1,808 research outputs found
Design and Development of an Automated Mobile Manipulator for Industrial Applications
This thesis presents the modeling, control and coordination of an automated mobile manipulator. A mobile manipulator in this investigation consists of a robotic manipulator and a mobile platform resulting in a hybrid mechanism that includes a mobile platform for locomotion and a manipulator arm for manipulation. The structural complexity of a mobile manipulator is the main challenging issue because it includes several problems like adapting a manipulator and a redundancy mobile platform at non-holonomic constraints. The objective of the thesis is to fabricate an automated mobile manipulator and develop control algorithms that effectively coordinate the arm manipulation and mobility of mobile platform.
The research work starts with deriving the motion equations of mobile manipulators. The derivation introduced here makes use of motion equations of robot manipulators and mobile platforms separately, and then integrated them as one entity. The kinematic analysis is performed in two ways namely forward & inverse kinematics. The motion analysis is performed for various WMPs such as, Omnidirectional WMP, Differential three WMP, Three wheeled omni-steer WMP, Tricycle WMP and Two steer WMP. From the obtained motion analysis results, Differential three WMP is chosen as the mobile platform for the developed mobile manipulator. Later motion analysis is carried out for 4-axis articulated arm. Danvit-Hartenberg representation is implemented to perform forward kinematic analysis. Because of this representation, one can easily understand the kinematic equation for a robotic arm. From the obtained arm equation, Inverse kinematic model for the 4-axis robotic manipulator is developed.
Motion planning of an intelligent mobile robot is one of the most vital issues in the field of robotics, which includes the generation of optimal collision free trajectories within its work space and finally reaches its target position. For solving this problem, two evolutionary algorithms namely Particle Swarm Optimization (PSO) and Artificial Immune System (AIS) are introduced to move the mobile platform in intelligent manner. The developed algorithms are effective in avoiding obstacles, trap situations and generating optimal paths within its unknown environments. Once the robot reaches its goal (within the work space of the manipulator), the manipulator will generate its trajectories according to task assigned by the user.
Simulation analyses are performed using MATLAB-2010 in order to validate the feasibility of the developed methodologies in various unknown environments. Additionally, experiments are carried out on an automated mobile manipulator. ATmega16 Microcontrollers are used to enable the entire robot system movement in desired trajectories by means of robot interface application program. The control program is developed in robot software (Keil) to control the mobile manipulator servomotors via a serial connection through a personal computer. To support the proposed control algorithms both simulation and experimental results are presented. Moreover, validation of the developed methodologies has been made with the ER-400 mobile platform
Case report- a rare survival of 2,4-D (ethyl ester) ingestions
2,4-Dichlorophenoxyacetic acid (usually called 2,4-D) is a widely used systemic herbicide. Ingestion of 2,4 D (Ethyl Ester) is rarely reported. Ingestion of this substance leads to neurotoxicity, cardiotoxicity, hematotoxicity and nephrotoxicity. Previously reported cases describe toxicities of this agent with very high fatality, only 2 survived case reports are available. In our case the substance was identified readily and treatment started within hours of ingestion with prompt gastric lavage and forced alkaline diuresis. At the time of admission patient had already lost consciousness (i.e. neurotoxicity), patient had developed muscle fibrillations and fasciculations (i.e. myotoxicity) and during the hospital stay he got acute kidney injury (i.e. nephrotoxicity) but all toxicities recovered with treatment. Previously reported fatal cases had late identification of substance and only symptomatic supportive treatment was given whereas we used aggressive approach with forced diuresis and haemodialysis. We are reporting third survived case of 2,4-D (Ethyl Ester) poisoning and emphasizing key points in the management, early identification of substance, early institution of forced alkaline diuresis and use of renal function tests as prognostic marker with timely hemodialysis.
GRNN-Immune Based Strategy for Estimating and Optimizing the Vibratory Assisted Welding Parameters to Produce Quality Welded Joints
Welding is the process of producing permanent joints with the application of pressure and/or heat energy. During welding operation, weldments may be subjected to uneven thermal stresses. These stresses influence the metallurgical structure of the component. Due to this, the strength of the weld joint is reduced. Therefore, vibratory weld treatment during welding has been proposed in the present work to enhance the flexural and impact strength of weldments. However, it is found that the mechanical properties have shown nonlinear behavior with the chosen input parameters. Hence, an efficient Neural Network (NN) based prediction tool is developed to approximate the mechanical properties of weldments without performing the experiments, output values can be predicted for the given input values. Further, an immune based strategy is integrated to the developed prediction tool in order to obtain desired quality welded joints.Welding is the process of producing permanent joints with the application of pressure and/or heat energy. During welding operation, weldments may be subjected to uneven thermal stresses. These stresses influence the metallurgical structure of the component. Due to this, the strength of the weld joint is reduced. Therefore, vibratory weld treatment during welding has been proposed in the present work to enhance the flexural and impact strength of weldments. However, it is found that the mechanical properties have shown nonlinear behavior with the chosen input parameters. Hence, an efficient Neural Network (NN) based prediction tool is developed to approximate the mechanical properties of weldments without performing the experiments, output values can be predicted for the given input values. Further, an immune based strategy is integrated to the developed prediction tool in order to obtain desired quality welded joints
Processing and Testing of Epoxy Polymer Composites using Tender Palm Shoot Fiber and Aluminium Particles as Hybrid Reinforcements
Every year tons of plant and animal wastes are produced in the world. Some of these waste products may find some potential application in our day-to-day life. Also pure polymers are non-biodegradable and usually don’t possess requisite mechanical strength. For the first time, tender palm shoots are used as fiber reinforcement in the epoxy resin. The main objective is to compare and fabricate natural fiber reinforced hybrid epoxy composites with tender palm shoots, palymra fiber, as natural reinforcements which are generally leftovers and Aluminium powder as conductive filler by hand lay-up process at various weight percentages. Different mechanical properties, water absorption characteristics, flammability and electrical conductivity are evaluated as per ASTM standards. The test results show that these composites can be used as alternative materials for low tensile and high impact applications
Delicate f(R) gravity models with disappearing cosmological constant and observational constraints on the model parameters
We study the theory of gravity using metric approach. In particular we
investigate the recently proposed model by Hu-Sawicki, Appleby Battye and
Starobinsky. In this model, the cosmological constant is zero in flat space
time. The model passes both the Solar system and the laboratory tests. But the
model parameters need to be fine tuned to avoid the finite time singularity
recently pointed in the literature. We check the concordance of this model with
the and baryon acoustic oscillation data. We find that the model
resembles the CDM at high redshift. However, for some parameter values
there are variations in the expansion history of the universe at low redshift.Comment: 16 pages and 9 figures, typos corrected, few references and minor
clarifications added, revised version to appera in PR
Breakdown of Simple Scaling in Abelian Sandpile Models in One Dimension
We study the abelian sandpile model on decorated one dimensional chains. We
determine the structure and the asymptotic form of distribution of
avalanche-sizes in these models, and show that these differ qualitatively from
the behavior on a simple linear chain. We find that the probability
distribution of the total number of topplings on a finite system of size
is not described by a simple finite size scaling form, but by a linear
combination of two simple scaling forms , for large , where and are some scaling functions of
one argument.Comment: 10 pages, revtex, figures include
An Exactly Solvable Anisotropic Directed Percolation Model in Three Dimensions
We solve exactly a special case of the anisotropic directed bond percolation
problem in three dimensions, in which the occupation probability is 1 along two
spatial directions, by mapping it to a five-vertex model. We determine the
asymptotic shape of the ininite cluster and hence the direction dependent
critical probability. The exponents characterising the fluctuations of the
boundary of the wetted cluster in d-dimensions are related to those of the
(d-2)-dimensional KPZ equation.Comment: 4 pages, RevTex, 4 figures. 1 reference added, minor change
Black Hole Mergers and Unstable Circular Orbits
We describe recent numerical simulations of the merger of a class of equal
mass, non-spinning, eccentric binary black hole systems in general relativity.
We show that with appropriate fine-tuning of the initial conditions to a region
of parameter space we denote the threshold of immediate merger, the binary
enters a phase of close interaction in a near-circular orbit, stays there for
an amount of time proportional to logarithmic distance from the threshold in
parameter space, then either separates or merges to form a single Kerr black
hole. To gain a better understanding of this phenomena we study an analogous
problem in the evolution of equatorial geodesics about a central Kerr black
hole. A similar threshold of capture exists for appropriate classes of initial
conditions, and tuning to threshold the geodesics approach one of the unstable
circular geodesics of the Kerr spacetime. Remarkably, with a natural mapping of
the parameters of the geodesic to that of the equal mass system, the scaling
exponent describing the whirl phase of each system turns out to be quite
similar. Armed with this lone piece of evidence that an approximate
correspondence might exist between near-threshold evolution of geodesics and
generic binary mergers, we illustrate how this information can be used to
estimate the cross section and energy emitted in the ultra relativistic black
hole scattering problem. This could eventually be of use in providing estimates
for the related problem of parton collisions at the Large Hadron Collider in
extra dimension scenarios where black holes are produced.Comment: 16 pages, 12 figures; updated to coincide with journal versio
Neutrino opacity in magnetised hot and dense nuclear matter
We study the neutrino interaction rates in hot matter at high densities in
the presence of uniform magnetic field. The neutrino cross-sections involving
both the charged current absorption and neutral current scattering reactions on
baryons and leptons have been considered. We have in particular considered the
interesting case when the magnetic field is strong enough to completely
polarise the protons and electrons in supernovae and neutron stars. The opacity
in such a situation is considerably modified and the cross-section develops
anisotropy. This has implications for phenomenon invoked in the literature to
explain the observed pulsar kicks.Comment: 22 latex pages and 7 postscript figure
Feasibility studies of the time-like proton electromagnetic form factor measurements with PANDA at FAIR
The possibility of measuring the proton electromagnetic form factors in the
time-like region at FAIR with the \PANDA detector is discussed. Detailed
simulations on signal efficiency for the annihilation of into a
lepton pair as well as for the most important background channels have been
performed. It is shown that precision measurements of the differential cross
section of the reaction can be obtained in a wide
angular and kinematical range. The individual determination of the moduli of
the electric and magnetic proton form factors will be possible up to a value of
momentum transfer squared of (GeV/c). The total cross section will be measured up to (GeV/c).
The results obtained from simulated events are compared to the existing data.
Sensitivity to the two photons exchange mechanism is also investigated.Comment: 12 pages, 4 tables, 8 figures Revised, added details on simulations,
4 tables, 9 figure
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