Optimal Trajectories With Respect to a Sthenic Criterion for Three Quadruped Walking Gaits

Author(s):  
A. Muraro ◽  
C. Chevallereau ◽  
Y. Aoustin

Abstract In this paper, optimal cyclic reference trajectories are designed for three walking gaits of a quadruped robot, the curvet, the amble, the trot, taking into account the actuators characteristics and for a given motion robot velocity. The objectives of this study are multiple: • Automatic design of admissible reference trajectories, • Definition of the maximal speed of the robot for given actuators, • Study of the evolution of the torque cost for various motion velocities, • Comparison of three different gaits with respect to a sthenic criterion. For the gaits studied, during some phases the system is underactuated. The design of the cyclic gaits takes this fact into account. The optimization problem is solved with an algebraic optimization technique. The actuated joint evolution is chosen as a polynomial function of time. The coefficients of the polynomial functions are optimization parameters. The evolution of the passive joint is defined using the dynamic model to have admissible trajectory. During the optimization process, the constraints on the ground reactions, the validity of impact, the torques, the joints velocities of the robot are taken into account. Simulation results are presented for the three gaits. All motions are realistics. Curvet is the less efficient gait with respect to the criterion studied. For slow motion, trot is the more efficient gait. But amble permits the fastest motion with the same actuators.


1997 ◽  
Vol 119 (4) ◽  
pp. 885-892 ◽  
Author(s):  
A. Agazzani ◽  
A. F. Massardo

The aim of this work is to demonstrate the capability of an original “modular” simulator tool for the thermoeconomic analysis of thermal-energy systems. The approach employed is based on the Thermoeconomic Functional Analysis (T.F.A.), which, through definition of the “functional productive diagram” and the establishment of the capital cost function of each component, allows the marginal costs and the unit product costs, i.e., the “internal economy,” of the functional exergy flows to be obtained in correspondence to the optimum point. The optimum design of the system is obtained utilizing a traditional optimization technique, which includes both physical structure of the energy system described in terms of thermodynamic variables and cost model (capital cost of the components, maintenance and amortization factors, unit fuel cost, unit electricity cost, etc.). As an application example to show the practicability of the tool, the thermoeconomic analysis of various complex multipressure combined cycles (with or without steam reheating) is carried out. The results are analyzed and discussed in depth.



2013 ◽  
Vol 24 (04) ◽  
pp. 1350019 ◽  
Author(s):  
OLEG RYBIN

A new optimization technique for evaluating the complex effective relative permittivity and permeability of elementary sub-slab whose thickness equals to the constant of a unit cell of a slab metamaterial is developed. The objective of the technique is based on a numerical solving of appropriate minimization problem for a cascaded network representation of the slab metamaterial utilizing the Effective Medium Theory (EMT) and the definition of S- and T-parameters of the metamaterials considered as a four-pole network. The technique is tested using the open source FDTD software package and the optimization technique obtained [O. Rybin and M. Raza, Int. J. Appl. Electrom. Mech.32, 207 (2010)].



Author(s):  
A. Agazzani ◽  
A. F. Massardo

The aim of this work is to demonstrate the capability of an original “modular” simulator tool for the thermoeconomic analysis of thermal-energy systems. The approach employed is based on the Thermoeconomic Functional Analysis (T.F.A.) which, through definition of the “functional productive diagram“ and the establishment of the capital cost function of each component, allows the marginal costs and the unit product costs, i.e. the “internal economy“, of the functional exergy flows to be obtained in correspondence to the optimum point. The optimum design of the system is obtained utilizing a traditional optimization technique which includes both physical structure of the energy system described in terms of thermodynamic variables and cost model (capital cost of the components, maintenance and amortization factors, unit fuel cost, unit electricity cost, etc.). As an application example to show the practicability of the tool, the thermoeconomic analysis of various complex multi-pressure combined cycles (with or without steam reheating) is carried out. The results are analyzed and discussed in depth.



Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 451
Author(s):  
Matteo Luca Ruggiero

We discuss the linear gravitoelectromagnetic approach used to solve Einstein’s equations in the weak-field and slow-motion approximation, which is a powerful tool to explain, by analogy with electromagnetism, several gravitational effects in the solar system, where the approximation holds true. In particular, we discuss the analogy, according to which Einstein’s equations can be written as Maxwell-like equations, and focus on the definition of the gravitoelectromagnetic fields in non-stationary conditions. Furthermore, we examine to what extent, starting from a given solution of Einstein’s equations, gravitoelectromagnetic fields can be used to describe the motion of test particles using a Lorentz-like force equation.



1996 ◽  
Vol 155 (1) ◽  
pp. 145-156
Author(s):  
JAGADEESAN SETHURAMAN ◽  
PRAKASH K RAMDOSS ◽  
RAGAVAN VAIDYANATHAN ◽  
GOPAL A. KRISHNAGOPALAN


2005 ◽  
Vol 13 (03) ◽  
pp. 433-454 ◽  
Author(s):  
FRÉDÉRIC MAGOULÈS ◽  
FRANÇOIS-XAVIER ROUX ◽  
LAURENT SERIES

This paper is dedicated to the optimal convergence properties of a domain decomposition method involving two-Lagrange multipliers at the interface between the subdomains and additional augmented interface operators. Most methods for optimizing these augmented interface operators are based on the discretization of continuous approximations of the optimal transparent operators.1–5 Such approach is strongly linked to the continuous equation, and to the discretization scheme. At the discrete level, the optimal transparent operator can be proved to be equal to the Schur complement of the outer subdomain. Our idea consists of approximating directly the Schur complement matrix with purely algebraic techniques involving local condensation of the subdomain degree of freedom on small patch defined on the interface between the subdomains. The main advantage of such approach is that it is much more easy to implement in existing code without any information on the geometry of the interface and of the finite element formulation used. Such technique leads to a so-called "black box" for the users. Convergence results and parallel efficiency of this new and original algebraic optimization technique of the interface operators are presented for acoustics applications.



2014 ◽  
Vol 7 (14) ◽  
pp. 27
Author(s):  
Jaime David Mora Paz ◽  
Oscar Darío Tascón Muñoz

A synthesis model for the concept design of a submarine is developed consisting of a parametric definition of the hull geometry, a maneuverability model based on slender-body theory, and a resistance formulation. This coupled model is suitable to be treated by a metaheuristic multiobjective optimization technique (a genetic algorithm) to find a set of design options that satisfy the need to minimize simultaneously the turning diameter and the resistance generated. According to typical data found in submarines like the one analyzed herein, the boundaries and some constraints are set for the design variables. Finally, some solutions for this design case are obtained considering the criteria adopted in this study.



2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Chitra Natesan ◽  
Senthil Kumar Ajithan ◽  
Priyadharshini Palani ◽  
Prabaakaran Kandhasamy

Microgrid became one of the key spot in research on distributed energy systems. Since the definition of the microgrid is paradigm of the first time, investigation in this area is growing continuously and there are numerous research projects in this moment all over the world. The increased infiltration of nonlinear loads and power electronic interfaced distribution generation system creates power quality issues in the distributed power system. In this paper, a comprehensive survey on microgrid to improve the power quality parameters is taken as the main objective. Furthermore, the detailed investigations are explored in this paper for the enhancement of power quality issues with the help of an optimization technique, filters, controllers, FACTS devices, compensators, and battery storage.



Author(s):  
Л.В. Надеина ◽  
Г.П. Поздеева ◽  
Е.В. Швагрукова

Постановка задачи. В статье предпринимается попытка исследовать семантику глаголов, обозначающих поступательное движение, в диалекте Scots и выявить способы метафорического моделирования семантики пешего перемещения в шотландской диалектной лексической метафоре. В задачи исследования входило определить группу диалектных метафорических глаголов, выявить параметры, по которым происходит создание метафорического образа поступательного типа движения, а также описать сферы аксиологической направленности метафорических образов данного типа движения в шотландском диалекте. Результаты исследования. Результаты исследования показали, что класс глаголов поступательного движения является самым многочисленным и наиболее дифференцированным из всех классов глаголов движения. В работе показано не просто изучение определенной формы движения, а выявление тех компонентов семантики в диалектной глагольной лексике, которые являются основой метафорического уподобления процессов и явлений разных сфер деятельности. При анализе глаголов, которые в исходном номинативном значении представляют движение, была не только исследована связь диалектных глаголов движения с оценкой, но и выявлено то, какие дополнительные оценочные смыслы они отражают. Выводы. В рамках проведенного исследования авторы пришли к выводу, что поскольку были проанализированы глаголы, представляющие движение/перемещение по твёрдой поверхности, то одним из основных признаков, на основе которого строился метафорический перенос, выступает компонент «скорость». Поэтому через образ медленного движения метафорически осмысляются физиологическая, эмоциональная, психологическая сферы человека, а быстрое перемещение, представленное не только быстрой ходьбой, но и бегом, образно осмысляется как характеристика социальных явлений, действий, поступков и поведения человека. Statement of the problem. The article attempts to explore the semantics of verbs denoting progressive movement in the Scots dialect and to identify the ways of metaphorical modeling of the semantics of walking in the Scottish dialect lexical metaphor. The objectives of the study include the definition of such a group of the dialectical verb metaphorical vocabulary, identification of the parameters by which the creation of a metaphorical image of the progressive type of movement takes place, as well as the description of the sphere of axiological orientation of metaphorical images of this type of movement in the Scottish dialect. Results of the study. The results of the study showed that the class of verbs of progressive motion is the most numerous and most differentiated of all classes of verbs of motion. The work shows not just the study of a certain form of movement, but the identification of those components of semantics in the dialectical verb vocabulary, which are the basis of metaphorical likening of processes and phenomena of different spheres of activity. In the analysis of the verb vocabulary, which in its original nominative meaning represents movement, we not only did the relationship of dialectic verbs of motion with the assessment be investigated, but also determined what additional appraisal meanings they reflect. Conclusion. As part of the study, the authors concluded that since the verbs representing movement on a hard surface were analyzed, the "speed" component is one of the main traits on which metaphorical transfer was based. Therefore, through the image of slow motion metaphorically understands the physiological, emotional, psychological spheres of the person, and the rapid movement, represented not only by fast walking, but also by running, figuratively understands as a characteristic of social phenomena, actions and behavior of a person.



1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.



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