrate the correctness and effectiveness of the present method.     

大面阵CCD相机高速图像压缩系统设计

针对大面阵CCD相机高分辨率、高帧频等特点,提出了一种适用于大面阵CCD相机高速实时图像压缩的系统。实验结果表明,该方案在压缩比为53:1时峰值信噪比可以达到36 dB,取得了很好的压缩性能。     

A novel approach for tracking high speed skaters in sports using a panning camera

This paper presents a computer vision system for tracking high-speed non-rigid skaters over a larger rink in short track speed skating competitions. The outputs of the tracking system are spatio-temporal trajectories of the skaters which can be further processed and analyzed by sports experts. To capture highly complex and dynamic scenes, the camera pans very fast, therefore, tracking amorphous skaters becomes a challenging task. We propose a new method for (1) automatically computing the transformation matrices to map each frame to the globally consistent model of the rink; (2) incorporating the hierarchical model based on the contextual knowledge and multiple cues into the unscented Kalman filter to improve the tracking performance when occlusions occur; (3) evaluating the precision of our practical system objectively. Experimental results show that the proposed algorithm is very efficient and effective on the video recorded in the World Short Track Speed Skating Championships.     

高速数字电路的串音现象研究

在数字信号的高速传输中,信号完整性的问题已越来越受到硬件工程师的高度关注。串音现象是信号完整性的问题之一,随着印刷电路板的布线密度增加,尤其是长距离并行线的布局,更容易发生串音现象。从上升沿时间、跨分割平面、传输模式、中间保护线是否接地四个方面阐述了影响串音的因素,并提出了相应的解决方法。     

高速电路的信号完整性分析

介绍了高速PCB设计中的信号完整性概念以及破坏信号完整性的原因,从理论和计算的层面上分析了高速电路设计中反射和串扰的形成原因,并介绍了IBIS仿真。     

高速受电弓非定常气动特性分析

为保证高速列车受电弓与接触网之间具有良好的接触特性,针对强烈气流干扰会引起受电弓振荡的问题,用脱体涡模拟(Detached Eddy Simulation,DES)方法研究高速列车受电弓在开、闭口运行条件下的非定常抬升、阻力特性.结果表明,开、闭口运行对受电弓气动特性的影响有较大不同,尤其对受电弓及其滑板的抬升力波动影响明显.开口运行时整弓和滑板的抬升力波动幅度明显大于闭口运行;而开、闭口运行对整弓和滑板气动阻力的大小与波动幅度的影响很小。     

基于高速嵌入式系统的信号完整性分析

提高信号完整性、减小串扰和反射是高速电路系统设计能否成功的关键.本文基于以ARM1176JZF-S S3C6410为核处理器的嵌入式开发系统,对高速电路进行了研究.通过信号完整性仿真分析,解决了DDR SDRAM差分时钟信号的反射问题和视频输出信号的串扰问题.     

基于CCD的航空相机镜头焦距自动测量系统

介绍了一种以线阵CCD固态传感器取代读数显微镜 ,能自动测量和实时显示结果的航空相机镜头焦距测量系统 ,论述了系统的工作原理、软件和硬件的设计及该系统的测量误差     

某航测相机的控制系统设计

就某航测相机控制分系统中的主要部分设计进行了比较详细的阐述。该相机控制系统主要包括测光机构控制、凸轮驱动控制、多快门同步控制、CCD相机同步控制、调光控制等部分。各部分依据控制流程,统一协调工作实现拍摄任务。     

六自由度机械臂建模与工作空间分析

在危险环境条件下,为确保人员安全,考虑使用机械臂代替人类的工作,针对以上需求设计一种六自由度机械臂。根据D-H多体运动学建模方法,分析建立机械臂各关节坐标系并确定连杆参数,建立机械臂的运动学模型;通过齐次变换推导末端执行器的姿态和位置,通过仿真和数学计算结果比较证明建模的准确性。根据关节空间到工作空间的映射关系,采用蒙特卡洛法分析、求解机械臂的工作空间,在MATLAB中描绘出工作空间的三维云图。为后续的机器人轨迹规划、运动控制和参数优化提供参考。     

航空相机稳定平台控制算法设计及其像移补偿

飞行过程中飞机姿态角速度变化会对摆扫式航空相机产生干扰,另外相机在拍摄时飞行方向上的景物与感光介质之间存在相对运动。为消除姿态角速度的干扰和前向像移,设计了一种基于F28335的机载相机两轴稳定平台系统。探讨了伺服控制系统的算法选择,介绍了硬件结构和软件流程。通过摇摆台试验证明,该两轴稳定平台动态精度高、运行可靠,满足相机拍摄时序和精度的要求。     

Analytical approach to sensitivity analysis of flutter speed in bridges considering variable deck mass

Design techniques based upon sensitivity analysis are not usual in the current design of suspension bridges. However, sensitivity analysis has been proved to be a useful tool in the car and aircraft industries. Evaluation of sensitivity analysis is a mandatory step in the way towards an efficient automated optimum design process which would represent a huge jump in the conception of long span bridges. Some of the authors of this paper were pioneers in establishing a methodology for obtaining the sensitivity analysis of flutter speed in suspension bridges a few years ago. That approach was completely analytical and required the evaluation of many matrices related to the phenomenon. In those works the total mass of the deck was considered as constant and such a circumstance supposed a limitation of the method. In the present paper the complete analytical formulation of the sensitivity analysis problem in bridges considering variable deck mass is presented, as well as its application to the design problem of the Great Belt Bridge. Analytical evaluation of sensitivities is a time demanding task, and in order to avoid excessive computation times, distributed computing strategies have been implemented which can be considered as an additional benefit of this approach. For the application example, it has been found that deck cross-section area and torsional inertia are the structural properties with the greatest influence on the flutter performance.