Residual Vibration Reduction of High-Speed Pick-and-Place Parallel Robot Using Input Shaping

Because of their elastic links and joints,high-speed parallel robots for pick-and-place operations inevitably suffer from residual vibrations that significantly degrade their positioning accuracy.An effective approach based on the input shaping technique is presented in this paper for suppressing the residual vibration in these parallel robots.After addressing the design principle of an input shaper for a parallel robot with flexible actuated joints,a robust optimal input shaper is developed by considering the configuration-dependent flexible modes and minimizing the maximum percentage of residual vibration at the end-effector.The input shaper allows a good overall performance to be achieved throughout the entire workspace.Experimental results on a 4-DOF SCARA-type parallel robot show that the residual vibration of the end-effector is dramatically reduced and the dynamic positioning accuracy of the robot significantly improved.

Input series out putparallel based multi-modular boost half bridge DC-DC converter with a dynamic control scheme

Multi-modular system plays an important role in power system architecture because low voltage and low power converters can be connected in any combination parallel or series at input/ output side in order to obtained any given power system specifications. Multi-modular boost haft bridge DC-DC converter in the configuration of input series output parallel has been investigated in this paper. The boost half bridge DC-DC converters are connected in input series output parallel con- figuration in order to achieve equal input voltage sharing and output current sharing between the con- verters. This can be achieved with the help of dynamic control scheme which consists of two loops, a voltage loop and a current loop, for each module. Dynamic behavior of multi-modular converter configuration has been observe by varying the load condition. Moreover, the results obtained through multi-modular converter describe that the system has good dynamic and steady state response. Al- though two converter modules are focused in this paper but it can be modified to any number of modules.

Input-parallel output-parallel configuration of boost half bridge DC-DC converter with control strategy

The concept of connecting two boost half bridge DC-DC converter modules in input-paral- lel output-parallel configuration is presented. The input-parallel-output-parallel （IPOP） converter consists of multiple boost half bridge （BHB） DC-DC converter modules which are connected in par- allel at the input and output side. This kind of converter is an attractive solution for high power ap- plications. The correlation between input current sharing （ICS） and output current sharing （OCS） of the IPOP converter basic modules is described. Two loop control strategies, consisting of input cur- rent loop and output voltage loop, have been developed to achieve equal ICS and OCS in this present work. The control strategy for the IPOP configuration of boost haft bridge DC-DC converter has been verified for different load conditions （half load and full load）, The IPOP system proposed here is comprising of two modules but it can be extended to three or more. The performance of the pro- posed system along with the control strategy is verified by simulation in MATLAB using Simpower tool. Finally the satisfactory simulation results are obtained.

Kinematics and Dynamics Analysis of a Quadruped Walking Robot with Parallel Leg Mechanism

It is desired to require a walking robot for the elderly and the disabled to have large capacity,high stiffness,stability,etc.However,the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function.Therefore,Improvement of enhancing capacity and functions of the walking robot is an important research issue.According to walking requirements and combining modularization and reconfigurable ideas,a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed.The proposed robot can be used for both a biped and a quadruped walking robot.The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized.The results show that performance of the walking robot is optimal when the circumradius R,r of the upper and lower platform of leg mechanism are 161.7 mm,57.7 mm,respectively.Based on the optimal results,the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory,and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed,which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process.Besides laying a theoretical foundation for development of the prototype,the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.

ON THE DYNAMIC MODELING AND CONTROL OF 2-DOF PLANAR PARALLEL MECHANISM WITH FLEXIBLE LINKS

The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.

Actuation Spaces Synthesis of Lower-Mobility Parallel Mechanisms Based on Screw Theory

The lower-mobility parallel mechanism has been widely used in the engineering field due to its numerous excellent characteristics.However,little work has been devoted to the actuator selection and placement that best satisfy the system's functional requirements during concept design.In this study,a unified approach for synthesizing the actuation spaces of both rigid and flexure parallel mechanisms has been presented,and all possible combinations of inputs could be obtained,laying a theoretical foundation for the subsequent optimization of inputs.According to the linear independence of actuation space and constraint space of the lower-mobility parallel mechanism,a general expression of actuation spaces in the format of screw systems is deduced,a unified synthesis process for the lower-mobility parallel mechanism is derived,and the efficiency of the method is validated with two selective examples based on screw theory.This study presents a theoretical framework for the input selection problems of parallel mechanisms,aiming to help designers select and place actuators in a correct and even optimal way after the configuration design.

小额信贷、绿色生产投入与农民收入增长——基于有机肥和化学农药施用成本

金融支持是推动农民长效增收的关键因素,其中小额信贷是重要的金融手段。通过将以有机肥和化学农药施用成本代表的绿色生产投入作为中介变量,构建并行中介模型,利用实地调研获得的401份样本数据实证分析小额信贷对农民收入的影响。结果表明:(1)小额信贷对农民收入具有直接的正向促进作用;(2)小额信贷对绿色生产投入中的有机肥施用成本增加和化学农药使用成本减少均产生正向作用;(3)小额信贷能够通过绿色生产投入间接对农民收入产生正向促进作用。为促进小额信贷更好地服务于农民收入增长,应建立政府与金融机构的风险共担机制,利用大数据技术完善小额信贷对农民的补贴制度,强化小额信贷机构和农民的环保意识,加强对有机种植和智慧农业的支持力度。

基于改进下垂控制的多模块谐振变换器均衡控制策略研究

当前,光伏、海上风电等新能源场站的直流汇流应用得到越来越多的关注,在新能源发电低压输入中高压汇流输出的场合,为了提升直流输电电压并进一步减小器件应力,多采用输入并联输出串联(IPOS)结构。虽然这种模块化串并联结构有着许多优势,但由于模块间器件参数误差,导致各模块存在电压电流不均衡的问题,影响整个功率变换系统的稳定运行。为此提出了面向直流汇流应用的IPOS多模块谐振变换器的改进下垂控制均衡方法,各模块间无需加入通信就实现各模块的输出电压和功率的完全均衡,改进了传统下垂控制电压与参考值不符的问题,并进一步提升了系统的动态响应性能。基于该控制方式,搭建了三路模块化IPOS谐振变换器原理样机,通过实验验证了所提改进下垂控制方法对IPOS系统的均衡效果。

基于神经网络的并联机床位姿误差分析与补偿研究

为了解决并联机床位姿误差补偿这一难题,以六自由度并联机床为研究对象,基于并联机床的运动学逆解建立了位姿误差模型,得到了并联机床驱动杆杆长误差和铰链点位置误差与并联机床动平台位姿误差的关系。铰链点位置误差可以通过调整杆长来弥补,由于驱动杆杆长误差难以测量,所以基于BP神经网络设计了一种改进的修正系统输入法对并联机床动平台的位姿误差进行补偿。仿真结果表明,经过补偿后的位姿误差明显小于补偿前的位姿误差,验证了并联机床位姿误差分析与补偿方法的可靠性。

单相无桥功率因数校正变换器拓扑族推演回顾与性能分类总结

随着多种节能标准与低碳政策的实施,单相无桥功率因数校正(power factor correction,PFC)拓扑受到更多关注。目前,虽然多种无桥拓扑已被提出并被应用于不同应用场合,但尚未有文献系统地概述这类无桥PFC拓扑结构特点并开展拓扑性能分析。该文通过将双变换单元进行输入并联输出并联(input-parallel output-parallel,IPOP)、输入并联输出串联(input-parallel output-series,IPOS),提出无桥拓扑族系统推演方法以及无桥拓扑IPOP与IPOS的分类。同时,以6种变换单元为例,推演28种无桥拓扑并作相关拓扑概述,说明无桥拓扑族系统推演方法的普适性。其次,通过对称性与对偶性,进一步简化无桥拓扑族的器件数量。然后,筛选出12种主要无桥拓扑与传统有桥拓扑比较,并分别介绍12种无桥拓扑性能特点。最后,基于性能对比结果,归纳IPOS与IPOP两类拓扑的优缺点与适用场景。

基于双模式分解多通道输入的VSC-STATCOM逆变器故障诊断模型

针对传统电压源型静止同步补偿器中逆变器故障诊断存在的信号特征提取不充分,深度学习网络识别能力不足以及高噪声情况下识别率较低等问题,提出了一种基于双模式分解、多通道输入(MCI)、并行卷积神经网络(PCNN)、双向长短时记忆(BiLSTM)网络和自注意力(SA)机制组合的逆变器故障诊断方法。首先利用变分模态分解和时变滤波经验模态分解对逆变器输出的三相电流进行分解,降低原始信号复杂程度,实现不同模态分量间的规律互补;其次,利用MCI-PCNN-BiLSTM-SA组合模型对特征矩阵进行深层特征提取、学习和识别;最后,通过仿真进行验证,结果表明所提方法特征提取能力较强,在无噪声情况下平均识别率高达99.48%,在高噪声情况下平均识别率达95.59%。

低冗余高可靠模块化输入并联输出串联电源系统及其控制方法

为了使输入并联输出串联电源系统同时具备模块级和系统级冗余能力,提出低冗余高可靠超宽电压范围电路结构及其控制方法。基于两级式电路和多模块串并联实现电源系统超宽电压输出,通过模块级部分子电路冗余设计,实现模块级和系统级N+X双重冗余,使得功率模块部分失效或多个模块全部失效时系统仍具有全电压、全功率输出能力。进一步提出模块化电源系统的分布-集中混合式控制策略,分布式自主控制保证了模块间应力均衡、并使得输出电压在目标值范围内,集中控制确保总输出电压精度。该文详细分析所提电路结构及其控制策略的原理、特性和实现方案,并通过0~1000 V/50 kW输出电源系统实验,验证了所提方案的有效性。

正交三偶极子阵列MIMO雷达近场目标定位

本文基于发射端和接收端都配备了正交三偶极子阵列的双基地多输入多输出(Multiple-Input MultipleOutput,MIMO)雷达系统,结合三线性分解提出了一种近场源多维参数估计算法。该算法首先利用接收端匹配滤波器的输出数据构建了一个三阶平行因子(Parallel Factor,PARAFAC)模型。同时为了加快算法的收敛速度以及避免所提算法对迭代的初值敏感,利用复平行因子分析(COMplex parallel FACtor analysis,COMFAC)算法来得到发射阵列和接收阵列导向矩阵的估计值。接着,根据发射阵列导向矩阵和接收阵列导向矩阵的结构特征得到每个目标的波离角(Direction-of-Departure,DOD)和波达角(Direction-of-Arrival,DOA)的粗估计值,并且基于双基地MIMO雷达阵列系统的几何关系得到从发射阵列到目标的距离以及从目标到接收阵列的距离的粗估计值。最后,基于得到的近场多维参数的粗估计值得到发射阵列和接收阵列的空间相位估计值,并进而从空间相位的估计值中得到更精确的DOD,DOA,从发射阵列到目标的距离和从目标到接收阵列的距离的精估计值。该算法适用于阵元间距为半波长的均匀线性阵列,相比于传统近场定位需满足阵元间隔为四分之一波长的前提,所提的MIMO阵列系统降低了阵列孔径损失,同时所提算法不需要进行谱峰搜索以及额外的参数配对操作。仿真结果表明,基于正交三偶极子阵列的MIMO雷达测向算法较传统标量阵列的算法具有较高的参数估计精度。

具射流反作用力喷砂除锈并联机构自抗扰控制

针对由喷砂除锈并联机构末端喷枪射流反作用力造成的非匹配干扰问题,提出一种喷砂除锈并联机构非线性自抗扰控制方法。采用解析法对并联机构进行运动学分析,采用拉格朗日法建立考虑非匹配干扰的并联机构动力学模型;通过应用等效输入干扰技术将系统的非匹配干扰转换为位于控制输入通道的匹配干扰,并与建模误差、关节摩擦力及外部干扰等集总为系统总干扰;设计非线性扩张状态观测器对系统集总干扰进行实时精确估计和补偿,进一步设计基于扩张状态观测器的自抗扰控制,以增强系统对集总干扰的鲁棒性,同时提高其轨迹跟踪控制性能。最后证明闭环系统的稳定性,并基于MATLAB软件和具射流反作用力喷砂除锈并联机构样机,对所提出控制方法进行仿真和样机实验,实验结果验证了所提出方法的有效性。

基于降维变换的低复杂度双基地EMVS-MIMO雷达高分辨多维参数估计

针对当前算法在实现双基地电磁矢量传感器多输入多输出(electromagnetic vector sensors multiple input multiple output,EMVS-MIMO)雷达的多维参数估计时计算代价较高的问题,通过利用降维变换技术来实现低复杂度的角度参数和极化参数求解。针对阵列接收数据维度较大问题,通过设计相应的波束空间变换矩阵来实现对阵列接收数据的降维处理。针对算法本身的较高计算复杂度问题,采用低计算复杂度的平行因子分解算法。所提算法能够精确地实现对发射因子矩阵和接收因子矩阵的求解。同时,通过新的旋转不变关系构建新的估计信号参数,可以实现对发射/接收俯仰角的求解。进一步,发射/接收方位角、发射/接收极化角和发射/接收极化相位差的估计可以通过发射/接收空间响应矩阵的重构来实现。仿真实验结果表明,所提算法在降低计算复杂度的同时能够保持优越的多维参数估计性能。

基于并行小波算法的多模态数据近似匹配模型构建

针对近似匹配过程易受数据冗余性、异构成分等的影响,提出了基于并行小波算法的多模态数据近似匹配模型。该模型首先采用并行小波算法剔除多模态数据中的噪声,避免噪声对匹配过程产生影响;其次采用张量分解的聚类算法将不同相似度的数据划分到不同类簇中,以消除不同类簇的数据差异度;最后将预处理后的数据输入到基于空间方向近似性的数据匹配模型中,通过计算参考数据与待匹配数据之间的空间方向近似度、编辑距离完成多模态数据的近似匹配。实验结果表明,所提方法的匹配查准率高、查全率高、匹配时间短。

具备低电压穿越能力的自均压型混合直流变换器研究

输入串联输出并联型(input-series output-parallel,ISOP)直流变换器广泛应用于能源互联网中的直流电网场景,其关键问题在于解决系统模块间输入电压不均衡。为此,结合谐振型和移相型双有源桥(dual active bridge,DAB)变换器,提出一种具备自适应均压能力的混合型模块化ISOP型直流变换器,系统同时具备谐振型DAB的高效率和移相型DAB的灵活控制能力。通过在DAB源端的滞后桥臂中点增设无源的LC谐振支路,该谐振支路与相邻子模块的2个半桥模块共同构成非隔离型双有源半桥,以此来实现系统输入电压的自适应均衡。此外,提出一种低电压穿越(low voltage ride-through,LVRT)方法,在DAB前端连接电压调整模块,模块内部的高频变压器的副边串联电感,当系统输入输出侧发生电压跌落时具备故障穿越的能力,提高系统的暂态可控性。最后,在MATLAB/SIMULINK环境下搭建模型进行验证,可以证明系统的自适应均压性能及故障穿越方法的有效性。

基于并联加载技术的中波三频共塔天调网络性能优化问题

对于中波三频共塔而言,天调网络在603 kHz频点处的Q值会显著上升,进而引起网络带宽极速降低,直接影响网络运行的安全性。深入研究了中波三频共塔的技术特点和天调网络的运行机理,利用并联加载技术改造铁塔,通过提高发射天线输入阻抗降低603 kHz工作频点处的Q值,可有效提升天调网络运行的安全性和可靠性。

一种基于平行因子分解的电磁矢量传感器MIMO雷达测向算法

现有的电磁矢量传感器?多输入多输出(Electromagnetic vector sensor multiple?input multiple?output, EMVS?MIMO)雷达大多限制收发阵元以半波长约束分布,极大限制了雷达测向的分辨率。针对此问题,本文提出了一种基于平行因子(Parallel factor, PARAFAC)分解方法对目标进行二维角度估计的算法,该算法适用于所有任意发射阵列几何以及任意稀疏的接收阵列几何。首先,对接收阵列的匹配滤波后的信号构造三阶平行因子张量模型。然后,利用PARAFAC分解,得到发射方向、接收方向以及复合因子矩阵的估计值。最后,联合旋转不变法、矢量叉积法和最小二乘法,得到目标的高分辨率、无模糊特性二维角度估计的闭式解。本文所提出的算法具有精度高、计算复杂度低的特点,计算机仿真验证了基于张量分解的算法在任意双基地EMVS?MIMO雷达模型上的应用,该算法能够准确地估计出多个目标的二维角度参数,证明了所提算法的有效性和优越性。

IPOP型双有源桥变换器均流控制方法研究

为提高双有源全桥变换器的功率容量,各种模块化组合方式被相继提出。基于输入并联输出并联的模块化组合方式,首先建立了变换器的降阶小信号模型,然后分析了变换器相与相间的均流原理并给出了变换器的相固有参数估算方法和并联均流控制策略,最后基于仿真模型对所提出的控制方法的合理性和正确性进行了验证。