Laboratoire d’analyse et d’architecture des systèmes
A.ORTHEY, O.ROUSSEL, O.STASSE, M.TAIX
Revue Scientifique : Robotics and Autonomous Systems, Vol.109, pp.97-108, Novembre 2018 , N° 18278
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.
C.MASONE, M.MOHAMMADI, P.R.GIORDANO, A.FRANCHI
Max Planck, IIT, Genova, INRIA Rennes, RIS
Revue Scientifique : International Journal of Robotics Research, 27p., Octobre 2018, doi 10.1177/0278364918802006 , N° 18304
This paper presents a novel bilateral shared framework for online trajectory generation for mobile robots. The robot navigates along a dynamic path, represented as a B-spline, whose parameters are jointly controlled by a human supervisor and by an autonomous algorithm. The human steers the reference (ideal) path by acting on the path parameters which are also affected, at the same time, by the autonomous algorithm in order to ensure: i) collision avoidance, ii) path regularity and iii) proximity to some points of interest. These goals are achieved by combining a gradient descent-like control action with an automatic algorithm that re-initializes the traveled path (replanning) in cluttered environments in order to mitigate the effects of local minima. The control actions of both the human and the autonomous algorithm are fused via a filter that preserves a set of local geometrical properties of the path in order to ease the tracking task of the mobile robot. The bilateral component of the interaction is implemented via a force feedback that accounts for both human and autonomous control actions along the whole path, thus providing information about the mismatch between the reference and traveled path in an integral sense. The proposed framework is validated by means of realistic simulations and actual experiments deploying a quadrotor UAV supervised by a human operator acting via a force-feedback haptic interface. Finally, a user study is presented in order to validate the effectiveness of the proposed framework and the usefulness of the provided force cues.
A.OLLERO, G.HEREDIA, A.FRANCHI, G.ANTONELLI, K.KONDAC, A.S.CORTES, A.VIGURIA, J.R.MARTINEZ-DE-DIOS, F.PIERRI, J.CORTES, A.SANTAMARIA-NAVARRO, M.A.TRUJILLO SOTO, R.BALACHANDRAN, J.ANDRADE-CETTO, A.RODRIGUEZ CASTANO
Seville, RIS, UNICAS, DLR, UPC, CATEC, University of Basilicata, IRI, UPC/CSIC
Revue Scientifique : IEEE Robotics and Automation Magazine, 9p., Octobre 2018, DOI: 10.1109/MRA.2018.2852789 , N° 18297
This paper summarizes new aerial robotic manipulation technologies and methods, required for outdoor industrial inspection and maintenance, developed in the AEROARMS project. It presents aerial robotic manipulators with dual arms and multi-directional thrusters. It deals with the control systems, including the control of the interaction forces and the compliance, the teleoperation, which uses passivity to tackle the trade-off between stability and performance, perception methods for localization, mapping and inspection, and planning methods, including a new control-aware approach for aerial manipulation. Finally, it describes a novel industrial platform with multi-directional thrusters and a new arm design to increase the robustness in industrial contact inspections. The lessons learned in the application to outdoor aerial manipulation for inspection and maintenance are pointed out.
R.BAILON-RUIZ, A.BIT-MONNOT, S.LACROIX
Manifestation avec acte : IEEE/RSJ International Conference on Intelligent Robots and Systems ( IROS ) 2018 du 01 octobre au 05 octobre 2018, Madrid (Espagne), Octobre 2018, 6p. , N° 18261
We present an approach to plan trajectories for a fleet of fixed-wing UAVs to observe a wildfire evolving over time. Realistic models of the terrain, of the fire propagation process, and of the UAVs are exploited, together with a model of the wind. The approach tailors a generic Variable Neighborhood Search method to these models and associated constraints. Simulation results show ability to plan observation trajectories for a small fleet of UAVs, and to update the plans when new information on the fire are incorporated in the fire model.
J.CARPENTIER, G.SAUREL, G.BUONDONNO, J.MIRABEL, F.LAMIRAUX, O.STASSE, N.MANSARD
Rapport LAAS N°18288, Octobre 2018, 6p.
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.
Ouvrage (contribution) : Biomechanics of Anthropomorphic Systems, Springer, N°ISBN 978-3-319-93870-7, Octobre 2018 , N° 18101
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  from Tokyo University is an example of the second category
R.BUDHIRAJA, J.CARPENTIER, N.MANSARD
Rapport LAAS N°18286, Octobre 2018, 7p.
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.
Y.AOUSTIN, C.CHEVALLEREAU, J.P.LAUMOND
Ouvrage (contribution) : Humanoid Robotics: A Reference, Springer, N°ISBN 978-94-007-6045-5, Octobre 2018 , N° 18021
T.SENTENAC, F.BUGARIN, B.DUCAROUGE, M.DEVY
Revue Scientifique : Advanced Engineering Informatics, Vol.38, pp.203-215, Octobre 2018 , N° 18184
In many industrial sectors, Non Destructive Testing (NDT) methods are used for the thermomechanical analysis of parts in assemblies of engines or reactors or for the control of metal forming processes. This article suggests an automated multi-view approach for the thermal 3D reconstruction required in order to compute 3D surface temperature models. This approach is based only on infrared cameras mounted on a Cartesian robot. The low resolution of these cameras associated to a lack of texture to infrared images require to use a global approach based first on an uncalibrated rectification and then on the simultaneous execution, in a single step, of the dense 3D reconstruction and of an extended self-calibration. The uncalibrated rectification is based on an optimization process under constraints which calculates the homographies without prior calculation of the Fundamental Matrix and which minimizes the projective deformations between the initial images and the rectified ones. The extended self-calibration estimates both the parameters of virtual cameras that could provide the rectified images directly, and the parameters of the robot. It is based on two criteria evaluated according to the noise level of the infrared images. This global approach is validated through the reconstruction of a hot object against a reference reconstruction acquired by a 3D scanner.
C.GABELLIERI, M.TOGNON, L.PALLOTTINO, A.FRANCHI
Rapport LAAS N°18263, Septembre 2018, 13p.
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.