Browsing by Author "Cheng, Pi-Ying"

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A CONTROL SYSTEM DESIGN FOR EFFICIENTLY OPERATING FREE-MOTION OF SERVO MECHANICAL PRESS
(2014-01-01)
Chen, Pin-Jyun
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Cheng, Pi-Ying
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Lin, Yu-Ting
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Cheng, Tseng-Jen
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機械工程學系
Servo press has the ability to improve the formability, quality, and productivity of metal products by working with various forming curves of slide. However, the operations of free-motion function are not very intuitional and efficient for most of servo presses so that it is difficult for operator to construct self-design forming curves. This article proposed a control system design of servo mechanical press which consists of an open-system controller and a real-time operating system to provide a convenient and efficient approach for operating free-motion function. In the proposed control system, operators determine the motion of slide by adjusting several control points of forming curve in a friendly and graphical interface. Then a calculating process based on the B-spline and curve fitting theories is applied in the controller to transform settings of operator into speed commands of servo motor automatically. Through this process, the controller is capable of driving servo motor smoothly and generating an expectant forming curve. In the latter section, some compare and analyses of setting of operator and actual results are demonstrated to verify the performance of proposed control system. By applying the proposed control system design to servo mechanical press, operators are able to create practical and satisfying forming curves more easily.
A Novel Automatic Concrete Surface Crack Identification Using Isotropic Undecimated Wavelet Transform
(2012)
Hoang-Nam Nguyen
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Kam, Tai-Yan
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Cheng, Pi-Ying
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機械工程學系
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Department of Mechanical Engineering
traditionally, concrete surface cracks are manually measured and recorded by experienced inspectors who observe cracks with their naked eye. This task is very costly, time-consuming and dangerous. Some automatic crack detection techniques utilizing image processing have been proposed. However, it is very difficult to automatically identify cracks sufficiently fast and accurate. This paper presents a novel automatic algorithm for effectively identifying cracks in concrete structures, which can be applied to high resolution photographs. Firstly, as cracks can be considered as elongated dark objects in concrete surface images, all dark objects are roughly identified using Isotropic Undecimated Wavelet Transform (IUWT) and morphological image processing. Secondly, all previous detected dark objects are classified into crack and non-crack objects by analyzing their cross section pixel intensity profiles, which are computed perpendicularly across their centre-lines in the original input image, using a novel method based on Savitzky-Golay filter. Therefore, both local and global changes in crack width can be readily quantified. Experiments show that our method can automatically detect true cracks in concrete surface images using a unique set of parameters.
An Automatic Approach for Accurate Edge Detection of Concrete Crack Utilizing 2D Geometric Features of Crack
(2014-12-01)
Hoang-Nam Nguyen
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Kam, Tai-Yan
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Cheng, Pi-Ying
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機械工程學系
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Department of Mechanical Engineering
The automatic edge detection of cracks on concrete structures plays an important role in the damage assessment process for cracked structures. In this paper, we proposed an automatic method for accurate edge detection of concrete cracks from real 2D images of concrete surfaces containing noisy and unintended objects. In the 2D image of a damaged concrete surface, cracks are usually observed as tree-like topology dark objects of which the branches are line-like and have local symmetry across their center axes. We utilize these two geometric properties of cracks to detect crack edges and discriminate them with edges of other unintended objects. The novel automatic crack edge detection is composed of two sequential stages. In the first stage, cracks are enhanced by a novel phase symmetry-based crack enhancement filter (PSCEF) based on their symmetric and line-like properties while non-crack objects are removed. Estimated crack center-lines are then obtained by thresholding the filtered images and applying morphological thinning algorithm to the binary image. In the second stage, the estimated center lines of the detected cracks are fitted by cubic splines and the pixel intensity profiles in the directions perpendicular to the splines are used to determine the edge points. The edge points are linked together to form the desired continuous crack edges. Various experiments of real concrete crack images are used to demonstrate the excellent performance of the proposed method.
BARRIER-OVERPASSING TRANSPORTER
(2008-08-07)
Cheng, Pi-Ying
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Guo, Fang-Fu
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Wong, Kian-Poh
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Lin, I-Chung
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Lee, Yu-Hsien
The present invention discloses a barrier-overpassing transporter, which comprises: a support frame carrying a rider or another load; a sensing/adjusting module detecting a tilting state of the support frame and maintaining the support frame in a horizontal state; a ground contact module arranged below the support frame supporting an effective load and lifting the support frame to overpass a surface of a barrier; and a wireless transceiver module collecting and transmitting information to enable adjustments and activities responding to interior states of the transporter. Thereby, the present invention can provide a safe, stable, reliable, comfortable, convenient and low-cost barrier-overpassing transporter.
Confocal displacement sensor with varifocal lens
(2015)
Weng, Chun-Jen
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Lan, Tzu-Hsien
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Hwang, Chi-Hung
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Liu, Da-Ren
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Chen, Chih-Yen
a confocal displacement sensor with a varifocal lens and a multi-wavelength rainbow laser was established in this study. The surface curvature of varifocal lens was varied by different current driving so that the focal length can be easily changed. Thus, we can quickly measure the distance between the sensor head and targets by detecting the reflective power according to the principle of confocal laser. This rainbow laser can operate at four different wavelengths. The laser beams with different colors can be used to measure the dispersion of varifocal lens. The range of measuring displacement with 20X objective lens in this displacement sensor is from 4.9mm to 5.9mm. The FWHM resolution of displacement is about 70 mu m. The step-height aluminate plate was measured by this system and the error of measuring distance is less than 35 mu m (0.75%).
Effect of Pd distribution on Pd-plated Cu wire using different electronic flame off settings
(2017-03-01)
Cheng, Pi-Ying
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Lai, Po-Ying
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Ye, Zheng-Jie
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Hsieh, Cheng-Li
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Ye, Jiun-Ming
Pd-coated Cu wires show interesting properties such as good electrical conductivity, thermal conductivity, and reliability and are widely used in microelectronic packaging. However, during the formation of free air balls (FABs) and bonded balls via Pd-coated Cu wires, the electronic flame off (EFO) current setting affects Pd distribution in FABs and bonded balls. This study investigated the effect of different EFO current settings on Pd distribution during the formation of FABs and bonded balls, and also analyzed the influence of EFO current settings on FAB formation. Pd distribution in FABs and bonded balls, as well as the distribution of other elements, were observed. The corrosion on the surface of a bonded ball was observed through high temperature storage tests (HTSTs). The result revealed that there were different Pd distributions in the formation processed via different EFO current settings of FABs and bonded balls. Further, different EFO current settings also resulted in a different FAB shape. The result of HTST indicated that proportional Pd distribution could decelerate the corrosion of a bonded ball.
Evaluation of the dynamic performance variation of a serial manipulator after eliminating the self-weight influence
(2011-09-01)
Cheng, Pi-Ying
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Cheng, Kuei-Jen
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機械工程學系
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Department of Mechanical Engineering
Manipulators used in the industrial field usually have a very stiff structure but without an equivalent payload on their end-effectors. This is because the stiff structure is used to prevent excessive deformation which will negatively impact the positioning accuracy of the manipulator, especially when the manipulator is fully extended. However, the stiff structure increases the weight of the manipulator and consumes much of the output of the constituent joint actuators in order to overcome the gravitational force resulting from the heavy structure. To cope with this problem, the concept of gravity balance was proposed decades ago, and there have been several approaches suggested to eliminate the influence of the self-weight of the structure. With the help of gravity balance, the output of the constituent joint actuators can fully be used to drive the manipulator and save considerable energy when the manipulator is in static or low-speed applications. For decades, many papers have discussed how to make a manipulator in gravity balance or how to design and apply a gravity balance mechanism to satisfy a certain application. However, none of them discuss what the influence on the dynamic performance of a manipulator is after it is equipped with a gravity balance mechanism or how to evaluate that influence. To rectify this insufficiency, this article utilizes acceleration radius to be the index of measuring the dynamic performance before and after a manipulator is equipped with a gravity balance mechanism and proposes a new index, the maneuverability ratio, to provide quantitative information to measure whether the dynamic performance of the manipulator increases or not after the gravity balance mechanism is applied. (C) 2011 Elsevier Ltd. All rights reserved.
Graphene-based chips fabricated by ultraviolet laser patterning for an electrochemical impedance spectroscopy
(2016-04-01)
Tseng, Shih-Feng
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Haiso, Wen-Tse
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Cheng, Pi-Ying
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Chung, Chien-Kai
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Lin, Yung-Sheng
This study aims to develop graphene-based impedance chips for an electrochemical impedance instrument fabricated by ultraviolet (UV) laser patterning. The finger-like electrode structure on multilayer graphene films coated on glass substrates was performed in a one-cycle laser patterning process. After a series of laser ablated line tests, the ablated line widths increased with increasing laser fluences. The optimal laser patterning parameters involved the laser fluence of 3.4 J/cm(2), scanning speed of 600 mm/s, and pulse repetition frequency of 100 kHz to remove completely a graphene electrode layer without damaging glass substrate. The patterned regions had no significant heat-affacted zones (HAZs) due to graphene materials with high thermal diffusivity. To clarify graphene removal completely, the patterned regions on graphene/glass substrates were detected by a Raman microscope. The developed impedance-sensing chips had been successfully applied to detect the phase separation for emulsions containing emulsifiers with 15%, 17.5%, and 20% Polysorbate 80 (Tween 80) concentrations. We found that the separation time increased with increasing the emulsifier concentration. (C) 2015 Elsevier B.V. All rights reserved.
High temperature storage reliability of palladium coated copper wire in different EFO current settings
(2018-01-01)
Cheng, Pi-Ying
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Lai, Po-Ying
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Ye, Jiun-Ming
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Chen, Tsung-Chia
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Hsieh, Cheng-Li
In recent years, palladium-coated copper (PdCu) wire has been widely used in microelectronic packaging. The electronic flame off (EFO) current setting will affect the distribution of palladium (Pd) during the free air ball (FAB) formation of PdCu wire. This study investigates the influence of EFO current settings on Pd distribution in the FAB and the bonded ball. The distribution and concentration of Pd is observed by using an electron probe micro analyzer (EPMA). Mechanical tests are used to evaluate the bond strength of the first bond. A high temperature storage test (HTST) is performed on the packaged IC at 200 degrees C for 500 h and 1000 h. The results indicate that different EFO current settings cause either complete or partial Pd coverage on FABs, which directly affects the Pd distribution at the bonded ball interface. The wire pull and ball shear tests show the bond strength decrease under three EFO current settings after HTST. This confirms that although Pd can serve as a protective layer for the bonded ball against attack from halides from within the epoxy molding compound (EMC), incomplete Pd coating and formation of the alloy may actually aggravate the corrosion on bonded ball.
High-performance graphene-based heaters fabricated using maskless ultraviolet laser patterning
(2019-06-01)
Tseng, Shih-Feng
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Cheng, Pi-Ying
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Hsiao, Wen-Tse
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Chen, Ming-Fu
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Chung, Chien-Kai
Graphene-based film heaters (GFHs) with laser-patterned electrode structures can be used in microheaters, thermal sensors, and thermostatic apparatuses for various high-value-added medical devices and creative products. To obtain uniform and higher temperatures, this study aims to design, fabricate, and measure GFHs with net-like electrode structures using ANSYS Workbench software, an ultraviolet laser processing system, and an infrared thermal imaging camera, respectively. The electric heating experiments (which were measured with an infrared thermal imaging camera) demonstrated that the temperatures of GFHs with net-like electrode structures were significantly higher than those of devices without patterned graphene films. Moreover, the temperatures of GFHs with net-like electrode structures increased rapidly with time when DC voltages higher than 12V were applied for at least 10s. A maximum temperature of 91.5 degrees C was obtained at 200s when a DC voltage of 18V was applied. Besides, minimal and maximal deviations of steady-state temperatures between experimental and simulated values were 6.9 degrees C and 10 degrees C under each corresponding DC voltage, respectively.
INVESTIGATION ON VELOCITY PERFORMANCE DEVIATION OF SERIAL MANIPULATORS RESULTED FROM FABRICATION ERRORS
(2017-01-01)
Cheng, Kuei-Jen
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Cheng, Pi-Ying
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機械工程學系
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Department of Mechanical Engineering
Manipulators were adopted in industrial field decades ago, but uncertainty still exists in their performance because of errors produced during the fabrication processes. This uncertainty would deteriorate the performance of manipulators and causes these manipulators unable to meet what are required in their specifications. Although the performance of manipulators has been discussed in many researches, these studies all focused on the positioning accuracy or the kinematic performance over a specific trajectory with or without the influence of fabrication errors. However, manipulators always need to perform tasks with requirements on velocity over its workspace, and fabrication errors always have influence on it. It is not practical to define the performance of a manipulator only based on its positioning accuracy or kinematic performance over a specific trajectory with or without the influence of fabrication errors. To complement this insufficiency, this article utilizes the concept of force ellipsoid to conduct the maximum achievable and sustainable velocity of a non-redundant serial manipulator and evaluates the effect of fabrication errors on the velocity performance of the manipulator over its workspace.
Laser Direct Imaging of Transparent Indium Tin Oxide Electrodes Using High Speed Stitching Techniques
(2014-09-01)
Cheng, Pi-Ying
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Hsiao, Wen-Tse
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Chung, Chien-Kai
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Tseng, Shih-Feng
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Liao, Ien-Chang
To accomplish an electrode patterning in large area, we present a high speed stitching technique used in an ultraviolet laser processing system and investigate the interaction between laser beams and indium tin oxide (ITO) thin films deposited on glass substrates. After optimizing the process parameters of the laser direct imaging (LDI) for the large-area electrode patterning, the ablated lines looked like regularly fish-scale marks of about a 40 mu m diameter and a 120 nm depth around the processing path. The parameters includes the laser power of 1 W, the scanning speed of galvanometers of 800 mm/s, and the laser pulse repetition frequency of 50 kHz. Moreover, the resistance value of the ablated ITO thin film is larger than 200M Omega that is electrically insulated from the other regions of electrode structure. LDI technology with UV laser beam has great potential applications in patterning on wafer or sapphire substrates and patterning a conductive layer deposited on the touch panels for semiconductor and optoelectric industries, respectively. (C) 2014 The Japan Society of Applied Physics
Laser structuring of parallel electrode array on graphene/glass substrates for rapid inspections of moisturizing efficacy
(2017-08-01)
Tseng, Shih-Feng
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Haiso, Wen-Tse
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Cheng, Pi-Ying
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Lin, Yung-Sheng
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Chang, Tien-Li
This research aims to structure thin layers of graphene materials for impedance sensing chips with a parallel electrode array and to investigate the interaction between nanosecond pulsed Nd:YVO4 lasers and graphene films coated on glass substrates. The optimal laser structuring conditions consisted of pulse repetition rate of 100 kHz, the scanning speed of two galvano scanners of 600 mm/s, the laser fluence of 3.4 J/cm(2), and parallel lines of the laser processing path with the line-scan spacing of 1 mu m in one-cycle process to produce the parallel electrode structures. The surface morphology, cross-sectional profile, optical spectra, and material characterizations on graphene/glass substrates were detected by a confocal laser scanning microscope, a scanning electron microscope (SEM), a spectrophotometer, and a Raman spectroscopy, respectively. The parallel electrode sensing chips had been successfully used to detect the moisturizing efficacy of solutions containing moisturizers with 0, 3, 6, and 9 wt% 1,3-Butylene Glycol concentrations. The experimental results showed that the electrochemical impedance spectroscopy combined with graphene sensing chips had high sensitivity and saving time than weight loss of solutions detected by the precision electronic balance.
Measuring the thickness of transparent objects using a confocal displacement sensor
(2017-01-01)
Weng, Chun-Jen
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Lu, Bo-Rong
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Cheng, Pi-Ying
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Hwang, Chi-Hung
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Chen, Chih-Yen
this paper reports on a confocal displacement sensor with varifocal lens used to measure the thickness of transparent materials. The focal length of the varifocal lens is adjusted by varying the current. Laser light passing through a transparent target lying within the range of the focal length crosses two interfaces; i.e., first from air to glass and then from glass to air. The signals associated with the interface were of higher intensity than that measure at other points along the z axis. A power meter is used to measure the power and LabVIEW is used to record a power-current graph. The current gap between the two peaks can be translated into values of displacement, indicating the thickness of the material.
Navigation of mobile robot by using D plus plus algorithm
(2012-10-01)
Cheng, Pi-Ying
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Chen, Pin-Jyun
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機械工程學系
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Department of Mechanical Engineering
The navigation of mobile robots is a vital aspect of technology in robotics. We applied the D++ algorithm, which is a novel and improved path-planning algorithm, to the navigation of mobile robots. The D++ algorithm combines Dijkstra\'s algorithm with the idea of a sensor-based method, such that Dijkstra\'s algorithm is adapted to local search, and the robot can determine its next move in real-time. Although the D++ algorithm frequently runs local search with limited ranges, it can compute optimum paths by expanding the size of the searching range to avoid local minima. In addition, we verified the performance of the D++ algorithm by applying it to a real robot in a number of environments. The use of the D++ algorithm enables robots to navigate efficiently in unknown, large, complex and dynamic environments.
Rapid displacement sensor based on fitting scan
(2016)
Ye, Zheng-Jie
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Hwang, Chi-Hung
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Cheng, Pi-Ying
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Chen, Chih-Yen
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Weng, Chun-Jen
A rapid displacement sensor with a varifocal lens based on a method of fitting scan is proposed for 3D surface profiling. The focal length of the varifocal lens can be adjusted by varying the driving current. By detecting the reflective power of the reflected laser, the displacement can be obtained. By integrating a LabVIEW program based on a Levenberg-Marquardt algorithm in this system, the measuring speed can be substantially improved. Finally, the 3D surface profile of a step-height sample was successfully scanned by this displacement sensor.
Small mechanical press with double-axis servo system for forming of small metal products
(2013-10-01)
Cheng, Pi-Ying
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Chen, Pin-Jyun
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Lin, Yu-Ting
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機械工程學系
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Department of Mechanical Engineering
Multi-axis servo systems have been applied to many machine tools in recent decades, but they are not commonly used for press machines. They are particularly uncommon for small presses because it is still believed that the precision of a small press is dependent on the precision of its components and parts. However, high-precision components and parts are difficult to manufacture and assemble, so the costs of small precision presses are roughly equal to or higher than those of large press machines. Moreover, the accuracy of conventional small presses worsens over long operation times, particularly when dealing with off-center loading frequency. Therefore, we propose a small mechanical press with an adjustable driving system, using a slide and double-axis servo system, for manufacturing small products. Through this proposed design, we expect higher-quality products to be produced for lesser cost than conventional small presses.
Surface profiling of object using varifocal lens with image contrast
(2019-10-01)
Chen, Chih-Yen
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Wang, Lijuan
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Fan, Chen-Liang
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Cheng, Pi-Ying
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Weng, Chun-Jen
The measurement of automated and fast focusing on the improvement of speed and accuracy is an important issue in industrial inspection and biomedical microscopy. In this study, we developed a novel optical imaging system in which varifocal lenses are used to characterize the 3D surface topography of samples. The performance of the proposed system was evaluated using twelve focusing algorithms. Experimental results demonstrate the feasibility and effectiveness of the proposed system in the near real-time construction of multi-focus fusion images with large depth of field from which to derive 3D surface profiles.
The D plus plus Algorithm: Real-Time and Collision-Free Path-Planning for Mobile Robot
(2010)
Cheng, Pi-Ying
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Chen, Pin-Jyun
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機械工程學系
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Department of Mechanical Engineering
This paper proposed an improved algorithm that we call "D++" which can be applied to real-time and collision-free path -planning to solve some problems of common methods at present. D++ algorithm combines the Dijkstra's algorithm with sensor-based method so that D++ algorithm can deal with problems of unknown, large, complex, or dynamic environment, and need only local environmental information initially to find a shortest path. In the later of this article, we demonstrated some examples to show that D++ algorithm is very efficient for path-planning and also very practicable on real mobile robot system.
The investigation of the maneuverability deterioration based on acceleration radius theory
(2009-12-01)
Cheng, Kuei-Jen
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Cheng, Pi-Ying
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機械工程學系
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Department of Mechanical Engineering
Maneuverability is the measure of the dynamic performance of a manipulator in a specific posture or configuration, and acceleration radius is one of the most utilized indices of it. Acceleration radius can be utilized as the reference to judge whether further dynamic analysis should be performed when evaluating the controllability and feasibility of the manipulator following the prescribed path with assigned kinematic and kinetic requirements in the planning phase. When utilizing acceleration radius as the dynamic reference in the planning phase, it can prevent wasting the calculation cost due to these non-necessary dynamic analyses, and it can also be utilized as the benchmark in the on-line control. However, the existence of the configuration errors is inevitable in reality, and it deteriorates the dynamic performance of a manipulator with the ideal configuration parameters and leads to the potential risk of failing to achieve an assigned dynamic task. To investigate the adverse behavior caused by the configuration errors and to provide some clues to avoid or reduce their influence, this article proposes a novel and systematic method which can be used to evaluate the maneuverability deterioration of a non-redunclant serial manipulator system due to the influence of configuration errors, and it also provides an index, deterioration rate, to quantitate this kind of deterioration. Deterioration rate can be utilized to quantitate the maneuverability deterioration due to the influence of configuration errors in a prescribed workspace or region and can also be treated as the safety or derating margin when proceeding with the control or path planning. (C) 2009 Elsevier Ltd. All rights reserved.