Auto-tracking single point diamond cutting on non-planar brittle material substrates by a high-rigidity force controlled fast tool servo

This paper presents auto-tracking single point diamond cutting, which can conduct precision cutting on non-planar brittle material substrates without prior knowledge of their surface forms, by utilizing a force controlled fast tool servo (FTS). Differing from traditional force feedback control machining based on a cantilever mechanism such as an atomic force microscope (AFM) that suffers from low-rigidity and limited machining area, the force controlled FTS utilizes a highly-rigid piezoelectric-type force sensor integrated with a tool holder of the FTS system to provide sufficient stiffness and robustness for force-controlled cutting of brittle materials. It is also possible for the system to be integrated with machine tools to deal with the difficulties in the cutting of large area non-planar brittle materials, which requires not only high machining efficiency but also a high stiffness. Experimental setup is developed by integrating the force controlled FTS to a four-axis ultra-precision diamond turning machine. For the verification of the feasibility and effectiveness of the proposed cutting strategy and system, auto-tracking diamond cutting of micro-grooves is conducted on an inclined silicon substrate and a convex BK7 glass lens, while realizing constant depths of cuts under controlled thrust forces.     

Tool wear monitoring system for CNC end milling using a hybrid approach to cutting force regulation

A tool wear monitoring system is indispensable for better machining productivity, with the guarantee of machining safety by informing of the time due for changing a tool in automated and unmanned CNC machining. Different from monitoring methods using other signals, the monitoring of the spindle current has been used without requiring additional sensors on the machine tools. For reliable tool wear monitoring, only the current signal from tool wear should be extracted from the other parameters to avoid exhaustive analyses on signals in which all of the parameters are fused together. In this paper, the influences of force components from different parameters on the measured spindle current are investigated, and a hybrid approach to cutting force regulation is employed for tool wear signal extraction from the spindle current. Finally, wear levels are verified with experimental results by means of real-time feedrate aspects, varied to regulate the force component from tool wear.     

Feedforward suppression of force ripple based on a simplex-optimized dither signal

This paper presents the design and realization of a feedforward dither signal to reduce the force ripple in an iron-core permanent magnet linear motor (PMLM). A composite control structure is used, consisting of three components: a simple feedforward component, a PID feedback component, and a ripple compensator (RC). The first two components are designed based on a dominant linear model of the motor. The dither signal is generated based on a signal model which is identified using a multidimensional simplex downhill method. In this way, a simple approach is available to eliminate or suppress the inherent force ripple, thus facilitating smooth precise motion while uncompromising on the maximum force achievable. Real-time experimental results verify the effectiveness of the proposed scheme for high precision motion trajectory tracking.     

电脑皮革切割机控制系统的研究

为解决目前国内皮革切割机存在的切割速度较慢、皮革材料的利用率较低等问题,将数控裁剪技术应用到皮革切割上,提出了以工业PC机加运动控制卡为主控核心的电脑皮革切割机控制系统设计方案;同时基于Windows XP系统,通过Visual C++开发控制软件,并在软件上结合皮革图样数据结构的特点,利用各种计算机图形学算法实现了电脑皮革切割机的切割路径优化、图样软件排版等功能。研究结果表明,采用该电脑皮革切割机进行皮革切割,其切割质量与效率都得到了有效的提高。     

应变式切削测力系统动态特性的研究

本文对应变式切削测力仪的动态性能进行了研究,比较测力仪弹性无件在粘贴应变片前后固有频率和阻尼比的变化。结论是：应变片的粘贴不会造成测力仪固有频率的损失;测力系统的通过频率取决于系统中固有频率最差的环节－动态应变仪。最后,用实验的方法验证了测力系统对动态力的测量结果。     

基于PMAC的数控火焰切割机数控系统开发

通过分析数控火焰切割机加工工艺的特点，开发了基于工业PC机和PMAC卡的数控火焰切割机数控系统，并对它的硬件和软件设计作了详细的论述，该数控系统已成功地应用于旧数控火焰切割机的改造中。     

曲柄滑块机构惯性力部分平衡的研究

指出了以往运用质量代换方法对曲柄滑块机构惯性力进行部分平衡的不足，运用MATLAB编程计算重新描绘出分别考虑一级惯性力和二级惯性力时各惯性力的变化曲线，通过优化程序重新估算了使机构中残存的最大惯性力的最小配重条件，并进行了理论对比。     

Simulation research on the anisotropic cutting mechanism of KDP crystal using a new constitutive model

Potassium dihydrogen phosphate (KDP) exhibits anisotropic and hydrostatic pressure-dependent mechanical characteristics during processing. However, none of the existed material models is capable of describing the mechanical properties of the crystal. Thus, a new constitutive model, which combines the anisotropic elastic and pressure-dependent plastic model has been proposed in this paper. In addition, the tensile stress failure criterion is adopted as the fracture criterion of KDP crystal. Subroutine of the new material model is programmed and integrated into the commercial finite element software LS-DYNA. On the basis of that, the unknown material parameters of KDP are successfully identified with the aid of the nanoindentation/scratch technique and finite-element simulation. Finally, 2-D and 3-D cutting simulations applying the new model are performed to investigate the influence of cutting parameters on the brittle ductile transition depth and cutting force. The simulation results show good agreement with the KDP cutting experiment results, which confirm the validity and capability of the proposed constitutive model.     

Development of cutting force prediction model for carbon fiber reinforced polymers based on rotary ultrasonic slot milling

Carbon fiber reinforced polymers (CFRP) have got widely increased applications in aviation, defense and other industries due to their properties of high specific strength/stiffness, high corrosion resistance and low-thermal expansion. The issues like excessive cutting forces and machining damages are encountered in machining due to heterogeneity, anisotropy and low heat dissipation of these materials. The cutting forces are required to be predicted/minimized through modeling. In this article, the novel axial and feed cutting force model has been developed and validated through rotary ultrasonic slot milling of CFRP composites. The variations less than 10% have been found between the measured and corresponding simulated values of the cutting forces. However, some higher variations have also been observed in the few cases mainly due to heterogeneity and anisotropy of such material. The cutting depth is a significant parameter for axial and feed forces, while the feed rate is significant for the axial force. Both the forces decreased with the increase of spindle speed, while they increased with the increase of feed rate and cutting depth. The developed models have been found to be robust and can be applied to optimize the cutting forces for such materials at the industry level.     

基于SOPC的自寻迹切割机器人运动控制系统研究

针对自寻迹移动切割机器人控制为非完整系统控制的特点,构建了机器人运动模型,并分析了其运动规律,设计了一种基于可编程片上系统(SOPC)技术的切割机器人运动控制系统.该系统以EP3C55芯片为控制核心,采用模糊控制策略实现了切割机器人的运动控制.实验结果表明,该控制系统运行平稳,控制响应快,能够满足切割机器人的实时控制的...     

Application of multi-objective controller to optimal tuning of PID gains for a hydraulic turbine regulating system using adaptive grid particle swam optimization

A hydraulic turbine regulating system (HTRS) is one of the most important components of hydropower plant, which plays a key role in maintaining safety, stability and economical operation of hydro-electrical installations. At present, the conventional PID controller is widely applied in the HTRS system for its practicability and robustness, and the primary problem with respect to this control law is how to optimally tune the parameters, i.e. the determination of PID controller gains for satisfactory performance. In this paper, a kind of multi-objective evolutionary algorithms, named adaptive grid particle swarm optimization (AGPSO) is applied to solve the PID gains tuning problem of the HTRS system. This newly AGPSO optimized method, which differs from a traditional one-single objective optimization method, is designed to take care of settling time and overshoot level simultaneously, in which a set of non-inferior alternatives solutions (i.e. Pareto solution) is generated. Furthermore, a fuzzy-based membership value assignment method is employed to choose the best compromise solution from the obtained Pareto set. An illustrative example associated with the best compromise solution for parameter tuning of the nonlinear HTRS system is introduced to verify the feasibility and the effectiveness of the proposed AGPSO-based optimization approach, as compared with two another prominent multi-objective algorithms, i.e. Non-dominated Sorting Genetic Algorithm II (NSGAII) and Strength Pareto Evolutionary Algorithm II (SPEAII), for the quality and diversity of obtained Pareto solutions set. Consequently, simulation results show that this AGPSO optimized approach outperforms than compared methods with higher efficiency and better quality no matter whether the HTRS system works under unload or load conditions.     

An activity-based predicate/transition net model of operational control planning for a flexible manufacturing system

An effective flexible manufacturing system (FMS) relies on a hierarchy of decisions, including the control of the FMS operation. The FMS operation usually is dynamically constrained by the limited resources such as pallets, machines, tools, carts, etc. Most analytical models make many assumptions and oversimplify the complicated decision problems. This study proposes the predicate/transition (Pr/Tr) net, a high level petri net, as a model for operational control planning. Firstly, the activities (modes) and their resources usage in FMS were analysed and aggregated into activity sets. Then, the flow of parts among activities was traced to obtain the mode transition diagram, and then the Pr/Tr net model was introduced. We incrementally defined the predicates and transitions into this model. Finally, a comprehensive FMS Pr/Tr net model was derived. By implementing it into a rule-based simulation model, it is well suited for FMS operational control planning because of its inclusiveness and high flexibility.     

Development of a cutting tool condition monitoring system for high speed turning operation by vibration and strain analysis

Cutting tool wear is a critical phenomenon which influences the quality of the machined part. In this paper, an attempt has been made to create artificial flank wear using the electrical discharge machining (EDM) process to emulate the actual or real flank wear. The tests were conducted using coated carbide inserts, with and without wear on EN-8 steel, and the acquired data were used to develop artificial neural networks model. Empirical models have been developed using analysis of variance (ANOVA). In order to analyze the response of the system, experiments were carried out for various cutting speeds, depths of cut and feed rates. To increase the confidence limit and reliability of the experimental data, full factorial experimental design (135 experiments) has been carried out. Vibration and strain data during the cutting process are recorded using two accelerometers and one strain gauge bridge. Power spectral analysis was carried out to test the level of significance through regression analysis. Experimental results were analyzed with respect to various depths of cut, feed rates and cutting speeds.     

基于VB的凸轮机构CAD动态图解系统开发

论述了直动平底从动件凸轮机构CAD/CAM系统的总体设计方案和各模块的主要功能,阐述了在AutoCAD2004的基础上,利用VB进行开发的原理和实现过程.通过实例验证表明,该软件界面友好,方便直观,既可用于工程实际,又可满足教学需要.     

Optimal clustering of MGs based on droop controller for improving reliability using a hybrid of harmony search and genetic algorithms

This paper proposes a novel method to address reliability and technical problems of microgrids (MGs) based on designing a number of self-adequate autonomous sub-MGs via adopting MGs clustering thinking. In doing so, a multi-objective optimization problem is developed where power losses reduction, voltage profile improvement and reliability enhancement are considered as the objective functions. To solve the optimization problem a hybrid algorithm, named HS-GA, is provided, based on genetic and harmony search algorithms, and a load flow method is given to model different types of DGs as droop controller. The performance of the proposed method is evaluated in two case studies. The results provide support for the performance of the proposed method.     

基于Vis-Mockup的空间对接机构数字化装配系统开发

建立了空间对接机构数字化装配系统的体系结构,在Vis-Mockup平台软件基础上,采用C#和SQL Server 2005数据库完成了系统开发,实现了空间对接机构的模型预处理、装配过程仿真和装配过程示教功能。该系统已在企业得到初步应用,主要用于培训和辅助装配人员进行航天产品的装配。该系统为装配人员提供了数字化的培训工具,改变了过去传统的培训模式,提高了培训的质量和效率。通过对数字化装配操作验证和装配工艺数据的统计计算,为产品设计改进和装配工艺优化提供了定量数据。通过对装配过程的三维仿真、记录装配顺序、路径和操作和三维动画再现,实现了装配知识、经验和操作技巧的保存和再现。     

Optimal design of a main driving mechanism for servo punch press based on performance atlases

The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy saving.To effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are proposed.In the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined.The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis.Thereafter,the performance atlases,which can present all possible design solutions,are depicted.As a result,the feasible solution of the mechanism with good motion/force transmission performance is obtained.And the solution can be flexibly adjusted by designer according to the practical design requirements.The proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.     

Development of a guiding system and visual feedback real-time controller for the high-speed self-align optical cable winding

Recently, the demand for the optical cable has been rapidly growing because of the increasing number of internet users and the high speed internet data transmission required. But the present optical cable winding systems have some serious problems such as pile-up and collapse of cables usually near the flange of the bobbin in the process of cables winding. To reduce the pile-up collapse in cable winding systems, a new guiding system is developed for a high-speed self-align cable winding. First, mathematical models for the winding process and bobbin shape fault compensation were proposed, the winding mechanism was analyzed and synchronization logics for the motions of winding, traversing, and the guiding were created. A prototype cable winding systems was manufactured to validate the new guiding system and the suggested logic. Experiment results showed that the winding system with the developed guiding system outperformed the system without the guiding system in reducing pile-up and collapse in high-speed winding. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Chang-woo Lee received a B.S. degree in Mechanical Engineering from Konkuk University in 2001. He received his M.S. and Ph.D. degrees from Konkuk university in 2003 and 2008, respectively. Dr. Lee is currently a researcher at the Flexible Display Roll to Roll Research Center at Konkuk University in Seoul, Korea. Dr. Lee’s research interests are in the area of fault tolerant control, R2R e-Printing line design, and tension-register control. He is the holder of several patents related to R2R e-Printing system. HyanKyoo Kang received the B.S. and M.S degree in 2000 and 2003 respectively from Konkuk University, Seoul, Korea, where he is currently working toward the Ph.D. degree in mechanical design. He took part in the development of an autoalign guiding system for high-speed winding in a cable winding system, a 3-D roll-shape diagnosis method in a steel rolling system, a design of register controller for high-speed converting machine and real-time control design of electronic printing machine. His research topics include register modeling and control for printed electronics and distributed real-time control. Kee-Hyun Shin (S’81-M’02) received the B.S. degree from Seoul National University, Seoul, Korea, and the M.S. and Ph.D. degrees in mechanical engineering from Oklahoma State University (OSU), Still-water. Since 1992, he has been a Professor with the Department of Mechanical and Aerospace Engineering, Konkuk University, Seoul, Korea. For more than 18 years, he has covered several research topics in the area of web handling, including tension control, lateral dynamics, diagnosis of defect rolls/rollers, and fault-tolerant real-time control in the Flexible Display Roll-to-Roll Research Center, Konkuk University, of which he has also been a Director. His research topics include distributed real-time control, embedded control, monitoring, and diagnosis and fault-tolerant control of large-scale systems such as steel plants, film-and-paper-making plants, aircraft, ships, and ubiquitous control of multirobot systems. He is the author of Tension Control (TAPPI Press, 2000) and is the holder of several patents related to R2R e-Printing system.