Bayesian Optimization Based Terrestrial Gait Tuning for a 12-DOF Alligator-Inspired Robot With Active Body Undulation

2018 ◽  
Author(s):  
Krishna Agrawal ◽  
Kushagra Jain ◽  
Dhawal Gupta ◽  
Raunak Srivastav ◽  
Abhijeet Agnihotri ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Critical Role ◽  
Parameter Tuning ◽  
The Body ◽  
Experimental Results ◽  
Bayesian Optimization ◽  
Terrestrial Locomotion ◽  
Gait Parameters ◽  
Rotational Degrees Of Freedom ◽  
The One

In addition to aiding in swimming, body undulation of an alligator plays a critical role in terrestrial locomotion by imparting stability. This paper reports design, fabrication and terrestrial locomotion control incorporating active body undulation of a 12-DOF alligator-inspired robot. Each of the four legs of the developed robot has two rotational degrees of freedom while the body can perform undulation using additional four rotational degrees of freedom. This paper also presents a Bayesian optimization based approach to tune the gait parameters of both leg oscillation and body undulation in order to maximize the average robot speed. We obtained improvement by a factor of 1.93 in average robot speed in comparison to the one obtained by randomly generated parameters and report the experimental results in this paper. In future, we plan to generalize the developed Bayesian optimization based parameter tuning approach for the swimming gait and thereby impart amphibious capabilities to the developed robot.

scholarly journals Jumping in frogs: assessing the design of the skeletal system by anatomically realistic modeling and forward dynamic simulation

2002 ◽  
Vol 205 (12) ◽  
pp. 1683-1702 ◽  
Author(s):  
William J. Kargo ◽  
Frank Nelson ◽  
Lawrence C. Rome
Keyword(s):  
Degrees Of Freedom ◽  
The Body ◽  
Joint Torque ◽  
Rotational Degree ◽  
Skeletal System ◽  
Dynamic Simulations ◽  
Inverse Dynamic ◽  
Maximal Distance ◽  
Out Of Plane ◽  
Rotational Degrees Of Freedom

SUMMARY Comparative musculoskeletal modeling represents a tool to understand better how motor system parameters are fine-tuned for specific behaviors. Frog jumping is a behavior in which the physical properties of the body and musculotendon actuators may have evolved specifically to extend the limits of performance. Little is known about how the joints of the frog contribute to and limit jumping performance. To address these issues, we developed a skeletal model of the frog Rana pipiens that contained realistic bones, joints and body-segment properties. We performed forward dynamic simulations of jumping to determine the minimal number of joint degrees of freedom required to produce maximal-distance jumps and to produce jumps of varied take-off angles. The forward dynamics of the models was driven with joint torque patterns determined from inverse dynamic analysis of jumping in experimental frogs. When the joints were constrained to rotate in the extension—flexion plane, the simulations produced short jumps with a fixed angle of take-off. We found that, to produce maximal-distance jumping,the skeletal system of the frog must minimally include a gimbal joint at the hip (three rotational degrees of freedom), a universal Hooke's joint at the knee (two rotational degrees of freedom) and pin joints at the ankle,tarsometatarsal, metatarsophalangeal and iliosacral joints (one rotational degree of freedom). One of the knee degrees of freedom represented a unique kinematic mechanism (internal rotation about the long axis of the tibiofibula)and played a crucial role in bringing the feet under the body so that maximal jump distances could be attained. Finally, the out-of-plane degrees of freedom were found to be essential to enable the frog to alter the angle of take-off and thereby permit flexible neuromotor control. The results of this study form a foundation upon which additional model subsystems (e.g. musculotendon and neural) can be added to test the integrative action of the neuromusculoskeletal system during frog jumping.

scholarly journals Effect of Molecular Rotational Degrees of Freedom on Mechanical and Thermodynamic Properties of Solid Methane at Temperatures above 50 K

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Antonina V. Leont’eva ◽  
Andrew Yu. Prokhorov ◽  
Anatoly Yu. Zakharov ◽  
Alexander I. Erenburg
Keyword(s):  
Temperature Interval ◽  
Spectral Properties ◽  
Degrees Of Freedom ◽  
Reliable Data ◽  
The Body ◽  
Data Set ◽  
Rotational Degrees Of Freedom ◽  
Triple Point Temperature ◽  
Equilibrium Vapor Pressure ◽  
Solid Methane

The paper presents an analysis of extensive data set of mechanical, structural, thermophysical, and spectral properties of solid methane in the temperature interval 0.5 · Ttr–Ttr (Ttr is the triple point temperature) under equilibrium vapor pressure. It is shown that the anomalies of the studied properties (or lack of reliable data) at temperatures 60–70 K have been observed in the body of the reviewed papers. We proposed that the observed anomalies are due to a transition between classical and quantum regimes of collective rotational degrees of freedom of methane molecules in this temperature interval.

Viscous Flow Computation around the Wigley Hull with the Maneuvering Motion using the Inertial Coordinate System on the Non-inertial Grids

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Yan Naing Win ◽  
Yasuyuki Toda
Keyword(s):  
Flow Field ◽  
Degrees Of Freedom ◽  
The Body ◽  
Uniform Motion ◽  
Ocean Engineering ◽  
Blade Element Theory ◽  
Wigley Hull ◽  
Computational Fluid Dynamics Cfd ◽  
The One ◽  
Element Theory

Computational Fluid Dynamics (CFD) technique for ship hydrodynamics has been well developed with advanced capabilities for resistance and propulsion, seakeeping, and maneuvering. The Authors’ laboratory (Laboratory 3 of Department of Naval Architecture and Ocean Engineering in Osaka University) specializes in resistance and propulsion field and has carried out several simulations based on the CFD code in non-inertial ship-fixed coordinates system. The purpose of this research is to transform the present computation code to the one in inertial coordinate and to investigate the flow field around the Wigley hull for several motions up to three degrees of freedom (3 DOF). The transformed code is simulated on the flat plate initially and the nature of the flow field is investigated and confirmed with the hydrodynamics theory. Then, the wigley hull motions are simulated in several ways such as; uniform motion, pure yaw and circular motion test. The features of the flow field and hydrodynamic forces acting on the hull are discussed based on the computed results. Finally, the propeller effect is implemented behind the wigley hull using the body-force concept by the quasi-steady infinite bladed Blade Element Theory and a propulsion characteristic is observed. The transformed computation code in inertial coordinate is found to be much easier to simulate the different kinds of maneuvering motions compared to the code in non-inertial system and this paper covers the detailed transformation steps and the discussions on the computation results of different motions.

Representing utility and deploying the body

2020 ◽  
Vol 43 ◽  
Author(s):  
David Spurrett
Keyword(s):  
Functional Activity ◽  
Degrees Of Freedom ◽  
The Body ◽  
Target Article ◽  
Processing Demands ◽  
The Many

Abstract Comprehensive accounts of resource-rational attempts to maximise utility shouldn't ignore the demands of constructing utility representations. This can be onerous when, as in humans, there are many rewarding modalities. Another thing best not ignored is the processing demands of making functional activity out of the many degrees of freedom of a body. The target article is almost silent on both.

‘If you shoulder a rifle […] let it be for Ireland’: James Connolly's War on War

2018 ◽  
Vol 13 (3) ◽  
pp. 364-381
Author(s):  
Margot Gayle Backus ◽  
Spurgeon Thompson
Keyword(s):  
World War I ◽  
The Body ◽  
Party Leader ◽  
Irish Nationalism ◽  
British Imperialism ◽  
Communications Networks ◽  
Easter Rising ◽  
Trade Unionist ◽  
The One ◽  
National Governments

As virtually all Europe's major socialist parties re-aligned with their own national governments with the outbreak of World War I, Irish socialist and trade unionist James Connolly found himself internationally isolated by his vociferous opposition to the war. Within Ireland, however, Connolly's energetic and relentless calls to interrupt the imperial transportation and communications networks on which the ‘carnival of murder’ in Europe relied had the converse effect, drawing him into alignment with certain strains of Irish nationalism. Connolly and other socialist republican stalwarts like Helena Molony and Michael Mallin made common cause with advanced Irish nationalism, the one other constituency unamenable to fighting for England under any circumstances. This centripetal gathering together of two minority constituencies – both intrinsically opposed, if not to the war itself, certainly to Irish Party leader John Redmond's offering up of the Irish Volunteers as British cannon fodder – accounts for the “remarkably diverse” social and ideological character of the small executive body responsible for the planning of the Easter Rising: the Irish Republican Brotherhood's military council. In effect, the ideological composition of the body that planned the Easter Rising was shaped by the war's systematic diversion of all individuals and ideologies that could be co-opted by British imperialism through any possible argument or material inducement. Although the majority of those who participated in the Rising did not share Connolly's anti-war, pro-socialist agenda, the Easter 1916 Uprising can nonetheless be understood as, among other things, a near letter-perfect instantiation of Connolly's most steadfast principle: that it was the responsibility of every European socialist to throw onto the gears of the imperialist war machine every wrench on which they could lay their hands.

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

Updating long-held assumptions about fat stigma: For women, body shape plays a critical role

2020 ◽  
Author(s):  
Jaimie Krems ◽  
Steven L. Neuberg
Keyword(s):  
Body Shape ◽  
Critical Role ◽  
The Body ◽  
Theoretical Assumption ◽  
Obesity Stigma ◽  
Obese Female ◽  
Three Samples ◽  
Female Bodies ◽  
Different Parts ◽  
Fat Stigma

Heavier bodies—particularly female bodies—are stigmatized. Such fat stigma is pervasive, painful to experience, and may even facilitate weight gain, thereby perpetuating the obesity-stigma cycle. Leveraging research on functionally distinct forms of fat (deposited on different parts of the body), we propose that body shape plays an important but largely underappreciated role in fat stigma, above and beyond fat amount. Across three samples varying in participant ethnicity (White and Black Americans) and nation (U.S., India), patterns of fat stigma reveal that, as hypothesized, participants differently stigmatized equally-overweight or -obese female targets as a function of target shape, sometimes even more strongly stigmatizing targets with less rather than more body mass. Such findings suggest value in updating our understanding of fat stigma to include body shape and in querying a predominating, but often implicit, theoretical assumption that people simply view all fat as bad (and more fat as worse).

The Woman Who Turned Into a Jaguar, and Other Narratives of Native Women in Archives of Colonial Mexico

2017 ◽  
Author(s):  
Lisa Sousa
Keyword(s):  
Gender Relations ◽  
Civil Disobedience ◽  
Indigenous Communities ◽  
The Body ◽  
Colonial Rule ◽  
Criminal Records ◽  
Native Women ◽  
Women's Lives ◽  
Important Position ◽  
The One

The Woman Who Turned Into a Jaguar examines gender relations in indigenous societies of central Mexico and Oaxaca from the 1520s to the 1750s, focusing mainly on the Nahua, Ñudzahui (Mixtec), Bènizàa (Zapotec), and Ayuk (Mixe) people. This study draws on an unusually rich and diverse corpus of original sources, including Ñudzahui- (Mixtec-), Tíchazàa- (Zapotec-), and mainly Nahuatl-language and Spanish civil and criminal records, published texts, and pictorial manuscripts. The sources come from more than 100 indigenous communities of highland Mexico. The book considers women’s lives in the broadest context possible by addressing a number of interrelated topics, including: the construction of gender; concepts of the body; women’s labor; marriage rituals and marital relations; sexual attitudes; family structure; the relationship between household and community; and women’s participation in riots and other acts of civil disobedience. The study highlights subtle transformations and overwhelming continuities in indigenous social attitudes and relationships. The book argues that profound changes following the Spanish conquest, such as catastrophic depopulation, economic pressures, and the imposition of Christian marriage, slowly eroded indigenous women’s status. Nevertheless, gender relations remained inherently complementary. The study shows how native women and men under colonial rule, on the one hand, pragmatically accepted, adopted, and adapted certain Spanish institutions, concepts, and practices, and, on the other, forcefully rejected other aspects of colonial impositions. Women asserted their influence and, in doing so, they managed to retain an important position within their households and communities across the first two centuries of colonial rule.

scholarly journals Task space adaptation via the learning of gait controllers of magnetic soft millirobots

2021 ◽  
pp. 027836492110218
Author(s):  
Sinan O. Demir ◽  
Utku Culha ◽  
Alp C. Karacakol ◽  
Abdon Pena-Francesch ◽  
Sebastian Trimpe ◽  
...  
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Bayesian Optimization ◽  
Small Scale ◽  
Soft Robots ◽  
Modeling And Control ◽  
Walking Gait ◽  
Physical Experiments ◽  
Efficient Learning ◽  
Task Environments

Untethered small-scale soft robots have promising applications in minimally invasive surgery, targeted drug delivery, and bioengineering applications as they can directly and non-invasively access confined and hard-to-reach spaces in the human body. For such potential biomedical applications, the adaptivity of the robot control is essential to ensure the continuity of the operations, as task environment conditions show dynamic variations that can alter the robot’s motion and task performance. The applicability of the conventional modeling and control methods is further limited for soft robots at the small-scale owing to their kinematics with virtually infinite degrees of freedom, inherent stochastic variability during fabrication, and changing dynamics during real-world interactions. To address the controller adaptation challenge to dynamically changing task environments, we propose using a probabilistic learning approach for a millimeter-scale magnetic walking soft robot using Bayesian optimization (BO) and Gaussian processes (GPs). Our approach provides a data-efficient learning scheme by finding the gait controller parameters while optimizing the stride length of the walking soft millirobot using a small number of physical experiments. To demonstrate the controller adaptation, we test the walking gait of the robot in task environments with different surface adhesion and roughness, and medium viscosity, which aims to represent the possible conditions for future robotic tasks inside the human body. We further utilize the transfer of the learned GP parameters among different task spaces and robots and compare their efficacy on the improvement of data-efficient controller learning.

scholarly journals Experiential ownership and body ownership are different phenomena

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Caleb Liang ◽  
Wen-Hsiang Lin ◽  
Tai-Yuan Chang ◽  
Chi-Hong Chen ◽  
Chen-Wei Wu ◽  
...  
Keyword(s):  
Conscious Experience ◽  
Distinct Type ◽  
Body Part ◽  
The Body ◽  
Body Ownership ◽  
Rubber Hand ◽  
Person Perspective ◽  
The One ◽  
First Time ◽  
Full Body

AbstractBody ownership concerns what it is like to feel a body part or a full body as mine, and has become a prominent area of study. We propose that there is a closely related type of bodily self-consciousness largely neglected by researchers—experiential ownership. It refers to the sense that I am the one who is having a conscious experience. Are body ownership and experiential ownership actually the same phenomenon or are they genuinely different? In our experiments, the participant watched a rubber hand or someone else’s body from the first-person perspective and was touched either synchronously or asynchronously. The main findings: (1) The sense of body ownership was hindered in the asynchronous conditions of both the body-part and the full-body experiments. However, a strong sense of experiential ownership was observed in those conditions. (2) We found the opposite when the participants’ responses were measured after tactile stimulations had ceased for 5 s. In the synchronous conditions of another set of body-part and full-body experiments, only experiential ownership was blocked but not body ownership. These results demonstrate for the first time the double dissociation between body ownership and experiential ownership. Experiential ownership is indeed a distinct type of bodily self-consciousness.

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