Browsing by Author "Chin, Jih-Hua"

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Force computation and continuous path tracking for hydraulic parallel manipulators
(2008-06-01)
Chin, Jih-Hua
;
Sun, Yen-His
;
Cheng, Ming Cheng
;
機械工程學系
;
Department of Mechanical Engineering
Machine tools, robots and parallel manipulators are useful platforms in manufacturing. For parallel manipulators, developing contour tracking ability and clarifying the role of force computation are of significance. This work presents a novel contour tracking control with force Computation for hydraulic parallel manipulators. Different trajectories are used to evaluate the tracking errors on an empirical hydraulic parallel manipulator. The proposed control law and tracking systems are effective and the force computation is proven highly effective in the frame of the contour tracking system. (C) 2007 Elsevier Ltd. All rights reserved.
Real-time interpolator and Contour Tracking in Link-space for a 3 DOF Parallel Mechanism
(2008)
Cheng, Yuan-Ming
;
Kuo, Chien-Hsun
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Chin, Jih-Hua
;
機械工程學系
;
Department of Mechanical Engineering
Parallel mechanisms could be hardly used in contour tracking because of their mechanism features. This study proposed a link-space real time contour tracking for a 3 DOF (Z - alpha and beta) hydraulic parallel mechanism. The essence of this approach is to convert control points of command trajectory to link space by inverse kinematics. A real-time interpolator was created and the multi-axis cross-coupled pre-compensation control (MCCPM) was constructed for link-space contour tracking. It was shown that a contour-accurate trajectory tracking could be performed which was impossible in the original Z-alpha-beta space. Other advantages of this link-space approach were time efficiency and the uniform tracking velocity.
Strengths and weaknesses of finite element modeling deep hole drilling as compared with beam and column equations
(2007-03-01)
Chin, Jih-Hua
;
Sheu, Shou-Der
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機械工程學系
;
Department of Mechanical Engineering
Deep hole drilling has been studied mainly experimentally in the past. Recently, some theories using beam or column equations have been proposed, which involved complicated mathematical efforts. This work analyzed deep hole drilling by a finite element model (FEM). Results of modal analysis on the established FEM were compared with results from Euler beam equations. Further analysis showed that the FEM could also predict straightness deviation as did the column equation. In addition, FEM could analyze the effects of variable support distance which neither beam nor column equation could. Other analysis results are also presented. The results in this study showed the strength and weakness of the FEM.
System gains configuration and coordination of redundant degrees of freedom by genetic algorithms for multi-axis machine system in manufacturing
(2007-05-01)
Chin, Jih-Hua
;
Chen, Yu-Cheng
;
機械工程學系
;
Department of Mechanical Engineering
In multi-axis machine tool systems, the configuration of system gains and the coordination of redundant degrees of freedom are often a problem of insurmountable difficulty. This study explores the use of a nontraditional scheme, the genetic algorithm, in the configuration of system gains and exploitation of redundant degrees of freedom. The off-line gains configuration functioned as a kind of system design which may serve as a starting point for on-line adaptation. The allocation of redundant DOF was done on-line. The success in this work inspired the idea of future on-line GA application and the possibility of integration of GA with other non-traditional algorithms for manufacturing. (c) 2007 Elsevier Ltd. All rights reserved.
Targeted suppression of vibration in deep hole drilling using magneto-rheological fluid damper
(2014-11-01)
Kong, Lingfei
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Chin, Jih-Hua
;
Li, Yan
;
Lu, Yanjun
;
Li, Pengyang
Under the concept of precision or targeted vibration suppression, a novel approach is developed to reduce the vibration of drilling tool system in deep-hole drilling process. The concept is to suppress the dominant vibration upon its emergence by variable damping or to force the harmful vibration morph into less harmful by different damper position. A magneto-rheological (MR) fluid damper is designed with adjustable damping capability to counteract emerging vibration. A series of experimental investigations are carried out on the BTA deep hole drilling process. The experimental results show that the adjustable MR damping brings down the vibration in all applications with different suppression effect. A relative optimal suppression can always be found. The suppressed vibration experiences a frequency shift which sheds light on the possible avoidance of matching of unwelcome frequency. Different damper locations have different but consistent suppression results which foresee a possibility of forcing the mode of vibration into less harmful one. A potential precision or targeted suppression of vibration upon its emergence is thus possible. (C) 2014 Elsevier B.V. All rights reserved.
Vibration suppression of drilling tool system during deep-hole drilling process using independence mode space control
(2020-04-01)
Kong, Lingfei
;
Cao, Shuai
;
Chin, Jih-Hua
;
Si, Yue
;
Miao, Falin
Deep-hole drilling technology is commonly used in the aerospace and automobile industries, for new-energy equipment manufacturing, and in the high-tech industries. While this technology produces high-quality holes, higher quality is pursued. A method to improve the processing quality is to suppress the vibration modes associated with long shafts. This problem was addressed with an aim of real-time application. In addition, a higher goal was set by way of providing a solution (in full) to the associated problem, to shed light on processes that bear similar features in manufacturing and for other industries. An operable control scheme was constructed by transforming the system dynamics to modal space for modal decoupling and truncation. The modal displacement and velocity information estimated by the modal filtering were introduced into the feedback gain matrix. All obstacles in traditional physical space were shunned. A damper/sensor position optimisation algorithm was suggested to minimise the modal spillover and acquire modal orthogonality, which led to a new method that has an edge on all preceding methods because of its stronger ability. A system capable of real-time suppression of modal vibration in a deep-hole drilling tool was built and implemented. Using hole roundness error as the criterium, it was found that further improvement of hole quality was achieved. The idea presented in this work may pave the way for elevating the quality of other manufacturing processes with similar weak stiffness features, such as those seen in long-shaft tools or thin-wall workpieces. The method may also provide a reference for other industries with relevant or comparable problems.