共查询到20条相似文献,搜索用时 140 毫秒
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车用油气悬架主动控制试验研究 总被引:3,自引:0,他引:3
针对简化的车辆模型,以操纵稳定性及行驶平顺性为控制目标,选择LMS(Least Means Squares)自适应滤波算法,对悬架系统的振动控制过程进行了仿真研究,收到了较好的效果,试验结果进一步证明该算法的有效性,表明LMS自适应滤波技术在车用油气悬架主动控制中的应用是可行的。 相似文献
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切削过程恒力控制对于提高生产率、保证加工精度至关重要,本文将信息理论与神经网络理论相结合,提出了恒力切削过程中基于最大熵的神经网络控制,与自适应神经网络控制相比,具有收敛快,振荡小的特点. 相似文献
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切削参数优化对于加工质量、生产效率、加工成本、产品利润具有非常重要的意义.数控加工过程中,单位生产成本和加工精度很大程度上决定了零件加工成本的高低和加工质量的好坏.建立以单位生产成本与加工精度为双目标的多工序车削优化模型进行切削参数优化选择十分必要.多工序车削模型同时充分考虑了粗精的刀具耐用度、切削功率、切削进给力、稳定切削区域、刀具表面切削温度及精车表面粗糙度等实际约束条件.运用高斯变异和多项式变异的NSGA-Ⅱ算法对多工序车削模型进行比较优化计算,优化实例表明多项式变异的NSGA-Ⅱ算法获得了更好的加工精度、单位生产成本的Pareto最优解集以及相应的粗精切削参数.用多项式变异的NSGA-Ⅱ算法得到的优化粗精切削参数进行切削试验,得到与NSGA-Ⅱ算法优化的加工精度、单位生产成本基本相符,为多工序车削切削参数优化提供了实践指导. 相似文献
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基于工艺系统刚度的加工误差分析 总被引:1,自引:0,他引:1
在切削加工过程中,工件和刀具正确的相对位置是保证零件加工精度的必要条件.工艺系统刚度及精度是影响工件、刀具位置的关键因素.因此研究工艺系统刚度,对提高零件的加工精度具有十分重要的意义.文章基于切削加工中工件的准静态受力分析,运用经典Hertz接触理论和有限元的方法,提出计算工艺系统刚度的新方法.该方法避免了有限元计算中接触单元的使用,无需多次非线形迭代计算.给出了基于工艺系统刚度的工件加工误差预报模型. 相似文献
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针对BP神经网络容易陷入局部极值导致识别精度低的问题,文章提出了一种基于混合粒子群算法(HPSO)的BP神经网络优化算法。在刀具磨损监测实验过程中,采集刀具切削的声发射(AE)信号,利用小波包分解算法对AE信号进行滤波,并进行特征提取。将频带能量特征和切削参数分别作为主特征和辅助特征,并对其对归一化处理。采用混合粒子群优化算法(HPSO)对BP神经网络预测模型进行优化,利用优化后的模型对测试样本进行模式识别,结果表明,优化后的HPSO-BP模型能够有效地降低神经网络陷入局部极值的情况,提高刀具磨损识别精度。 相似文献
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Youngbin Park Tae-Yong Kim Joongwon Woo Dongwon Shin Jongwon Kim 《International Journal of Machine Tools and Manufacture》1998,38(8):911-930
Continuous sliding mode control is applied to turning processes for cutting force regulation. The motivation of the use of the slide mode control scheme is to solve the nonlinearity problem caused by the feedrate override command element in the commercial CNC machine tool. When the adaptive control algorithm is applied to the commercial CNC machine tool, it is one of the practical methods that the programmed feedrate is overridden after the control algorithm is carried out. However, most CNC lathe manufacturers offer limited number of data bits for feedrate override, thus resulting in nonlinear behavior of the machine tools. Such nonlinearity brings ‘quantized' or discrete effect so that the optimal feedrate is rounded off before being fed into the CNC system. To compensate for this problem, continuous sliding mode control is applied. Simulation and experimental results are presented in comparison with those obtained from applying adaptive control which is a widely used approach in cutting force regulation. Adaptive control loses its effectiveness in the presence of nonlinearity since it generally requires linear parametrization of the control law or the system dynamics. Experiments are conducted under various machining conditions, subject to changes in spindle speed, material of work-piece, and type of machining process. The suggested slide mode controller shows smoother cutting force fluctuation, which cannot be achieved by the conventional adaptive controller. The experimental set-up reflects the emphasis on the practicality of the sliding mode controller. In order to avoid the use of a dynamometer in the course of measuring the cutting force, the indirect cutting force measuring system is used by means of feed drive servo-motor current sensing. 相似文献
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Marchenko Tikhon Tae Jo Ko Seung Hyun Lee Hee Sool Kim 《International Journal of Machine Tools and Manufacture》2004,44(2-3):237-245
Conventionally used linear or circular interpolators are undesirable for the precision machining of 3D free-form surfaces for the following reasons: the transmission errors due to the huge number of point data, discontinuity of curve segmentation, and unsmooth motion speed. In this regard, modern CNC machine tools are designed with a function for machining arbitrary parametric curves. However, these systems do not consider controlling feedrate adaptively, which dominates the quality of the machining process. This paper proposes a NURBS interpolator based on the adaptive feedrate control for the constant material removal rate. This is accomplished by varying feedrate using the curvature of a surface. The curvature-compensated feedrate system has important potential applications in ensuring part accuracy and protecting the cutting tool. The simulated and experimental results show it is applicable to real machining. 相似文献
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A direct adaptive control algorithm, which is spindle speed and drive dynamics independent, has been developed for machining operations. The combined dynamics of feed motion and cutting process are modelled as a third order system whose parameters may vary with spindle speed and part geometry changes during machining. The algorithm does not use any specific time interval, thus sampling time dependent discrete transfer functions and pole assignments are avoided. The adaptive controller is designed to have a closed loop characteristic function which behaves like an open loop regular and stable machining operation. The proposed direct adaptive controller is practical, can be used in any multi-axes machining, and can be combined with chatter suppression techniques which require spindle speed regulation. The algorithm is applied to the adaptive control of milling. Satisfactory results are obtained in constraining the maximum cutting forces and dimensional surface errors in milling experiments. 相似文献
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Chu-Hsiang Chiou Min-Sung Hong Kornel F. Ehmann 《International Journal of Machine Tools and Manufacture》2003,43(15):363-1620
The eigenstructure assignment algorithm is proposed for controlling machining chatter by changing the response of the machine tool structure to dynamic cutting forces through the change of its modal properties so that the interaction between the tool and workpiece can be altered. The determination of the desired modal shapes is derived from a concept similar to gain scheduling in adaptive control system theory. By using computer simulations, the desired eigenstructure of the machine tool structure for different cutting conditions is determined and used to form the scheduling table. The gain matrix is adjusted according to the scheduling table and cutting conditions. It was found from experimental results that by changing the principal direction of the machine tool structure, the machining system could be stabilized and that the use of the proper eigenstructure to suppress machine tool chatter could significantly increase the material removal rate. Simulations have shown that the responses of the controlled machining system have been altered from unstable to stable, proving the feasibility of the proposed chatter control concept. 相似文献
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通过设计采用四工位专用夹具替代单工位夹具,开发了可连续加工不同规格板材拉伸试样全流程数控宏程序和定向精度补偿数控宏程序,形成一种新的加工方法与流程。通过实际应用,可有效节省加工过程机床非机动时间,最大限度提高效率,解决了由于刀具磨损和材料切削性能等因素影响造成的精度误差和试样两头部与平行部轴线的偏差问题。试验方法操作简单,连续加工过程稳定,对减轻劳动强度、缩短流程、降低刀具消耗、实现无人值守加工等具有重要的实际意义。 相似文献
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工程陶瓷材料硬脆、导电率低,难以获得高效精密的电加工效果.本文针对工程陶瓷电火花加工特点,在分析国内外工程陶瓷电火花加工技术的基础上,提出了基于遗传算法的工程陶瓷电火花加工方法.该方法结合遗传算法、神经网络及模糊控制理论构造了多环式自适应控制系统,在线对加工过程进行断丝预防、加工工艺自适应和加工参数自适应监测与控制,从而为难加工材料实现高效精密的电火花加工提供理论与技术指导. 相似文献
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Amir Rashid Cornel Mihai Nicolescu 《International Journal of Machine Tools and Manufacture》2006,46(12-13):1626-1636
This paper presents the development implementation and testing of an active controlled palletised workholding system for milling operations. The traditional approach to controlling vibration in a machining system is to develop control systems for cutting tools or machine spindles as in the case of milling machines. This work is a deviation from the traditional approach and targets a workholding system for the control of unwanted vibration. Palletised workholding systems, due to their compact design, offer an opportunity to design active control systems that are economical and easier to implement in the case of milling machines. The active control system developed here is based on an adaptive filtering algorithm, the filtered X-LMS, and employs piezo-actuators for dynamic control force. The system has been tested experimentally to demonstrate the reduction in dynamic force due to vibration. Extensive testing has been carried out to validate the performance of the system in terms of parameters of practical importance such as improvement in surface finish and increase in tool life. 相似文献
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To understand the effects of elastic deformation of the tool and the crater phenomenon generated by the cutting force and high pressure during metal cutting processing on the cutting process, an iterative mathematical model for calculating the tool-chip contact is developed in this paper under the assumption of elastic cutting tools. In this model, the finite-element method is used to simulate the cutting of mild steel by a cutting tool of three different materials. The results obtained in the simulation are found to match experimental data reported by related studies. The simulation results also indicate that tools with a smaller stiffness produce greater elastic deformation. Further, decrease of the rake angle due to elastic deformation of the tool can result in greater difficulty in internal deformation of the material and an increase in cutting force. The micro-crater phenomenon on the tool face generated by high pressure at the tool-chip interface is the preliminary symptom of crater wear on the tool face. Therefore, under some machining conditions, such as in precision machining or in automation processing where tool compensation is required, the phenomenon of elastic deformation of the tool must be considered carefully to ensure product precision. 相似文献
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Study of the correlation between surface roughness and cutting vibrations to develop an on-line roughness measuring technique in hard turning 总被引:3,自引:0,他引:3
Dong Young Jang Young-Gu Choi Hong-Gil Kim Alex Hsiao 《International Journal of Machine Tools and Manufacture》1996,36(4):453-464
Surface roughness is one of the important factors in all areas of tribology and in evaluating the quality of a machining operation. In order to achieve computer controlled machining in a flexible manufacturing system, a technique is needed for the on-line, real-time monitoring of each machining process parameter that affects surface roughness. As the first step in developing such an algorithm, research on the correlation between surface roughness and cutting vibration is reported in this paper. The algorithm utilizes the relative cutting vibrations between tool and workpiece, which are measured through an inductance pickup and filtered by an analog bandpass filter for a specific vibrational component. The cutting vibration signals of a specific :frequency are superimposed onto the kinematic roughness, which is calculated by the tool edge radius and feed rate. Experimental results show good correlation between the simulated roughness obtained using the proposed algorithm and the roughness actually measured with a surface profilometer 相似文献