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Hai Le Xuan,Quoc-Dong Hoang,Soon Geul Lee,Dat Pham Xuan,Hoang Tran Viet,Minh Pham Van,Hung Pham Van,Hung Pham Viet,PHAM DUC TUAN,Duc Anh Nguyen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2
Ballbots, which have been studied for over ten years, are under-actuated mobile robots that operate using the inverted pendulum paradigm. Controlling a ballbot poses a number of challenges, including maintaining the stable upright posture from the ground in all directions and making sure it follows the desired trajectory. External factors such as a minor change in contact surface properties or fabrication errors can affect the system's stabilization and transfer capabilities. In this study, an adaptive hierarchical sliding mode control algorithm based on an artificial neural network is developed to make the ballbot robust to external factors. The use of the proposed controller ensures system stability despite uncertainties including friction, accidental centrifugal forces and gravity that occur when the ballbot follows the reference trajectory. The system stability is guaranteed on the basis of Lyapunov theory. Control efficiency and robot stability under system uncertainties are demonstrated by numerical simulation.
Xuan The Le,Dung Tien Pham,Tuan Anh Pham,Tung Thanh Tran,Thanh Huu Khuat,Hoa Quang Le,Ut Ngoc Vu 한국수산과학회 2019 Fisheries and Aquatic Sciences Vol.22 No.3
Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.
Pham Xuan Hien,Do Anh Tuan,전병훈 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.1
A consistent set of low-energy electron-collision cross sections for the tetramethylsilane (TMS) molecule has been derived from the measured electron transport coefficients for a pure TMS molecule by using an electron swarm study and a two-term approximation of the Boltzmann equation for energy. The electron transport coefficients, which were calculated by using the derived set, are consistent with the experimental data over a wide range of E/N values (ratio of the electric field E to the neutral number density N). The present set of electron collision cross sections for the TMS molecule, therefore, is the best available so far for quantitative numerical modeling of plasma discharges for processing procedures with materials containing TMS molecules. The electron-transport coefficients in TMS-Ar and TMS-O<sub>2</sub> mixtures were also calculated and analyzed in a wide range of E/N ratios for the first time. The presence of a remarkable synergism in the Townsend first ionization coefficient has been pointed out in the TMS-O<sub>2</sub> mixtures.
Determination of the Electron Collision Cross Section Set for the C2F6 Molecule
Pham Xuan Hien,Do Anh Tuan,Byung-Hoon Jeon 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.12
The electron drift velocity and the density-normalized longitudinal diffusion coefficient in the pure C2F6 molecule over the E/N range of 0.1-100 Td have been measured using a double shutter drift tube, where E is the electric field and N is the neutral number density. Our electron drift velocity values are in good agreement with those reported in a previous work on the C2F6 molecule. The negative differential conductivity phenomenon was found in the electron drift velocity. The results of our new measurements on the pure C2F6 molecule, along with the available electron transport coefficients, in 0.524 and 5.47 % C2F6 - Ar mixtures were used to successfully obtain the most reliable set of electron-collision cross sections for the C2F6 molecule by using a multi-term Boltzmann analysis.
Adaptive Neural Network Second-order Sliding Mode Control of Dual Arm Robots
Le Anh Tuan,주영훈,Le Quoc Tien,Pham Xuan Duong 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.6
An adaptive robust control system is considered for dual-arm manipulators (DAM) using the combinationof second-order sliding mode control (SOSMC) and neural networks. The SOSMC deals with the system robustnesswhen faced with external disturbances and parametric uncertainties. Meanwhile, the radial basis function network(RBFN) is to constitute an adaptation mechanism for approximating the unknown dynamic model of DAM. Thestability of model estimator-integrated controller is analyzed using Lyapuov theory. To show the effectiveness ofproposed controller, a four DOFs-DAM is applied as an illustrating example. The results reveal that the controllerworks well, excellently adapt to no information of robot modeling.
Parameter Estimator Integrated-sliding Mode Control of Dual Arm Robots
Le Anh Tuan,주영훈,Pham Xuan Duong,Le Quoc Tien 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.6
This paper presents the parameter estimator-integrated sliding mode control of dual arm robots. Todo so, a robust adaptive controller is designed for 3D cooperative motion of dual-arm robots based on the frameof second-order sliding mode control (SOSMC). Additionally, the method of the model-reference adaptive control(MRAC) is also utilized for constituting an adaptation mechanism then integrating it into the control loop to estimatethe unknown robot parameters. By doing so, the proposed controller is robust with disturbances and parametricuncertainties. Furthermore, the adaptive behavior is also achieved in which the control system does not need theinformation of many system parameters. Finally, the applicability and feasibility of the proposed controller ispresented through a 4 four degree-of-freedoms (DOFs) dual-arm manipulator.
Le, Xuan The,Pham, Dung Tien,Pham, Tuan Anh,Tran, Tung Thanh,Khuat, Thanh Huu,Le, Hoa Quang,Vu, Ut Ngoc The Korean Society of Fisheries and Aquatic Scienc 2019 Fisheries and Aquatic Sciences Vol.22 No.8
Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.