Browsing by Author "Chen, Jen-Hao"

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3D Vision for Object Grasp and Obstacle Avoidance of a Collaborative Robot
(2019-01-01)
Song, Kai-Tai
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Chang, Yu-Hsien
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Chen, Jen-Hao
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents a design and experimental study of 3D robotic vision for bin picking and obstacle avoidance. Through the 3D vision algorithm, the robotic picking system is able to analyze the imagery of cluttered objects, classify the objects and estimate the pose of identified objects for grasping. In order to facilitate the robot to work with a human nearby, obstacle avoidance during task execution is developed based on 3D vision. In this design, a RealSense SR300 RGB-D camera is utilized to acquire RGB images and depth images of clustered workpieces. A deep neural network (DNN) approach to object recognition is designed and combined with point cloud segmentation to enhance 3D object-pose estimation for grasping. The robot avoids obstacles to assure safe operation during execution of the bin picking task. Practical experiments using a Techman TM5 6-DOF robot arm show that the proposed method effectively accomplishes obstacle avoidance in pick-and-place operations.
A model for semiconductor quantum dot molecule based on the current spin density functional theory
(2006-11-01)
Liu, Jinn-Liang
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Chen, Jen-Hao
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Voskoboynikov, O.
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應用數學系
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電子工程學系及電子研究所
Based on the current spin density functional theory, a theoretical model of three vertically aligned semiconductor quantum dots is proposed and numerically studied. This quantum dot molecule (QDM) model is treated with realistic hard-wall confinement potential and external magnetic field in three-dimensional setting. Using the effective-mass approximation with band nonparabolicity, the many-body Hamiltonian results in a cubic eigenvalue problem from a finite difference discretization. A self-consistent algorithm for solving the Schrodinger-Poisson system by using the Jacobi-Davidson method and GMRES is given to illustrate the Kohn-Sham orbitals and energies of six electrons in the molecule with some magnetic fields. It is shown that the six electrons residing in the central dot at zero magnetic field can be changed to such that each dot contains two electrons with some feasible magnetic field. The Forster-Dexter resonant energy transfer may therefore be generated by two individual QDMs. This may motivate a new paradigm of Fermionic qubits for quantum computing in solid-state systems. (C) 2006 Elsevier B.V. All rights reserved.
Collision-Free Motion Planning for Human-Robot Collaborative Safety under Cartesian Constraint
(2018-01-01)
Chen, Jen-Hao
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Song, Kai-Tai
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a real-time motion planning and control design of a robotic arm for human-robot collaborative safety. A novel collision-free motion planning method is proposed not only to keep robot body from colliding with objects but also preserve task under the Cartesian constraint of the environment. Multiple KinectV2 depth cameras are utilized to model and track dynamic obstacles (e.g. Humans and objects) inside the robot workspace. Depth images are applied to generate point cloud of segmented objects in the environment. A K-nearest neighbor (KNN) searching algorithm is used to cluster and find the closest point from the obstacle to the robot. Then a Kalman filter is applied to estimate the obstacle position and velocity. For the collision avoidance in collaborative operation, attractive and repulsive potential is generated for robot end effector based on the task specification and obstacle observation. Practical experiments show that the 6-DOF robot arm can effectively avoid an obstacle in a constrained environment and complete the original task.
Magnetic quantum number dependence of hydrogen photoelectron spectra under circularly polarized pulse in barrier suppression ionization regime
(2018-08-01)
Jheng, Shih-Da
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Jiang, Tsin-Fu
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Chen, Jen-Hao
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Liu, Jinn-Liang
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物理研究所
Photoelectron spectra and transition mechanisms of a hydrogen atom in the n = 2 state under circularly polarized pulses in the barrier suppression ionization (BSI) regime, found by solving the time-dependent Schrodinger equation, are presented in detail. The photoelectron peak emerges from low-energy, in contrast to being centered at higher energy in the case of ionization from the ground state. We show that the magnetic quantum number dependence of photoelectron angular distributions on initial states yields 3- and 2-band structures for 2p(-) and 2p(0) in zenith angle, respectively, and 1-band structures for both 2p(+) and 2s. The intermediate transition pathways from these initial states to the corresponding final states are also revealed.
Study of the circular dichroism of He+ ion
(2019-12-01)
Chen, Jen-Hao
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Liu, Jinn-Liang
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Jheng, Shih-Da
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Cheng, Szu-Cheng
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Jiang, Tsin-Fu
We study the mechanism of circular dichroism (CD) in He+ under XUV and NIR pulses in the experimental condition presented by Ilchen et al. [Phys. Rev. Lett. 118, 013002 (2017)] and in a range of pulse intensities and durations by solving the time-dependent Schrodinger equation (TDSE) in momentum space. The method enables investigation of the ionization and intermediate transition probabilities of He+ in detail. We show that the lowest-order perturbation theory (LOPT) is qualitatively sufficient to describe experimental results and find that ionization favors co- and counter-rotating pulses for NIR intensities in and beyond LOPT regimes, respectively. In the experimental pulse duration, we show that a sub-peak along the first above-threshold ionization peak exists in the counter-rotating case due to one-photon absorption from excited states, which cannot be obtained by solving TDSE with a short duration of 22 fs, since the energy band width is too wide to resolve this substructure. We present the variation of CD values with NIR intensities. (C) 2019 Optical Society of America
The effect of band nonparabolicity on modeling few-electron ground states of charge-tunable InAs/GaAs quantum dot
(2009-01-01)
Hsieh, Yi-Chern
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Chen, Jen-Hao
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Tseng, Shi-Chang
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Liu, Jinn-Liang
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應用數學系
Based on the current spin density functional theory and the nonparabolic effective mass approximation, a three-dimensional model is presented to Study the few-electron system in InAs/GaAs quantum dot for which the electron spectra have been obtained from the capacitance-voltage (CV) measurements by Miller et al. [Phys. Rev. B 56 (1997) 6764]. The model is an extension of the single-electron model proposed by Filikhin et al. [Solid State Comm. 140 (2006) 483]. Our results call quantitatively well interpret the experimental CV data. It is shown that the energy differences between the parabolic and nonparabolic approximations are comparable with the exchange-correlation energies, Moreover, the nonparabolic effect is shown to be increasingly more significant than that of parabolic case in higher magnetic fields. It is also more pronounced for larger number of electrons. (C) 2008 Elsevier B.V. All rights reserved.