Automatic Calibration of Camera and LRF based on Morphological Pattern and Optimal Angular Back-projection Error

Van-Dung Hoang,조강현 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.6

Nowadays, integration systems based on cameras and LRFs have been applied in many researches on robotics, such as autonomous navigation vehicles, and intelligent transportation systems. The systems using multiple sensors usually require extracting the relative information of sensors posed, which support for processing. Therefore, the task of calibration of cameras and laser devices is very important. This paper presents an automatic calibration method for determining the relative position and direction of a camera with respect to a laser rangefinder. The calibration method makes use of depth discontinuities of calibration patterns, which emphasizes laser range-beams supporting easy automatic estimation of the occurred position of laser scans on the calibration pattern. The laser range scans are also used for estimating corresponding depth image points from the camera. Finally, the relative parameters between the camera and the laser device are discovered using the set of depth point correspondences of the LRF and the camera. This paper also presents new criterion for evaluating the error of extrinsic parameters estimation based on optimal error of angular deviation between the projection and back-projection of 3D corresponding points. The evaluation results demonstrate outperformance of this method.

A Simplified Solution to Motion Estimation Using an Omnidirectional Camera and a 2-D LRF Sensor

Van-Dung Hoang,Kang-Hyun Jo IEEE 2016 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS - Vol.12 No.3

<P>Recently, omnidirectional camera-based motion estimation has been improved as a result of planarmotion assumption, which helps reduce the computational time. In practice in outdoor terrains, vehicle motion does not satisfy this assumption. Motivated by this problem, this paper proposes a method that uses the minimal set of parameters of geometric constraint for estimating the pseudo-three-dimensional motion of the vehicle based on an omnidirectional camera and a laser range finder (LRF). To reduce the number of the parameters for accelerating the computational speed, it is supposed that the vehicle moves under the nonholonomic four-wheel motion model, which requires constraints between rotation and translation components. The method consists of two stages. First, the LRF is used to estimate the orientation and the translation magnitude of the vehicle movement. Second, a pair of corresponding points in sequential images is used along with the results of the first stage to estimate the motion of the vehicle. Furthermore, this paper also presents a closed-form solution for problem solving. The experimental results, using synthetic and real data in different terrain conditions, demonstrate that the proposed method provides the higher accuracy with the lower computational time as compared with the state-of-the-art methods.</P>

Motion Estimation Based on Two Corresponding Points and Angular Deviation Optimization

Hoang, Van-Dung,Le, My-Ha,Jo, Kang-Hyun IEEE 2017 IEEE transactions on industrial electronics Vol.64 No.11

<P>Recently, there have been several studies on vision-based motion estimation under a supposition that planar motion follows a nonholonomic constraint. This allows reducing computational time. However, the vehicle motion in an outdoor environment does not accept this assumption. This paper presents a method for estimating the vision-based 3-D motion of a vehicle with several parts as follows. First, the Ackermann steering model is applied to reduce constraint parameters of the 3-D motion. In difference to the previous contribution, the proposed approach requires only two corresponding points of consecutive images to estimate the vehicle motion. Second, motion parameters are extracted based on a closed-form solution on geometric constraints. Third, the estimation approach applies the bundle adjustment-based quasiconvex optimization. This task aims to take into account advantage of omnidirectional vision-based features for reducing errors. The omnidirectional vision supports for landmarks tracking in long travel and large rotation, which is appropriate for a bundle adjustment technique. Evaluated results show that the proposed method is applicable in the practical condition of outdoor environments.</P>

Pedestrian Detection Approach Based on Modified Haar-Like Features and AdaBoost

Van-Dung Hoang,Andrey Vavilin,Kang-Hyun Jo 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Pedestrian detection is an important task in many applications such as intelligent transportation systems, image retrieval, surveillance systems, automated personal assistance, etc. This paper proposes a set of modified Haar-like features that have parallelogram shapes. Using the proposed feature descriptors to develop a rapid detection system for pedestrian detection based on decision tree structure used boosting algorithm. The experimental results showed that the proposed method could produce high accuracy detection rate with lower false positive rate and higher recall rate than original Haar-like features and it is efficiency with different resolutions and gestures under a variety of backgrounds as well as lighting.

Factors Affecting Night-Time Economic Development: Research in Hanoi, Vietnam

Ngoc Son NGUYEN(Ngoc Son NGUYEN ),Vu Hiep HOANG(Vu Hiep HOANG ),Quoc Dung NGO(Quoc Dung NGO ),Van Hoa HOANG(Van Hoa HOANG ) 한국유통과학회 2023 Asian Journal of Business Environment (AJBE) Vol.13 No.2

Purpose: The purpose of the study is to explore the factors which influence the night-time economic development in Hanoi, Vietnam. The results can help policymakers achieve a scientific basis to plan the development of night-time economy in Hanoi. Research design, data and methodology: The research model is developed from literature review with 7 independent variables, including natural conditions and resources, infrastructure, safety, environmental issues, promotion and international integration, development of sharing economy, and institution and policy. This model is then adjusted by exploratory factors analysis to have 4 new variables: Institution and environment, Infrastructure and safety, Promotion and sharing, and Nature and resources. The model is regressed based on the data of 463 observations of night-time economy in Hanoi, Vietnam. Results: Consistent with the current literature addressing night-time economy, the results show positive impacts of all of the independent variables studied. Conclusions: It is recommended for the local authorities to strengthen advertising and promoting investment for NTE development in Hanoi city and also enhance the role of state management in NTE activities by raising awareness of the state management apparatus towards a more open-minded multi-dimensional view of the NTE, developing the NTE to overcome the barrier of thinking “if it cannot be managed, it is forbidden” in state management agencies, and defining responsibilities and authority among state management agencies in the management of NTE activities and strengthening decentralization and decentralization of powers for localities in the management and development of NTE.

Distance-based Formation Tracking with Unknown Bounded Reference Velocity

Dung Van Vu,Minh Hoang Trinh,Hyo-Sung Ahn 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

This paper studies a distance-based formation tracking problem in the d-dimensional space. The formation has a directed acyclic leader-following structure with d leaders moving at a same unknown bounded velocity. Distributed control laws are proposed for follower agents to maintain the desired formation shape and move at the leaders’ velocity in finite time. Simulation results are also provided to support the theoretical analysis.

Determinants of Middle Managers' Leadership in the Vietnamese Economic-Defense Enterprises

HOANG, Cuong Van,NGUYEN, Ngoc Huu,NGUYEN, Loan Quynh Thi,TRAN, Manh Dung Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8

The purpose of this study is to investigate factors affecting the leadership capacity of middle managers and then evaluate the corresponding effect on the performance of subordinates in Vietnamese economic and defense enterprises. Data for the study was collected from questionnaire survey of 15 economic and defense enterprises, preceded by in-depth interviews with respondents who are subordinates of the departments/divisions of these enterprises. The research used logistic regression estimator to address econometric issues and to improve the accuracy of the regression coefficients. Our results show that the determinants of the leadership capacity of mid-level managers in defense and economic enterprises include: (i) personal qualities and qualities of managerial officials (understanding, courage), fairness, assertiveness and compliance), and leadership behaviors of two leadership styles - (ii) a transforming leadership style (influenced by ideals, inspirations, concerns) subordinates, stimulating intellect) and (iii) transactional leadership style (rewarding, detecting and handling problems for subordinates). Based on these results, our study suggests that middle managers should possess superior knowledge, care more about subordinates, understand the strengths and weaknesses of each subordinate, always be creative, assertive and courageous people as well as have high standards of competency and morality in order to become outstanding leaders in Vietnamese economic and defense enterprises.

Self-adjusting on-line cutting condition for high-speed milling process

Tien-Dung Hoang,Quang-Vinh Nguyen,Van-Cuong Nguyen,Ngoc-Hien Tran 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8

The paper presents an intelligent control system for self-adjusting on-line cutting condition for high speed machining (self-HSM) with considering the tool-wear amount to keep the machined product’s quality in allowable limit. For realizing the self-HSM, the empirical analysis of variance (ANOVA) and artifical neural network (ANN) are used. The ANOVA is used for generating the empirical functions which are used as the boundary condition as well as constraint evaluation. The ANN is used for generating the new optimal cutting condition. Then, the self-HSM updates this cutting condition on the real machine - HS Super MC500. The new optimal cutting parameter is sent to the controller for updating the new machining condition to keep the machined part’s quality. The integration of the empirical analysis and ANN enables generating the optimal cutting parameters correctly and efficiently for high-speed milling.

A survey of IoT malware and detection methods based on static features

Quoc-Dung Ngo,Huy-Trung Nguyen,Van-Hoang Le,Doan-Hieu Nguyen 한국통신학회 2020 ICT Express Vol.6 No.4

Due to a lack of security design as well as the specific characteristics of IoT devices such as the heterogeneity of processor architecture, IoT malware detection has to deal with very unique challenges, especially on detecting cross-architecture IoT malware. Therefore, the IoT malware detection domain is the focus of research by the security community in recent years. There are many studies taking advantages of well-known dynamic or static analysis for detecting IoT malware; however, static-based methods are more effective when addressing the multi-architecture issue. In this paper, we give a thorough survey of static IoT malware detection. We first introduce the definition, evolution and security threats of IoT malware. Then, we summarize, compare and analyze existing IoT malware detection methods proposed in recent years. Finally, we carry out exactly the methods of existing studies based on the same IoT malware dataset and an experimental configuration to evaluate objectively and increasing the reliability of these studies in detecting IoT malware.

Advanced Magnetic Materials Produced by Using Rapid Quenching Technology

Nguyen Hoang Nghi,Nguyen Van Dung,Trinh Thi Thanh Nga,Bui Thi Khanh Nhung,Mai Thanh Tung,Nguyen Huu Tinh,Hoang Nhat Hieu,Bui Xuan Chien,Nguyen Thi Hong Tam 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.6

Amorphous alloys produced by using a rapid quenching technique are considered to be a precursor for producing nanosized and multiphase structures by precipitation (the top-down method). By using this technique, several new magnetic materials with different magnetic properties based on different physical mechanisms have been manufactured and investigated. Three new magnetic materials, a nanocrystalline soft magnetic material, a soft-hard permanent magnet and a Me-3d granular alloy with a GMR effect, what were prepared under local conditions, are presented and discussed in the experimental point of view. Amorphous alloys produced by using a rapid quenching technique are considered to be a precursor for producing nanosized and multiphase structures by precipitation (the top-down method). By using this technique, several new magnetic materials with different magnetic properties based on different physical mechanisms have been manufactured and investigated. Three new magnetic materials, a nanocrystalline soft magnetic material, a soft-hard permanent magnet and a Me-3d granular alloy with a GMR effect, what were prepared under local conditions, are presented and discussed in the experimental point of view.