4WD mobile robot for autonomous steering using single camera based vision system

2014 ◽  
Vol 2 (3) ◽  
pp. 168-182
Author(s):  
Min Hyuc Ko ◽  
Kyoung Chul Kim ◽  
Abhijit Suprem ◽  
N. Prem Mahalik ◽  
Boem Sahng Ryuh
Keyword(s):  
Mobile Robot ◽  
System Integration ◽  
Large Scale ◽  
Vision System ◽  
Second Phase ◽  
Performance Study ◽  
Content Type ◽  
Brushless Dc ◽  
Weed Mapping ◽  
Stepper Motors

Purpose – The purpose of this paper is to demonstrate System-of-Systems (SoS) approach to design and development of unmanned robotic platform for greenhouse agricultural application. Design/methodology/approach – SoS design approach is important in developing engineering products. It was observed that while system integration considers designs in a multi-disciplinary level framework, SoS is viewed as a solution focussed approach. In this paper, the authors have demonstrated SoS approach to develop a mobile robot platform. The wheels of the platform are independently controlled by using brushless DC and stepper motors based on fieldbus type Distributed Control System scheme. Findings – The constraints for autonomous traveling were identified during the first phase followed by development of 12 distinct sub-routines during second phase of training. Optimal camera installation angle, driving speeds, steering angle per pixel were found to be valuable constraints for feed-forward parameters for real-time driving. The platform was field tested in a tomato planted greenhouse for yield and weed mapping. Research limitations/implications – The paper focusses on studying vision-based autonomous four-wheel-drive (4WD) constraints and their implementation limitations. Practical implications – The platform was field tested in a tomato planted greenhouse for yield and weed mapping. Social implications – The platform can be used for agricultural operations such as crop scouting, monitoring, spraying, and mapping in a medium to large-scale greenhouse setting. Originality/value – The research and presentation is original. Starting from its mechanical specification to wheel performance study, development of path patterns for training and global navigation algorithm for testing and validation were achieved. The platform can autonomously be driven without any manual intervention.

Mobile robot motion control and autonomous navigation in GPS-denied outdoor environments using 3D laser scanning

2019 ◽  
Vol 39 (3) ◽  
pp. 469-478
Author(s):  
Qifeng Yang ◽  
Daokui Qu ◽  
Fang Xu ◽  
Fengshan Zou ◽  
Guojian He ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Motion Control ◽  
Autonomous Navigation ◽  
Laser Scanning ◽  
Large Scale ◽  
Laser Scanner ◽  
Geometric Feature ◽  
Content Type ◽  
Localization Accuracy ◽  
Novel Approach

Purpose This paper aims to propose a series of approaches to solve the problem of the mobile robot motion control and autonomous navigation in large-scale outdoor GPS-denied environments. Design/methodology/approach Based on the model of mobile robot with two driving wheels, a controller is designed and tested in obstacle-cluttered scenes in this paper. By using the priori “topology-geometry” map constructed based on the odometer data and the online matching algorithm of 3D-laser scanning points, a novel approach of outdoor localization with 3D-laser scanner is proposed to solve the problem of poor localization accuracy in GPS-denied environments. A path planning strategy based on geometric feature analysis and priority evaluation algorithm is also adopted to ensure the safety and reliability of mobile robot’s autonomous navigation and control. Findings A series of experiments are conducted with a self-designed mobile robot platform in large-scale outdoor environments, and the experimental results show the validity and effectiveness of the proposed approach. Originality/value The problem of motion control for a differential drive mobile robot is investigated in this paper first. At the same time, a novel approach of outdoor localization with 3D-laser scanner is proposed to solve the problem of poor localization accuracy in GPS-denied environments. A path planning strategy based on geometric feature analysis and priority evaluation algorithm is also adopted to ensure the safety and reliability of mobile robot’s autonomous navigation and control.

Conceptualizing sources, key concerns and critical factors for manufacturing flexibility adoption

2016 ◽  
Vol 27 (3) ◽  
pp. 379-407 ◽  
Author(s):  
Ruchi Mishra ◽  
Ashok K. Pundir ◽  
L. Ganapathy
Keyword(s):  
Quantitative Research ◽  
Large Scale ◽  
Second Phase ◽  
Manufacturing Flexibility ◽  
Critical Factors ◽  
Focus Group Interviews ◽  
Content Type ◽  
Key Issues ◽  
Group Interviews

Purpose – The purpose of this paper is to investigate factors influencing manufacturing flexibility adoption and simultaneously explores some of the key issues prevailing in manufacturing flexibility adoption in Indian context. The study also stratifies critical factors for successful manufacturing flexibility adoption. Design/methodology/approach – Using exploratory sequential design, a series of focus group interviews were conducted with Indian manufacturing professionals and these interviews were supplemented by 127 follow-up structured questionnaires. Findings – Two major themes emerged from the first phase of the study – role played by some of the unexplored antecedents of manufacturing flexibility and key issues in manufacturing flexibility adoption. In the second phase, a list of factors was categorized based on their degree of importance in manufacturing flexibility adoption. Research limitations/implications – Being qualitative in nature, the study suffers from inherent risk of subjectivity associated with manufacturing practitioners. A large-scale survey and rigorous quantitative analysis would be helpful to further validate the list of factors and underlying relationships among proposed factors. Practical implications – The identified list of factors and some of the key issues in manufacturing flexibility adoption can be of great help to practitioners. The stratified list of factors can be further used by academicians to develop an instrument for manufacturing flexibility adoption. Originality/value – The paper identifies a set of factors that affects manufacturing flexibility adoption. It offers a basis for instrument development for manufacturing flexibility adoption and provides direction for future quantitative research in manufacturing flexibility area.

The civic mission of schools and students’ participation in school governance

2019 ◽  
Vol 9 (2) ◽  
pp. 229-241
Author(s):  
Timothy Wai Wa Yuen ◽  
Chi Keung Eric Cheng ◽  
Chunlan Guo ◽  
Yan Wing Leung
Keyword(s):  
High School Students ◽  
Empirical Model ◽  
Large Scale ◽  
School Leaders ◽  
Student Participation ◽  
School Governance ◽  
Second Phase ◽  
Positive Contribution ◽  
Content Type ◽  
School Vision

Purpose The purpose of this paper is to examine the relationships between the civic mission of schools and students on participation in school governance through an empirical study. It articulates the importance of school mission on nurturing citizenship of high school students. Design/methodology/approach The research used a mixed method with questionnaire survey in the first phase and qualitative interviews in the second phase. Quantitative data were obtained from a survey completed by 3,209 students and 495 teachers (including principals) from 51 secondary schools in Hong Kong. Qualitative data were collected from 41 individual interviews with principals and teachers and 17 focus group interviews with 56 students in five case study schools. Findings Both students and teachers believed that good citizenship qualities should include students’ participation in school governance. Schools in general took up the civic mission to nurture good and participatory citizens. A mission of nurturing students to become good and participatory citizens made a significant and positive contribution toward achieving students’ actual participation in school governance. However, students’ actual impact on major school policies was minimal. A paradox existed whereby students, knowing their influence over managerial issues was much circumscribed, still gave it a higher rating than their teachers. Originality/value The paper contributes an empirical model for school leaders to develop school vision for promoting student participation in school governance. Based on a large-scale research supported by public funding, the paper contributes an empirical model for school leaders to develop school vision for promoting student participation in school governance. It further adds to the literature on relationship between citizenship education, civic mission of school and student participation in governance.

scholarly journals Systems Analysis of NADH Dehydrogenase Mutants Reveals Flexibility and Limits of Pseudomonas taiwanensis VLB120’s Metabolism

2020 ◽  
Vol 86 (11) ◽  
Author(s):  
Salome C. Nies ◽  
Robert Dinger ◽  
Yan Chen ◽  
Gossa G. Wordofa ◽  
Mette Kristensen ◽  
...  
Keyword(s):  
Respiratory Chain ◽  
Large Scale ◽  
Nadh Dehydrogenase ◽  
Metabolic Flexibility ◽  
Second Phase ◽  
Content Type ◽  
Depth Analysis ◽  
Nadh Dehydrogenases ◽  
The Impact

ABSTRACT Obligate aerobic organisms rely on a functional electron transport chain for energy conservation and NADH oxidation. Because of this essential requirement, the genes of this pathway are likely constitutively and highly expressed to avoid a cofactor imbalance and energy shortage under fluctuating environmental conditions. We here investigated the essentiality of the three NADH dehydrogenases of the respiratory chain of the obligate aerobe Pseudomonas taiwanensis VLB120 and the impact of the knockouts of corresponding genes on its physiology and metabolism. While a mutant lacking all three NADH dehydrogenases seemed to be nonviable, the single or double knockout mutant strains displayed no, or only a weak, phenotype. Only the mutant deficient in both type 2 dehydrogenases showed a clear phenotype with biphasic growth behavior and a strongly reduced growth rate in the second phase. In-depth analyses of the metabolism of the generated mutants, including quantitative physiological experiments, transcript analysis, proteomics, and enzyme activity assays revealed distinct responses to type 2 and type 1 dehydrogenase deletions. An overall high metabolic flexibility enables P. taiwanensis to cope with the introduced genetic perturbations and maintain stable phenotypes, likely by rerouting of metabolic fluxes. This metabolic adaptability has implications for biotechnological applications. While the phenotypic robustness is favorable in large-scale applications with inhomogeneous conditions, the possible versatile redirecting of carbon fluxes upon genetic interventions can thwart metabolic engineering efforts. IMPORTANCE While Pseudomonas has the capability for high metabolic activity and the provision of reduced redox cofactors important for biocatalytic applications, exploitation of this characteristic might be hindered by high, constitutive activity of and, consequently, competition with the NADH dehydrogenases of the respiratory chain. The in-depth analysis of NADH dehydrogenase mutants of Pseudomonas taiwanensis VLB120 presented here provides insight into the phenotypic and metabolic response of this strain to these redox metabolism perturbations. This high degree of metabolic flexibility needs to be taken into account for rational engineering of this promising biotechnological workhorse toward a host with a controlled and efficient supply of redox cofactors for product synthesis.

Financial distress determinants among SMEs: empirical evidence from Sweden

2020 ◽  
Vol 47 (3) ◽  
pp. 547-560 ◽  
Author(s):  
Darush Yazdanfar ◽  
Peter Öhman
Keyword(s):  
Financial Crisis ◽  
Financial Distress ◽  
Large Scale ◽  
Global Financial Crisis ◽  
Binary Logistic Regression ◽  
Data Availability ◽  
Cross Sectional ◽  
Data Set ◽  
Content Type ◽  
The Global Financial Crisis

PurposeThe purpose of this study is to empirically investigate determinants of financial distress among small and medium-sized enterprises (SMEs) during the global financial crisis and post-crisis periods.Design/methodology/approachSeveral statistical methods, including multiple binary logistic regression, were used to analyse a longitudinal cross-sectional panel data set of 3,865 Swedish SMEs operating in five industries over the 2008–2015 period.FindingsThe results suggest that financial distress is influenced by macroeconomic conditions (i.e. the global financial crisis) and, in particular, by various firm-specific characteristics (i.e. performance, financial leverage and financial distress in previous year). However, firm size and industry affiliation have no significant relationship with financial distress.Research limitationsDue to data availability, this study is limited to a sample of Swedish SMEs in five industries covering eight years. Further research could examine the generalizability of these findings by investigating other firms operating in other industries and other countries.Originality/valueThis study is the first to examine determinants of financial distress among SMEs operating in Sweden using data from a large-scale longitudinal cross-sectional database.

The dialectics of authoring expansive learning: tracing the long tail of a Change Laboratory

2016 ◽  
Vol 28 (4) ◽  
pp. 245-262 ◽  
Author(s):  
Annalisa Sannino ◽  
Yrjö Engeström ◽  
Johanna Lahikainen
Keyword(s):  
Large Scale ◽  
Scale Transformation ◽  
Dialectical Tensions ◽  
Content Type ◽  
Organization Model ◽  
Expansive Learning ◽  
Conceptual Argument ◽  
University Library ◽  
Dialectical Process ◽  
Cultural Historical Activity

Purpose The paper aims to examine organizational authoring understood as a longitudinal, material and dialectical process of transformation efforts. The following questions are asked: To which extent can a Change Laboratory intervention help practitioners author their own learning? Are the authored outcomes of a Change Laboratory intervention futile if a workplace subsequently undergoes large-scale organizational transformations? Does the expansive learning authored in a Change Laboratory intervention survive large-scale organizational transformations, and if so, why does it survive and how? Design/methodology/approach The paper develops a conceptual argument based on cultural–historical activity theory. The conceptual argument is grounded in the examination of a case of eight years of change efforts in a university library, including a Change Laboratory (CL) intervention. Follow-up interview data are used to discuss and illuminate our argument in relation to the three research questions. Findings The idea of knotworking constructed in the CL process became a “germ cell” that generates novel solutions in the library activity. A large-scale transformation from the local organization model developed in the CL process to the organization model of the entire university library was not experienced as a loss. The dialectical tension between the local and global models became a source of movement driven by the emerging expansive object. Practitioners are modeling their own collective future competences, expanding them both in socio-spatial scope and interactive depth. Originality/value The article offers an expanded view of authorship, calling attention to material changes and practical change actions. The dialectical tensions identified serve as heuristic guidelines for future studies and interventions.

Dynamic output feedback control for nonlinear large-scale interconnected systems

2020 ◽  
Vol 39 (4) ◽  
pp. 801-821
Author(s):  
Ezzeddine Touti ◽  
Ali Sghaier Tlili ◽  
Muhannad Almutiry
Keyword(s):  
Decentralized Control ◽  
Output Feedback ◽  
Large Scale ◽  
Optimization Problem ◽  
Lyapunov Theory ◽  
Interconnected Systems ◽  
Dynamic Output Feedback ◽  
Content Type ◽  
Dynamic Output ◽  
Control Scheme

Purpose This paper aims to focus on the design of a decentralized observation and control method for a class of large-scale systems characterized by nonlinear interconnected functions that are assumed to be uncertain but quadratically bounded. Design/methodology/approach Sufficient conditions, under which the designed control scheme can achieve the asymptotic stabilization of the augmented system, are developed within the Lyapunov theory in the framework of linear matrix inequalities (LMIs). Findings The derived LMIs are formulated under the form of an optimization problem whose resolution allows the concurrent computation of the decentralized control and observation gains and the maximization of the nonlinearity coverage tolerated by the system without becoming unstable. The reliable performances of the designed control scheme, compared to a distinguished decentralized guaranteed cost control strategy issued from the literature, are demonstrated by numerical simulations on an extensive application of a three-generator infinite bus power system. Originality/value The developed optimization problem subject to LMI constraints is efficiently solved by a one-step procedure to analyze the asymptotic stability and to synthesize all the control and observation parameters. Therefore, such a procedure enables to cope with the conservatism and suboptimal solutions procreated by optimization problems based on iterative algorithms with multi-step procedures usually used in the problem of dynamic output feedback decentralized control of nonlinear interconnected systems.

scholarly journals Second Phase Precipitation in As-Welded and Solution Annealed Alloy 22 Welds

2006 ◽  
Vol 128 (4) ◽  
pp. 644-647 ◽  
Author(s):  
Bassem S. El-Dasher ◽  
Sharon G. Torres
Keyword(s):  
Large Scale ◽  
Thick Plate ◽  
Electron Backscatter Diffraction ◽  
Second Phase ◽  
Solution Annealing ◽  
Annealed Alloy ◽  
Precipitation Characteristics ◽  
Alloy 22 ◽  
Tcp Phases ◽  
Backscatter Diffraction

The precipitation characteristics of tetrahedrally close-packed (TCP) phases during the welding and the subsequent solution annealing process of Alloy 22 1 1∕2in. thick plate double-U prototypical welds are investigated. Electron backscatter diffraction was used to provide large scale microstructural observation of the weld cross section, and scanning electron microscopy was used to map the location of the TCP phases. Analysis shows that TCP precipitation occurs congruent to the weld passes, with the solution annealing reducing the sizes of coarser precipitates.

scholarly journals Large-Scale Synonymous Substitutions in Cucumber Mosaic Virus RNA 3 Facilitate Amino Acid Mutations in the Coat Protein

2018 ◽  
Vol 92 (22) ◽  
Author(s):  
Tomofumi Mochizuki ◽  
Rie Ohara ◽  
Marilyn J. Roossinck
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Viral Genome ◽  
Large Scale ◽  
Viral Rna ◽  
Wild Type ◽  
Competitive Fitness ◽  
Content Type ◽  
Synonymous Substitutions ◽  
Cp Gene

ABSTRACTThe effect of large-scale synonymous substitutions in a small icosahedral, single-stranded RNA viral genome on virulence, viral titer, and protein evolution were analyzed. The coat protein (CP) gene of the Fny stain of cucumber mosaic virus (CMV) was modified. We created four CP mutants in which all the codons of nine amino acids in the 5′ or 3′ half of the CP gene were replaced by either the most frequently or the least frequently used synonymous codons in monocot plants. When the dicot host (Nicotiana benthamiana) was inoculated with these four CP mutants, viral RNA titers in uninoculated symptomatic leaves decreased, while all mutants eventually showed mosaic symptoms similar to those for the wild type. The codon adaptation index of these four CP mutants against dicot genes was similar to those of the wild-type CP gene, indicating that the reduction of viral RNA titer was due to deleterious changes of the secondary structure of RNAs 3 and 4. When two 5′ mutants were serially passaged inN. benthamiana, viral RNA titers were rapidly restored but competitive fitness remained decreased. Although no nucleic acid changes were observed in the passaged wild-type CMV, one to three amino acid changes were observed in the synonymously mutated CP of each passaged virus, which were involved in recovery of viral RNA titer of 5′ mutants. Thus, we demonstrated that deleterious effects of the large-scale synonymous substitutions in the RNA viral genome facilitated the rapid amino acid mutation(s) in the CP to restore the viral RNA titer.IMPORTANCERecently, it has been known that synonymous substitutions in RNA virus genes affect viral pathogenicity and competitive fitness by alteration of global or local RNA secondary structure of the viral genome. We confirmed that large-scale synonymous substitutions in the CP gene of CMV resulted in decreased viral RNA titer. Importantly, when viral evolution was stimulated by serial-passage inoculation, viral RNA titer was rapidly restored, concurrent with a few amino acid changes in the CP. This novel finding indicates that the deleterious effects of large-scale nucleic acid mutations on viral RNA secondary structure are readily tolerated by structural changes in the CP, demonstrating a novel part of the adaptive evolution of an RNA viral genome. In addition, our experimental system for serial inoculation of large-scale synonymous mutants could uncover a role for new amino acid residues in the viral protein that have not been observed in the wild-type virus strains.

scholarly journals Biological Impact of a Large-Scale Genomic Inversion That Grossly Disrupts the Relative Positions of the Origin and Terminus Loci of theStreptococcus pyogenesChromosome

2019 ◽  
Vol 201 (17) ◽  
Author(s):  
Dragutin J. Savic ◽  
Scott V. Nguyen ◽  
Kimberly McCullor ◽  
W. Michael McShan
Keyword(s):  
Dna Sequences ◽  
Parental Strain ◽  
Large Scale ◽  
Galleria Mellonella ◽  
Acute Infection ◽  
Relative Length ◽  
Published Data ◽  
Rich Medium ◽  
Content Type

ABSTRACTA large-scale genomic inversion encompassing 0.79 Mb of the 1.816-Mb-longStreptococcus pyogenesserotype M49 strain NZ131 chromosome spontaneously occurs in a minor subpopulation of cells, and in this report genetic selection was used to obtain a stable lineage with this chromosomal rearrangement. This inversion, which drastically displaces theorisite relative to the terminus, changes the relative length of the replication arms so that one replichore is approximately 0.41 Mb while the other is about 1.40 Mb in length. Genomic reversion to the original chromosome constellation is not observed in PCR-monitored analyses after 180 generations of growth in rich medium. Compared to the parental strain, the inversion surprisingly demonstrates a nearly identical growth pattern in the first phase of the exponential phase, but differences do occur when resources in the medium become limited. When cultured separately in rich medium during prolonged stationary phase or in an experimental acute infection animal model (Galleria mellonella), the parental strain and the invertant have equivalent survival rates. However, when they are coincubated together, bothin vitroandin vivo, the survival of the invertant declines relative to the level for the parental strain. The accompanying aspect of the study suggests that inversions taking place nearoriCalways happen to secure the linkage oforiCto DNA sequences responsible for chromosome partition. The biological relevance of large-scale inversions is also discussed.IMPORTANCEBased on our previous work, we created to our knowledge the largest asymmetric inversion, covering 43.5% of theS. pyogenesgenome. In spite of a drastic replacement of origin of replication and the unbalanced size of replichores (1.4 Mb versus 0.41 Mb), the invertant, when not challenged with its progenitor, showed impressive vitality for growthin vitroand in pathogenesis assays. The mutant supports the existing idea that slightly deleterious mutations can provide the setting for secondary adaptive changes. Furthermore, comparative analysis of the mutant with previously published data strongly indicates that even large genomic rearrangements survive provided that the integrity of theoriCand the chromosome partition cluster is preserved.

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