共查询到19条相似文献,搜索用时 328 毫秒
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现代电控液压动力转向系统广泛应用于各种车型,由于影响汽车转向灵敏度特性的因素很多,有一些问题具有随机性和不确定性.模糊灰色数学理论作为处理不确定性信息、少信息手段之一,可以较好地弥补概率方法在复杂系统分析中的可靠性数据不足的缺陷.本文作者综合利用灰色模糊理论方法,对于影响因素多、信息不确定以及信息量少的液压动力转向系统进行多目标全局寻优的研究,并通过对汽车转阀的灰色关联度的研究,构建了汽车液压转阀模糊灰色GM(1,1)模型,为动力转向器的设计提供了理论基础. 相似文献
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针对锌净化除钴过程生产数据存在噪声和系统参数缓慢变化的问题,提出一种基于灰色模糊LSSVM的钴离子浓度预测模型。对样本数据进行灰色累加,削弱原始数据序列中的噪声,使数据规律性增强,灰色累加后数据作为LSSVM输入,提高模型抗干扰能力和预测能力;由于锌净化除钴工序的系统参数随时间发生变化,提出对不同时期的样本赋予不同的模糊加权值;利用改进PSO的全局优化能力和快速收敛性,优化LSSVM模型的惩罚因子和核函数参数,避免人为选择参数的盲目性。对硫酸锌溶液净化除钴过程生产数据的仿真结果表明,灰色模糊LSSVM预测值能很好地跟踪实际值的变化趋势,满足钴离子浓度预测要求。 相似文献
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金属材料海洋环境腐蚀数据咨询管理及预测诊断系统 总被引:4,自引:1,他引:4
采用面向对象的编程语言Visual Basic(VB)编制了金属材料海洋环境腐蚀数据咨询管理和预测诊断系统。系统中包含常用金属材料实海腐蚀数据和腐蚀形貌图谱的图文数据库.除常用的数据库管理功能外,还具有一定的腐蚀预测和腐蚀形貌诊断功能。腐蚀预测可分为人工神经网络模型预测和灰色模型预测。人工神经网络模型根据材料的合金成分或海水环境因素对材料的腐蚀进行预测,而灰色模型用于对材料的长期腐蚀数据进行计算并给出灰色模型参数。由扫描得到的金属材料的腐蚀形貌图像的灰度值分布或分形特征值和对应的腐蚀形貌作为知识库,通过模糊模式识别理论建立了腐蚀形貌分析诊断系统。可以对材料的腐蚀形貌进行诊断。 相似文献
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基于灰色系统理论的柱塞套内圆珩磨过程模型研究 总被引:2,自引:0,他引:2
探讨利用灰色系统模型描述柱塞套内孔珩磨过程,利用灰色系统理论建立了柱塞套内圆珩磨过程尺寸精度的数学模型,结果表明,模型的精度高,计算值与实际测量值吻合程度较好,灰色系统模型适于描述内圆珩磨过程。 相似文献
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海底行走机构对海底矿产开采具有重要意义,针对深海底行走机构所需要解决的控制问题主要是速度同步、抗负载慢变干扰和随即干扰。构建行走机构液压系统,根据系统设计参数,建立各个环节的数学模型,进行仿真分析,并以此为基础搭建系统的软件仿真实验平台。为了实现速度同步控制和抗干扰控制,综合灰色预测控制、数据驱动建模控制、模糊控制、常规PID等控制技术,分别对轮边马达子系统和变量泵-轮边马达系统提出了"灰色预测模糊PID控制"和"多模型参考模糊自适应控制"的算法,并在软件仿真平台上进行仿真实验以验证这些算法的有效性。根据二阶参考特征模型的特点,将多参考模型、模糊控制与小误差范围内的常规PI控制相结合,通过对系统在不同误差范围内多模型的控制补偿,能够使系统在参考模型的引导之下较好地达到预期的控制目标。 相似文献
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运用灰色系统的理论及方法,将疲劳应力与寿命的相互制约关系看成一个灰色系统,将疲劳试验的应力水平均匀分成数级,并找出与之对应的安全寿命的白化值。通过对安全寿命值数列的一次累加,生成一个光滑离散函数。据此建立灰色系统模型,并求解灰色系统的微分方程 。通过残差模型的修正,提高模型精度,再运用灰色系统模型的还原模型,可计算出任一应力水平下的安全寿命值。为机床主轴的安全寿命计算提供了新的途径,具有较大的推广应用价值。 相似文献
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将灰色系统理论与时间序列分析方法结合,建立灰色组合模型。引入Box-Jenkins模型,对随机性成分建模。应用灰色组合模型预测管道腐蚀速率的变化趋势,通过实例分析,检验了该模型的预测效果,并与其它几种方法比较,得出其精度非常高的结论。 相似文献
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Shinn-Horng Chen Jyh-Horng Chou Jin-Jeng Li 《International Journal of Machine Tools and Manufacture》2002,42(3)
In this paper the grey-fuzzy control scheme is proposed to control the turning process with constant cutting force under various cutting conditions. The grey-fuzzy control scheme consists of two parts: the grey predictor and the fuzzy logic controller. When we use the grey-fuzzy control scheme to design the constant turning force system, it is necessary to adjust the control parameters of both the grey predictor and the fuzzy controller (i.e., the sample size and grey constants of the grey predictor, and the scaling factors of the fuzzy controller) for guaranteeing stability and obtaining optimal control performances. Therefore, in order to search for the optimal control parameters by way of systematic reasoning instead of the time-consuming trial-and-error procedure, in this paper the Taguchi method is applied to search for the optimal control parameters of both the grey predictor and the fuzzy controller such that the grey-fuzzy controller is an optimal controller. Computer simulations are performed to verify the effectiveness of the above optimal grey-fuzzy control scheme designed by the Taguchi method. It is shown that satisfactory performances have been achieved by the optimal grey-fuzzy control scheme designed in this way. 相似文献
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Application of grey predictor and fuzzy speed regulator in controlling a retrofitted machining table 总被引:1,自引:0,他引:1
Shiuh-Jer Huang Yaw-Wen Lin 《International Journal of Machine Tools and Manufacture》1996,36(4):477-489
In this work, the control plant is an a.c. servo motor retrofitted traditional manually operated milling machine with a lead-screw transmission system. This obsolescent milling machine has non-linear time-varying behavior due to obvious backlash and irregular coulomb friction of the sliding surfaces. The system model is difficult to derive and identify for classical control design. In order to achieve the objectives of reducing the tracking error and path error and increasing the motion speed, a combination of PI control with grey prediction, cross-coupling and feedforward control loops and fuzzy speed regulator is proposed to control this machining table. The grey prediction loop is employed to improve the robustness and tracking accuracy of the control system. The fuzzy speed regulator is used to achieve the maximum machining speed under a specified error tolerance. The experimental results show that this control method achieves satisfactory performance of transient response, tracking and robustness under the influence of about 0.4 mm backlash on each axis and large stick-slip friction. This performance verifies the applicability of this economical approach to the automation of traditional milling machines. 相似文献
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Constant turning force operation with a fixed metal removal rate via a prior fuzzy controller system
This study examines constant metal removal rate (MRR) with constant turning force (CTF) that operates by means of a prior fuzzy controller (PFC) that is able to automatically manipulate the spindle speed to maintain the MRR at a specified suitable value. Fuzzy-control techniques and grey theory are integrated to integrate a PFC into the constant turning force operation. The most important difference between the PFC and conventional fuzzy controller (FC) is that the fuzzy control signal is determined by the future predicted-state value obtained by a grey model instead of by the present-state value used in the traditional fuzzy controller (FC). Hence, the control signal can be obtained in advance and ensure the safety of the system. This study adopts an auxiliary fixed metal removal rate (MRR) controller, which can respond to the lathe power, machining roughness or tool chatter, and which in constant turning force (CTF) operations is adopted because when the controlled system is a non-linear function, as Fc = aKffp, the productivity will always decrease. With the exponential function, the increase in cutting depth a will entail decrease in the feed f, thus reducing the metal removal rate (MRR), which is defined as MRR = afVc (mm3 s−1). A suitable solution is to increase the cutting speed Vc (mm s−1). Consequently, the concept of the MRR is built into the auxiliary controller to improve the CTF control system. 相似文献
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针对传统层次分析法(AHP)在构建刀具优选判断矩阵时没有考虑评价工程师主观判断的模糊性和指标属性的模糊性,导致刀具优选可信度和准确性降低的问题。分析了影响刀具选择的约束因素,建立了一种两级结构的多目标刀具优选模型,包括刀具的加工时间T、加工质量Q、加工成本C、资源消耗R、环境影响E五个优化目标;提出并设计了基于三角模糊数的模糊层次分析法(FAHP)及灰色关联分析(GRA)法进行求解刀具优选层次模型的算法,在三角模糊数互补判断矩阵传统计算权重方法的基础上,进行了算法优化。结合某航空制造企业叶片榫头铣削刀具优化选择的案例,证明了该方法用于刀具优选是可行且有效的。 相似文献