Browsing by Author "Chieng, WH"

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A novel master switching method for electronic cam control with special reference to multi-axis coordinated trajectory following
(2006-02-01)
Chang, YH
;
Chieng, WH
;
Liao, CS
;
Jeng, SL
;
機械工程學系
Multi-axis coordinated trajectory following is important in CNC machines and metal cutting tools. Recently, flight simulators with electrical actuators have been in increasing demand. However, the coordinate control scheme affects the accuracy of the motion because motors have an insufficient load-capacity relative to the hydraulic actuators. The electronic cam (ECAM) is typically used to perform coordinated control. However, selection of the master may determine potentially very different characteristics of motion. This study proposes an automatic master switching method. The conditions and results of the master switching method for ECAM are detailed. The robustness and stability of the proposed control system is also demonstrated using the well-known structured perturbation analysis tool, mu. (c) 2005 Elsevier Ltd. All rights reserved.
A novel washout filter design for a six degree-of-freedom motion simulator
(2004-06-01)
Liao, CS
;
Huang, CF
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
The motion cue performed by a motion simulator is restrained by the workspace of the simulator structure. A typical reasoning is then to build a large motion simulator. unless it is for entertainment, which involves in small simulators. This study proposes a novel approach to designing the washout filter of the motion control of a six degree-of-freedom motion simulator for entertainment purposes. Using information obtained from the inverse kinematics of the simulator, the workspace boundary, detected in real-time, is fed into the washout filter as a reference for the motion planning. The main focus of this approach is to make the motion cue feasible for use in a simulator with a restricted workspace, while ensuring the robustness of the driving system. In this paper, different indices are established to specify the performance of the motion cue. A classical linear washout filter was implemented and compared with the proposed washout filter using the performance indices to demonstrate the benefits of the latter.
An elastic suspension design framework for tuned gyroscopes
(1997-03-01)
Yang, YN
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
This paper presents a design for a new tuned gyroscope framework consisting of a heavy rotor supported by a heli-flex suspension. Inherently free of 2 omega drift-error the gyro can be precisely tuned by adjusting pre-extension between two ends of its helix. The symmetrical support structure of this isotropic helical suspension design significantly reduces error moment caused by linear acceleration, and the device eliminates G(2) drift by virtue of its desirable anisoelasticity characteristic. The gyro design is simple, highly manufacturable, and when appropriate suspension parameters are used, produces a long-term drift-rate of 0.01 deg./hr.
An elastic suspension design framework for tuned gyroscopes
(1997-03-01)
Yang, YN
;
Chieng, WH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
This paper presents a design for a new tuned gyroscope framework consisting of a heavy rotor supported by a heli-flex suspension. Inherently free of 2 omega drift-error the gyro can be precisely tuned by adjusting pre-extension between two ends of its helix. The symmetrical support structure of this isotropic helical suspension design significantly reduces error moment caused by linear acceleration, and the device eliminates G(2) drift by virtue of its desirable anisoelasticity characteristic. The gyro design is simple, highly manufacturable, and when appropriate suspension parameters are used, produces a long-term drift-rate of 0.01 deg./hr.
Analysis and synthesis of geometric models using tree structured relations
(1997-09-01)
Tsai, PL
;
Fu, CC
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
In this study, we propose a methodology capable of analysing and synthesizing relational geometric design models, based on a mapping between geometric nodes (points) on the model and the physical dimensions of the solid model. The relations that include translation and rotation between the geometric nodes are stored in a toe structure. Based on this methodology, an implementation is developed that allows a designer to freely synthesize and analyse geometric relations among admissible physical dimensions of the object. Meanwhile the management of the underlying parameterized relational geometric data automatically occurs. (C) 1997 Elsevier Science Ltd.
Analysis and synthesis of geometric models using tree structured relations
(1997-09-01)
Tsai, PL
;
Fu, CC
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
In this study, we propose a methodology capable of analysing and synthesizing relational geometric design models, based on a mapping between geometric nodes (points) on the model and the physical dimensions of the solid model. The relations that include translation and rotation between the geometric nodes are stored in a toe structure. Based on this methodology, an implementation is developed that allows a designer to freely synthesize and analyse geometric relations among admissible physical dimensions of the object. Meanwhile the management of the underlying parameterized relational geometric data automatically occurs. (C) 1997 Elsevier Science Ltd.
Design of the swinging-block and turning-block mechanism with special reference to the mechanical advantage
(2004-03-01)
Yu, WJ
;
Huang, CF
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
This study describes a novel and complete solution for turning-block and swinging-block design with particular reference to the maximal average mechanical advantage over a specific swing angle span of the output link. The method yields an optimal set of link lengths for the turning-block and the swinging-block mechanisms. The torque was integrated with respect to the crank swing angle that yields a transmission energy form to maximize the average mechanical advantage. The optimal design solution is determined from the stationary value of the transmission energy. Results of this study can provide a valuable reference for efforts to achieve the high precision and high torque required in the mechanical design.
Electronic cam motion generation with special reference to constrained velocity, acceleration, and jerk
(2004-07-01)
Liao, CS
;
Jeng, SL
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
Electronic cam motion involves velocity tracking control of the master motor and trajectory generation of the slave motor. Special concerns such as the limits of the velocity, acceleration, and jerk are beyond the considerations in the conventional electronic cam motion control. This study proposes the curve-fitting of a Lagrange polynomial to the cam profile, based on trajectory optimization by cubic B-spline interpolation. The proposed algorithms may yield a higher tracking precision than the conventional master-slaves control method does, providing an optimization problem is concerned. The optimization problem contains three dynamic constraints including velocity, acceleration, and jerk of the motor system. (C) 2004 ISA-The Instrumentation, Systems, and Automation Society.
Method for finding multiple roots of polynomials
(2006-02-01)
Yan, CD
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Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
Conventional numerical methods for finding multiple roots of polynomials are inaccurate. The accuracy is unsatisfactory because the derivatives of the polynomial in the intermediate steps of the associated root-finding procedures are eliminated. Engineering applications require that this problem be solved. This work presents an easy-to-implement method that theoretically completely resolves the multiple-root issue. The proposed method adopts the Euclidean algorithm to obtain the greatest common divisor (GCD) of a polynomial and its first derivative. The GCD may be approximate because of computational inaccuracy. The multiple roots are then deflated into simple ones and then determined by conventional root-finding methods. The multiplicities of the roots are accordingly calculated. A detailed derivation and test examples are provided to demonstrate the efficiency of this method. (c) 2006 Elsevier Ltd. All rights reserved.
Modeling and analysis of nonlinear guideway for double-ball bar (DBB) measurement and diagnosis
(1997-05-01)
Lai, JM
;
Liao, JS
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
The purpose of this paper is to study nonlinear geometric errors in multi-axis machine tools. A general mathematical model for guideway systems that can be applied to high-precision machine tools such as CNC lathes is introduced. Using this model, most nonlinear error sources in the guideway systems can be diagnosed by measuring the contouring error using a double-ball bar (DBB). Diagnostic software has been developed to identify system parameters based on the least-squares estimation method. Inputting two or three contouring errors pattern data into this software enables parameters to be identified quickly, based on the nonlinear model. (C) 1997 Published by Elsevier Science Ltd.
Modeling and analysis of the intermediate shaft between two universal joints
(1996-01-01)
Sheu, PP
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Chieng, WH
;
Lee, AC
;
交大名義發表
;
機械工程學系
Unlike a single universal joint, in which the output shaft rotates with a fluctuating speed depending on the misalignment angle, a double universal joint is used to connect two offset shafts. If a double universal joint is correctly arranged with equal joint angles in perfect alignment, the output shaft rotates in a synchronous motion with uniform speed. However, in practice, the intermediate shaft of a double universal joint system suffers from bending moments induced by joint friction and velocity fluctuation induced by the joint angles. These factors distort the linear relationship between the input and output shafts. In this paper, the effects of joint angles and joint friction on the steady-state responses of a double universal joint system are examined. The mass matrix, damping matrix, stiffness matrix, and nonconservative force of a universal joint are derived analytically for finite element modeling. The formulation introduced generates an elementary matrix suitable for the analysis of complex rotor-bearing system's that include double universal joints.
Modeling and diagnosis of motion error of multi-axis machines using a ball bar test
(1996-09-01)
Jeng, SL
;
Chieng, WH
;
Lee, AC
;
交大名義發表
;
機械工程學系
The contouring accuracy of a multi-axis machine has a critical effect on the quality of many advanced technology products. One of the best approaches to assessing the contouring performance of machine tools is through double ball bar measurement. During circular interpolation motion, the machine traverses, with two axes at a time, a circular trajectory, with each axis subject to sinusoidal changes in acceleration, velocity, and position. The motion error is measured by detecting the relative distance between a point on the spindle nose and another point on the machine table and plotting this distance in polar coordinates. The present paper derives mathematical models and diagnosis procedures for first and second-order motion error resulting from the active degrees of freedom of a multi-axis machine. The theoretical results are verified by both computer simulation and double ball bar testing experiments.
Modeling of piezoelectric actuator for compensation and controller design
(2003-01-01)
Tzen, JJ
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Jeng, SL
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
This work proposes a novel method for describing the hysteretic non-linearity of a piezoelectric actuator. The hysteresis behavior of piezoelectric actuators, including the minor loop trajectory and the residual displacement near zero input, are modeled by a set of hysteresis operators, including a gain and an input-dependent lag, as well as the parameter scheduling method. A hysteresis model, using the identified parameters, and containing only the dominant hysteresis operator, is presented herein. Based upon a simplified hysteresis model, tracking is-controlled to reduce the non-linear effects in the characteristics of the piezoelectric actuator. A proportional-integral (PI) controller, with inverse model feed-forward, suppresses the tracking error to within +/-1% full span range (FSR) of the actuator, noticeably improving the tracking performance of the piezoelectric actuator. (C) 2002 Elsevier Science Inc. All rights reserved.
Optimum magnetic bearing design considering performance limitations
(1996-09-01)
Hsiao, FZ
;
Fan, CC
;
Chieng, WH
;
Lee, AC
;
交大名義發表
Magnetic bearings are subject to three practical performance limitations: the peak force capacity, force slew rate limitation, and displacement sensitivity. In conventional designs, we usually first design a feasible bearing, and then investigate these three limitations. Unfortunately, one usually fails to design the most suitable magnetic bearing in actual cases. In this paper, a methodology for dealing with the performance limitations through the concept of optimum design is presented. The objective functions are to maximize the force slew rate limitation and to minimize the displacement sensitivity under several design constraints. Using the optimization solver software package, we developed a systematic method for determining the characteristics of magnetic hearings. By considering the performance limitations and design constraints, we achieve a better design than that produced using the conventional trial-and-error method.
Polygon-to-object boundary clipping in object space for hidden surface removal in computer-aided design
(1995-09-01)
Chieng, WH
;
Hoeltzel, DA
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
Since technique for both polygon-to-polygon clipping and polygon-to-object boundary (contour) clipping have been developed, it appears that the visibility problem may exhibit potential for improvement in its time complexity. This paper provides some insight and results concerning the performance of an object-space hidden surface removal algorithm based on polygon-to-object boundary (contour) clipping. The applicability of these results to the graphic rendering of partially visible objects in an incremental computer-aided geometric design system, such as that used in mechanical design, is demonstrated. The polygon-to-object boundary clipping algorithm is compared with the more conventional polygon-to-polygon approach to clipping for hidden surface removal. Examples are included which demonstrate the potential for improving the performance of software-based hidden surface removal algorithms used in computer-aided geometric design applications.
Polygon-to-object boundary clipping in object space for hidden surface removal in computer-aided design
(1995-09-01)
Chieng, WH
;
Hoeltzel, DA
;
機械工程學系
;
Department of Mechanical Engineering
Since technique for both polygon-to-polygon clipping and polygon-to-object boundary (contour) clipping have been developed, it appears that the visibility problem may exhibit potential for improvement in its time complexity. This paper provides some insight and results concerning the performance of an object-space hidden surface removal algorithm based on polygon-to-object boundary (contour) clipping. The applicability of these results to the graphic rendering of partially visible objects in an incremental computer-aided geometric design system, such as that used in mechanical design, is demonstrated. The polygon-to-object boundary clipping algorithm is compared with the more conventional polygon-to-polygon approach to clipping for hidden surface removal. Examples are included which demonstrate the potential for improving the performance of software-based hidden surface removal algorithms used in computer-aided geometric design applications.
Precision alignment of mask etching with respect to crystal orientation
(1998-12-01)
Lai, JM
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Chieng, WH
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Huang, YC
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機械工程學系
;
電子工程學系及電子研究所
For most micro-mechanical devices, a high precision alignment of mask pattern to crystal orientation is preferred. Such alignment even becomes critical for devices that simultaneously require a smooth sidewall and minimal undercut. In this article, we present an innovative pre-etching pattern to determine the [110] crystal orientation on [100] silicon wafers. This pattern etched on the wafer allows us to determine the crystal orientation within an accuracy of 0.01 degrees. Such a pre-etching pattern can be used as a valuable reference for all subsequent mask patterns.
Structural design and analysis of micromachined ring-type vibrating sensor of both yaw rate and linear acceleration
(2005-01-14)
Weng, JH
;
Chieng, WH
;
Lai, JM
;
機械工程學系
;
Department of Mechanical Engineering
This work presents the design and analysis of a micromachined ring-type motion sensor which can sense both the yaw rate and linear acceleration of a device in that it is installed. It integrates the functions of a gyroscope and an accelerometer. The design of the microstructure is based on the structure of a vibrating ring gyroscope. The analysis, considering the symmetry of the structure, implies that the rotational symmetry and mirror symmetry of the microstructure markedly affect the performance of the sensor. The modes of vibration determined using finite element analysis and the theoretical calculation of the resonant frequency of the structure are presented. The sensitivities of the characteristic of the sensor to the design specification, the fabrication errors and the theoretical errors are discussed. The structure is fabricated based on deep silicon etching and wafer bonding techniques. The process is developed for eliminating the aspect ratio dependent effect (ARDE) in dry etching process. (C) 2004 Elsevier B.V. All rights reserved.
Structural fabrication of a ring-type motion sensor
(2004-05-01)
Weng, JH
;
Chieng, WH
;
Lai, JM
;
機械工程學系
;
Department of Mechanical Engineering
The structural fabrication of a ring-type motion sensor is described. This micromachined ring-type sensor can be used to detect both yaw rate and linear acceleration. The fabrication is based on deep silicon etching and wafer bonding. An aspect ratio dependent effect (ARDE) always occurs in the dry etching process for a micro electromechanical systems (MEMS) device. Additionally, three processes are developed and modified progressively for eliminating ARDE from the fabrication results. Results indicate that the proposed process provides more flexibility than other processes with respect to the structural fabrication of a MEMS device. The sensitivity of the sensor characteristic to the manufacturing errors is considered as well.
The joint displacement method for multiloop kinematic analysis
(1995-12-01)
Yang, YN
;
Chieng, WH
;
Lee, AC
;
交大名義發表
;
機械工程學系
We present a kinematic formulation, referred to as the joint displacement method. In the kinematic analysis; the closed-loop kinematic chain of interest must be transformed into several open-loop chains by imagining that some joints are relaxed (disconnected), and by replacing them as physical entities with a set of constraint equations. This formulation requires only a minimal number of generalized coordinates, hence it provides;a highly efficient approach for real-time kinematic analysis of spatial mechanisms, heretofore unseen in the literature. For-example, the Jacobian matrix for the RSCR mechanism is 3 x 3 and the CPU time required to perform Gauss elimination is 182 times shorter than that in the traditional link-coordinate method which requires a 17 x 17 Jacobian matrix. This method is applicable to both single loop and multiloop spatial mechanisms with revolute, cylindrical, translational, spherical and universal joints. A general-purpose computer program that implements the joint displacement method has been developed and tested on a variety of mechanisms.