Dependence of computed trajectory on step-size in a nonlinear dynamic system: an investigation into cutting tool dynamics

The nonlinear model of an orthogonal cutting process devised by Grabec is studied to demonstrate the importance of choosing an appropriate step-size and evolutionary algorithm for numerically integrating a system of nonlinear differential equations. Two different algorithms are used for computing the system trajectory, and the dependence of the phase portrait on the step-size is shown. A qualitative understanding to connect the proper step-size and the system nonlinearity is established.     

A Novel Twist Deformation Model of Soft Tissue in Surgery Simulation

Real-time performance and accuracy are two most challenging requirements in virtual surgery training. These difficulties limit the promotion of advanced models in virtual surgery, including many geometric and physical models. This paper proposes a physical model of virtual soft tissue, which is a twist model based on the Kriging interpolation and membrane analogy. The proposed model can quickly locate spatial position through Kriging interpolation method and accurately compute the force change on the soft tissue through membrane analogy method. The virtual surgery simulation system is built with a PHANTOM OMNI haptic interaction device to simulate the torsion of virtual stomach and arm, and further verifies the real-time performance and simulation accuracy of the proposed model. The experimental results show that the proposed soft tissue model has high speed and accuracy, realistic deformation, and reliable haptic feedback.     

A Fuzzy Logic-Based Prediction Model for Kerf Width in Laser Beam Machining

In laser beam machining, the main concern is the machining quality as kerf width of the end product. It is essential for industrial applications to cut the workpiece with minimum kerf width. However, it is difficult to develop a precise functional relationship between input and output variables in laser machining. Therefore, an effort has been conducted to build up an intelligent fuzzy expert system (FES) model to predict the kerf width in CO₂ laser cutting. The employed input parameters were assisting gas pressure, laser power, cutting speed, and standoff distance. The fuzzy logic was performed on fuzzy toolbox in MATLAB R2009b by employing Mamdani technique. In total, 81 experiments were carried out and experimental results were used for training and testing of the developed fuzzy model. Relative error and goodness of fit were used to investigate the accuracy of the prediction ability and the values of 3.852% and 0.994, respectively, were found to be satisfactory. This paper will extend knowledge about the prediction of kerf width by using FES model.     

嵌入式智能音乐播放系统的设计与实现

针对目前音乐播放系统的空间和时间受限问题,设计并实现了一种基于移动端的智能音乐播放系统。该系统由移动端软件APP和服务端两部分构成,服务端包括路由器、智能网络机顶盒和音响设备,具备定时播放和移动端实时控制播放的功能。该系统是采用基于STUN(Simple Traversal of User Datagram Protocol over NATs)的网络地址转换(Network Address Translation,NAT)穿透方式的远程控制以及家庭电视网络机顶盒来实现的。它不仅可以实现家庭音响的定时播放,还能通过移动端来远程控制音乐的播放。此外,可以实现歌曲的远程更新和歌曲播放时间的随意控制及更改。实验结果表明,该系统效果良好,具有广阔的应用前景及商业价值,可应用于家庭、商场、学校等有特定需求的环境。文章以家庭音乐播放系统为例进行设计说明。     

高速激光切割机床数控加工态势识别系统

当前方法设计的系统对机床数控加工态势进行识别时,没有对噪声进行回放,对切割平面度、切割定位精度、机床平稳性进行识别时,识别结果不准确,存在识别准确率低的问题。该文提出高速激光切割机床数控加工态势识别系统设计方法,首先,通过运动控制卡,伺服控制模块及加工态势识别模块构成高速激光切割机床数控加工态势识别系统的架构;其次,在加工态势识别模块中设计系统初始化、态势识别、自动诊断报警、运动控制、图形转码和G代码编译等子模块,在此基础上,通过噪音采集、噪音回放和信号分析等方法提高加工态势识别的准确率;最后,采用HMM算法构建高速激光切割机床数控加工态势识别模型,实现加工态势识别。实验结果表明,加工态势设计方法设计的系统可有效识别机床的切割平面度、切割定位精度和机床平稳性,识别准确率较高。     

An expert system approach to fracture mechanics

The usefulness of an arificial intelligence approach to some deterministic problems is discussed. An expert system approach to fracture mechanics problems is devised. Production rules for a simple expert system for crack tip mesh mapping are given. The knowledge acquisition process described in the references is used. Linear 2D fracture problems can be solved by the given program, though the methodology would be similar for non-linear or 3D problems.     

基于产生式知识表示的铝用炭素煅烧过程专家控制系统的设计

将基于知识的规则模型和解析的数学模型相结合,建立两级结构的实时专家控制系统(ECS)。由具有专家自学习和自适应功能的实时专家系统(ES),以专家优化方式寻找煅烧过程中煅烧带的最优温度、长度和位置,由实时控制系统(RTCS)采用基于CARMA模型和最小二乘法的自校正调节算法和经典PID算法分别进行给料量和负压的控制,保证生产过程在最优生产条件下进行。系统于2003年底正式投入运行,长期运行结果表明系统可靠性高、实用性好,既稳定了生产,又提高了产品质量,实现了节能。     

Application of genetic algorithms to fault diagnosis in nuclear power plants

A nuclear power plant (NPP) is a complex and highly reliable special system. Without expert knowledge, fault confirmation in the NPP can be prevented by illusive and real-time signals. A new method of fault diagnosis, based on genetic algorithms (GAs) has been developed to resolve this problem. This NPP fault diagnosis method combines GAs and classical probability with an expert knowledge base. By assessing the state of the NPP, the GA colony undergoes a transformation that produces an individual adapted to the NPP's condition. Experiments performed on the 950 MW full size simulator at the Beijing NPP simulation training center show that this method has comparative adaptability to diagnose signals and faults changed with time, imperfect expert knowledge, illusive signals and other phenomena.     

Virtual prototyping and manufacturing planning by using tri-dexel models and haptic force feedback

This paper presents a new method of using the tri-dexel volumetric models and a haptics force feedback for virtual prototyping and manufacturing planning. In the proposed method, the initial polyhedral surface model is converted to a tri-dexel volumetric model by using a depth-peeling dexelization algorithm. In the virtual prototyping process, the tri-dexel volumetric model is updated by the swept volume of a moving cutter via a haptic force feedback interface device. A collision detection algorithm is proposed for the virtual sculpting and the pencil-cut planning with real-time haptic force feedback to the users. Tool paths are generated for machining the virtual sculpted parts via the simulation and verification on a virtual CNC machine tool before they are actually machined. Computer implementation and practical examples are also presented in this paper. The proposed method enables the haptic-aided virtual prototyping and manufacturing planning of complex surface parts.     

Intent Inference Based Trajectory Prediction and Smooth for UAS in Low-Altitude Airspace with Geofence

In order to meet the higher accuracy requirement of trajectory prediction for Unmanned Aircraft System (UAS) in Unmanned Aircraft System Traffic Management (UTM), an Intent Based Trajectory Prediction and Smooth Based on Constrained State-dependent-transition Hybrid Estimation (CSDTHE-IBTPS) algorithm is proposed. Firstly, an intent inference method of UAS is constructed based on the information of ADS-B and geofence system. Moreover, a geofence layering algorithm is proposed. Secondly, the Flight Mode Change Points (FMCP) are used to define the relevant mode transition parameters and design the guard conditions, so as to generate the mode transition probability matrix and establish the continuous state-dependent-transition model. After that, the constrained Kalman filter (CKF) is applied to improve State-dependent-transition Hybrid Estimation (SDTHE) algorithm by applying equality constraint to the velocity of UAS in the straight phase and turning phase, respectively, and thus the constrained state-dependent-transition hybrid estimation (CSDTHE) algorithm is constructed. Finally, the results of intent inference and hybrid estimation are used to make trajectory prediction. Furthermore, each flight segment of trajectory is smoothed respectively by Rauch-Tung-Striebel (RTS) backward smooth method using the proposed CSDTHE-RTS algorithm, so as to obtain more accurate trajectory prediction results. The simulation shows that the proposed algorithm can reduce the errors of trajectory prediction and the time delay of intent inference.     

Virtual prototyping and manufacturing planning by using tri-dexel models and haptic force feedback

This paper presents a new method of using the tri-dexel volumetric models and a haptics force feedback for virtual prototyping and manufacturing planning. In the proposed method, the initial polyhedral surface model is converted to a tri-dexel volumetric model by using a depth-peeling dexelization algorithm. In the virtual prototyping process, the tri-dexel volumetric model is updated by the swept volume of a moving cutter via a haptic force feedback interface device. A collision detection algorithm is proposed for the virtual sculpting and the pencil-cut planning with real-time haptic force feedback to the users. Tool paths are generated for machining the virtual sculpted parts via the simulation and verification on a virtual CNC machine tool before they are actually machined. Computer implementation and practical examples are also presented in this paper. The proposed method enables the haptic-aided virtual prototyping and manufacturing planning of complex surface parts.     

BEM solution of delamination problems using an interface damage and plasticity model

The problem of quasistatic and rate-independent evolution of elastic-plastic-brittle delamination at small strains is considered. Delamination processes for linear elastic bodies glued by an adhesive to each other or to a rigid outer surface are studied. The energy amounts dissipated in fracture Mode I (opening) and Mode II (shear) at an interface may be different. A concept of internal parameters is used here on the delaminating interfaces, involving a couple of scalar damage variable and a plastic tangential slip with kinematic-type hardening. The so-called energetic solution concept is employed. An inelastic process at an interface is devised in such a way that the dissipated energy depends only on the rates of internal parameters and therefore the model is associative. A fully implicit time discretization is combined with a spatial discretization of elastic bodies by the BEM to solve the delamination problem. The BEM is used in the solution of the respective boundary value problems, for each subdomain separately, to compute the corresponding total potential energy. Sample problems are analysed by a collocation BEM code to illustrate the capabilities of the numerical procedure developed.     

弹道修正弹的外弹道实时解算算法研究

目的　探讨一种外弹道弹道诸元实时解算算法 ,为以后计算弹道偏差量提供依据 .方法　先建立解算模型 ,然后通过分析误差来验证模型是否正确 .结果　根据模型 ,能够计算出任一时刻的弹道诸元 ,与标准质点外弹道方程的计算结果比较 ,相对误差均在 0 .1 %以内 .结论　本解算算法是可行的 ,能够为弹道偏差解算提供可靠依据     

一种增量式半监督VPMCD齿轮故障在线诊断方法

针对齿轮故障诊断中难以获得大量故障样本的问题及实时在线诊断的需求,提出了一种基于增量式半监督多变量预测模型(Incremental Semi-supervised Variable Predictive Model based Class Discriminate,ISVPMCD)的齿轮故障在线检测方法。首先使用VPMCD方法给少量的已知样本建立初始预测模型,接着利用VPMCD方法中的判据给未标识样本赋予初始伪标识,然后通过互相关准则筛选出伪标识样本,最后利用伪标识样本和已知样本作为训练样本更新初始预测模型,使得更新的预测模型能兼顾整个样本集的信息,从而可以有效地解决小样本的故障诊断问题,另外,由于该方法在实时更新新样本的过程中不需要再次建立判别模型,从而缩短了分类时间,为实时在线诊断提供了新的思路。对UCI标准数据以及齿轮实测数据的分析结果表明,适合于小样本的ISVPMCD模式识别方法可以更快更准确地识别齿轮工作状态和故障类型。     

AdHapticA: Adaptive Haptic Application Framework

Research performed in the area of haptics has produced some remarkable results with a variety of haptic devices. However, haptic-based applications are designed to consider only a particular haptic device. Therefore, the functionality of a haptic-based system is limited by the chosen device's features, such as workspace, device's inertia, friction, number of points of interaction, number of degrees of freedom, and maximum force that can be exerted. In short, these haptic-based systems are limited for use with a certain haptic device. Without a doubt, the need for a software tool to adapt existing haptic-based systems to the capabilities of another haptic device is evident. On the other hand, one of the main advantages of using haptic devices is the possibility of saving data during the haptic interaction. Our proposed framework, which is called Adaptive Haptic Application (AdHapticA), deals with both issues: It automatically adapts a haptic-based system to be used with another haptic device and saves the corresponding haptic data for quantitative evaluation. The AdHapticA framework can be used to study the feasibility of certain haptic devices to meet the requirements of an application. A case study is presented to evaluate single-point interaction and hand exoskeleton haptic devices for authentication purposes by using the same virtual scenario. The applicability of the proposed framework is shown, and the results obtained from the haptic data are captured when a particular application is performed with either single-point (desktop device) or multipoint interaction devices (hand exoskeleton). Therefore, the results have shown that current hand exoskeleton devices are less suitable for tasks that require a certain level of precision, like haptic-biometric-based tasks.      

中央空调的故障诊断系统

阐述专家控制系统的特点和中央空调的组成，描述中央空调专家控制系统结构，详细说明该系统的软、硬件设计。该系统是以微型计算机为上位机，以PLC为下位机的控制系统。软件的设计着重于专家控制系统软件的开发。     

Real-time cutting simulation system of a milling operation for autonomous and intelligent machine tools

The conceptual architecture of autonomous and intelligent machine tools has been proposed not only to generate flexibly the process and operation plan but also to utilize the machine tools and cutting tools' performance while satisfying the requirements of the products and avoiding unexpected machining trouble. In order to realize the autonomous milling, machining strategy such as tool paths and cutting conditions must be decided, not in advance like current NC machining, but in a real-time manner. The objective of this research is to develop a real time machining optimization with machining simulation. Consequently, a cutting simulation system called a virtual machining simulator has been developed for this purpose. This simulator can calculate the changing geometry of the workpiece and estimate the instantaneous cutting force, torque, etc using the physical model. This estimated information enables the system to decide the suitable cutting conditions according to the machinability evaluated. In this paper, the machining status is evaluated and the cutting conditions are modified in real time so that the requirement of the machining operation is satisfied by referring to the physical model. The reliable and safe machining operation is carried out by maintaining the cutting force and torque desired value.     

An Integrated Suture Simulation System with Deformation Constraint Under A Suture Control Strategy

Current research on suture simulation mainly focus on the construction of suture line, and existing suture simulation systems still need to be improved in terms of diversity, soft tissue effects, and stability. This paper presents an integrated liver suture surgery system composed of three consecutive suture circumstances, which is conducive to liver suture surgery training. The physically-based models used in this simulation are based on different mass-spring models regulated by a special constrained algorithm, which can improve the model accuracy, and stability by appropriately restraining the activity sphere of the surrounding mass nodes around the suture points. We also studied the kinematic model to update the status of suture points in real time, according to an external force exerted by the operators, which can sense synchronous force feedback in return as well. Moreover, in case that the sutured wounds tear open again, a suture control strategy is designed to ensure the stability of the whole suturing procedure. Several experiments are carried out to validate the model performance in terms of model accuracy, suture control effects, and comprehensive training effects. The experiment results show that the proposed models have realistic visual and haptic feedback, stable control on the suture, as well as good training effects as an integrated liver suture surgery system compared to other suture simulation systems which only simulate suture on a single kind of soft tissue.     

基于VERICUT的炮管膛线电解加工阴极建模和数控仿真研究

渐速膛线电解加工的阴极需要通过实验反复修正,试验难度大,研制周期长。根据加工对象的几何参数和弹道方程建立数学模型,在Pro/E中建立阴极工作齿、炮管毛坯的几何模型并导入VERICUT,在VERICUT中设置机床参数和数控系统,添加刀具的轨迹G代码,进行加工过程的仿真,检验设计的阴极齿形状是否合理以及确定加工过程中出现的过切或欠切情况,优化阴极。研究表明,在电解加工阴极设计中采用VERICUT是一条可行的途径。     

真空冶金设备抽气装置专家系统及应用实例

介绍了专家系统的特点和应用,分析了大型真空冶金抽气装置的特性、故障多发原因以及排查中的困难,指出采用专家系统的可行性和实际意义,明确了在真空冶金抽气装置中建立专家系统的具体内容.以宝钢RH-KTB炉外精炼真空系统为例,给出了设备运行监测方案,建立了专家系统知识库,编制的软件可对设备的运行状态进行即时评价和故障预报,当真空系统出现故障时,采用逆向推理机制,从目标出发,寻找故障可能原因,并给出推理解释.专家系统对监测参数阈值的机器学习,提高了专家系统实际应用中的推理效率和准确性.专家系统软件经离线测试和现场在线应用达到预期的目标,可以推广应用.