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International Conference on Machine Learning and Cybernetics (ICMLC)

作者： Tao Wu Bin Li Long-Wen Wang Yu Huang National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China

In order to improve production efficiency, inspecting and sorting of LED dies are done respectively in prober and sorter. During the inspection, dies may be broken, fragmentized, tiny moved, or deflected slightly, besides, visual scan can also lead to location deviation when the wafer is moved from prober to sorter. All of this can cause some dies mismatch in the sorting stage, which is never allowed. In order to get integrated match of dies, the position relations between adjacent dies are considered, techniques including diagnosing criterion of position relatives, redundant visual scanning, forward and backtrack algorithm with cross priority are put forward. It is proved with experimental results that such re-index approach is more applicable than traditional index method. When dies arrange in good order, match rate is more than 99.5%, by compassion, that of traditional index method is less than 92%. When the wafer is deflected slightly or locally fragmentized, match rate of the former is more than 92.5%, by contrast, that of the latter is less than 50% in same situation.

关键词： Indexes Light emitting diodes Visualization Machine learning Cybernetics Dies Magnetic heads

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Study on real-time correction method of die declination angles in LED sorting system

Study on real-time correction method of die declination angl...

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IEEE International Conference on Mechatronics and Automation

作者： Tao Wu Bin Li LongWen Wang Yu Huang National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China

All dies are required to keep consistent angles in LED chip sorting. Usually, rectification orient real-time vision is used for this but it may decrease production efficiency greatly, because one correction may need several adjustments. Considering that all dies to be sorted are adhesive to wafer tape, each is rotated, locations of all other dies change. It is a problem for following positioning and sorting. To solve this problem, an on-line angle correction method basing on translation compensation is put forward. In this way, angle deviations of dies are transformed as translations of recycling bins. Each die declination can be corrected without any rotations. It does little impact on sorting efficiency because the translation of recycling bins acts concurrently with the die ejection and transporting, etc. Techniques on figuring out displacement compensations are discussed in detail. In addition, SPN model of declination angle correction is built to analyze its influence to production rate. With theoretical analysis and experimental results, it is revealed that sort efficiency may decrease by only 3% for angle correction. Such effect is perfectly acceptable.

关键词： Recycling Sorting Lenses Markov processes Clocks Mouth Computer numerical control

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Study on path-optimization by grade for sorting dies

Study on path-optimization by grade for sorting dies

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IEEE International Conference on Mechatronics and Automation

作者： Tao Wu Bin Li Longwen Wang Yu Huang National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China

Semiconductor light-emitting die (LED) has now become one of the most popular lighting devices. Before dies are put into process of package, they need be inspected and sorted strictly, so following waste will be saved. Cost of inspection and sort is relatively high, it is urgently needed to improve sort efficiency and reduce sort time. To get efficient solution, detailed view of working flow is presented to make analysis on performance and its influenced factors. It can be revealed that positioning of recycle bins is the major influence factor. Performance may decrease by 3.2 to 0.9 dies per second. Because of this, a path optimization method according grade priority is put forward. In this way, the dies with same grade should get priority to be sorted first. Techniques about die search and merge by grade, traversal of forward and backtrack with cross priority are described in detail. With results of reasonable simulations and a case experiment, this optimization is proved highly effective to reduce sort time and improve dies production rate.

关键词： Recycling Sorting Light emitting diodes Production Optimization Lenses Machine vision

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Study on auto-path planning according to grade priority for sorting dies

Study on auto-path planning according to grade priority for ...

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International Conference on Machine Learning and Cybernetics (ICMLC)

作者： Tao Wu Bin Li Long-Wen Wang Yu Huang National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China

Semiconductor light-emitting diode (LED) has now become one of the most popular lighting devices. Before diodes are put into process of package, they need be inspected and graded strictly, so following waste will be saved. Cost of inspection and sort is relatively high, it is urgently needed to improve sort efficiency and reduce sort time. This is a problem needs comprehensive consideration. Sort performance is influenced by acts such as feeding, ejecting, transporting, placing, recycle bin positioning, and so on. Stochastic Petri net model of concurrent control of multi-shafts scheduling is built to analyze the performance and its influenced factors. It can be revealed that positioning of recycle bins is the major influence factor. Because of this, a path planning method according grade, the diodes with same grade should get priority to be sorted first, is put forward. Techniques about die search and merge by grade, traversal of forward and backtrack with cross priority are described in detail. With reasonable simulations, this optimization is obviously proved effective to reduce sort time and improve diodes production rate.

关键词： Recycling Light emitting diodes Markov processes Lenses Production Planning Machine learning

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Double-sided weld seam detection system for aircraft T-joint welds by using vision sensor

Double-sided weld seam detection system for aircraft T-joint...

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IEEE/ASME International Conference on Mechtronic and Embedded systems and Applications, MESA

作者： WenJun Shao Yu Huang XiaoLong Zhang Gen Li National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781509061914

Laser welding technology for skin-stringer joints is widely used in aircraft manufacturing. Double-sided laser beam welding of skin-stringer joints is an approved method for producing defect-free welds. The main drawback for the use of single-sided welding method for T-joints is the occurrence of weld defects. In order to achieve dual-beam laser welded T-joint, a dual-beam laser welding platform based on multi-axis CNC machine is set up in this article. A novel control method of double-sided seam tracking and error compensation based on vision sensor is proposed. The result shows that the dual-beam laser welding system can achieve dynamic deviation compensation accurately in the double-sided welding process at a high speed.

关键词： Welding Laser beams Tracking Aircraft control systems Power lasers

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Study on Parallel Scheduling of LED Dies Measurement and Grading

Study on Parallel Scheduling of LED Dies Measurement and Gra...

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2010 11th International Conference on Electronic Packaging technology & High Density Packaging(2010 电子封装技术与高密度封装国际会议)

作者： Tao Wu Bin Li Longwen Wang Kanghua Lin National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan430074

The light-emitting diode (LED) is the world's most efficient light source being mass produced today. However, the packaging cost is relatively high, which has been the main factor restricting widespread application of LED lighting. As the LED industry becomes prosperous, short time consumption for single die measurement is particularly concerned by semiconductor manufacturers. Parallel scheduling methods used for speed improvement are put forward. Focusing on the cooperation between tester and prober, techniques on command flow communication between up station and motion control board, simultaneous control of X/Y driven shafts and up driven dovetails, parallel scheduling between testing process and positioning process are discussed in detail. Using these methods, average speed of measurement is improved from 2.5 LED dies per second to 5.2 LED dies per second. With experimental results, it is proved effective and efficient for proposed system. Such method is available for all similar equipments.

关键词： LED chip measurement parallel scheduling time consumption.

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Towards Safe Inter-train Distance Minimization via Reachability Analysis and Mixed H2/H∞control

Towards Safe Inter-train Distance Minimization via Reachabil...

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2022 Chinese Automation Congress, CAC 2022

作者： Yang, Min Lv, Jidong Liu, Hongjie Zhang, Miao Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing China China Academy of Railway Sciences Corporation Limited National Research Center of Railway Intelligence Transportation System Engineering Technology Signal and Communication Research Institute Beijing China

ISBN: (纸本)9781665465335

In high-speed railway, designing a reasonable controller of train control system is an important way to enhance the transportation capacity, while considering more dynamic behaviors of the preceding train, such as position, speed and acceleration etc, through V2V communication. In this paper we propose a novel method towards the safe inter-train distance minimization problem via reachability analysis and mixed H2/H∞ control. Firstly, by considering the disturbance behavior of the preceding train, a linear closed-loop system is modeled, in which the gains of a state feedback and a state feedback/feedforward, refer to controller A and controller B respectively, are designed using mixed H2/H∞ control theory. Then, the N-step forward reachable set for the two given controllers is presented to compute the maximum position error, which determines the minimum safe inter-train distance. Furthermore, backward reachability analysis algorithm is used to find the maximal initial state set, which guarantees that the state trajectory stay within the safe set in presence of disturbance. Finally, the proposed method is applied to a typical emergency braking scenario during two-train tracking. The experimental results show that the safety margin can be reduced by 54% and the maximal initial state set can be enlarged conspicuously when a feedforward term is used in the controller. © 2022 IEEE.

关键词： controllers

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Accurate tracking control of a linear fast tool servo unit for noncircular cutting

Accurate tracking control of a linear fast tool servo unit f...

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IEEE International Conference on Mechatronics and Automation

作者： Xuefeng Chang Youping Chen Wu Ai Zude Zhou National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan Hubei China

In this paper, an accurate position tracking control scheme is proposed for a moving-coil-type linear DC motor driven fast tool servo unit for noncircular cutting application. A sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the position command. Moreover a disturbance observer is used to estimate and compensate exogenous disturbance to improve robustness and stability of the fast tool servo unit. Because the reference input is approximately periodic in noncircular cutting process. Therefore, the periodic error can he further reduced by augmenting an iterative learning controller to the existing sliding mode controller for repetitive position tracking. The experimental results of noncircular cutting adopting the proposed control method, including tracking performance and robustness of the system, are much improved.

关键词： Servomechanisms Sliding mode control control systems Error correction Robust control Three-term control DC motors Robust stability Machining Fuzzy control

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Laser patterning with beam shaping on indium tin oxide thin films of glass/plastic substrate

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Thin Solid Films 2009年第4期518卷 1072-1078页

作者： Chen, Ming-Fei Hsiao, Wen-Tse Ho, Yu-Sen Tseng, Shih-Feng Chen, Yu-Pin Department of Mechatronics Engineering National Changhua University of Education Changhua 50058 Taiwan System Control and Integration Division Instrument Technology Research Center National Applied Research Laboratories Hsinchu 30076 Taiwan PCB Department Tongtai Machine and Tool CO. Kaohsiung 82151 Taiwan

In this research the laser beam shaper component has been used to obtain top-hat intensity distribution laser beam to perform line scribing and to perform electrode patterning on Indium thin oxide (ITO) thin films deposited on glass and plastic substrate. ITO films were removed with third harmonic Nd:YAG laser processing system. The pulse duration, laser output power, pulse repetition rate and scanning speed parameters of straight line patterning and electrode patterning on different types of substrates were discussed, respectively. The experimental results are measured by optical microscope and scanning electron microscope to evaluate the processing parameters and surface properties of ITO thin films. © 2009.

关键词： Indium compounds

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A novel seam measuring method of complex tight butt joint for laser welding

A novel seam measuring method of complex tight butt joint fo...

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IEEE International Conference on Mechatronics and Automation

作者： Jiayong Wu Pingjiang Wang Xingdou Fu Biao Liu Jihong Chen National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan Hubei China

Seam measuring of complex tight butt joint without misalignment for laser welding is a challenging problem. The allowable seam gap width and misalignment in laser welding process are less than 0.1 mm for thin sheet around 2 mm thickness. Current measuring methods or sensors can not stably and accurately extract 3D seam position and seam gap width, due to narrow seam gap and too little misalignment of the butt joint. Furthermore, almost all sensors can not provide seam surface normal vector directly along with seam position and seam gap width. A novel seam measuring method, integrating the 2D machine vision and 3D structured light vision techniques, is proposed. By projecting a unique pattern of three structured light stripes onto the seam surface, 3D seam position, seam gap width and seam surface normal vector can be accurately acquired from a single image, using the 2D/3D vision information fusion approach. Experimental results demonstrate that the proposed seam measuring method is capable of extracting the integrated seam features of tight butt joint without misalignment stably and accurately.

关键词： Welding Current measurement Laser fusion Position measurement Focusing Surface fitting Computer vision Laser beams Surface emitting lasers Machine vision

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