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16374
01/02/2017

Small-angle scattering studies of intrinsically disordered proteins and their complexes

T.CORDEIRO, F.HERRANZ TRILLO, A.URBANEK, A.ESTANA, J.CORTES, N.SIBILLE, P.BERNADO

CBS, RIS

Revue Scientifique : Current Opinion in Structural Biology, Vol.42, pp.15-23, Février 2017 , N° 16374

Lien : https://hal.laas.fr/hal-01391541

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Abstract

Intrinsically Disordered Proteins (IDPs) perform a broad range of biological functions. Their relevance has motivated intense research activity seeking to characterize their sequence/structure/function relationships. However, the conformational plasticity of these molecules hampers the application of traditional structural approaches, and new tools and concepts are being developed to address the challenges they pose. Small-Angle Scattering (SAS) is a structural biology technique that probes the size and shape of disordered proteins and their complexes with other biomolecules. The low-resolution nature of SAS can be compensated with specially designed computational tools and its combined interpretation with complementary structural information. In this review, we describe recent advances in the application of SAS to disordered proteins and highly flexible complexes and discuss current challenges.

138033
15520
24/01/2017

Classification of outdoor 3D lidar data based on unsupervised Gaussian mixture models

A.O.MALIGO, S.LACROIX

RIS

Revue Scientifique : IEEE Transactions on Automation Science and Engineering, Vol.14, N°1, pp.5-16, Janvier 2017 , N° 15520

Lien : https://hal.archives-ouvertes.fr/hal-01232096

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3D point clouds acquired with lidars are an important source of data for the classification of outdoor environments by autonomous terrestrial robots. We propose here a two-layer classification system. The first layer consists of a Gaussian mixture model, issued from unsupervised training, which defines a large set of data-oriented classes. The second layer consists of a supervised, manual grouping of the unsupervised classes into a smaller set of task-oriented classes. Because it uses unsupervised learning at its core, the system does not require any manual labeling of datasets. We evaluate the system on two datasets of different nature, and the results show its capacity to adapt to different data while providing classes which are exploitable in a target task.

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16305
18/12/2016

Combining system design and path planning

L.DENARIE, K.MOLLOY, M.VAISSET, T.SIMEON, J.CORTES

RIS, IDEA

Manifestation avec acte : International Workshop on the Algorithmic Foundations of Robotics ( WAFR ) 2016 du 18 décembre au 20 décembre 2016, San Francisco (USA), Décembre 2016, 16p. , N° 16305

Lien : https://hal.inria.fr/hal-01364042

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Abstract

This paper addresses the simultaneous design and path planning problem, in which features associated to the bodies of a mobile system have to be selected to find the best design that optimizes its motion between two given configurations. Solving individual path planning problems for all possible designs and selecting the best result would be a straightforward approach for very simple cases. We propose a more efficient approach that combines discrete (design) and continuous (path) optimization in a single stage. It builds on an extension of a sampling-based algorithm, which simultaneously explores the configuration-space costmap of all possible designs aiming to find the best path-design pair. The algorithm filters out unsuitable designs during the path search, which breaks down the combinatorial explosion. Illustrative results are presented for relatively simple (academic) examples. While our work is currently motivated by problems in computational biology, several applications in robotics can also be envisioned.

138509
16306
12/12/2016

Bearing rigidity theory in SE(3)

G.MICHIELETTO, A.CANEDESE, A.FRANCHI

RIS, University of Padova

Manifestation avec acte : IEEE Conference on Decision and Control ( CDC ) 2016 du 12 décembre au 14 décembre 2016, Las Vegas (USA), Décembre 2016, 6p. , N° 16306

Lien : https://hal.archives-ouvertes.fr/hal-01371084

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Abstract

Rigidity theory has recently emerged as an efficient tool in the control field of coordinated multi-agent systems, such as multi-robot formations and UAVs swarms, that are characterized by sensing, communication and movement capabilities. This work aims at describing the rigidity properties for frameworks embedded in the three-dimensional Special Euclidean space SE(3) wherein each agent has 6DoF. In such scenario, it is assumed that the devices are able to gather bearing measurements w.r.t. their neighbors, expressing them into their own body frame. The goal is then to identify the framework transformations that allow to preserve such measurements maintaining it rigid. Rigidity properties are mathematically formalized in this work which differs from the previous ones as it faces the extension in three-dimensional space dealing with the 3D rotations manifold. In particular, the attention is focused on the infinitesimal SE(3)-rigidity for which a necessary and sufficient condition is provided.

138507
16444
02/12/2016

Temporal and hierarchical models for planning and acting in robotics

A.BIT-MONNOT

RIS

Doctorat : INP de Toulouse, 2 Décembre 2016, 199p., Président: R.ALAMI, Rapporteurs: J.HERTZBERG, F.PECORA, Examinateurs: A.CESTA, C.PRALET, D.E.SMITH, Directeurs de thèse: M.GHALLAB, F.INGRAND , N° 16444

Lien : https://hal.laas.fr/tel-01444926

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Abstract

The field of AI planning has seen rapid progress over the last decade and planners are now able to find plans with hundreds of actions in a matter of seconds. Despite those important progresses, robotic systems still tend to have a reactive architecture with very little deliberation on the course of the plan they might follow. In this thesis, we argue that a successful integration with a robotic system requires the planner to have capacities for both temporal and hierarchical reasoning. The former is indeed a universal resource central in many robot activities while the latter is a critical component for the integration of reasoning capabilities at different abstraction levels, typically starting with a high level view of an activity that is iteratively refined down to motion primitives. As a first step to carry out this vision, we present a model for temporal planning unifying the generative and hierarchical approaches. At the center of the model are temporal action templates complemented with a specification of the initial state as well as the expected evolution of the environment over time. In addition, our model allows for the specification of hierarchical knowledge possibly with a partial coverage. Consequently, our model generalizes the existing generative and hierarchical approaches together with an explicit time representation. In the subsequent chapter, we introduce a planning procedure suitable for our planning model. In order to support hierarchical features, we extend the existing Partial-Order Causal Link approach used in many constraint-based planners, with the notions of task and decomposition. We implement it in FAPE (Flexible Acting and Planning Environment) together with automated problem analysis techniques used for search guidance. We show FAPE to have performance similar to state of the art temporal planners when used in a generative setting, and the addition of hierarchical information to lead to further performance gain. Next, we study the usual methods used to reason on temporal uncertainty while planning. We relax the usual assumption of total observability and instead provide techniques to reason on the observations needed to maintain a plan dispatchable. We show how such needed observations can be detected at planning time and incrementally dealt with by considering the appropriate sensing actions. In a final chapter, we discuss the place of the proposed planning system as a central component for the control of a robotic actor. We demonstrate how the explicit time representation facilitates plan monitoring and action dispatching when dealing with contingent events that require observation. We take advantage of the constraint-based and hierarchical representation to facilitate both plan-repair procedures as well opportunistic plan refinement at acting time.

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16202
11/11/2016

Model checking real-time properties on the functional layer of autonomous robots

M.FOUGHALI, B.BERTHOMIEU, S.DAL ZILIO, F.INGRAND, A.MALLET

RIS, VERTICS, IDEA

Manifestation avec acte : International Conference on Formal Engineering Methods ( ICFEM ) 2016 du 11 novembre au 14 novembre 2016, Tokyo (Japon), Novembre 2016, 16p. , N° 16202

Lien : https://hal.archives-ouvertes.fr/hal-01346080

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Abstract

Software is an essential part of robotic systems. As robots and autonomous systems are more and more deployed in human environments, we need to use elaborate validation and verification techniques in order to gain a higher level of trust in our systems. This motivates our determination to apply formal verification methods to robotics software. In this paper, we describe our results obtained using model-checking on the functional layer of an autonomous robot. We implement an automatic translation from GenoM, a robotics model-based software engineering framework, to the formal specification language Fiacre. This translation takes into account the semantics of the robotics middleware. TINA, our model-checking toolbox, can be used on the synthesized models to prove real-time properties of the functional modules implementation on the robot. We illustrate our approach using a realistic autonomous navigation example.

138502
16421
08/11/2016

PVTOL aerial manipulators with a rigid or an elastic joint: analysis, control, and comparison

B.YUKSEL, A.FRANCHI

MPI, RIS

Rapport LAAS N°16421, Novembre 2016, 20p.

Lien : https://hal.archives-ouvertes.fr/hal-01388462

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In this paper we present the dynamic Lagrangian modeling, system analysis, and nonlinear control of a robot constituted by a planar-vtol (PVTOL) underactuated aerial vehicle equipped with a rigid-or an elastic-joint arm, which constitutes an aerial manipulator. For the design of the aerial manipulator, we first consider generic offsets between the center of mass (CoM) of the PVTOL, and the attachment point of the joint-arm. Later we consider a model in which these two points are the coinciding. It turns out to be that the choice of this attachment point is significantly affecting the capabilities of the platform. Furthermore, in both cases we consider the rigid-and elastic-joint arm configurations. For each of the resulting four cases we formally assess the presence of exact linearizing and differentially flat outputs and the possibility of using the dynamic feedback linearization (DFL) controller. Later we formalize an optimal control problem exploiting the differential flatness property of the systems, which is applied, as an illustrative example, to the aerial throwing task. Finally we provide extensive and realistic simulation results for comparisons between different robot models in different robotic tasks such as aerial grasping and aerial throwing, and a discussion on the applicability of computationally simpler controllers for the coinciding-point models to generic-point ones. Further exhaustive simulations on the trajectory tracking and the high-speed arm swinging capabilities are provided in a technical attachment.

138309
16223
09/10/2016

Takeoff and landing on slopes via inclined hovering with a tethered aerial robot

M.TOGNON, A.TESTA, E.ROSSI, A.FRANCHI

RIS, UNISALENTO

Manifestation avec acte : IEEE/RSJ International Conference on Intelligent Robots and Systems ( IROS ) 2016 du 09 octobre au 14 octobre 2016, Daejeon (Corée), Octobre 2016, 6p. , N° 16223

Lien : https://hal.archives-ouvertes.fr/hal-01350883

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In this paper we face the challenging problem of takeoff and landing on sloped surfaces for a VTOL aerial vehicle. We define the general conditions for a safe and robust maneuver and we analyze and compare two classes of methods to fulfill these conditions: free-flight vs. passively-tethered. Focusing on the less studied tethered method, we show its advantages w.r.t. the free-flight method thanks to the possibility of inclined hovering equilibria. We prove that the tether configuration and the inclination of the aerial vehicle w.r.t. the slope are flat outputs of the system and we design a hierarchical nonlinear controller based on this property. We then show how this controller can be used to land and takeoff in a robust way without the need of either a planner or a perfect tracking. The validity and applicability of the method in the real world is shown by experiments with a quadrotor that is able to perform a safe landing and takeoff on a sloped surface.

138494
16204
09/10/2016

Cooperative aerial tele-manipulation with haptic feedback

M.MOHAMMADI, A.FRANCHI, D.BARCELLI, D.PRATTICHIZZO

IIT, Genova, RIS

Manifestation avec acte : IEEE/RSJ International Conference on Intelligent Robots and Systems ( IROS ) 2016 du 09 octobre au 14 octobre 2016, Daejeon (Corée), Octobre 2016, 7p. , N° 16204

Lien : https://hal.archives-ouvertes.fr/hal-01348539

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Abstract

In this paper, we propose a bilateral tele-operation scheme for cooperative aerial manipulation in which a human operator drives a team of Vertical TakeOff and Landing (VTOL) aerial vehicles, that grasped an object beforehand, and receives a force feedback depending on the states of the system. For application scenarios in which dexterous manipulation by each robot is not necessary, we propose using a rigid tool attached to the vehicle through a passive spherical joint, equipped with a simple adhesive mechanism at the tool-tip that can stick to the grasped object. Having more than two robots, we use the extra degrees of freedom to find the optimal force allocation in term of minimum power and forces smoothness. The human operator commands a desired trajectory for the robot team through a haptic interface to a pose controller, and the output of the pose controller along with system constraints, e.g., VTOL limited forces and contact maintenance, defines the feasible set of forces. Then, an on-line optimization allocates forces by minimizing a cost function of forces and their variation. Finally, propeller thrusts are computed by a dedicated attitude and thrust controller in a decentralized fashion. Human/Hardware in the loop simulation study shows efficiency of the proposed scheme, and the importance of haptic feedback to achieve a better performance.

138496
16203
09/10/2016

A rigidity-based decentralized bearing formation controller for groups of quadrotor UAVs

F.SCHIANO, A.FRANCHI, D.ZELAZO, P.ROBUFFO-GIORDANO

INRIA Rennes, RIS, TECHNION

Manifestation avec acte : IEEE/RSJ International Conference on Intelligent Robots and Systems ( IROS ) 2016 du 09 octobre au 14 octobre 2016, Daejeon (Corée), Octobre 2016, 8p. , N° 16203

Lien : https://hal.archives-ouvertes.fr/hal-01348543

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Abstract

This paper considers the problem of controlling a formation of quadrotor UAVs equipped with onboard cameras able to measure relative bearings in their local body frames w.r.t. neighboring UAVs. The control goal is twofold: (i) steering the agent group towards a formation defined in terms of desired bearings, and (ii) actuating the group motions in the 'null-space' of the current bearing formation. The proposed control strategy relies on an extension of the rigidity theory to the case of directed bearing frameworks in R^3 × S^1. This extension allows to devise a decentralized bearing controller which, unlike most of the present literature, does not need presence of a common reference frame or of reciprocal bearing measurements for the agents. Simulation and experimental results are then presented for illustrating and validating the approach.

138498
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