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从阀控非对称液压缸特性出发,对负载压力和负载流量进行了重新定义,并推导出适用于阀控非对称液压缸和阀控对称液压缸的数学模型,为阀控缸系统的静动态特性分析提供了理论基础。 相似文献
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带遗忘因子的预测迭代学习控制在阀控非对称缸系统中的应用研究 总被引:1,自引:0,他引:1
弹性负载下的阀控非对称缸是典型的非线性、时变系统,针对传统PD型迭代学习控制容易造成系统抖动这一问题,设计一种带遗忘因子的预测迭代学习控制器。建立阀控非对称缸系统的模型,比较分析其工作特性。介绍迭代学习控制基本原理,并分析常规PD型算法存在的问题。为克服迭代学习控制算法在阀控非对称缸控制中的抖动问题,设计具有遗忘因子的迭代学习算法,并通过仿真分析不同遗忘因子取值对控制效果的影响。为补偿遗忘因子造成的迭代性能降低问题,加入预测给定环节。仿真与试验研究均表明,这种带遗忘因子的预测迭代学习控制算法能够很好应用于阀控非对称缸系统,它有效克服系统抖动问题,并且具有很好的迭代精度。 相似文献
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根据阀控非对称弯辊缸系统的非对称特性,修正系统负载并给出了匹配非对称阀控制非对称缸系统的传递函数。研究了匹配非对称阀控制非对称缸力控制系统的非线性补偿和动压反馈控制策略。探讨了用双阀联动来等效匹配非对称阀控制非对称缸系统的可行性。仿真和实验结果验证了双阀联动控制工作辊弯辊系统的控制策略,为分析和综合非对称阀控制非对称缸系统奠定了基础。 相似文献
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针对非对称系统具有更强的信号放大能力,提出了一种新型二维非对称双稳随机共振(NTABSR)系统。首先,在绝热近似理论的前提下,对其输出信噪比进行了理论分析。并研究了各系统参数对于系统输出信噪比的影响,实验结果表明,在其他参数不变的情况下,通过改变非对称因子,可以使系统获得更高的输出信噪比。然后,将该系统应用于两种不同型号轴承的故障信号诊断中,通过自适应遗传算法对系统参数进行寻优后,得到检测结果。并将检测结果与二维对称双稳随机共振(TSBSR)系统进行了对比。最终,实验结果表明,NTABSR系统的性能优于TSBSR系统。这为该系统在后续理论分析与实际工程应用提供了良好的理论支撑与应用价值。 相似文献
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孙成通 《机械制造与自动化》2005,34(4):30-34
以阀控非对称液压缸为例,建立了液压伺服系统的动态模型,给出了该系统的仿真模型,利用MATLAB中的SIMULINK的图形功能对液压系统的动态特性进行仿真,把抽象理论变为直观可视的图形,从而给理论分析带来方便。通过试验得到了输出位移曲线和压力曲线,同时较详细地讨论了影响液压伺服系统压力跃变的主要因素。 相似文献
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针对位移传感器在液压系统应用中存在的不足,提出了一种液压缸活塞杆的位移软测量方法。该方法基于泵控缸系统的伺服电机转速、转矩信号以及泵、缸、油液相关参数,建立其液压缸活塞杆的位移软测量模型。根据油液黏温、黏压特性补偿活塞杆的位移,以减少软测量位移误差,并在MATLAB/Simulink中建立伺服电机泵控缸系统模型和位移软测量模型。结果表明:所提出的位移软测量方法比位移传感器获取的位移精度略差,但响应速度快,是一种替代位移传感器来获取液压缸位移的有效方案。 相似文献
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针对目前轧机伺服液压缸故障诊断过程中,故障特征提取困难,信号非线性变化,数据量大的问题,提出了一种基于深度置信网络的轧机伺服液压缸故障诊断的方法。根据轧机系统工作原理,建立轧机系统仿真模型,对轧机内泄漏故障状况进行模拟。利用深度置信网络在智能故障诊断的优越性,将信号归一化处理后放入深度置信网络进行训练,然后通过反向传播学习,优化网络各参数,提高诊断精度。深度置信网络模型由多层玻尔兹曼机以及顶层BP神经网络组成。与传统BP神经网络方法进行比较,结果表明,在训练样本数据足够的条件下,深度置信网络模型在伺服液压缸内泄漏故障诊断具有更高的诊断精度。 相似文献
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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. 相似文献
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The coupling effect of normal stress and shear stress on orthotropic materials happens when applied loading deflects from
the directions of the principal axes of the material coordinate system. By taking account of the coupling effects, formulas
of equivalent stress and strain for cubic single crystal materials are cited. Using the equivalent strain and equivalent stress
for such material and a variable k, which is introduced to express the effect of asymmetrical cyclic loading on fatigue life, a low cycle fatigue (LCF) life
prediction model for such material in multiaxial stress starts is proposed. On the basis of the yield criterion and constitutive
model of cubic single crystal materials, a subroutine to calculate the thermo elastic-plastic stress-strain of the material
on an ANSYS platform was developed. The cyclic stress-strain of DD3 notched specimens under asymmetrical loading at 680°C
was analyzed. Low cycle fatigue test data of the single crystal nickel-based superalloy are used to fit the different parameters
of the power law with multiple linear regression analysis. The equivalent stress and strain for a cubic single crystal material
as failure parameters have the largest correlation coefficient. A power law exists between k and the failure cycle. The model was validated with LCF test data of CMSX-2 and DD3 single crystal nickel-based superalloys.
All the test data fall into the factor of 2.5 for CMSX-2 hollow cylinder specimens and 2.0 scatter band for DD3 notched specimens,
respectively. 相似文献
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基于传统液压缸伺服系统建模参数的复杂性、不确定性、以及系统的时变性等问题,提出了一种基于MATLAB-AMESim的液压缸位置伺服系统辨识方法。该文以组成足式机器人驱动单元的液压缸为研究对象,简单介绍了液压缸的组成结构及工作原理;其次建立液压缸控制系统模型、传递函数,阐述了液压缸伺服系统辨识方法原理和基本过程;最后,通过MATLAB-AMESim软件搭建单缸位置伺服系统进行系统辨识仿真,将仿真结果与实际液压缸位置伺服系统测试结果进行对比。实验表明基于MATLAB-AMESim的液压缸位置伺服系统辨识仿真具有良好的实用性,验证了系统模型辨识方法的有效性。 相似文献