Kinematics and Robot Design I, KaRD2018

This volume collects the papers published on the Special Issue “Kinematics and Robot Design I, KaRD2018” (https://www.mdpi.com/journal/robotics/special_issues/KARD), which is the first issue of the KaRD Special Issue series, hosted by the open access journal “MDPI Robotics”. The KaRD series aims at creating an open environment where researchers can present their works and discuss all the topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”. KaRD2018 received 22 papers and, after the peer-review process, accepted only 14 papers. The accepted papers cover some theoretical and many design/applicative aspects

A hybrid type small 5-axis CNC milling machine

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.Includes bibliographical references (leaves 116-119).5-axis CNC milling machines are important in a number of industries ranging from aerospace to consumer-die-mold machining because they can deliver high machining accuracy with a spindle tilting capacity. Most of these machines have serial mechanisms so that low static and dynamic stiffness become very critical design issues especially for high speed machining. Parallel mechanisms have recently received attention from machine tool designers because of their inherent potential for stiffness and because of their compactness. However, much of the promised advantages of parallel machines only occur within a very small region of their workspace with the expense of the large machine-tool foot print. We discuss some of the kinematic and structural challenges to extracting machining performance from serial and parallel machines. We compare a hybrid machine, which combines serial and parallel mechanisms, with typical serial and parallel machines such as Euler angle machines and the Hexapod. In particular, we consider singularities, reversal characteristics, and manufacturability. We show that hybrid machines can benefit from the advantages of serial and parallel mechanisms while avoiding most potential pitfalls of both mechanisms. However, hybrid structures can suffer from the manufacturing problem of over-constraint. We show that the degree of over-constraint depends on the size of the parallel machine. We have designed and fabricated a small hybrid 5-axis motion platform, the MIT-SS-1, which can tolerate this over-constraint through a novel layout of axes. Numerical and experimental test results of the MIT-SS-1 are presented and compared. Finally we show that this structure has potential as a small 5-axis CNC milling machine.by Seung-Kil Son.Ph.D

Advances in Mechanical Systems Dynamics 2020

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era. The 18th century was a very important time for science and was characterized by the development of classical mechanics. This development progressed in the 19th century, and new, important applications related to industrialization were found and studied. The development of computers in the 20th century revolutionized mechanical system dynamics owing to the development of numerical simulation. We are now in the presence of the fourth industrial revolution. Mechanical systems are increasingly integrated with electrical, fluidic, and electronic systems, and the industrial environment has become characterized by the cyber-physical systems of industry 4.0. Within this framework, the status-of-the-art has become represented by integrated mechanical systems and supported by accurate dynamic models able to predict their dynamic behavior. Therefore, mechanical systems dynamics will play a central role in forthcoming years. This Special Issue aims to disseminate the latest research findings and ideas in the field of mechanical systems dynamics, with particular emphasis on novel trends and applications

Models for design and control of a solar-hybrid vehicle with a tracking solar roof

2010 - 2011Our planet faces significant challenges in the twenty-first century because energy consumption is expected to double globally during the first half of this century. Faced with increasingly constrained oil supplies, humanity must look to other sources of energy, such as solar, to help us meet the growing energy demand. A useful measure of the level of a country’s development is through its energy consumption and efficiency. Excessive fossil fuel energy use not only has caused severe and growing damage to the environment from greenhouse gas emissions and oil spills, but also has brought political crises to countries in the form of global resource conflicts and food shortages. Solar and other forms of renewable energy offer a practical, clean, and viable solution to meet our planet’s growing environmental and energy challenges. Solar radiation is the most important natural energy resource because it is a renewable, free and largely diffused source. The Sun provides the Earth with an enormous amount of energy. Naturally, the Sun has always held the attention of humanity and been the subject of worship by many cultures over the millennia, such as the Egyptians, Incans, Greeks, and Mayans, among many others. The potential of solar energy to produce heat and electricity to be supplied for our modern economies in a variety of productive activities has been widely demonstrated but not yet widely adopted around the globe due to relatively cheap fossil fuels. The main problem of this kind of energy source is that it is not constant during the day and not readily dispatched. In contrast, modern lifestyles demand a continuous and reliable supply of energy. However, there are ways to overcome these shortfalls. In chapter 1 there is a general presentation of solar irradiance and the main solar angles: global solar irradiance is composed by diffuse, reflected and direct radiation. To direct radiation the geometrical relationship between the Sun and the Earth must be known. Nowadays solar technologies are involved to industrial maturity: to capture solar energy as much as possible firstly arrays with an optimal fixed tilt have been developed, then solar tracking arrays. For many of reasons, especially energetic, environmental, economic, a big interest nowadays has been developed for hybrid vehicles, particularly hybrid electric vehicles HEV; but in recent years HSV are attracting increasing interest. The last ones use solar energy. These kind of vehicles are described in chapter 2. It must be underlined that there is a great difference between hybrid solar vehicles and solar cars: in fact solar cars now do not represent a realistic alternative for traditional cars, because they depend only on sun availability and have high costs. Instead HSV do not have problems concerning the autonomy range, because they have an electric motor and also a traditional combustion engine. However until now in literature a little interest has been given to the hybrid solar vehicles despite HEV but at the University of Salerno a prototype of HSV has been developed and another one is going to be developed. Formulating the control algorithm for determining the fuel efficient power split between two energy sources is referred to as the supervisory control or energy management problem. In chapter 3, the main control strategies, used also for the energy management of HEV, are examined. Control strategies may be classified into non-causal and causal controllers respectively. Furthermore, a second classification can be made among heuristic, optimal and sub-optimal controllers. Great importance has given to three different strategies: Dynamic Programming DP, Genetic Algorithm GA and Rule–Based strategy RB. For each one the techniques of optimizations are described. An HSV vehicle has been modeled, and for this model especially RB strategy and GA optimization have been applied to see the most convenient one to apply on HSV prototype developed at University of Salerno. So a comparison of RB strategy with the other two is shown, and its advantages and facilities are described through experimental data. In chapter 3 this comparison shows that the adoption the results obtained by the optimization through RB strategy are close to the ones obtained with the other two optimizations. So this strategy seems convenient for two main reasons: · the previous knowledge of the driving cycle is not always required; · there are not strict mathematical operations. For these reasons RB strategy has been applied: it has been shown that it is necessary to compute the mean value of power traction and to establish the value of the sun factor. P tr can be evaluated with a backward or forward strategy: · Backward: the mean value is evaluated on the previous knowledge of the data, taking the mean value of the power during a certain period; · Forward: the mean value of the power is predicted. In chapter 4 numeric and experimental results about the application of this optimization strategy have been shown. First of all fuel consumption has been computed through a program developed in MATLAB, taking driving cycle from literature: it has been demonstrated that the values of fuel consumptions computed with backward and forward strategies of power traction are not very different. Then, through experimental tests, the adoption of on-board solar energy prediction is presented and there is also the demonstration of the beneficial to select the best solution in terms of energy management. Finally the program, previously developed for a generic HSV, has been adapted to the HSV prototype developed at University of Salerno considering also experimental driving cycles: the validation of Rule–Based strategy applied on the HSV prototype is presented through experimental tests. After it has been decided to adopt RB strategy for the on- board energy management of the HSV prototype through the adaptation of the MATLAB program into a program developed in LabVIEW. In chapter 5 a moving solar roof for an Hybrid Solar Vehicle is presented, and differences between a tracking system for mobile and fixed applications are underlined. With an optimal orientation of the roof, that means when the angle of incidence between the normal to the roof and the sun ray tends to zero, there is a considerable gain of energy. The mobile solar roof has been realized as a parallel robot with three degrees of freedom. A mathematical model has been developed in MATLAB, the design has been realized through the software 3D SolidWorks, the control system had been realized at the beginning with a PLC, then with a webcam placed in the middle of the mobile roof and the control has been developed through a program realized in LabVIEW. The model of the proposed roof has been developed and validated over experimental data obtained by a small scale real prototype. The kinematic model presented has allowed the optimization of roof geometry and shape. The best orienting properties are reached with shapes approaching a circular one, and with the minimum distance between globular joints. The optimal solution has been determined by an integrated analysis of both roof and vehicle shape. The economic feasibility of this project but especially the energetic gain has been evaluated: this model has been designed to be mobile only during parking phases for two main reasons: · The HSV analyzed must be used only for a urban use, so the driving phase lasts only 1-2 hours and the largest part of the day is a parking phase; · If the solar roof is mobile also during the driving phase some aerodynamic losses and instabilities could happen. The adoption of a moving solar roof for vehicle applications can substantially enhance the energy recovered during parking phases, for a solar electric or hybrid vehicle. Moreover, this system can result particularly useful at high latitudes, where an horizontal panel would be strongly penalized by low sun height. The adoption of a moving roof can therefore extend the potential market of solar assisted vehicles. In order to maximize benefits of the mobile solar roof, the energy consumption related to its movement must be minimized, and unnecessary movements avoided. To this end, a control procedure based on the use of insulation data provided by the solar panel, information derived by a GPS module and by processing the sky images taken by a webcam has been presented. The webcam has been placed in the middle of the mobile platform of the prototype, it makes a picture of the sky; in this picture two points are signed: the center of the picture and the center of mass of the points with maximum brightness. The main idea is that the center of the picture tends to go on the center of mass of the points of maximum brightness. Through this control system it has been also valuated the best interval between two different orientations, and the result is that during the day the interval between two different orientation changes, and it is convenient to orient the roof in the middle of each intervals, that means that if it has been computed that the best interval at 9.00 a.m. is one hour, there is a bigger gain of solar energy if the roof is oriented at 9.00 a.m. with the best orientation of 9.30 a.m. until 10a.m. and so on. [edited by author]X n.s

Optimisation du comportement de cellules robotiques par gestion des redondances : application à la découpe de viande et à l’Usinage Grande Vitesse

Industrial robots have evolved fundamentally in recent years to reach the industrial requirements. We now find more suitable anthropomorphic robots leading to the realization of more complex tasks like deformable objects cutting such as meat cutting or constrained to high stresses as machining. The behavior study of anthropomorphic robots, parallel or hybrid one highlights a kinematic and dynamic anisotropy, which impacts the expected accuracy. This thesis studied the integration of the kinematic redundancy that can partially overcome this problem by well setting the task to achieve it in a space compatible with the expected capacity. This work followed a three-step approach: analytical modeling of robotic cells by serial equivalent based on the TCS method, formalizing the constraints of meat cutting process and machining process and a multicriteria optimization.The first originality of this work focuses on the development of a 6 DoFs model to analyze the operator actions who naturally optimizes his arm behavior to ensure the task it performs. The second originality concerns the optimized placement of structural redundancy (9 DoFs robotic cell) where positioning parameters are incorporated as controllable variables (11 DoFs robotic cell). Thus, the thesis makes contributions to : - the definition of criteria adapted to the realization of complex and under high stress task for the management of the kinematic redundancy; - the structural behavior identification, under stress, by metrology tools (Laser tracker ) and the self- adaptation paths by using an industrial force control; - the behavior optimization to improve the cutting process quality (meat cutting and machining).Les robots industriels ont évolué fondamentalement ces dernières années pour répondre aux exigences industrielles de machines et mécanismes toujours plus performants. Ceci se traduit aujourd’hui par de nouveaux robots anthropomorphes plus adaptés laissant entrevoir la réalisation de tâches plus complexes comme la découpe d’objets déformables telle que la découpe de viande ou soumis à de fortes sollicitations comme l’usinage. L’étude du comportement des robots anthropomorphes, à structures parallèles ou hybrides montre une anisotropie aussi bien cinématique, que dynamique, impactant la précision attendue. Ces travaux de thèse étudient l’intégration des redondances cinématiques qui permettent de pallier en partie ce problème en positionnant au mieux la tâche à réaliser dans un espace de travail compatible avec les capacités attendues. Ces travaux ont suivi une démarche en trois étapes : la modélisation analytique de cellules robotiques par équivalent sériel basée sur la méthode TCS, la formalisation des contraintes des processus de découpe de viande et d’usinage et une résolution par optimisation multicritère. Une première originalité de ces travaux réside en le développement d’un modèle à 6 degrés de liberté permettant d’analyser les gestes de l’opérateur qui optimise naturellement le comportement de son bras pour garantir la tâche qu’il réalise. La seconde originalité concerne le placement optimisé des redondances structurales (cellules à 9 ddls) où les paramètres de positionnement sont incorporés comme des variables pilotables (cellule à 11 ddls). Ainsi, ces travaux de thèse apportent des contributions à : - la définition de critères adaptés à la réalisation de tâches complexes et sollicitantes pour la gestion des redondances cinématiques ; - l’identification du comportement des structures sous sollicitations par moyen métrologique (Laser tracker) et l’auto-adaptation des trajectoires par l’utilisation d’une commande en effort industrielle ; - l’optimisation du comportement permettant l’amélioration de la qualité de réalisation des différents processus de coupe (découpe de viande et usinage)

MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics

El libro de actas recoge las aportaciones de los autores a través de los correspondientes artículos a la Dinámica de Sistemas Multicuerpo y la Mecatrónica (Musme). Estas disciplinas se han convertido en una importante herramienta para diseñar máquinas, analizar prototipos virtuales y realizar análisis CAD sobre complejos sistemas mecánicos articulados multicuerpo. La dinámica de sistemas multicuerpo comprende un gran número de aspectos que incluyen la mecánica, dinámica estructural, matemáticas aplicadas, métodos de control, ciencia de los ordenadores y mecatrónica. Los artículos recogidos en el libro de actas están relacionados con alguno de los siguientes tópicos del congreso: Análisis y síntesis de mecanismos ; Diseño de algoritmos para sistemas mecatrónicos ; Procedimientos de simulación y resultados ; Prototipos y rendimiento ; Robots y micromáquinas ; Validaciones experimentales ; Teoría de simulación mecatrónica ; Sistemas mecatrónicos ; Control de sistemas mecatrónicosUniversitat Politècnica de València (2011). MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/13224Archivo delegad

Molecular phylogeny of horseshoe crab using mitochondrial Cox1 gene as a benchmark sequence

An effort to assess the utility of 650 bp Cytochrome C oxidase subunit I (DNA barcode) gene in delineating the members horseshoe crabs (Family: xiphosura) with closely related sister taxa was made. A total of 33 sequences were extracted from National Center for Biotechnological Information (NCBI) which include horseshoe crabs, beetles, common crabs and scorpion sequences. Constructed phylogram showed beetles are closely related with horseshoe crabs than common crabs. Scorpion spp were distantly related to xiphosurans. Phylogram and observed genetic distance (GD) date were also revealed that Limulus polyphemus was closely related with Tachypleus tridentatus than with T.gigas. Carcinoscorpius rotundicauda was distantly related with L.polyphemus. The observed mean Genetic Distance (GD) value was higher in 3rd codon position in all the selected group of organisms. Among the horseshoe crabs high GC content was observed in L.polyphemus (38.32%) and lowest was observed in T.tridentatus (32.35%). We conclude that COI sequencing (barcoding) could be used in identifying and delineating evolutionary relatedness with closely related specie

Crab and cockle shells as heterogeneous catalysts in the production of biodiesel

In the present study, the waste crab and cockle shells were utilized as source of calcium oxide to transesterify palm olein into methyl esters (biodiesel). Characterization results revealed that the main component of the shells are calcium carbonate which transformed into calcium oxide upon activated above 700 °C for 2 h. Parametric studies have been investigated and optimal conditions were found to be catalyst amount, 5 wt.% and methanol/oil mass ratio, 0.5:1. The waste catalysts perform equally well as laboratory CaO, thus creating another low-cost catalyst source for producing biodiesel. Reusability results confirmed that the prepared catalyst is able to be reemployed up to five times. Statistical analysis has been performed using a Central Composite Design to evaluate the contribution and performance of the parameters on biodiesel purity

The Chepang language: Phonology, Nominal and Verbal morphology - synchrony and diachrony of the varieties of the Lothar and Manahari Rivers

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The systematics of the crabs of the family varunidae (Brachyura, Decapoda)

Ph.DDOCTOR OF PHILOSOPH