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Gyroscopically stabilized robot: Balance and tracking

International Journal of Advanced Robotic Systems 2004年第1期1卷 23-32页

作者： Ou, Yongsheng Xu, Yangsheng Chinese University of Hong Kong Department of Automation and Computer-Aided Engineering Hong Kong

The single wheel, gyroscopically stabilized robot - Gyrover, is a dynamically stable but statically unstable, underactuated system. In this paper, based on the dynamic model of the robot, we investigate two classes of nonholonomic constraints associated with the system. Then, based on the backstepping technology, we propose a control law for balance control of Gyrover. Next, through transferring the systems states from Cartesian coordinate to polar coordinate, control laws for point-to-point control and line tracking in Cartesian space are provided.

关键词： Robots

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computer-aided-DESIGN AND RAPID TOOL DEVELOPMENT IN INJECTION-MOLDING PROCESSES

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computerS & INDUSTRIAL engineering 1995年第1期29卷 659-662页

作者： BILES, WE GORNET, TJ DAVIS, K YI, A Henry Vogt Center for Computer-Aided Engineering & Factory Automation University of Louisville Louisville Kentucky USA 40292

Rapid prototyping is taking hold as a means of speeding the time of market for new plastics products. The computer technology that facilitates this emerging new technology is 3-D solids modeling in CAD. This paper describes how CAD technology is linked to a selective laser sintering (SLS) process to form a mold insert for an injection molding modular die. A usable mold insert can be made ready for production in:a matter of days, compared to many weeks for the traditional model-shop approaches to new mold development.

关键词： Concurrent engineering

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PLANNING AND CONTROL OF 3-D NANO-MANIPULATION

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Acta Mechanica Sinica 2004年第2期20卷 117-124页

作者：李广勇席宁王越超于蒙蒙冯伟强 Department of Electrical and Computer Engineering Michigan State UniversityMI 48824USA Shengyang Institute of Automation Chinese Academy of SciencesShenyang110016China Department of Electrical Engineering Princeton UniversityPrincetonNJ 08544USA Department of Automation and Computer-Aided Engineering The Chinese University of Hong KongHong KongChina

The use of atomic force microscope(AFM)as a nanomanipulator has been evolving for various kinds of nano-manipulation *** to the bow effect of the piezo scanner of the AFM, the AFM space is different from the Cartesian *** nanomanipulation based on AFM is only a 2-D operation and does not consider the bow effect of the *** this paper,different 3-D nanomanipulation tasks using AFM such as nanolithography,pushing and cutting have been discussed. 3-D path planning is performed directly in the AFM space and the 3-D paths are generated based on the 3-D topography information of the surface represented in the AFM *** approach can avoid the mappings between the AFM space and Cartesian space in *** following the generated motion paths,the tip can either follow the topography of the surface or move across the surface by avoiding collision with *** using this method can be considered as the'true' 3-D operations since the cantilever tip can be controlled to follow any desired 3-D trajectory within the range of AFM *** experimental study shows the effectiveness of the planning and control scheme.

关键词： AFM nano-manipulation

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Bilateral recovering of sharp edges on feature-insensitive sampled meshes

Bilateral recovering of sharp edges on feature-insensitive s...

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作者： Wang, Charlie C. L. IEEE Department of Automation and Computer-Aided Engineering Chinese University of Hong Kong Shatin N.T Hong Kong Department of Automation and Computer-Aided Engineering Chinese University of Hong Kong

A variety of computer graphics applications sample surfaces of 3D shapes in a regular grid without making the sampling rate adaptive to the surface curvature or sharp features. Triangular meshes that interpolate or approximate these samples usually exhibit relatively big error around the insensitive sampled sharp features. This paper presents a robust general approach conducting bilateral filters to recover sharp edges on such insensitive sampled triangular meshes. Motivated by the impressive results of bilateral filtering for mesh smoothing and denoising, we adopt it to govern the sharpening of triangular meshes. After recognizing the regions that embed sharp features, we recover the sharpness geometry through bilateral filtering, followed by iteratively modifying the given mesh's connectivity to form singlewide sharp edges that can be easily detected by their dihedral angles. We show that the proposed method can robustly reconstruct sharp edges on feature-insensitive sampled meshes. © 2006 IEEE.

关键词： computer graphics

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Numerical simulation of the effect of void fraction and inlet velocity on two-phase turbulence in bubble-liquid flows

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Acta Mechanica Sinica 2006年第5期22卷 425-432页

作者： Lixing Zhou Rongxian Li Ruxu Du Department of Engineering Mechanics Tsinghua University Beijing 100084 China Shenzhen Research Institute Tsinghua UniversityShenzhen China Department of Automation and Computer Aided Engineering The Chinese University of Hong Kong Hong Kong China

There are contradicted opinions on whether bubbles enhance or reduce the liquid turbulence. In this paper, the effect of void fraction and inlet velocity on the bubble-liquid two-phase turbulence of the multiple bubble-liquid jets in a two-dimensional channel is studied by using the two-phase second-order moment turbulence model. The results confirm the phenomena observed in experiments and reported in references that at a low void fraction and low inlet velocities the bubbles enhance the liquid turbulence, whereas at a high void fraction and high inlet velocities the bubbles reduce the liquid turbulence.

关键词： Bubble-liquid flows Two-phase turbulence Second-order moment model

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Optimization of heterogeneous solids with level set methods

Optimization of heterogeneous solids with level set methods

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ICMA 2004 - International Conference on Manufacturing automation: Advanced Design and Manufacturing in Global Competition

作者： Wang, M.Y. Department of Automation and Computer-aided Engineering Chinese University of Hong Kong Hong Kong

ISBN: (纸本)1860584683

A heterogeneous object is referred to as a solid object made of different constituent materials. The object is of a finite collection of regions of a set of prescribed material classes of continuously varying material properties. These properties have a discontinuous change across the interface of the material regions. We present a variational framework of Mumford-Shah model for a well-posed formulation for the design of the heterogeneous solids. We discuss two approaches to the optimization problem of free-discontinuities: a multi-phase level-set model and a multi-material phase-field model, both to represent the discontinuities implicitly. These models yield a computational system of coupled geometric evolution and/or diffusion partial differential equations. Promising features of the proposed method include strong regularity in problem formulation, topological flexibility, and inherent capabilities of geometric, physical and material modeling, incorporating dimension, shape, topology, material properties, and even micro-structures within a common framework for optimization of the heterogeneous solids. The proposed methods are illustrated with several 2D examples of topology optimization of multi-material structures, material design, and compliant mechanism synthesis. © Professional engineering Publishing 2004.

关键词： Materials science

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A detection system for human abnormal behavior

A detection system for human abnormal behavior

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作者： Wu, Xinyu Ou, Yongsheng Qian, Huihuan Xu, Yangsheng Department of Automation and Computer-Aided Engineering Chinese University of Hong Kong Hong Kong

ISBN: (纸本)0780389123

This paper introduces a real-time video surveillance system which detects human abnormal behaviors. We present two approaches to such a problem. The first one employs Principal Component Analysis for feature selection and Support Vector Machine for classification of human behaviors. The proposed feature selection method is based on the border information of four consecutive blobs. The second approach computes optical flow to obtain the velocity of each pixel for determining whether a human behavior is normal or not. Both algorithms are successfully implemented in crowded environments for detecting the human abnormal behaviors, such as (1) running people in a crowded environment, (2) bending down movement while most are walking or standing, (3) a person carrying a long bar and (4) a person waving hand in the crowd. Experimental results demonstrate the two methods proposed are robust and efficient in detecting human abnormal behaviors. © 2005 IEEE.

关键词： Intelligent systems

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A NEW METHOD FOR MONITORING AND TUNING PLASTIC INJECTION MOLDING MACHINES

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CONTROL AND INTELLIGENT SYSTEMS 2008年第2期36卷 129-136页

作者： Lau, H. Y. Li, X. Du, R. SML International Ltd. University of Brimingham Department of Automation and Computer Aided Engineering Chinese University of Hong Kong Shatin NT Hong Kong

This paper presents a new method for monitoring and tuning plastic injection molding machines. It consists of two parts: quality monitoring using the Radial Basis Function Neural Network (RBFNN), and operation parameter tuning using Support Vector Machine (SVM) and Virtual Search Method (VSM). The quality is measured by the part weight, which is estimated using hydraulic pressure signal and ram position signals through a RBFNN. The tuning is aimed at finding the optimal setting of the machine operation condition. It is done in two steps: first, a SVM model is established as the virtual model to track the part quality variations, and then the quality variation is minimized by tuning the machine operating conditions using VSM. The new method is validated by two sets of practical experiments, and the results are very promising.

关键词： plastic injection molding monitoring optimization Artificial Neural Network (ANN) Support Vector Machine (SVM) Virtual Search Method (VSM)

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Direct estimation of the stereo geometry from monocular normal flows

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2nd International Symposium on Visual Computing, ISVC 2006

作者： Ding, Yuan Ronald, Chung Department of Automation and Computer-Aided Engineering Chinese University of Hong Kong Shatin Hong Kong

ISBN: (纸本)3540486283

The increasing use of active vision systems makes it necessary to determine the relative geometry between the cameras in the system at arbitrary time. There has been some work on on-line estimation of the relative camera geometry parameters. However, many of them are based on epipolar geometry, motion correspondences, or even presence of some calibration reference objects in the scene. In this paper, we describe a method that allows the relative geometry of two cameras be estimated without assuming that their visual fields picture the same object, nor that motion correspondences in each camera are fully estimated beforehand. The method starts from monocular normal flows in the two cameras and estimates the relative geometry parameters without evening accessing the full optical flows. Experimental results are shown to illustrate the performance of the method. © Springer-Verlag Berlin Heidelberg 2006.

关键词： Stereo vision

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Solving variational inequality problems with linear constraints based on a novel recurrent neural network

Solving variational inequality problems with linear constrai...

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4th International Symposium on Neural Networks (ISNN 2007)

作者： Xia, Youshen Wang, Jun College of Mathematics and Computer Science Fuzhou University China Department of Automation and Computer-Aided Engineering Chinese University of Hong Kong Hong Kong

ISBN: (纸本)9783540723943

Variational inequalities with linear inequality constraints are widely used in constrained optimization and engineering problems. By extending a new recurrent neural network [14], this paper presents a recurrent neural network for solving variational inequalities with general linear constraints in real time. The proposed neural network has one-layer projection structure and is amenable to parallel implementation. As a special case, the proposed neural network can include two existing recurrent neural networks for solving convex optimization problems and monotone variational inequality problems with box constraints, respectively. The proposed neural network is stable in the sense of Lyapunov and globally convergent to the solution under a monotone condition of the nonlinear mapping without the Lipschitz condition. Illustrative examples show that the proposed neural network is effective for solving this class of variational inequality problems.

关键词： Neural networks

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