The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Atsuo Kawamura - One of the best experts on this subject based on the ideXlab platform.
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Bipedal Trajectory Generation Based on Combining Inertial Forces and Intrinsic Angular Momentum Rate Changes: Eulerian ZMP Resolution
IEEE Transactions on Robotics, 2012Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This paper aims to present a technique to generate feasible and dynamically equilibrated ZMP-based center of mass trajectories that can be applied to bipedal robots. In this regard, we utilize the ZMP concept in the spherical coordinate frame so that we can fully exploit its properties as this strategy enables us to efficiently combine Intrinsic Angular Momentum rate change terms with inertial force terms. That being said, this strategy has certain advantages: 1) In the case of bipedal walking, undesired torso angle fluctuations are more restrainable compared with other methods, in which Angular Momentum information is omitted or zero-referenced. 2) Composite rigid body inertia, which is a multibody property of robot dynamics, can be characterized during the trajectory generation task. Thus, relatively more dynamically consistent trajectories may be obtained. 3) The motion interference between the sagittal and lateral planes is naturally included. In this paper, we mainly investigate the first two advantages. Applying the method described above, we conducted bipedal walking experiments on our actual bipedal robot MARI-3. As the result, we obtained repetitive, continuous, and dynamically equilibrated walking cycles, in which undesired torso angles were well suppressed. Furthermore, ZMP error tends to decrease since inertial parameters of the robot are characterized. In conclusion, the method is validated to be efficient in inducing less ZMP error and in suppressing undesired torso angle variations, compared with both flywheel-superimposed and conventional ZMP-based trajectory generation methods.
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eulerian zmp resolution based bipedal walking discussions on the Intrinsic Angular Momentum rate change about center of mass
International Conference on Robotics and Automation, 2010Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This paper is aimed at implementing Eulerian ZMP Resolution method to bipedal walking pattern generation. The main strategy in this method is to ensure the dynamic balance by generating feasible ZMP-based CoM trajectories. For this purpose, we employ ZMP equations in spherical coordinates, so that the Intrinsic Angular Momentum rate change about center of mass is included explicitly in a natural way. This fact results in two merits: 1) Undesired torso angle fluctuation and body twists are expected to be more restrainable comparing to other methods in which Intrinsic Angular Momentum information is ignored or zero-referenced. 2) The interference between motions in sagittal and lateral planes can be extracted. In this article, we mainly investigate the first merit and briefly discuss about the second merit. Applying the aforementioned technique, Eulerian ZMP Resolution, we simulated bipedal walking on a 3-D dynamic simulator. Secondarily, we conducted bipedal walking experiments on the actual bipedal robot. In conclusion, we obtained dynamically equilibrated bipedal walking cycles, which satisfactorily verify the efficiency of Eulerian ZMP Resolution technique over conventional methods.
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ICRA - Eulerian ZMP resolution based bipedal walking: Discussions on the Intrinsic Angular Momentum rate change about center of mass
2010 IEEE International Conference on Robotics and Automation, 2010Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This paper is aimed at implementing Eulerian ZMP Resolution method to bipedal walking pattern generation. The main strategy in this method is to ensure the dynamic balance by generating feasible ZMP-based CoM trajectories. For this purpose, we employ ZMP equations in spherical coordinates, so that the Intrinsic Angular Momentum rate change about center of mass is included explicitly in a natural way. This fact results in two merits: 1) Undesired torso angle fluctuation and body twists are expected to be more restrainable comparing to other methods in which Intrinsic Angular Momentum information is ignored or zero-referenced. 2) The interference between motions in sagittal and lateral planes can be extracted. In this article, we mainly investigate the first merit and briefly discuss about the second merit. Applying the aforementioned technique, Eulerian ZMP Resolution, we simulated bipedal walking on a 3-D dynamic simulator. Secondarily, we conducted bipedal walking experiments on the actual bipedal robot. In conclusion, we obtained dynamically equilibrated bipedal walking cycles, which satisfactorily verify the efficiency of Eulerian ZMP Resolution technique over conventional methods.
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Humanoids - Bipedal walking trajectory generation based on ZMP and Euler's equations of motion
2010 10th IEEE-RAS International Conference on Humanoid Robots, 2010Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This article is aimed at presenting a technique to generate bipedal walking trajectories that can be applied to humanoid robots. The proposed method is based on maintatining the dynamic balance by using the ZMP criterion throughout single support phases. To be able to reach this goal, we employed ZMP equations in spherical coordinates, so that the rate change of Intrinsic Angular Momentum terms in ZMP equations are included naturally by using Euler's equations of motion. Thus, undesired torso angle fluctuations are successfully suppressed comparing to other methods in which Intrinsic Angular Momentum rate changes are ignored or zero-referenced. Applying the aforementioned technique, we firstly performed simulations on a 3-D dynamic simulator. Upon simulations, we conducted walking experiments on the actual robot MARI-3. In conclusion, we obtained dynamically equilibrated and bipedal walking cycles in which torso angles are well suppressed in comparison with the conventional approach.
Barkan Ugurlu - One of the best experts on this subject based on the ideXlab platform.
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YAW MOMENT COMPENSATION FOR BIPEDAL ROBOTS VIA Intrinsic Angular Momentum CONSTRAINT
International Journal of Humanoid Robotics, 2012Co-Authors: Barkan Ugurlu, Jody A. Saglia, Nikos G. Tsagarakis, Darwin G. CaldwellAbstract:This paper is aimed at describing a technique to compensate undesired yaw moment, which is inevitably induced about the support foot during single support phases while a bipedal robot is in motion. The main strategy in this method is to rotate the upper body in a way to exert a secondary moment that counteracts to the factors which create the undesired moment. In order to compute the yaw moment by considering all the factors, we utilized Eulerian ZMP Resolution, as it is capable of characterizing the robot's rotational inertia, a crucial component of its dynamics. In doing so, Intrinsic Angular Momentum rate changes are smoothly included in yaw moment equations. Applying the proposed technique, we conducted several bipedal walking experiments using the actual bipedal robot CoMan. As the result, we obtained 61% decrease in undesired yaw moment and 82% regulation in yaw-axis deviation, which satisfactorily verify the efficiency of the proposed approach, in comparison to off-the-shelf techniques.
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Bipedal Trajectory Generation Based on Combining Inertial Forces and Intrinsic Angular Momentum Rate Changes: Eulerian ZMP Resolution
IEEE Transactions on Robotics, 2012Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This paper aims to present a technique to generate feasible and dynamically equilibrated ZMP-based center of mass trajectories that can be applied to bipedal robots. In this regard, we utilize the ZMP concept in the spherical coordinate frame so that we can fully exploit its properties as this strategy enables us to efficiently combine Intrinsic Angular Momentum rate change terms with inertial force terms. That being said, this strategy has certain advantages: 1) In the case of bipedal walking, undesired torso angle fluctuations are more restrainable compared with other methods, in which Angular Momentum information is omitted or zero-referenced. 2) Composite rigid body inertia, which is a multibody property of robot dynamics, can be characterized during the trajectory generation task. Thus, relatively more dynamically consistent trajectories may be obtained. 3) The motion interference between the sagittal and lateral planes is naturally included. In this paper, we mainly investigate the first two advantages. Applying the method described above, we conducted bipedal walking experiments on our actual bipedal robot MARI-3. As the result, we obtained repetitive, continuous, and dynamically equilibrated walking cycles, in which undesired torso angles were well suppressed. Furthermore, ZMP error tends to decrease since inertial parameters of the robot are characterized. In conclusion, the method is validated to be efficient in inducing less ZMP error and in suppressing undesired torso angle variations, compared with both flywheel-superimposed and conventional ZMP-based trajectory generation methods.
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eulerian zmp resolution based bipedal walking discussions on the Intrinsic Angular Momentum rate change about center of mass
International Conference on Robotics and Automation, 2010Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This paper is aimed at implementing Eulerian ZMP Resolution method to bipedal walking pattern generation. The main strategy in this method is to ensure the dynamic balance by generating feasible ZMP-based CoM trajectories. For this purpose, we employ ZMP equations in spherical coordinates, so that the Intrinsic Angular Momentum rate change about center of mass is included explicitly in a natural way. This fact results in two merits: 1) Undesired torso angle fluctuation and body twists are expected to be more restrainable comparing to other methods in which Intrinsic Angular Momentum information is ignored or zero-referenced. 2) The interference between motions in sagittal and lateral planes can be extracted. In this article, we mainly investigate the first merit and briefly discuss about the second merit. Applying the aforementioned technique, Eulerian ZMP Resolution, we simulated bipedal walking on a 3-D dynamic simulator. Secondarily, we conducted bipedal walking experiments on the actual bipedal robot. In conclusion, we obtained dynamically equilibrated bipedal walking cycles, which satisfactorily verify the efficiency of Eulerian ZMP Resolution technique over conventional methods.
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ICRA - Eulerian ZMP resolution based bipedal walking: Discussions on the Intrinsic Angular Momentum rate change about center of mass
2010 IEEE International Conference on Robotics and Automation, 2010Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This paper is aimed at implementing Eulerian ZMP Resolution method to bipedal walking pattern generation. The main strategy in this method is to ensure the dynamic balance by generating feasible ZMP-based CoM trajectories. For this purpose, we employ ZMP equations in spherical coordinates, so that the Intrinsic Angular Momentum rate change about center of mass is included explicitly in a natural way. This fact results in two merits: 1) Undesired torso angle fluctuation and body twists are expected to be more restrainable comparing to other methods in which Intrinsic Angular Momentum information is ignored or zero-referenced. 2) The interference between motions in sagittal and lateral planes can be extracted. In this article, we mainly investigate the first merit and briefly discuss about the second merit. Applying the aforementioned technique, Eulerian ZMP Resolution, we simulated bipedal walking on a 3-D dynamic simulator. Secondarily, we conducted bipedal walking experiments on the actual bipedal robot. In conclusion, we obtained dynamically equilibrated bipedal walking cycles, which satisfactorily verify the efficiency of Eulerian ZMP Resolution technique over conventional methods.
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Humanoids - Bipedal walking trajectory generation based on ZMP and Euler's equations of motion
2010 10th IEEE-RAS International Conference on Humanoid Robots, 2010Co-Authors: Barkan Ugurlu, Atsuo KawamuraAbstract:This article is aimed at presenting a technique to generate bipedal walking trajectories that can be applied to humanoid robots. The proposed method is based on maintatining the dynamic balance by using the ZMP criterion throughout single support phases. To be able to reach this goal, we employed ZMP equations in spherical coordinates, so that the rate change of Intrinsic Angular Momentum terms in ZMP equations are included naturally by using Euler's equations of motion. Thus, undesired torso angle fluctuations are successfully suppressed comparing to other methods in which Intrinsic Angular Momentum rate changes are ignored or zero-referenced. Applying the aforementioned technique, we firstly performed simulations on a 3-D dynamic simulator. Upon simulations, we conducted walking experiments on the actual robot MARI-3. In conclusion, we obtained dynamically equilibrated and bipedal walking cycles in which torso angles are well suppressed in comparison with the conventional approach.
Osvaldo M. Moreschi - One of the best experts on this subject based on the ideXlab platform.
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Angular Momentum in general relativity and the supertranslation problem
2015Co-Authors: Emanuel Gallo, Osvaldo M. MoreschiAbstract:We review the notion of total quantities based on the notion of charge integrals. We provide with a new definition of Intrinsic Angular Momentum free from supertranslation ambiguities that agrees with the Komar integral for the case of axial symmetry.
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Intrinsic Angular Momentum for radiating spacetimes which agrees with the Komar integral in the axisymmetric case
Physical Review D, 2014Co-Authors: Emanuel Gallo, Osvaldo M. MoreschiAbstract:Fil: Gallo, Emanuel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Fisica Enrique Gaviola. Universidad Nacional de Cordoba. Instituto de Fisica Enrique Gaviola; Argentina
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Intrinsic Angular Momentum in general relativity
arXiv: General Relativity and Quantum Cosmology, 2004Co-Authors: Osvaldo M. MoreschiAbstract:There are several definitions of the notion of Angular Momentum in general relativity. However non of them can be said to capture the physical notion of Intrinsic Angular Momentum of the sources in the presence of gravitational radiation. We present a definition which is appropriate for the description of Intrinsic Angular Momentum in radiative spacetimes. This notion is required in calculations involving radiation of Angular Momentum, as for example is expected in binary coalescence of black holes.
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Intrinsic Angular Momentum and centre of mass in general relativity
Classical and Quantum Gravity, 2004Co-Authors: Osvaldo M. MoreschiAbstract:There are several definitions in the literature of the notion of total Angular Momentum in general relativity. However, none of them can be said to capture the physical notion of Intrinsic Angular Momentum of the sources in the presence of gravitational radiation. We present a definition of Angular Momentum for radiative spacetimes which does not suffer from any ambiguity of supertranslations. We have succeeded in providing an appropriate notion of Intrinsic Angular Momentum and, at the same time, a definition of centre of mass frame at future null infinity. This notion is required in calculations involving radiation of Angular Momentum, as, for example, is expected in binary coalescence of black holes.
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Unambiguous Angular Momentum of radiative spacetimes and asymptotic structure in terms of the center of mass system
arXiv: General Relativity and Quantum Cosmology, 2003Co-Authors: Osvaldo M. MoreschiAbstract:We present a definition of Angular Momentum for radiative spacetimes which does not suffer from any ambiguity of supertranslations. We succeed in providing an appropriate notion of {\it Intrinsic} Angular Momentum; and at the same time a definition of center of mass frame at future null infinity. We use the center of mass frame to present the asymptotic structure equations for vacuum spacetimes.
Stephen M. Barnett - One of the best experts on this subject based on the ideXlab platform.
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Quasi-Intrinsic Angular Momentum
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007Co-Authors: Roberta Zambrini, Stephen M. BarnettAbstract:In this work we pointed out that the orbital AM has an intermediate and distinct character between Intrinsic and extrinsic, it is quasi-Intrinsic. We propose a device to measure directly the variance as well as the Angular spectrum of any optical field. This device consists of an interferometer with a pair of Dove prisms (DP) in its arms, azimuthally rotated to a relative angle thetas, and a pi/2 phase plate (PP). The novelty of this device, when compared to holographic measurements, lies in the fact that the measurement spans the angle space and provides the exact OAM spectrum -via a Fourier transform-for any spatial profile of the input beam. A second important use of this interferometer is to access directly the variance V, by measuring M(thetas) for small angles, with limited experimental effort.
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Quasi-Intrinsic Angular Momentum and the measurement of its spectrum.
Physical review letters, 2006Co-Authors: Roberta Zambrini, Stephen M. BarnettAbstract:We introduce the concept of quasi-Intrinsic Angular Momentum to denote fields for which the mean value of the Angular Momentum is unaltered by a lateral shift of the rotation axis but the spectrum changes. This property is exemplified by the orbital Angular Momentum of a beam of light about its propagation direction. We propose an interferometric experiment to measure efficiently the exact Angular Momentum spectrum and variance for light beams with any arbitrary spatial distribution.
Roberta Zambrini - One of the best experts on this subject based on the ideXlab platform.
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Quasi-Intrinsic Angular Momentum
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007Co-Authors: Roberta Zambrini, Stephen M. BarnettAbstract:In this work we pointed out that the orbital AM has an intermediate and distinct character between Intrinsic and extrinsic, it is quasi-Intrinsic. We propose a device to measure directly the variance as well as the Angular spectrum of any optical field. This device consists of an interferometer with a pair of Dove prisms (DP) in its arms, azimuthally rotated to a relative angle thetas, and a pi/2 phase plate (PP). The novelty of this device, when compared to holographic measurements, lies in the fact that the measurement spans the angle space and provides the exact OAM spectrum -via a Fourier transform-for any spatial profile of the input beam. A second important use of this interferometer is to access directly the variance V, by measuring M(thetas) for small angles, with limited experimental effort.
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Quasi-Intrinsic Angular Momentum and the measurement of its spectrum.
Physical review letters, 2006Co-Authors: Roberta Zambrini, Stephen M. BarnettAbstract:We introduce the concept of quasi-Intrinsic Angular Momentum to denote fields for which the mean value of the Angular Momentum is unaltered by a lateral shift of the rotation axis but the spectrum changes. This property is exemplified by the orbital Angular Momentum of a beam of light about its propagation direction. We propose an interferometric experiment to measure efficiently the exact Angular Momentum spectrum and variance for light beams with any arbitrary spatial distribution.
