杆式风洞应变天平动态解耦-补偿

采用串行动态解耦-补偿网络实现多维力/力矩传感器的动态解耦-补偿,对已有的设计方法进行了改进。基于单通道加载实验数据,通过系统辨识方法设计网络的各个环节。具体针对六维杆式风洞应变天平,采用负阶跃单元加载法进行动态标定实验。对力矩加载实验数据进行预处理。采用OE模型描述串行动态解耦-补偿网络中的各个环节,通过基于预报误差的系统辨识方法确定其参数。对实验数据处理的结果表明,所设计的杆式风洞应变天平动态解耦-补偿网络能将杆式天平的维间动态耦合误差由高至88.85%降低至6%以内,主通道阶跃响应调节时间缩短至30 ms以内且超调量降低至5%以下,从而大幅度改善了杆式风洞应变天平的动态性能。     

悬挂式测力天平频响函数研究

对风洞天平进行动态特性研究有助于评估天平结构设计的合理性,频响函数可以直观反映测试系统的动态特性.针对一种新型悬挂式测力天平,设计一种动态标定装置并进行了相关实验.采用电磁铁和砝码对飞行器模型施加负阶跃载荷,由输入载荷和天平输出辨识频响函数.辨识频响函数时,通过布莱克曼窗和数据段重叠对数据进行预处理以回避周期延拓问题....     

风洞用盒式应变天平系统动态响应分析

建立与盒式应变天平系统等效的质量-弹簧-阻尼系统理论模型,并以此理论模型为基础,对其进行系统动态响应分析。分析时,通过改变盒式应变天平系统中测量元件的刚度,得出该天平系统中不同质量块在给定的动载作用下的位移响应。计算结果表明测量元件的刚度越大,结构的响应频率越高,质量块的位移响应曲线与所加动载荷的形式越吻合。基于此结论,根据输入的载荷形式,通过调节测试元件的刚度,使计算结果能够准确地反映出载荷的真实情况,从而为基于响应曲线反推外加动载荷提供理论指导。     

应变天平系统动力学分析

针对应变天平系统在风洞实验中测量非定常载荷时存在明显不确定度的现象,采用有限元软件ANSYS对天平系统进行动力学分析。分析结果表明,天平系统在动态测试实验中,天平系统在动态测试实验中,系统自身刚度对测试结果存在影响。当支撑座材料刚度足够大时,载荷满足解耦条件,即可用Y方向载荷作用代替X,Y方向载荷共同作用。且无论支撑座刚度大小如何,X和Y方向的载荷对测试点应变的作用相互不干涉。为设计天平系统时材料的选择与动态实验中应变天平系统载荷的加载提供一定的参考。     

基于弯曲法的AFM微悬臂梁弹性常数标定技术

原子力显微镜(atomic force microscopy,AFM)在微纳米尺度力学测量领域有着广泛应用,其微悬臂梁探针的弹性常数是直接影响测量结果准确性的关键因素之一.弯曲法是标定微悬臂梁弹性常数的一类重要方法,基于弯曲标定原理提出了一种新的技术实现方案,并研制了相应的标定系统.借助精密运动定位台使微悬臂梁接触超精密天平并产生弯曲,分别以天平和光杠杆机构同步测得接触力和梁的弯曲量,再根据胡克定律直接算得弹性常数.利用所研制的系统对多种型号的微悬臂梁进行了标定,实验结果表明该系统具有良好的准确性和重复性,测量相对标准差小于5％.     

脉冲风洞天平动态标定加载系统设计

由于脉冲风洞试验时间短,冲击载荷大,试验过程有强烈振动,影响天平的测力精度,因此,需要对天平模型进行动态标定.针对风洞天平的动态标定所需要的高频率、重载荷稳定的动态力,设计了一套动态力加载系统.机械结构运用电动机带动丝杠副的结构设计,控制部分采取嵌入式PC,在系统内虚拟出软PLC.传感器检测模块和电动机驱动模块等通过EtherCAT总线与软PLC通讯,实现硬件的模块化集成.经试验测试,该系统能满足风洞天平的测试要求.     

基于正弦力加载的力传感器动态标定技术研究

针对国内现有动态标定装置精度不高、重复性较差的问题,提出了一种基于正弦力加载的新型力传感器动态标定方法;对该标定方法做了详细介绍,阐述了该标定系统中最关键的正弦机构的工作原理;利用基于最小二乘的曲线拟合法对力传感器和位移传感器输出正弦电压的幅值进行了求解,并以此为基础,依据相应公式在LabVIEW中设计了数据处理程序,实现了对力传感器动态灵敏度的精确求解;搭建了实验平台,对Interface 1010AJ型力传感器进行了1 Hz~5 Hz的动态标定,并分析了实验结果。研究结果表明,该新型的力传感器动态标定系统具有良好的精度,其误差在1.5%内。     

应变片用于斯特林发动机活塞位移的动态测量

结合自由活塞斯特林发动机的结构特点,提出了采用应变片响应板弹簧变形来动态测量活塞位移的方法。根据应变片的电阻应变效应与应变仪的电桥原理,建立了一套应变片测量位移的动态标定试验系统,将动态标定数据与静态标定数据进行了比较分析。试验结果表明,应变片测量位移的方法存在一定的正反向、动静态差异,应变片的粘贴位置也会直接影响测量准确性。基于应变片传感器体积小,与板弹簧结合粘贴无需占用专门的空间,通过标定校准和合理的安装位置,仍然是一种较好的位移测量传感器。     

位移传感器动态精度实验系统的研制

根据传感器动态精度理论研究的要求 ,研制了能反映不同速率动态信号激励下系统动态响应的位移传感器动态精度实验系统。该系统可实现动态输入信号速率的无级调速 ,由计算机采集输出信号并进行数据处理。     

轻型臂关节力矩传感器的设计

介绍了轻型臂智能关节力矩传感器的弹性体及信号调理电路设计，进行了传感器静态标定试验的研究，为改善传感器的动态响应特性，根据“逆模型”思想，采用最小二乘法、基于函数联接型神经网络法以及辅助变量法设计了力矩传感器的动态补偿器。实验结果表明，辅助变量法具有更好的补偿作用，设计的力矩传感器满足轻型臂系统的要求。     

热力耦合作用下的风洞应变天平校准技术

为研究温度对风洞应变天平测量的影响,以热力耦合作用下的天平校准技术为着力点,通过响应面实验设计方法确立热力耦合加载矩阵,基于六自由度校准系统及构建的温度环境对一台六分量风洞应变天平实施热力耦合加载,采用多元回归方法建立了包含温度、力、力矩参数的天平公式,最后利用验证载荷检验天平公式的准确性,检验结果显示：温度及力/力矩载荷作用下,天平各分量的综合加载误差优于0.3%;天平公式能准确表征天平在热力耦合作用下的综合性能。研究结果表明,热力耦合作用下的风洞应变天平校准技术能够用于评定及修正温度对天平测量的影响。     

一种六维腕力传感器动态响应的研究

十字梁腕力传感器广泛应用于机器人系统。腕力传感器的响应特性决定了传感应变片的粘贴和传感器的标定方法，也影响机器人系统的动态特性。针对十字梁六维腕力传感器的结构特点，以Lagrange方程为基础，建立六维腕力传感器的动力学模型，研究腕力传感器在力（力矩）作用下的响应特性以及传感器参数对传感器响应的影响。     

Extended octagonal ring transducers for measurement of tractor-implement forces

The extended octagonal ring transducers are popular devices for force and moment measurements in agricultural engineering research due to its capability in measuring forces independently in two dimensions and resultant moment in one dimension. In this study design, construction and calibration of extended octagonal ring transducers are discussed. The transducers were designed to measure the two force components of the soil reaction with minimum cross-sensitivity. Strain distributions in the extended octagonal rings were analyzed using finite element method to locate optimal strain gauge positions to minimize cross-sensitivity between the two force components. A Data acquisition system consisted of a programmable DT800 data logger with 12 differential voltage and 16 frequency channels, and a PC for storing the data for further graphing and analysis. The system was tested for its sensitivity, cross-sensitivity, linearity and repeatability. The results of the calibration tests revealed that the system was well working for a range of draught and vertical forces up to 25 kN. The results showed a high degree of linearity between bridge output voltage and force applied. The minimum coefficient of determination, R ², was found to be 0.99. The interactions of the applied forces on the orthogonal force bridges were less than one percent. The system could best be used for the measurement of draught (horizontal) and vertical forces where medium size equipment is attached with a tractor.     

WRIST FORCE SENSOR''S DYNAMIC PERFORMANCE CALIBRATION BASED ON NEGATIVE STEP RESPONSE

Negative step response experimental method is used in wrist force sensor＇s dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor＇s load in working. This experimental method needn＇t special experiment equipments. Experiment＇s dynamic repeatability is good. So wrist force sensor＇s dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn＇t require that wavelet primary function be orthogonal and needn＇t wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor＇s dynamic characteristics are identified by the frequency response function.     

高速转子动平衡补偿技术研究

在对高速回转系统进行平衡措施以减少振动量的研究中,结合电磁式间接在线动平衡头和电磁式在线混合动平衡头的优点,开发一种节能的高速转子在线动平衡补偿装置;利用电磁场的耦合作用,无接触地在加重平面处形成与所需离心力等效的旋转电磁力,实现在线实时精密补偿;并运用影响系数法控制策略,利用旋转极坐标合成矢量力,使转子质心落回旋转中心;同时,时空旋转电磁力消失,转子系统在极坐标合成力的作用下实现最终动平衡。     

New method to improve dynamic stiffness of electro-hydraulic servo systems

Most current researches working on improving stiffness focus on the application of control theories.But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated,so the control action is lagged.Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms.In this paper,the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed.On this basis,the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward.And a scheme using double servo valves to realize flow feedforward compensation is presented,in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time.The two valves are arranged in parallel to control the cylinder jointly.Furthermore,the model of flow compensation is derived,by which the product of the amplitude and width of the valve’s pulse command signal can be calculated.And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations.Using the proposed scheme,simulations and experiments at different positions with different force changes are conducted.The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time.That is,system dynamic load stiffness is evidently raised.This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.     

基于动态响应的高速压力机综合平衡优化

针对曲柄式高速压力机动平衡中存在的机身激振力与激振力矩平衡相互制约的问题,提出了一种基于动态响应的综合优化模型。通过有限元模拟获得机身在单位简谐载荷作用下的动态响应向量,通过傅里叶级数分解得到实际激振载荷的振幅向量,以此构造了一个直接以机身振动响应为对象的综合平衡优化模型,该模型能够适用于一般机械系统。     

风电齿轮箱动态响应分析及实验测量

运用达朗伯原理建立了风电齿轮箱传动系统的纯扭转集中参数动力学模型,箱体模型采用有限元法建立,通过作用在箱体支撑孔上的轴承力建立了齿轮箱动力学模型.采用龙格-库塔法求解了传动系统的轮齿动态啮合力,计算了箱体在动态啮合力作用下的振动响应.同时对齿轮箱进行了实验测量,并把测量得到的齿轮箱振动响应数据和模型计算的结果进行了对比,验证了模型的正确性.通过这些分析,为风电齿轮箱动态设计中减少振动噪声、提高承载能力与可靠性奠定了基础.