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412documents trouvés

18278
01/11/2018

Motion Planning in Irreducible Path Spaces

A.ORTHEY, O.ROUSSEL, O.STASSE, M.TAIX

AIST, GEPETTO

Revue Scientifique : Robotics and Autonomous Systems, Vol.109, pp.97-108, Novembre 2018 , N° 18278

Lien : https://hal.archives-ouvertes.fr/hal-01873197

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Abstract

The motion of a mechanical system can be defined as a path through its configuration space. Computing such a path has a computational complexity scaling exponentially with the dimensionality of the configuration space. We propose to reduce the dimensionality of the configuration space by introducing the irreducible path --- a path having a minimal swept volume. The paper consists of three parts: In part I, we define the space of all irreducible paths and show that planning a path in the irreducible path space preserves completeness of any motion planning algorithm. In part II, we construct an approximation to the irreducible path space of a serial kinematic chain under certain assumptions. In part III, we conduct motion planning using the irreducible path space for a mechanical snake in a turbine environment, for a mechanical octopus with eight arms in a pipe system and for the sideways motion of a humanoid robot moving through a room with doors and through a hole in a wall. We demonstrate that the concept of an irreducible path can be applied to any motion planning algorithm taking curvature constraints into account.

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18288
01/10/2018

The Pinocchio C++ library – A fast and flexible implementation of rigid body dynamics algorithms and their analytical derivatives

J.CARPENTIER, G.SAUREL, G.BUONDONNO, J.MIRABEL, F.LAMIRAUX, O.STASSE, N.MANSARD

GEPETTO

Rapport LAAS N°18288, Octobre 2018, 6p.

Lien : https://hal.laas.fr/hal-01866228

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Abstract

We introduce Pinocchio, an open-source software framework that implements rigid body dynamics algorithms and their analytical derivatives. Pinocchio does not only include standard algorithms employed in robotics (e.g. forward and inverse dynamics) but provides additional features essential for the control, the planning and the simulation of robots. In this paper, we describe these features and detail the programming patterns and design which make Pinocchio efficient. We also offer a short tutorial for easy handling of the framework.

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18101
01/10/2018

An overview of humanoid robots technologies

O.STASSE, T.FLAYOLS

GEPETTO

Ouvrage (contribution) : Biomechanics of Anthropomorphic Systems, Springer, N°ISBN 978-3-319-93870-7, Octobre 2018 , N° 18101

Lien : https://hal.laas.fr/hal-01759061

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Abstract

Humanoid robots are challenging mechatronics structures with several interesting features. Choosing a humanoid robot to develop applications or pursue research in a given direction might be difficult due to the strong interdependence of the technical aspects. This paper aims at giving a general description of this interdependence and highlight the lessons learned from the impressive works conducted in the past decade. The reader will find in the annex a table synthesizing the characteristics of the most relevant humanoid robots. Without focusing on a specific application we consider two main classes of humanoid robots: the ones dedicated to industrial application and the ones dedicated to human-robot interaction. The technical aspects are described in a way which illustrates the humanoid robots bridging the gap between these two classes. Finally this paper tries to make a synthesis on recent technological developments 1. 1 Mechanical structure 1.1 General design principal Humanoid robots are complex mechatronic systems. As such, it is necessary to consider the the mechanical structure, the computational system and the algorithms as a whole and for a given application. The robot's size, weight and strength are important factors when designing its structure. Let us consider two general classes of applications: physical performances while doing motion generation and validation of biological and/or cognitive models. The ATLAS robot from Boston Dynamics is an example of the first category, while the Kenshiro robot [45] from Tokyo University is an example of the second category

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18021
01/10/2018

Historical Perspective of Humanoid Robot Research in Europe

Y.AOUSTIN, C.CHEVALLEREAU, J.P.LAUMOND

LS2N, GEPETTO

Ouvrage (contribution) : Humanoid Robotics: A Reference, Springer, N°ISBN 978-94-007-6045-5, Octobre 2018 , N° 18021

Lien : https://hal.archives-ouvertes.fr/hal-01697135

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18286
01/10/2018

Dynamics Consensus between Centroidal and Whole-Body Models for Locomotion of Legged Robots

R.BUDHIRAJA, J.CARPENTIER, N.MANSARD

GEPETTO

Rapport LAAS N°18286, Octobre 2018, 7p.

Lien : https://hal.laas.fr/hal-01875031

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Abstract

It is nowadays well-established that locomotion can be written as a large and complex optimal control problem. Yet, current knowledge in numerical solver fails to directly solve it. A common approach is to cut the dimensionality by relying on reduced models (inverted pendulum, capture points, centroidal). However it is difficult both to account for whole-body constraints at the reduced level and also to define what is an acceptable trade-off at the whole-body level between tracking the reduced solution or searching for a new one. The main contribution of this paper is to introduce a rigorous mathematical framework based on the Alternating Direction Method of Multipliers, to enforce the consensus between the centroidal state dynamics at reduced and whole-body level. We propose an exact splitting of the whole-body optimal control problem between the centroidal dynamics (under-actuation) and the manipulator dynamics (full actuation), corresponding to a rearrangement of the equations already stated in previous works. We then describe with details how alternating descent is a good solution to implement an effective locomotion solver. We validate this approach in simulation with walking experiments on the HRP-2 robot.

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18247
07/09/2018

Differential Dynamic Programming for Multi-Phase Rigid Contact Dynamics

R.BUDHIRAJA, J.CARPENTIER, C.MASTALLI, N.MANSARD

GEPETTO

Rapport LAAS N°18247, Septembre 2018, 6p.

Lien : https://hal.archives-ouvertes.fr/hal-01851596

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Abstract

A common strategy today to generate efficient locomotion movements is to split the problem into two consecutive steps: the first one generates the contact sequence together with the centroidal trajectory, while the second one computes the whole-body trajectory that follows the centroidal pattern. Yet the second step is generally handled by a simple program such as an inverse kinematics solver. In contrast, we propose to compute the whole-body trajectory by using a local optimal control solver, namely Differential Dynamic Programming (DDP). Our method produces more efficient motions, with lower forces and smaller impacts, by exploiting the Angular Momentum (AM). With this aim, we propose an original DDP formulation exploiting the Karush-Kuhn-Tucker constraint of the rigid contact model. We experimentally show the importance of this approach by executing large steps walking on the real HRP-2 robot, and by solving the problem of attitude control under the absence of external forces.

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18233
24/08/2018

Whole-body musculo-skeletal model V1

G.MALDONADO, P.SOUERES, B.WATIER

GEPETTO

Rapport LAAS N°18233, Août 2018, 15p.

Lien : https://hal.archives-ouvertes.fr/hal-01841355

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Abstract

The main goal of this project was to build a basic musculo-skeletal model of the human body in order to be able of analyzing and simulating human motion. To this end, an OpenSim [4] musculo-skeletal model was modified and augmented based on previous works of the literature. The resulting model is also compatible with Pinocchio [3], an open source C++ library for efficient rigid multi-body dynamics computations based on revisited Roy Featherstone’s algorithms. This allows users for creating powerful simulations of whole-body human-based motions with anthropomorphic systems. Using Pinocchio with the model permits also to use state-of-the-art libraries written in C++ or python (e.g. from robotics, machine learning,...)

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18212
16/08/2018

Benchmarking the HRP-2 humanoid robot during locomotion

O.STASSE, K.GIRAUD ESCLASSE, E.BROUSSE, M.NAVEAU, R.REGNIER, G.AVRIN, P.SOUERES

GEPETTO, LNE, Max Planck

Rapport LAAS N°18212, Août 2018, 24p.

Lien : https://hal.archives-ouvertes.fr/hal-01832890

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Abstract

In this paper we report results from a campaign of measurement in a laboratory allowing to put a humanoid robot HRP-2 in a controlled environment. We have investigated the effect of temperature variations on the robot capabilities to walk. In order to benchmark various motions modalities and algorithms we computed a set of performance indicators for bipedal locomotion. The scope of the algorithms for motion generation evaluated here is rather large as it spans analytical solutions to numerical optimization approaches able to realize real-time walking or multi-contacts.

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18267
15/08/2018

On the coordination of highly dynamic human movements: an extension of the Uncontrolled Manifold approach applied to precision jump in parkour

G.MALDONADO, F.BAILLY, P.SOUERES, B.WATIER

GEPETTO

Revue Scientifique : Scientific Reports, Vol.8, N°1, Août 2018 , N° 18267

Lien : https://hal.archives-ouvertes.fr/hal-01863170

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Abstract

The human body generally has more degrees of freedom than necessary for generating a given movement. According to the motor abundance principle, this redundancy is beneficial as it provides the central nervous system with flexibility and robustness for the generation of movements. Under the hypothesis of the Uncontrolled Manifold, the additional degrees of freedom are used to produce motor solutions by reducing the variability that affects the motion performance across repetitions. In this paper, we present a general mathematical framework derived from robotics to formulate kinematic and dynamic tasks in human movement. On this basis, an extension of the Uncontrolled Manifold approach is introduced to deal with dynamic movements. This extension allows us to present a complex experimental application of the proposed framework to highly dynamic task variables in parkour movements. This experiment involves dynamic tasks expressed in terms of linear and angular momenta. The results show that the central nervous system is able to coordinate such skilled tasks which appear to be preferentially controlled and hierarchically organized. The proposed extension is promising for the study of motion generation in anthropomorphic systems and provides a formal description to investigate kinematics and dynamics tasks in human motions.

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17069
29/07/2018

Implementation, Identification and Control of an Efficient Electric Actuator for Humanoid Robots

F.FORGET, K.GIRAUD ESCLASSE, R.GELIN, N.MANSARD, O.STASSE

GEPETTO, Aldebaran

Manifestation avec acte : International Conference on Informatics in Control, Automation and Robotics ( ICINCO ) 2018 du 29 juillet au 31 juillet 2018, Porto (Portugal), Juillet 2018, 8p. , N° 17069

Lien : https://hal.archives-ouvertes.fr/hal-01494676

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Abstract

Autonomous robots such as legged robots and mobile manipulators imply new challenges in the design and the control of their actuators. In particular, it is desirable that the actuators are back-drivable, efficient (low friction) and compact. In this paper, we report the complete implementation of an advanced actuator based on screw, nut and cable. This actuator has been chosen for the humanoid robot Romeo. A similar model of the actuator has been used to control the humanoid robot Valkyrie. We expose the design of this actuator and present its Lagrangian model. The actuator being flexible, we propose a two-layer optimal control solver based on Differential Dynamical Programming. The actuator design, model identification and control is validated on a full actuator mounted in a work bench. The results show that this type of actuation is very suitable for legged robots and is a good candidate to replace strain wave gears.

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