72 research outputs found
Design of Robot Vehicle Undercarriage with Ability to Operate in Broken Terrain
AbstractThis article deals with an undercarriage design of robot vehicle that will be able to work in broken terrain. It is a frequently solved problem in mechatronics. High requirements for its application in area of rescue assistance, fire fighting, in nuclear and space industry as well are taken into consideration. Within the frame of designing commercially available software, e.g., MATLAB/Simulink and SolidWorks have been used to analyze a one degree mathematical model and a six-wheeled spatial model. A series of computation have been performed to determine the appropriate stiffness and damping parameters
Kinematics of Serial Manipulators
This book chapter deals with kinematic modeling of serial robot manipulators (open-chain multibody systems) with focus on forward as well as inverse kinematic model. At first, the chapter describes basic important definitions in the area of manipulators kinematics. Subsequently, the rigid body motion is presented and basic mathematical apparatus is introduced. Based on rigid body conventions, the forward kinematic model is established including one of the most used approaches in robot kinematics, namely the Denavit-Hartenberg convention. The last section of the chapter analyzes inverse kinematic modeling including analytical, geometrical, and numerical solutions. The chapter offers several examples of serial manipulators with its mathematical solution
Using virtual scanning to find optimal configuration of a 3D scanner turntable for scanning of mechanical parts
The article describes a method of simulated 3D scanning of triangle meshes based on ray casting which is used to find the optimal configuration of a real 3D scanner turntable. The configuration include the number of scanners, their elevation above the rotary table and the number of required rotation steps. The evaluation is based on the percentage of the part surface covered by the resulting point cloud, which determines the ability to capture all details of the shape. Principal component analysis is used as a secondary criterion to also evaluate the ability to capture the overall general proportions of the model.Web of Science2116art. no. 534
Chimney sweeping robot based on a pneumatic actuator
The need of improving the quality of professions led to the idea of simplification of processes during chimney sweeping. These processes have been essentially the same for tens of years. The goal of this paper is to bring an automation element into the chimney sweeping process, making the job easier for the chimney sweeper. In this paper, an essentially in-pipe robot is presented, which uses brushes to move while simultaneously cleaning the chimney or pipeline. The problem of the robot motion was reduced using an in-pipe robot due to the environments and obstacles that the robot has to face. An approach of using a pneumatic actuator for motion is presented along with the mechanical design. The next part of this paper is focused on the mathematical model of the robot motion, as well as its simulation and testing in the experimental pipeline. The simulations were compared with the experimental measurements and a few analyses were conducted describing the simulation model and its differences with the real robot, as well as considering certain parameters and their impact on the performance of the robot. The results are discussed at the end of the paper.Web of Science1111art. no. 487
Environmental awareness gained during a citizen science project in touristic resorts is maintained after 3 years since participation
The research leading to these results has received funding from Project AWARE Foundation, ASTOI Association, Milano, Ministry of Tourism of the Arab Republic of Egypt, Settemari S. p. A Tour Operator, Scuba Nitrox Safety International, Viaggio nel Blu Diving Center.Tourism is one of the largest economic sectors in the world. It has a positive effect on the economy of many countries, but it can also lead to negative impacts on local ecosystems. Informal environmental education through Citizen Science (CS) projects can be effective in increasing citizen environmental knowledge and awareness in the short-term. A change of awareness could bring to a behavioral change in the long-term, making tourism more sustainable. However, the long-term effects of participating in CS projects are still unknown. This is the first follow-up study concerning the effects of participating in a CS project on cognitive and psychological aspects at the basis of pro-environmental behavior. An environmental education program was developed, between 2012 and 2013, in a resort in Marsa Alam, Egypt. The study directly evaluated, through paper questionnaires, the short-term (after 1 week or 10 days) retention of knowledge and awareness of volunteers that had participated in the activities proposed by the program. After three years, participants were re-contacted via email to fill in the same questionnaire as in the short-term study, plus a new section with psychological variables. 40.5% of the re-contacted participants completed the follow-up questionnaires with a final sample size of fifty-five people for this study. Notwithstanding the limited sample size, positive trends in volunteer awareness, personal satisfaction regarding the CS project, and motivation to engage in pro-environmental behavior in the long-term were observed.Publisher PDFPeer reviewe
An analytical model of surface mass densities of cold dark matter haloes - with an application to MACHO microlensing optical depths
The cold dark matter (CDM) scenario generically predicts the existence of
triaxial dark matter haloes which contain notable amounts of substructure.
However, analytical halo models with smooth, spherically symmetric density
profiles are routinely adopted in the modelling of light propagation effects
through such objects. In this paper, we address the biases introduced by this
procedure by comparing the surface mass densities of actual N-body haloes
against the widely used analytical model suggested by Navarro, Frenk and White
(1996) (NFW).
We conduct our analysis in the redshift range of 0.0 - 1.5. In cluster sized
haloes, we find that triaxiality can cause scatter in the surface mass density
of the haloes up to sigma_+ = +60% and sigma_- = -70%, where the 1-sigma limits
are relative to the analytical NFW model given value. Subhaloes can increase
this scatter to sigma_+ = +70% and sigma_- = -80%. In galaxy sized haloes, the
triaxial scatter can be as high as sigma_+ = +80% and sigma_- = -70%, and with
subhaloes the values can change to sigma_+ = +40% and sigma_- = -80%.
We present an analytical model for the surface mass density scatter as a
function of distance to the halo centre, halo redshift and halo mass. The
analytical description enables one to investigate the reliability of results
obtained with simplified halo models. Additionally, it provides the means to
add simulated surface density scatter to analytical density profiles. As an
example, we discuss the impact of our results on the calculation of
microlensing optical depths for MACHOs in CDM haloes.Comment: 10 pages, 6 figures and 4 tables, accepted to MNRAS October 11th 200
Optimizing a quadruped robot: a comparison of two methods
Robots that have been optimized in simulation often underperform in the real world in comparison to their simulated counterparts. This difference in performance is often called a reality-gap. In this paper, we use two methods, genetic algorithm and topology optimization, to optimize a quadruped robot. We look at the original and optimized robots' performance in simulation and reality and compare the results. Both methods show improvement in the robot's efficiency, however the topology optimization behaves in a more predictable manner and shows similar results in simulation and in real laboratory testing. Modifying robot morphology with a genetic algorithm, although less predictable, has a potential for more improvement in efficiency.Web of Science20214355434
Upgrade of biaxial mechatronic testing machine for cruciform specimens and verification by FEM analysis
This article deals with the modernization of an existing loading system for the analysis of elastic-plastic properties of sheet metals in plane stress. The identification of the beginning of plastic deformation of sheet metal in plane strain is important in the cold pressing of sheet metal and in the assessment of the load capacity of thin-walled structures in the automotive and aerospace industry. The design of the control structure of the hydraulic part of the loading system for cross testing was carried out to automatize the whole process of experimental evaluation. For this purpose, proportional pressure-reducing valves together with control electronics were designed. Thus, the loading system is a control system for which a control algorithm has been designed and implemented on a PC. A computer simulation was performed to verify the functionality of the load system. An FEM simulation was performed to verify the correctness of the proposed numerical models and to confirm the experimental results. A numerical nonlinear model of the selected material was applied for the specification of plastic deformations. From the results, it is possible to state the appropriateness of the used models as well as the appropriateness of using modernized equipment for subsequent analysis of the plastic deformation of cruciform specimens.Web of Science1010art. no. 91
From Galaxy Clusters to Ultra-Faint Dwarf Spheroidals: A Fundamental Curve Connecting Dispersion-supported Galaxies to Their Dark Matter Halos
We examine scaling relations of dispersion-supported galaxies over more than
eight orders of magnitude in luminosity by transforming standard fundamental
plane parameters into a space of mass (M1/2), radius (r1/2), and luminosity
(L1/2). We find that from ultra-faint dwarf spheroidals to giant cluster
spheroids, dispersion-supported galaxies scatter about a one-dimensional
"fundamental curve" through this MRL space. The weakness of the M1/2-L1/2 slope
on the faint end may imply that potential well depth limits galaxy formation in
small galaxies, while the stronger dependence on L1/2 on the bright end
suggests that baryonic physics limits galaxy formation in massive galaxies. The
mass-radius projection of this curve can be compared to median dark matter halo
mass profiles of LCDM halos in order to construct a virial mass-luminosity
relationship (Mvir-L) for galaxies that spans seven orders of magnitude in
Mvir. Independent of any global abundance or clustering information, we find
that (spheroidal) galaxy formation needs to be most efficient in halos of Mvir
~ 10^12 Msun and to become inefficient above and below this scale. Moreover,
this profile matching technique is most accurate at the high and low luminosity
extremes (where dark matter fractions are highest) and is therefore quite
complementary to statistical approaches that rely on having a well-sampled
luminosity function. We also consider the significance and utility of the
scatter about this relation, and find that in the dSph regime observational
errors are almost at the point where we can explore the intrinsic scatter in
the luminosity-virial mass relation. Finally, we note that purely stellar
systems like Globular Clusters and Ultra Compact Dwarfs do not follow the
fundamental curve relation. This allows them to be easily distinguished from
dark-matter dominated dSph galaxies in MRL space. (abridged)Comment: 27 pages, 18 figures, ApJ accepted. High-res movies of 3D figures are
available at http://www.physics.uci.edu/~bullock/fcurve/movies.htm
Biped robot with unconventional kinematics
The article deals with the design of a robot with an unconventional kinematic structure, which is able to vertically stabilize the position of the robot base for the placement of sensors and handling superstructures. The robot concept was designed to have as few actuators as possible. The robot's kinematics was solved for the purpose of simulating the robot's movement and implementation into the robot's control system.Web of Science20225824581
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