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18288
15/01/2019

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

Manifestation avec acte : IEEE/SICE International Symposium on System Integration ( SII ) 2019 du 14 janvier au 16 janvier 2019, Paris (France), Janvier 2019, 6p. , N° 18288

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.

145395
18101
01/01/2019

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, Vol.281, N°310, Janvier 2019 , N° 18101

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

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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

144064
17381
27/11/2018

2PAC: Two point attractors for center of mass trajectories in multi contact scenarios

S.TONNEAU, A.DEL PRETE, J.PETTRE, N.MANSARD

GEPETTO, IRISA

Revue Scientifique : ACM Transactions on Graphics, Vol.37, N°5, 176p., Novembre 2018 , N° 17381

Lien : https://hal.archives-ouvertes.fr/hal-01609055

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Synthesizing motions for legged characters in arbitrary environments is a long-standing problem that has recently received a lot of attention from the computer graphics community. We tackle this problem with a procedural approach that is generic, fully automatic and independent from motion capture data. The main contribution of this paper is a point-mass-model-based method to synthesize Center Of Mass trajectories. These trajectories are then used to generate the whole-body motion of the character. The use of a point mass model often results in physically inconsistent motions and joint limit violations. We mitigate these issues through the use of a novel formulation of the kinematic constraints which allows us to generate a quasi-static Center Of Mass trajectory, in a way that is both user-friendly and computationally efficient. We also show that the quasi-static constraint can be relaxed to generate motions usable for applications of computer graphics (on average 83% of a given trajectory remain physically consistent). Our method was integrated in our open-source contact planner and tested with different scenarios-some never addressed before-featuring legged characters performing non-gaited motions in cluttered environments. The computational efficiency of our trajectory generation algorithm (under ten ms to compute one second of motion) enables us to synthesize motions in a few seconds, one order of magnitude faster than state-of-the-art methods.

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18263
23/11/2018

A Study on Force-based Collaboration in Flying Swarms

C.GABELLIERI, M.TOGNON, L.PALLOTTINO, A.FRANCHI

RIS, Pise

Manifestation avec acte : International Conference on Swarm Intelligence ( ANTS ) 2018 du 29 octobre au 31 octobre 2018, Rome (Italie), Novembre 2018, 13p. , N° 18263

Lien : https://hal.laas.fr/hal-01846465

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Abstract

This work investigates collaborative aerial transportation by swarms of agents based only on implicit information, enabled by the physical interaction among the agents and the environment. Such a coordinating mechanism in collaborative transportation is a basic skill in groups of social animals. We consider cable-suspended objects transported by a swarm of flying robots and we formulate several hypothesis on the behavior of the overall system which are validated thorough numerical study. In particular, we show that a nonzero internal force reduces to one the number of asymptotically stable equilibria and that the internal force intensity is directly connected to the convergence rate. As such, the internal force represents the cornerstone of a communication-less cooperative manipulation paradigm in swarms of flying robots. We also show how a swarm can achieve a stable transportation despite the imprecise knowledge of the system parameters.

145258
18353
19/11/2018

A Truly Redundant Aerial Manipulator System with Application to Push-and-Slide Inspection in Industrial Plants

M.TOGNON, H.TELLO CHAVEZ, E.GASPARIN, Q.SABLE, D.BICEGO, A.MALLET, M.LANY, G.SANTI, B.REVAZ, J.CORTES, A.FRANCHI

RIS, Sensima Inspection, IDEA

Rapport LAAS N°18353, Novembre 2018, 9p.

Lien : https://hal.laas.fr/hal-01910343

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Abstract

We present the design, control and motion planning of an aerial manipulator for a non-trivial physical interaction task, namely pushing while sliding on curved surfaces. The proposed robotic system is motivated by the increasing interest on autonomous Non-Destructive Tests used for the integrity assessment of industrial plants. The proposed aerial manipulator consists of a multidirectional-thrust aerial vehicle to enhance physical interaction capabilities, endowed with a 2-DoFs lightweight arm to enlarge its workspace. This combination constitutes a truly redundant manipulator that goes beyond standard aerial manipulators with collinear multirotors. The robot controller is based on a PID method with 'displaced' positional part inspired by controllers for manipulators with elastic joints and grounded on several experimental trial-and-error tests. In this work we experimentally show that the proposed aerial manipulator system, equipped with an Eddy Current probe, is able to scan a metallic pipe sliding the sensor over its surface and preserving the contact. From the acquired data, a weld on the pipe is successfully detected and mapped.

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18345
09/11/2018

Cross-cultural (France and Japan) and Multidisciplinary Discussion on Artificial Intelligence and Robotics: Tendencies and Research Prospects

N.ABE

GEPETTO

Rapport LAAS N°18345, Novembre 2018, 24p.

Lien : https://halshs.archives-ouvertes.fr/halshs-01907840

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Abstract

Artificial Intelligence (AI) is rapidly developing through a “Deep Learning model” that is based on a neural network and more powerful learning system than a traditional algorithm system. Our society is facing rapid technological changes that could lead to dramatic social impact in the economic, societal, educational and ethical landscape. In this context, the importance of multidisciplinary discussion and research in the field of Intelligent Systems (AI and Robot) is increasingly recognized. The present discussion paper aims to summarize the current state and research on Intelligent Systems and social impact and proposes multidisciplinary projects covering both engineering and social science studies. It presents three promising research topics that can provide us with a better understanding of Intelligent Systems and our attitude or relationship towards the technology: 1) international and national (France and Japan) initiatives with regard to the social impact of AI, 2) trust and acceptability in Intelligent Systems, and 3) Human-Machine Interaction.

Résumé

L'intelligence artificielle (IA) se développe rapidement grâce au « Deep learning », un modèle d'apprentissage automatique basé sur un réseau neuronal qui est plus puissant qu'un système algorithmique traditionnel. Notre société est confrontée à des changements technologiques rapides qui pourraient avoir un impact social dramatique dans les paysages économique, sociétal, éducatif et éthique. Dans ce contexte, l'importance de la discussion et de la recherche multidisciplinaires dans le domaine des systèmes intelligents (IA et robot) est de plus en plus reconnue. Le présent document vise à récapituler l'état actuel de la recherche sur les systèmes intelligents et leur impact social et à proposer des projets multidisciplinaires couvrant à la fois les études en ingénierie et en sciences sociales. Il présente trois thèmes de recherche prometteurs qui peuvent nous permettre de mieux comprendre les systèmes intelligents et notre attitude ou notre relation vis-à-vis de la technologie : 1) les initiatives internationales et nationales (France et Japon) concernant l'impact social de l'IA, 2) la confiance et l'acceptabilité des systèmes intelligents et 3) l'interaction homme-machine.

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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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18330
26/10/2018

C-CROC: Continuous and Convex Resolution of Centroidal dynamic trajectories for legged robots in multi-contact scenarios

P.FERNBACH, S.TONNEAU, O.STASSE, J.CARPENTIER, M.TAIX

GEPETTO

Rapport LAAS N°18330, Octobre 2018, 16p.

Lien : https://hal.laas.fr/hal-01894869

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Abstract

Synthesizing legged locomotion requires planning one or several steps ahead (literally): when and where, and with which effector should the next contact(s) be created between the robot and the environment? Validating a contact candidate implies \textit{a minima} the resolution of a slow, non-linear optimization problem, to demonstrate that a Center Of Mass (COM) trajectory, compatible with the contact transition constraints, exists. We propose a conservative reformulation of this trajectory generation problem as a convex 3D linear program, CROC. It results from the observation that if the COM trajectory is a polynomial with only one free variable coefficient, the non-linearity of the problem disappears. This has two consequences. On the positive side, in terms of computation times CROC outperforms the state of the art by at least one order of magnitude, and allows to consider interactive applications (with a planning time roughly equal to the motion time). On the negative side, in our experiments our approach finds a majority of the feasible trajectories found by a non-linear solver, but not all of them. Still, we demonstrate that the solution space covered by CROC is large enough to achieve the automated planning of a large variety of locomotion tasks for different robots, demonstrated in simulation and on the real HRP-2 robot, several of which were rarely seen before. Another significant contribution is the introduction of a Bezier curve representation of the problem, which guarantees that the constraints of the COM trajectory are verified continuously, and not only at discrete points as traditionally done. This formulation is lossless, and results in more robust trajectories. It is not restricted to CROC, but could rather be integrated with any method from the state of the art.

144942
18334
26/10/2018

Hyper-parameter optimization tools comparison for Multiple Object Tracking applications

J.MADRIGAL DIAZ, C.MAURICE, F.LERASLE

RAP

Revue Scientifique : Machine Vision and Applications, 16p., Octobre 2018, doi 10.1007/s00138-018-0984-1 , N° 18334

Lien : https://hal.archives-ouvertes.fr/hal-01897032

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Abstract

Commonly, when developing an algorithm it is necessary to define a certain number of variables that control its behavior. Optimal parameters result in better performance that could translate into profits for companies, stand out among similar applications or better ranking on algorithm competitions. However, it is not a simple task to find the combination of parameters that provides the best results. Manual tuning could be a stressful and difficult task even for expert users. In this paper we present, evaluate and compare several tools in the literature for hyper-parameter optimization. We focus on 4 tools that have been selected due to their number of citations, code availability and impact on literature: MCMC, SMAC, TPE and Spearmint. We analyze these tools in the context of Multi Object Tracking (MOT) that have not been well studied in the literature. MOT itself has been well-studied topic with multiple parameters to be tuned. We evaluate these tools using public benchmarks such as PETS09 or ETH and using the publicly available source code provided by the authors. We analyze the impact of these tools in terms of stability, performance, and usabil-ity, among others. Our results show how the use of these tools change the performance of the application and how this would affect the results of real ranked competitions. Our goal is (1) to encourage the reader to use these tools and (2) to provide a guide that helps to choose the most pertinent tool.

144949
18324
24/10/2018

Exhaustive exploration of the conformational landscape of small cyclic peptides using a robotics approach

M.JUSOT, D.STRATMANN, M.VAISSET, J.CHOMILIER, J.CORTES

RIS, IMPMC, IDEA

Revue Scientifique : Journal of Chemical Information and Modeling, 42p., Octobre 2018, DOI: 10.1021/acs.jcim.8b00375 , N° 18324

Lien : https://hal.laas.fr/hal-01893751

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Abstract

Small cyclic peptides represent a promising class of therapeutic molecules with unique chemical properties. However, the poor knowledge of their structural characteristics makes their computational design and structure prediction a real challenge. In order to better describe their conformational space, we developed a method, named EGSCyP, for the exhaustive exploration of the energy landscape of small head-to-tail cyclic peptides. The method can be summarized by (i) a global exploration of the conformational space based on a mechanistic representation of the peptide and the use of robotics-based algorithms to deal with the closure constraint, (ii) an all-atom refinement of the obtained conformations. EGSCyP can handle D-form residues and N-methylations. Two strategies for the side-chains placement were implemented and compared. To validate our approach, we applied it to a set of three variants of cyclic RGDFV pentapeptides, including the drug candidate Cilengitide. A comparative 1 analysis was made with respect to replica exchange molecular dynamics simulations in implicit solvent. It results that the EGSCyP method provides a very complete characterization of the conformational space of small cyclic pentapeptides.

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