单线激光雷达摆动扫描装置及其控制

为弥补单线激光雷达在获取障碍物的几何形状信息上能力较弱的缺点,采用了一种基于无急回特性曲柄摇杆机构的ALV车载激光雷达摆动装置;分析了曲柄摇杆机构的运动特点及无急回特性装置杆长条件;为实现激光雷达在车体平面匀速扫描功能,使用多项式拟合的方法计算出驱动曲柄旋转的直流电机转速与激光雷达摆角之间的关系;建立了系统数学模型,设计了直流电机转速PID控制器,仿真结果表明当负荷力矩不断变化时,系统响应速度快,跟踪误差小;实验数据证明该激光雷达摆动装置实现了期望功能,性能可靠,能够满足ALV主动环境感知的要求.     

一级倒立摆状态反馈控制系统设计

倒立摆控制系统是一个复杂的、不稳定的、非线性系统,对倒立摆系统的研究能有效的反映控制中的许多典型问题。对一级直线型倒立摆,首先运用牛顿运动定律建立倒立摆系统的运动方程,进而求出系统的状态空间表达式,建立数学模型。其次运用状态反馈极点配置法,以小车的位移、速度,摆杆与竖直向上的偏角、摆角变化速度作为四个状态变量,由给定的控制要求求出状态反馈增益矩阵,将极点配置在控制要求的位置。另外考虑到系统的某些状态如小车速度和摆杆角速度不容易直接测量等,本文分别基于小车和摆杆子系统设计了两个全维观测器,分别对状态量进行了重构并给出了仿真结果分析。     

基于单片机的电磁控制运动系统

系统以单片机STC89C52RC主控核心,STC89C52RC根据预置摆角和周期值输出一定占空比的PWM脉冲波,通过L298N驱动调节电磁铁电压,实现对摆杆摆角与周期的控制。同时应用摆杆支撑轴悬挂的角度传感器SYD35D4输出的模拟电压信号,经A/D转换电路MAX1113转换为数字信号,送至单片机处理后,最终在LCD上直观显示测量摆角、预置摆角、测量周期、预置周期。     

一种利用GPS测量降落伞摆角的方法

空降过程中降落伞摆角的大小是降落伞稳定性的一项重要性能指标。提出了利用单GPS测量降落伞摆角的方法,并利用该方法进行了实际的测量实验。结果表明：该测量系统能够实时获得降落伞在空中的摆角值,较为精确地反映了降落伞摆角的变化趋势。     

一种吊钩摆角远程无线监测系统的设计

起重机吊装作业中吊钩若出现偏摆则可能会造成事故,因此加强吊钩摆角监测十分重要.在充分分析了起重机吊装作业的实际环境,以及对吊钩偏摆监测的应用模式基础上,提出了一种基于微机电系统(MEMS)的吊钩摆角无线测量方案,通过测量吊钩的姿态角与起重机的方位角,建立数学模型,进行融合计算得出吊钩的偏摆角.所设计的系统采用JY901模块作为传感单元,以ZigBee作为无线传感网络,采用3G通信技术将数据传输到云端解析,最后基于B/S模式进行远程监测.该系统易于安装,便于监测,完全适用于起重机现场的作业环境.     

基于骨架模型的运动机构的优化设计

在Pro/E中,骨架模型为运动机构的概念设计提供了一个强大的工具,也为在Pro/E中进行运动机构的优化提供了方便。合理设计骨架模型,可使得机构优化更加快捷、准确、直观。     

Pro/ENGINEER和3DVIA Composer在机械类专业教学中的应用

本文以《机械基础》为例,介绍了Pro/ENGINEER和3DVIA Composer在机械类专业课程教学中的应用。先以实例介绍了利用Pro/ENGINEER wildfire4.0的Mechanism模块进行单缸机构设计和仿真运动,并进行运动学分析及获取测量数据;同时介绍了应用3DVIA Composer将3D设计软件(如Pro/ENGINEER)的设计成果制作成3D动画交互式PPT课件的详细步骤。     

防摆吊具刚柔耦合动力学分析与结构拓扑优化

传统吊装夹具应用在有色金属板电解、检测、分拣等工序的搬运等过程,易会出现摆动磕碰等情况,需要设计一种在吊装运动过程中可以防止金属板摆动和减少对金属板表面质量损坏的防摆机构。通过在Pro/E中建立吊装夹具三维模型并装配出整体机构,由于防摆机构在工况下高速运动并且为薄板零件,所以通过柔性体替代刚体进行动力学分析,以模仿真实运动情况。利用HyperMesh做模态分析,导出MNF文件到ADAMS中,建立机构的刚柔耦合模型。动力学分析输出各构件在防摆机构夹紧运动过程中各铰接处的受力情况以及接触处的冲击载荷。利用OptiStruct进行拓扑优化使得机构整体结构减重48.1%,减轻工业机器人的工作负载,减少对金属板表面的冲击,以获取更好的运动性能。     

摇杆式履带悬架的构型推衍及其在煤矿救灾机器人上的应用

为使机器人行走机构既能被动地适应崎岖的非结构地形,又能克服台阶、沟道等规则障碍,将履带行 走机构引入摇杆式移动系统中．通过增加摆臂履带和固定关节角,推衍了多种型式的摇杆式履带悬架构型,分析了 各悬架构型的特点．结合煤矿井下非结构的地形环境与爆炸性气体环境,提出了一种采用对称的W 形履带悬架的 摇杆式履带机器人移动系统,并制作了样机．分析了该移动系统的抗倾覆、攀爬台阶、下台阶、跨越沟道等越障特 性并进行了性能试验．性能分析与样机试验表明,摇杆式履带机器人移动平台可适应复杂的非结构地形,具有良好 的越障性能,可攀爬100 mm 高的台阶,下450 mm 高的台阶,跨越260 mm 宽的沟道．     

基于MEMS的吊车系统摆角无线测量

提出并实现一种基于微机电系统(MEMS)的吊车系统摆角无线测量方案。测量系统包含2套具有无线通信功能的基于MEMS的航姿参考系统(AHRS)模块,一套安装在吊车本体用于检测吊车本体的空间姿态,另一套安装于吊钩用于检测负载的空间姿态,以吊车本体姿态为基准校核负载的空间姿态,计算得到负载相对吊车本体的空间摆角。对提出的吊车系统摆角测量技术搭建了实验装置进行验证,实验模块集成Zig Bee无线通信和基于MEMS的AHRS。实验结果表明:装置能够有效实现吊车系统摆角的有效测量。     

一种圆形指针式仪表倾斜检测方法

圆形指针式仪表的倾斜,不利于仪表数字参数区域字符图像的定位和识别。提出一种基于检测仪表名称倾斜的方法来获得圆形指针式仪表的倾斜角度。该方法将仪表表盘上的仪表名称看成一个整体,结合Canny算子、形态学与Hough变换算子来检测其倾斜角度,然后根据该倾斜角度绕仪表表盘中心点对表盘进行旋转校正,使仪表参数区域字符回到固定位置,方便仪表数字参数区域字符的定位与提高数字字符识别的正确率。实验结果表明：该算法能快速准确地检测出圆形指针式仪表图像的倾斜角度,有一定的实用价值。     

Fuzzy ARTMAP classification of invariant features derived using angle of rotation from a neural network

Conventional regular moment functions have been proposed as pattern sensitive features in image classification and recognition applications. But conventional regular moments are only invariant to translation, rotation and equal scaling. It is shown that the conventional regular moment invariants remain no longer invariant when the image is scaled unequally in the x- and y-axis directions. We address this problem by presenting a technique to make the regular moment functions invariant to unequal scaling. However, the technique produces a set of features that are only invariant to translation, unequal/equal scaling and reflection. They are not invariant to rotation. To make them invariant to rotation, moments are calculated with respect to the principal axis of the image. To perform this, the exact angle of rotation must be known. But the method of using the second-order moments to determine this angle will also be inclusive of an undesired tilt angle. Therefore, in order to correctly determine the amount of rotation, the tilt angle which differs for different scaling factors in the x- and y-axis directions for the particular image must be obtained. In order to solve this problem, a neural network using the back-propagation learning algorithm is trained to estimate the tilt angle of the image and from this the amount of rotation for the image can be determined. Next, the new moments are derived and a Fuzzy ARTMAP network is used to classify these images into their respective classes. Sets of experiments involving images rotated and scaled unequally in the x- and y-axis directions are carried out to demonstrate the validity of the proposed technique.     

联合收割机清粮筛的运动仿真与优化

清粮筛筛面的运动状态是影响清粮性能的关键因素.为了优化清粮筛机构的工作参数(结构参数和运动参数),提高清粮性能,运用CAD/CAE运动学仿真软件对清粮筛进行了3D建模和运动仿真分析,考察了筛面加速度的变化规律.仿真结果表明:在相同的变动比例下,筛面的加速度对连杆长度的变化最为敏感;曲柄的转速对筛面的加速度也有重要的影响.因此选择连杆长度和曲柄转速作为关键参数,以振动最小和筛面加速度最大为优化的目标.经优化:该机构在谷物清选时, 清粮筛的其他结构参数不变,连杆LAB =0.46 m、曲柄转速n= 330 r/min为最佳.     

Comparative analysis of a new 3×PPRS parallel kinematic mechanism

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications. However, constraints such as end-effector rotation (i.e., platform tilt angle) and configuration-dependent stiffness often limit their usage. A new six degree-of-freedom (dof) PKM architecture based on a 3×PPRS topology that addresses these concerns is presented in this paper – specifically, the proposed PKM can achieve high (end-effector) tilt angles with enhanced stiffness. The mechanism is also compared with similar three known 6-dof architectures, through which it is shown that the proposed PKM indeed exhibits higher stiffness relative to these three reference PKMs. The static stiffness is derived using matrix structural analysis, and the dynamic stiffness is obtained via finite-element analysis. A prototype of the proposed PKM that was designed and built is presented.     

Tilt detection and servo control method for the holographic data storage system

Recently photopolymer with disk type substrate is selected as a media of the holographic data storage system. Because shape of the media is a disk, a disk tilt must be occur when the media rotates. When disk tilt occurs the angle between the reference beam and the media is changed by the tilt, thus the data can not be recorded with a right angle or another data page is retrieved. The holographic data storage system is very weak to the tilt disturbance by the Bragg effect, therefore it is necessary to detect the disk tilt angle and compensate it. In this study, we measure the amount of the tilt error using external photo detector and compensate it by rotating the angle of galvano mirror with our own algorithm.     

立方氮化硼抛光过程的计算机仿真技术

为了提高立方氮化硼超硬材料的抛光效率,采用计算机仿真技术开发了曲柄摇杆抛光机构.从运动学和几何学原理出发,建立了曲柄摇杆机构的数学模型,得出了工件中心点的瞬时速度和运动轨迹,并开发了相应的计算机动态仿真软件,以图形的形式显示了工件中心点运动轨迹曲线以及瞬时速度曲线.研究了曲柄摇杆机构中各杆长度对工件中心点运动轨迹及瞬时速度的影响规律,寻求出了符合设计条件的最优组合参数,并将其成功地用于立方氮化硼材料的精密抛光技术中,加工效率比传统的抛光方式提高50%,取得了良好的效果.计算机仿真技术的应用,为新型机床的设计提供了一种简便有效的分析方法.     

Optimal design of discrete-value tilt angle of PV using sequential neural-network approximation and orthogonal array

This report presents a method for combining sequential neural-network approximation and orthogonal arrays (SNAOA) to determine the tilt angle for photovoltaic (PV) modules. An orthogonal array is first conducted to obtain the initial solution set. The set is then treated as the initial training sample. Next, a back-propagation sequential neural network is trained to simulate the feasible domain for seeking the optimal tilt angle of PV modules. The size of the training sample is greatly reduced due to the use of the orthogonal array. In addition, a restart strategy is also incorporated into the SNAOA so that the searching process may have a better opportunity to reach a near global optimum. The objective is to maximize the output power energy of the modules. In this study, seven Taiwanese areas were selected for analysis. The sun’s position at any time and location was predicted by the mathematical procedure of Julian dating; then, the solar irradiation was obtained at each site under a clear sky. To confirm the computer simulation results, an experimental system is conducted for determining the optimal tilt angle of the PV modules. The results show that the annual optimal angle for the Taipei area is 23.25°; for Taichung, 22.25°; for Tainan, 21.25°; for Kaosiung, 20.75°; for Hengchung, 20.25°; for Hualian, 22.25°; and for Taitung, 21° in Taiwan, and the actual best annual tilt angles are close to the computer simulation results. Additional results related to SNAOA are also reported and discussed as well.     

Naturalistic data collection of head posture during smartphone use

Association between smartphone use and head-down tilt posture has not yet been quantitatively evaluated in natural settings. This study aimed to objectively assess the angle and duration of head-down tilt posture of smartphone users during a typical working day via naturalistic data collection. Thirty-one college students conducted their typical school activities while their head posture and smartphone-app usage records were collected simultaneously for 8?hours. Participants spent 125.9?minutes (median usage duration) on their smartphones with significantly larger head-down tilt (p?<?.05) than when they were not using the phone. Head tilt angle greater than 30° was found to be more common when using the phone, while head tilt less than 20° was more common when they were not using the phone. Study findings provide empirical evidence that supports an association between the duration of smartphone use and the intensity of head-down tilt posture.

Practitioner Summary: Head postures of young smartphone users were quantified for 8?hours continuously during a typical workday using a wearable sensor. Participants spent more time in larger head-down tilt postures (greater than 30°) when they were using their smartphones as compared to when they were not using them.     

EO characteristics for a photoaligned VA‐1/4 π cell on a photopolymer layer

The generation of a liquid‐crystal (LC) tilt angle on a copolymer with chalconyl and cholesteryl moiety characteristics was performed, and the electro‐optical (EO) performance of the photoaligned vertical‐alignment (VA) 1/4 π cell by polarized UV exposure on a homeotropic photopolymer surfaces was studied. The LC tilt angles decreased as UV exposure time increased on the copolymer surfaces. A tilt angle of 87° in NLC was observed with an UV exposure of 3 min on the photoalignment‐2 surface. The LC tilt angle is attributed to increased chalcone moiety with increasing UV exposure time. Excellent voltage‐transmittance (V‐T) curves of the photoaligned VA 1/4 π cell by polarized UV exposure on the photopolymer surface for 3 min containing a cholesteryl moiety of 8% were obtained. The V‐T and response‐time characteristics can be improved by the presence of a cholesteryl moiety in the photopolymer.     

Study on wet patterning of thin films in vertical‐transfer wet station for thin‐film‐transistor manufacturing

Abstract— To overcome the “pseudo‐puddling effect” in a low‐angle‐tilt transfer system with an oversized glass substrate over 2 m, a vertical transfer is suggested. The aim of the present work is to study the wet‐etching behavior of an aluminum/molybdenum double layer deposited on the glass substrate in a vertical transfer wet etching system and compare it with a typical 5°‐tilt‐transfer system. Compared with the tilt‐transfer wet station, the vertical etching system has three advantages, namely, 50% space savings, higher throughput due to the high etch rate, and good etch uniformity over the entire glass for thin‐film‐transistor application. The computational fluid‐dynamics analysis is used to predict the change of the etch uniformity as a function of the tilt angle of the glass substrate.