Materials Science Forum Vols. 505-507

Abstract: This paper demonstrates how to design and implement the emulators for a real-world automated manufacturing system (AMS). In order to develop and validate system control software for managing AMSs, most laboratories have constructed an experimental test using actual manufacturing equipment. These experimental systems typically occupy a large amount of lab space and require considerable human expertise to operate. In this paper, a scenario-based development environment for the equipment design and implementation are described. The intended advantage of the proposed environment is that, the designer can make an experimental test in a computer and does not need the actual manufacturing equipment. The proposed environment can be used to design and implement a real-world automated manufacturing cell controller at National Taiwan University of Science and Technology (NTUST). We start with a new methodology to model the operation sequences of the system’s equipment (i.e., machine) called scenario. Modeling methodology is the key to the application of scenarios to automated manufacturing systems. The scenarios methodology is able to clearly depict the communication signals for the equipment. And it also can be used to model the resource utilization features within a manufacturing system. Using scenario, we have developed an emulator for an automated manufacturing cell which faithfully replicates the operating characteristics of an ensemble of physical equipment that would typically comprise an AMS.

Abstract: The wafer defect inspection is an important process before die packaging. The defective regions were usually identified through visual judgment with the aid of a scanning electron microscope. Dozens of people visually check dies and mark their regions manually. Thus, potential misjudgment may be introduced due to human fatigue. In addition, the process can incur significant personnel costs. Self-Organizing Neural Networks (SONNs) have been proven to have the capabilities of unsupervised auto-clustering. In this paper, a hierarchical self-organizing neural networks (HSONN) with consideration of multiple textural information is proposed to replace the traditional electrical testing and the human inspection processes. The proposed HSONN is consists of 3 layers, each layer is a specific cluster to separate the block of wafer image into normal and defective regions. The suspicious defective regions are used as inputs to the next layer of HSONN for subsequent classification of the defective regions. Through the hierarchical classify, the output of the 3th layer denotes the detecting defective regions. Based on real-world data, the experimental results show that the proposed method successfully identifies the defective regions on wafers with good performances.

Abstract: This paper deals with a new scheme for prognostics of ball bearing based on Self-Organizing Map (SOM), back propagation neural-network and complex Morlet Wavelet methods. It uses complex Morlet wavelet-based envelope to extract successfully the characteristic frequencies of ball bearing. Then the minimum quantization error (MQE) indicator deriving from SOM is used for performance degradation assessment. Based on Weight Application to Failure Times (WAFT) technology, which deriving from back propagation neural networks, a prognostics model of ball bearing is developed successfully. And the experimental results show that the proposed methods are greatly superior to the currently used L10 bearing life prediction.

Abstract: A large-scale elevating transporter that has multi-wheels to be steered independently is a very complex mechatronic system. Aiming at its real-time coordinated motion control, a multi-mode steering system based on Networked Control System (NCS) is proposed to tackle the problem in the paper. Through motion synthesis, such as kinematics and dynamics modeling and analysis, and using the inherent real-time data sharing of the NCS, a cross-coupled control algorithm for improving contour accuracy is developed. This control methodology is then applied to the coordinated motion control of a practical product with multi-steering modes successfully.

Abstract: Life testing is an important technique to assess the reliability and lifetime of components with long life and high reliability. To some expensive products, it is difficult to supply a large of samples and long test time to carry out the life testing, so this paper investigates the accelerated model and presents statistical method based on hybrid Weibull distribution under variable synthetic stresses. Based on the cumulative exposure theory, the failure probability can be cumulated with transform rate that can convert the fault proportion at certain stress into another stress. Using the genetic algorithm, the parameters of accelerated model can be estimated according to the accelerated stress profile. Then the lifetime at normal stress can be calculated with accelerated life model under normal stress profile. Application of hydraulic pump indicates that this method can reduce test time and test samples greatly.

Abstract: A CAD/CAM idea with its relation model including the analyses of braid process, yarns internal geometry and mechanical properties is proposed. An infrastructure of CAD/CAM system with platform and criterions which endure expandability is introduced. Based on the platform, some subsystems are built to accomplish various tasks such as 3D modeling, finite element analysis and braided process simulation. In order to implement the platform, parameter transferring is analyzed and an example is given. Based on the braiding process of composite, the axis direction stiffness/flexibility matrix, cell stiffness and engineering constants is acquired by the analysis of yarns and cell. At last, a proper and feasible collaborative environment and the tasks assignment is proposed. Based on the platform, an analysis instance is finished and the results are exhibited.

Abstract: This paper is focused on the performance analysis of a newly developed 6-DOF Parallel-Kinematics Machine (PKM). The design related analysis issues such as the instantaneous kinematics, manipulability, accuracy, and stiffness are addressed. This new PKM has three identical RPRS legs to support the moving platform. Since all joint axes, excluding the three spherical joints at the leg-ends, are parallel to each other and perpendicular to the base plane, this 6-DOF 3RPRS PKM exhibits decoupled motion characteristics such that translation along the vertical direction and rotation about horizontal axes are only driven by the three active-prismatic joints, while translation in horizontal planes and rotation about vertical axes are mainly driven by the three active-revolute joints. The PKM also has a large cylindrical reachable workspace and high stiffness in vertical directions. These features make it a promising 6-DOF machine structure for light machining and heavy parts assembly tasks.

Abstract: The main difficulties in dealing with extremely high speed precision contouring control are system uncertainties and external disturbances, which exist in all CNC mechanisms and hard to be eliminated. Up to the present, numerous control strategies for multi-axial contouring control have been proposed. Some of them are only for specific contour conditions. This paper surveys several formulations in dealing with contouring control system, instead of the controller design. The distinguishing features of these control structures are also addressed.

Abstract: In this paper, a new design of three degrees-of-freedom (DOF) plane motion system actuated by electromagnetic forces is proposed and experimentally studied. The advantages of electromagnetic driven system lie in the elimination of the backlash, friction and wear phenomena. With this new structure design the coupling between the z translation, pitching and rolling motions becomes simpler than the conventional designs. A PI controller is applied and achieves the required high precision performance of the system. The experimental studies support the effectiveness of the system.

Abstract: This paper presents PID tuning rules for first-order plus integrator systems. These tuning rules are derived by optimizing the integrated absolute errors of set point and load disturbance responses under robustness and bandwidth constrains. For deriving the tuning formulas, PID controllers for some normalized systems were designed. The relationship between the controller parameters, the parameters that characterize the system dynamics and the normalized gain crossover frequency are determined and the tuning formulas are then derived. Experimental results are provided to demonstrate the effectiveness of these tuning rules.