scispace - formally typeset
Search or ask a question
Author

Anh-Duc Pham

Other affiliations: Soongsil University
Bio: Anh-Duc Pham is an academic researcher from University of Da Nang. The author has contributed to research in topics: Reducer & Cycloid. The author has an hindex of 5, co-authored 14 publications receiving 162 citations. Previous affiliations of Anh-Duc Pham include Soongsil University.

Papers
More filters
Journal ArticleDOI
TL;DR: This paper presents review of high precision reducers (HPRs) for industrial robots driving 4th industrial revolution, and provides HPRs market along with industrial robots, and principle, characteristics, and three main performances of H PRs are discussed.
Abstract: New industrial revolution - “The 4th industrial revolution” must be a remarkable milestone for the second decade of the twenty-first century. Many countries are competing to innovate their manufacturing chains for eco-friendly and energy-efficient productions. Although this green or sustainable manufacturing system evolves under the support of cyber-physical system (or digital twin) based on ICT technology, industrial robots also play important roles in this speedy, flexible and effective manufacturing chains. Recently, low-cost industrial robots or collaborative robots, are rising in a highly interactive environment with humans. Although an industrial robot consists of many important components such as mechanical parts (kinematic structure and reducer) and electric parts (servo motor, driver, sensors, and controller), precision reducer takes approximately 25% of material-cost and governs important performance indices of industrial robots. This paper presents review of high precision reducers (HPRs) for industrial robots driving 4th industrial revolution. First, we provide HPRs market along with industrial robots. According to previous studies, HPRs for industrial robots can be classified based on their principles: planetary reducer, cycloid reducer, and harmonic drive (HD). Then, principle, characteristics, and three main performances (hysteresis, rotational transmission error (RTE) and efficiency) of HPRs are discussed. In addition, compensation methods overcoming accuracy limits of HPRs are summarized. Finally, other applications of HPRs except industrial robots are presented.

107 citations

Journal ArticleDOI
TL;DR: A hybrid Artificial Intelligence (AI) for slope stability assessment based on metaheuristic and machine learning based on the Least Squares Support Vector Classification is proposed.
Abstract: This research proposes an AI approach for slope evaluation.The method is based on the Least Squares Support Vector Classification.The Firefly Algorithm is used to optimize the assessment model.A dataset that contains 168 real slopes is utilized to construct the AI model.Experiments prove that the new method is a superior tool for slope evaluation. Slope stability assessment is a critical research area in civil engineering. Disastrous consequences of slope collapse necessitate better tools for predicting their occurrences. This research proposes a hybrid Artificial Intelligence (AI) for slope stability assessment based on metaheuristic and machine learning. The contribution of this study to the body of knowledge is multifold. First, advantages of the Firefly Algorithm (FA) and the Least Squares Support Vector Classification (LS-SVC) are combined to establish an integrated slope prediction model. Second, an inner cross-validation with the operating characteristic curve computation is embedded in the training process to reliably construct the machine learning model. Third, the FA, an effective and easily implemented metaheuristic, is employed to optimize the model construction process by appropriately selecting the LS-SVM's hyper-parameters. Finally, a dataset that contains 168 real cases of slope evaluation, recorded in various countries, is used to establish and confirm the proposed hybrid approach. Experimental results demonstrate that the new hybrid AI model has achieved roughly 4% improvement in classification accuracy compared with other benchmark methods.

82 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the lost motion of a cycloid reducer combining FE and kinematic analyses, and concluded that the loss motion depends on not only its torsional stiffness but also its tolerance.
Abstract: Cycloid reducers have a high reduction ratio, high efficiency, high stiffness and are a compact size, compared to conventional reducer mechanisms, so that they are attractive candidates for limited space and precision applications such as industrial robots and cars. However, the integrated performance of torsional stiffness and backlash or lost motion has not been studied yet. This paper investigates the lost motion of a cycloid reducer combining FE and kinematic analyses. First, we introduce the cycloid reducer and its hysteresis curve. Next, a kinematic analysis of the cycloid reducer is performed considering tolerance. Then, an iterative FE analysis of the lost motion of the cycloid reducer is performed combining the results of the kinematic analysis. We conclude that the lost motion of the cycloid reducer depends on not only its torsional stiffness but also its tolerance.

35 citations

Journal ArticleDOI
TL;DR: In this article, the hysteresis characteristics of a cycloid reducer using a nonlinear spring with a dead zone was investigated. But the analysis was performed in a single-stage manner, and the results showed that the dead zone for the nonlinear springs represented the clearance of each connecting element.
Abstract: Cycloid reducers are widely used for high-precision industrial instruments and robots because of many advantages: high efficiency, high stiffness and a high reduction ratio in a compact size. Nevertheless, the few studies that have investigated the hysteresis characteristics of a cycloid reducer used a time-consuming iterative procedure. This paper presents an efficient FE analysis procedure for the hysteresis characteristics of a cycloid reducer using a nonlinear spring with a dead zone. First, we introduced a cycloid reducer and performed a kinematic analysis of the cycloid disk with tolerance. Next, connecting elements of the cycloid reducer such as the input bearing, pin-roller and output roller were approximated as nonlinear springs with a dead zone. In particular, the dead zone for the nonlinear springs was introduced to represent the clearance of each connecting element. Then, a full FE model of the cycloid reducer was built incorporating the nonlinear springs, and the hysteresis characteristic of the cycloid reducer was directly evaluated at one time so as to significantly save its analysis effort and time. Results showed that tolerance had a great effect on torque and the torsional angle relationship of the cycloid reducer. such as lost motion, back lash and torsional rigidity.

19 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented an efficiency analysis of a cycloid reducer with tolerance using the approximate force distribution of an ideal cycloid reduction with and without any tolerances.
Abstract: High precision reducers such as cycloid reducers have been used to meet the mechanical system requirements of industrial robots for advantages such as: high reduction ratio, large torque capability, and high efficiency. Although efficiency of reducers is one of important performances, there are few studies on efficiency of a cycloid reducer considering its tolerance. This paper presents efficiency analysis of a cycloid reducer with tolerance using the approximate force distribution of an ideal cycloid reducer. First, we present an FE analysis of a cycloid reducer with tolerances. Then, we approximate force distribution of the cycloid reducer with tolerance using an ideal cycloid reducer without any tolerance. The approximated force distribution of the cycloid reducer can be easily calculated using the theory of the ideal cycloid reducer. Finally, efficiency analysis of the cycloid reducer is performed using the approximate force distribution. Tolerance has great effect on efficiency on a cycloid reducer.

15 citations


Cited by
More filters
Journal ArticleDOI
06 Apr 2016
TL;DR: Marshall has unique expertise in leveraging new digital tools, 3D printing, and other advanced manufacturing technologies and applying them to propulsion systems design and other aerospace materials to meet NASA mission and industry needs.
Abstract: Propulsion system development requires new, more affordable manufacturing techniques and technologies in a constrained budget environment, while future in-space applications will require in-space manufacturing and assembly of parts and systems. Marshall is advancing cuttingedge commercial capabilities in additive and digital manufacturing and applying them to aerospace challenges. The Center is developing the standards by which new manufacturing processes and parts will be tested and qualified. Rapidly evolving digital tools, such as additive manufacturing, are the leading edge of a revolution in the design and manufacture of space systems that enables rapid prototyping and reduces production times. Marshall has unique expertise in leveraging new digital tools, 3D printing, and other advanced manufacturing technologies and applying them to propulsion systems design and other aerospace materials to meet NASA mission and industry needs. Marshall is helping establish the standards and qualifications “from art to part” for the use of these advanced techniques and the parts produced using them in aerospace or elsewhere in the U.S. industrial base.

481 citations

Journal ArticleDOI
TL;DR: In this paper, a gradient boosting machine (GBM) was used to predict the slope stability of the circular slope in the R Environment software, trained and tested with the parameters obtained from the detailed investigation of 221 actual slope cases between 1994 and 2011 with circular mode failure available in the literature.

190 citations

Journal ArticleDOI
TL;DR: This research demonstrated that integrated AI approaches had great potential to predict slope stability and FA was efficient in the hyper-parameter tunning and provides useful recommendations for future slope stability analysis that can be used for a wider application in the rest of industrial engineering.

124 citations

Journal ArticleDOI
16 May 2019
TL;DR: This paper first reviews the fundamentals of prognostics and health management techniques for REBs, and provides overviews of contemporary REB PHM techniques with a specific focus on modern artificial intelligence (AI) techniques (i.e., shallow learning algorithms).
Abstract: The objective of this paper is to present a comprehensive review of the contemporary techniques for fault detection, diagnosis, and prognosis of rolling element bearings (REBs). Data-driven approaches, as opposed to model-based approaches, are gaining in popularity due to the availability of low-cost sensors and big data. This paper first reviews the fundamentals of prognostics and health management (PHM) techniques for REBs. A brief description of the different bearing-failure modes is given, then, the paper presents a comprehensive representation of the different health features (indexes, criteria) used for REB fault diagnostics and prognostics. Thus, the paper provides an overall platform for researchers, system engineers, and experts to select and adopt the best fit for their applications. Second, the paper provides overviews of contemporary REB PHM techniques with a specific focus on modern artificial intelligence (AI) techniques (i.e., shallow learning algorithms). Finally, deep-learning approaches for fault detection, diagnosis, and prognosis for REB are comprehensively reviewed.

109 citations

Journal ArticleDOI
TL;DR: This paper presents review of high precision reducers (HPRs) for industrial robots driving 4th industrial revolution, and provides HPRs market along with industrial robots, and principle, characteristics, and three main performances of H PRs are discussed.
Abstract: New industrial revolution - “The 4th industrial revolution” must be a remarkable milestone for the second decade of the twenty-first century. Many countries are competing to innovate their manufacturing chains for eco-friendly and energy-efficient productions. Although this green or sustainable manufacturing system evolves under the support of cyber-physical system (or digital twin) based on ICT technology, industrial robots also play important roles in this speedy, flexible and effective manufacturing chains. Recently, low-cost industrial robots or collaborative robots, are rising in a highly interactive environment with humans. Although an industrial robot consists of many important components such as mechanical parts (kinematic structure and reducer) and electric parts (servo motor, driver, sensors, and controller), precision reducer takes approximately 25% of material-cost and governs important performance indices of industrial robots. This paper presents review of high precision reducers (HPRs) for industrial robots driving 4th industrial revolution. First, we provide HPRs market along with industrial robots. According to previous studies, HPRs for industrial robots can be classified based on their principles: planetary reducer, cycloid reducer, and harmonic drive (HD). Then, principle, characteristics, and three main performances (hysteresis, rotational transmission error (RTE) and efficiency) of HPRs are discussed. In addition, compensation methods overcoming accuracy limits of HPRs are summarized. Finally, other applications of HPRs except industrial robots are presented.

107 citations