基于模糊PID算法的车载液压调平动态特性联合仿真研究

基于车载平台液压调平系统,为了减少支腿的跟踪误差及其同步误差,降低支腿之间的运动耦合,采用模糊PID控制算法实现调平过程中动态特性控制。利用AMESim和MATLAB/Simulink分别建立调平液压回路和模糊PID控制器的仿真模型并进行联合仿真研究。结果表明,加入模糊PID算法比常规PID算法能够有效的减少支腿的跟踪误差和定位误差以及支腿之间同步误差,有效提高调平精度。     

高机动雷达载车平台结构强度分析与优化

文中采用边界位移补偿法优化某高机动雷达载车平台多撑腿结构强度。通过调整撑腿的边界位移,分析不同载荷工况下影响载车平台强度的因素,优化载车平台撑腿调平方案,提高结构强度性能。仿真结果表明,优化方案显著提高载车平台的强度性能,满足雷达载车平台风载荷环境下的强度要求。     

基于Fuzzy-PID控制的调平支腿精确定位的仿真研究

在某型装备多支腿调平过程中,调平液压支腿定位精度和调平策略的选取是影响调平系统整体性能的两个重要因素。为了提高调平系统的整体性能,提出了基于Fuzzy-PID控制器提高单个液压支腿定位精度的方法。利用AMESim及SIMULINK联合仿真技术建立了某装备调平系统的单个液压支腿回路仿真模型和Fuzzy-PID控制器模型,并进行了联合仿真,结果表明,Fuzzy-PID控制器具有较强的鲁棒性,稳态精度高,对时变性和非线性较强的系统具有很好的控制效果。     

基于PSO的模糊PID车载平台调平控制系统研究

为解决车载平台调平控制系统响应速度慢、自适应能力差的问题,对一款液压马达带动滚珠丝杠的调平支腿,建立其数学模型,提出了基于粒子群优化(Particle Swarm Optimization,PSO)的模糊比例积分微分(Proportional Integral Derivative,PID)控制方案.通过结合PSO算法...     

四点调平系统刚柔耦合建模及机液联合仿真

随着调平系统安全性和承载稳定性要求的提高,在提高调平精度的同时,提出了控制各支腿所受载荷不超过一定变化范围的要求。针对四点对称分布的调平系统,分析其数学模型,得出各支腿受力变化的影响因素,通过仿真结果和历史实验数据进行验证。首先利用Motion建立调平系统的三维动力学模型,然后在AMESim中建立液压控制系统模型,最后再对系统进行联合仿真并分析。结果表明,支腿受力大小与对角支腿高度和的差异以及负载偏心程度有关。采用的刚柔耦合模型的机液联合仿真方法,可为类似课题的研究提供借鉴作用。     

Error analysis and auto-calibration for a Cartesian-guided tripod machine tool

This paper focuses on the error analysis and calibration methodologies for a parallel kinematic machine (PKM) called a Cartesian-guided tripod (CGT). The CGT volumetric error due to the geometric error, kinematic parameter error and nonlinear machine stiffness were studied. It is well known that the PKM nonlinear machine stiffness can produce significant volumetric errors from several tens to several hundreds of micrometres depending on the averaged value and deviation range for the machine stiffness. For most PKMs, joint level sensors are used to estimate the virtual Cartesian movements of the cutting tool. The nonlinear stiffness effect is not detected by this indirect metrology method and must be compensated for by a calibration methodology. A solution for the nonlinear stiffness effect implemented on the CGT involves using a passive Cartesian guiding/metrology leg that is independent of the driving legs to directly measure the Cartesian movement of the motion platform. Because the metrology loop of the Cartesian guiding/metrology leg is separated from the kinematic loops of the driving legs, the volumetric accuracy of the CGT is immunised against thermal errors and load deformations on the drive mechanisms. The passive Cartesian guiding/metrology leg is also used for the auto-calibration of the CGT kinematic parameters. The auto-calibration methodology and simulation results were studied and reported.     

3-6Stewart平台安全机构设计

提出了一种通过优化杆长的最大伸长比来进行Stewart平台安全机构设计的方法。首先用 Stewart平台上平面顶点轨迹圆的集合定义了顶点空间 ,并通过设计伸长比 ,生成不同的顶点空间 ;进而在考虑上平面几何约束的条件下建立约束方程 ,在顶点空间内 ,将满足约束条件的机构的设计问题转化为三角形方程组解的存在性问题 ;最后利用 Strum定理来确保在任一组顶点轨迹圆上都存在满足约束条件的实解。仿真实验表明 ,应用该方法设计出的 Stewart平台不但能够满足机构的约束 ,而且具有最大的工作空间。     

3/6-SPS 并联机构刚度和弹性变形的解析法分析

针对并联机构中机构的刚度和弹性变形随外载荷变化的问题,以3/6-SPS 并联机构为例,采用解析法求解分析其总刚度矩阵和弹性变形。首先,分析该并联机构受力位置并确定驱动力及其姿态;然后,分析该机构的驱动约束分支的弹性变形,导出驱动约束分支的伴随矩阵;最后求解出该并联机构的总刚度矩阵和弹性变形。得到结论：当建立3/6-SPS 并联机构的总刚度矩阵和求解弹性变形时,必须理清刚度和位姿、广义六维力之间的关系。     

消防云梯车自动调平系统及调控策略研究

针对消防云梯车作业平台调平控制系统的要求,采用PLC控制液压支撑腿实现自动调平。对预支撑阶段各支撑腿的控制提出了四支撑腿趋向同一平面的控制方法,达到良好的预调平效果,为后面自动调平减轻调节任务,缩短自动调平的时间。     

基于加权广义逆求解被动过约束刚-柔耦合并联机构的受力问题*

提出一种直接应用力映射矩阵的加权广义逆求解一般被动过约束并联机构(指分支提供给动平台的约束力/力偶数目大于等于1的被动过约束并联机构)的超静定受力问题的方法。基于小变形叠加原理和螺旋理论得到了分支约束力螺旋系刚度矩阵的一般表达式。推导一般被动过约束并联机构的各分支约束力螺旋系幅值与六维外力之间的映射关系式,进而证明了该关系式恰好是力映射矩阵的加权广义逆,其中加权矩阵为各分支约束力螺旋系刚度矩阵组成的分块对角阵的逆。以3-RRC空间三自由度被动过约束并联机构和一个并联振动平台为例,直接应用加权广义逆求解了机构各分支约束力螺旋系的幅值,并进行仿真验证。基于加权广义逆求解被动过约束并联机构的超静定受力问题大大简化了求解过程且解的形式统一、简单。     

5R柔性并联机器人系统运动微分方程

为了描述平面5R柔性并联机器人的运动学和动力学特性,需要建立机器人的运动微分方程。针对刚性活动平台和柔性杆件的运动学耦合特点,改进了一套适用于刚体、柔性体耦合的有限元建模方法,推导出单元弹性广义坐标相对于系统弹性广义坐标的转换矩阵,综合考虑了科氏阻尼、离心刚度和几何非线性的影响,利用运动弹性动力学理论,建立了平面5R柔性并联机器人的运动微分方程,避免了采用运动学和动力学约束方程的弊端,提高了建模精度。计算实例表明,该方程反映了机器人的弹性振动特性,杆件的弹性变形对机器人的运动误差具有重要影响。     

球铰刚度计算模型及靠冗余支链实现并联机床刚度的改善

以Stewart机构为例提出一种基于解析法和有限元法的刚度分析新方法。应用有限元软件模拟球铰内的非线性接触变形,将计算结果抽象成一个特征参数带入机构的刚度解析模型中,然后得到机构的刚度矩阵,以解决在解析模型中无法处理铰链刚性的问题,并采用有限元软件证实该方法的可靠性。如果在解析模型中忽略球铰变形,则整个机构的刚度解析结果将产生较大误差。在此基础上,应用该方法定量研究采用主动冗余支链对提高并联机床刚性的效果。结果表明,在一定工作空间范围内,主动冗余支链可以显著提高并联机床的刚性。     

一种仿动物关节或腿刚度的机械腿结构设计方法

针对当前机械腿关节和动物腿关节之间、机械腿和动物腿之间的刚度曲线都有一定偏差的问题,提出了一种仿动物关节或腿刚度的机械腿结构设计方法。基于虚功原理和曲线插值法获得了动物关节或腿刚度曲线方程,并进行了Patran、Nastran、Adams联合仿真,提出了仿动物关节或腿刚度的机械腿结构设计方法及其优化方法。基于人体基本参数及人跳跃过程中腿刚度相关参数,进行了仿人腿踝关节刚度的机械腿结构实例设计和轻量化设计。仿真结果验证了该设计方法的有效性和可行性。     

Improved flexural–torsional stability analysis of thin-walled composite beam and exact stiffness matrix

A simple but efficient method to evaluate the exact element stiffness matrix is newly presented in order to perform the spatially coupled stability analysis of thin-walled composite beams with symmetric and arbitrary laminations subjected to a compressive force. For this, the general bifurcation-type buckling theory of thin-walled composite beam is developed based on the energy functional, which is consistently obtained corresponding to semitangential rotations and semitangential moments. A numerical procedure is proposed by deriving a generalized eigenvalue problem associated with 14 displacement parameters, which produces both complex eigenvalues and multiple zero eigenvalues. Then the exact displacement functions are constructed by combining eigenvectors and polynomial solutions corresponding to non-zero and zero eigenvalues, respectively. Consequently exact element stiffness matrices are evaluated by applying member force–displacement relationships to these displacement functions. As a special case, the analytical solutions for buckling loads of unidirectional and cross-ply laminated composite beams with various boundary conditions are derived. Finally, the finite element procedure based on Hermitian interpolation polynomial is developed. In order to verify the accuracy and validity of this study, the numerical, analytical, and the finite element solutions using the Hermitian beam elements are presented and compared with those from ABAQUS's shell elements. The effects of fiber orientation and the Wagner effect on the coupled buckling loads are also investigated intensively.     

三自由度虚拟轴机床静力学及动力学的若干研究

针对我国特殊钢的钢坯局部修磨问题,开发出一种三自由度虚拟轴机床。建立静力学和动力学方程,并对静力学和动力学特性进行了研究。由于机床的外力和外力矩分别由驱动杆和平行机构承受,其力学模型和位置控制都变得简单易行。通过结构柔度系数矩阵对机床刚度特性进行考虑,表明在工作空间的横截面内,越接近中心,机床刚度越高。动力学方程的仿真表明各杆驱动力有相似性,且运动平台的质量对各杆驱动力的影响较大。     

新型四足步行机器人串并混联腿的运动学分析

针对串联四足机器人行走惯量大,自重/载重比大的问题,提出一种新型串并混联四足步行机器人,并对该机器人的串并混联腿进行运动学分析。该机器人由一个运载平台和四条结构相同的串并混联腿组成,每条腿均由髋关节、大腿、小腿顺次连接构成,其中髋关节为3-RRR并联机构。以能耗最小姿态为最优姿态,基于矢量法求解了该串并混联腿的运动学正解和反解,利用MATLAB和ADAMS软件验证了正解和反解的正确性;基于矢量法和微分变换法求出了该混联腿的速度雅克比矩阵和加速度矩阵,分析了其奇异性,并利用MATLAB软件绘制出该腿的工作空间。结果表明:该腿在髋关节连杆直径d=22mm,大腿杆件直径D=50mm,膝关节转角θ4∈[105°,155°]时,工作空间呈球冠形,最大内接圆半径R=400mm,高度为H∈[500mm,900mm]。本研究对该新型串并混联四足步行机器人的刚度分析、动态性能、机构优化设计和系统控制等的进一步研究具有重要意义。     

基于性能图谱的2自由度RR&PRR解耦球面并联机构承载能力研究

2自由度解耦球面并联机构动平台通过两条支链与静平台连接,第1条支链由两个转动副(R)组成,第2条支链由1个移动副(P)、2个转动副(R)组成。在机构设计无量纲法建立2自由度解耦球面并联机构空间模型的基础上,对该机构的承载能力性能指标进行系统的分析,提出了应用性能指标均值及其波动情况描述机构承载能力性能的新方法,以等值线的形式绘制了该机构的承载能力性能图谱。     

Design and analysis of a tripod machine tool with an integrated Cartesian guiding and metrology mechanism

This paper introduces a novel parallel kinematic mechanism (PKM) machine called Cartesian-Guided Tripod (CGT) developed for high-speed machining of precise dies and molds. CGT has two kinds of functional independent legs, the driving functional leg and the integrated Cartesian guiding/metrology functional leg, parallel-linked to the platform. The guiding/metrology functional leg constraints and measures the platform motions in Cartesian coordinates. Because of the separation of metrology function from the drive mechanisms, the metrology loop of CGT is immunized to the geometric-, thermal-, and force-induced errors of the drive mechanisms. Another feature of this CGT is that the kinematic parameters can be auto-calibrated on line. CGT has explicit solutions of the inverse and forward kinematic analysis. This allows system specifications, such as the footprint/workspace ratio, maximum Cartesian speed/acceleration and even stiffness, be easily related to the machine component specifications. The CGT drive mechanism can be divided into two basic types: sliding leg and telescoping leg. The telescoping leg CGT has the higher edges in the kinematic categories than the sliding leg CGT. Conversely, the sliding leg CGT has better static rigidity and dynamic stiffness than the telescoping leg CGT.     

Modelling and parameter design of a 3-DOF compliant platform driven by magnetostrictive actuators

Precision platforms composed of smart-material-based actuators and compliant mechanisms show advantages of high accuracy and fast response. This research focuses on a 3-degree-of-freedom compliant platform driven by magnetostrictive actuators. A parameterized physical model is established for the platform with consideration of three kinds of coupling effects. The magneto-mechanical coupling of the magnetostrictive actuator is described by a modified Jiles-Atherton model. The structural coupling of the platform is characterized in the process of stiffness matrix modelling and coordinate system transformation of the compliant components. The coupling between the magnetostrictive actuator and the compliant structure is considered in the overall actuation model. Parameter design is performed based on the numerical simulation of the proposed model. Due to the coupling effect, the dimensions of the compliant amplifier affect both the amplification ratio and the actuation stroke of the actuator. Thus, a combined optimization is essential to obtain the optimal design. The influences of the key dimensions on platform stiffness and actuation performances are demonstrated. With optimized key dimensions, the parasitic displacements can be effectively reduced at very little cost of the moving strokes. Open-loop experiments are taken to verify the accuracy of the proposed physical model, and closed-loop experiments are performed to demonstrate the platform performance on precision positioning. The main errors are caused by the friction in a sliding pair and the inertia of the loads.     

基于可拓学方法的耦合设计问题研究

公理设计指导下的产品概念设计不可避免会遇到耦合设计问题。为此,将可拓学中转换桥方法引入耦合问题消解研究,通过分析公理设计中耦合问题和可拓学中对立问题的关系,提出一种应用可拓学进行解耦的方法。由设计矩阵确定耦合问题,进而对耦合问题进行了形式化描述,据此构造出公理设计下基于转换桥的解耦流程。文中以环锭细纱机振动和磨损问题验证了方法有效性和可行性。