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456documents trouvés

17111
09/07/2017

Nonlinear control of multi-rotor aerial vehicles based on the zero-moment direction

G.MICHIELETTO, A.CENEDESE, L.ZACCARIAN, A.FRANCHI

RIS, University of Padova, MAC

Manifestation avec acte : IFAC World Congress 2017 du 09 juillet au 14 juillet 2017, Toulouse (France), Juillet 2017, 6p. , N° 17111

Lien : https://hal.laas.fr/hal-01513229

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Abstract

A quaternion-based nonlinear control strategy is here presented to steer and keep a generic multi-rotor platform in a given reference position. Exploiting a state feedback structure, the proposed solution ensures the stabilization of the aerial vehicle so that its linear and angular velocity are zero and its attitude is constant. The main feature of the designed controller is the identification of a zero-moment direction in the feasible force space, i.e., a direction along which the control force intensity can be assigned independently of the control moment. The asymptotic convergence of the error dynamics is confirmed by simulation results on a hexarotor with tilted propellers.

140185
17113
28/06/2017

Toward a Correct-and-Scalable Verification of Concurrent Robotic Systems: Insights on Formalisms and Tools

M.FOUGHALI

RIS

Manifestation avec acte : International Conference on Application of Concurrency to System Design ( ACSD ) 2017 du 28 juin au 30 juin 2017, Zaragosse (Espagne), Juin 2017, 10p. , N° 17113

Lien : https://hal.archives-ouvertes.fr/hal-01515012

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Abstract

Formal verification of robotic functional components is extremely important. Indeed, with the growing involvement of autonomous systems in everyday life, we may no longer rely on classical testing and simulation to establish our trust in them. However, the formalization of such systems is challenging considering the various existing formalisms and their respective advantages/drawbacks. One may express more easily in one formalism and verify more easily in another depending on the aspects/properties they are modeling/verifying. Furthermore, both the reusability of the formalization and the scalability of the obtained formal models are crucial elements in the verification process. In this paper, we present modeling concurrency aspects of robotic functional components in Time Petri Nets, Timed Automata and Timed Automata extended with urgencies. Formal models are automatically generated and verification is conducted on each of them. Both the expressiveness of the formalisms and scalability of the obtained models are evaluated and future directions are consequently outlined.

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17046
31/05/2017

Adaptive closed-loop speed control of BLDC motors with applications to multi-rotor aerial vehicles

A.FRANCHI, A.MALLET

RIS, IDEA

Manifestation avec acte : IEEE International Conference on Robotics and Automation ( ICRA ) 2017 du 29 mai au 03 juin 2017, Singapour (Singapour), Mai 2017, 6p. , N° 17046

Lien : https://hal.laas.fr/hal-01476812

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This paper introduces the adaptive bias and adaptive gain (ABAG) algorithm for closed-loop electronic speed control (ESC) of the brushless direct current (BLDC) motors typically used to spin the propellers in multi-rotor aerial robots. The ABAG algorithm is adaptive and robust in the sense that it does not require the knowledge of any mechanical/electrical parameter of the motor/propeller group and that neither a pre-calibration nor the knowledge of the feedforward/nominal input is needed. The ABAG algorithm is amenable to an extremely low complexity implementation. We experimentally prove that it can run in 27.5 µs on a 8 MHz microcontroller with no floating point unit and limited arithmetic capabilities allowing only 8-bit additions, subtractions and multiplications. Besides the controller implementation we present a self-contained open source software architecture that handles the entire speed control process, including clock synchronization, and over-current and blockage safeties. The excellent performance and robustness of ABAG are shown by experimental tests and aerial physical interaction experiments.

139881
17038
29/05/2017

Control of statically hoverable multi-rotor aerial vehicles and application to rotor-failure robustness for hexarotors

G.MICHIELETTO, M.RYLL, A.FRANCHI

RIS

Manifestation avec acte : IEEE International Conference on Robotics and Automation ( ICRA ) 2017 du 29 mai au 03 juin 2017, Singapour (Singapour), Mai 2017, 6p. , N° 17038

Lien : https://hal.laas.fr/hal-01476816

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Abstract

Standard hexarotors are often mistakenly considered 'by definition' fail-safe multi-rotor platforms because of the two additional propellers when compared to quadrotors. However this is not true, in fact, a standard hexarotor cannot statically hover with 'only' five propellers. In this paper we provide a set of new general algebraic conditions to ensure static hover for any multi-rotor platform with any number of generically oriented rotors. These are elegantly formulated as the full-rankness of the control moment input matrix, and the non-orthogonality between its null-space and the row space of the control force input matrix. Input saturations and safety margins are also taken into account with an additional condition on the null-space of control moment input matrix. A deep analysis on the hoverability properties is then carried out focusing on the propeller loss in a hexarotor platform. Leveraging our general results we explain why a standard hexarotor is not robust and how it can be made robust thanks to a particular tilt of the rotors. We finally propose a novel cascaded controller based on a preferential direction in the null-space of the control moment input matrix for the large class of statically hoverable multi-rotors, which goes far beyond standard platforms, and we apply this controller to the case of failed tilted hexarotor.

139273
17037
29/05/2017

Towards robotic MAGMaS: multiple aerial-ground manipulator systems

N.STAUB, M.MOHAMMADI, D.BICEGO, D.PRATTICHIZZO, A.FRANCHI

RIS, IIT, Genova

Manifestation avec acte : IEEE International Conference on Robotics and Automation ( ICRA ) 2017 du 29 mai au 03 juin 2017, Singapour (Singapour), Mai 2017, 6p. , N° 17037

Lien : https://hal.laas.fr/hal-01476813

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Abstract

In this paper we lay the foundation of the first heterogeneous multi-robot system of the Multiple Aerial-Ground Manipulator System (MAGMaS) type. A MAGMaS consists of a ground manipulator and a team of aerial robots equipped with a simple gripper manipulator the same object. The idea is to benefit from the advantages of both kinds of platforms, i.e., physical strength versus large workspace. The dynamic model of such robotic systems is derived, and its characteristic structure exhibited. Based on the dynamical structure of the system a nonlinear control scheme, augmented with a disturbance observer is proposed to perform trajectory tracking tasks in presence of model inaccuracies and external disturbances. The system redundancy is exploited by solving an optimal force/torque allocation problem that takes into account the heterogeneous system constraints and maximizes the force manipulability ellipsoid. Simulation results validated the proposed control scheme for this novel heterogeneous robotic system. We finally present a prototypical mechanical design and preliminary experimental evaluation of a MAGMaS composed by a kuka LWR4 and quadrotor based aerial robot.

139261
17036
29/05/2017

6D physical interaction with a fully actuated aerial robot

M.RYLL, G.MUSCIO, F.PIERRI, E.CATALDI, G.ANTONELLI, F.CACCAVALE, A.FRANCHI

RIS, University of Basilicata, UNICAS

Manifestation avec acte : IEEE International Conference on Robotics and Automation ( ICRA ) 2017 du 29 mai au 03 juin 2017, Singapour (Singapour), Mai 2017, 6p. , N° 17036

Lien : https://hal.laas.fr/hal-01476814

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This paper presents the design, control, and experimental validation of a novel fully–actuated aerial robot for physically interactive tasks, named Tilt-Hex. We show how the Tilt-Hex, a tilted-propeller hexarotor, is able to control the full pose (position and orientation independently) using a geometric control, and to exert a full-wrench (force and torque independently) with a rigidly attached end-effector using an admittance control paradigm. An outer loop control governs the desired admittance behavior and an inner loop based on geometric control ensures pose tracking. The interaction forces are estimated by a momentum based observer. Control and observation are made possible by a precise control and measurement of the speed of each propeller. An extensive experimental campaign shows that the Tilt-Hex is able to outperform the classical underactuated multi-rotors in terms of stability, accuracy and dexterity and represents one of the best choice at date for tasks requiring aerial physical interaction.

139259
17039
29/05/2017

Dynamic decentralized control for protocentric aerial manipulators

M.TOGNON, B.YUKSEL, G.BUONDONNO, A.FRANCHI

RIS, MPI, Rome

Manifestation avec acte : IEEE International Conference on Robotics and Automation ( ICRA ) 2017 du 29 mai au 03 juin 2017, Singapour (Singapour), Mai 2017, 6p. , N° 17039

Lien : https://hal.laas.fr/hal-01476817

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We present a control methodology for underactuated aerial manipulators that is both easy to implement on real systems and able to achieve highly dynamic behaviors. The method is composed by two parts: i) a nominal input/state trajectory generator that takes into account the full-body dynamics of the system exploiting its differential flatness property; ii) a decentralized feedback controller acting on the actuated degrees of freedom that confers the needed robustness to the closed-loop system. We demonstrate that the proposed controller is able to precisely track dynamic trajectories when implemented on a standard hardware. Comparative experiments clearly show the benefit of using the nominal input/state generator.

139275
17130
24/05/2017

A finite state machine modeling language and the associated tools allowing fast prototyping for FPGA devices

B.VANDEPORTAELE

RIS

Manifestation avec acte : International Workshop IEEE Electronics, Control, Measurement, Signals and their application to Mechatronics ( ECMSM ) 2017 du 24 mai au 26 mai 2017, Saint Sébastien (Espagne), Mai 2017, pp.253-258 , N° 17130

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Abstract

The VHDL hardware description language is commonly used to describe Finite State Machine(FSM) models to be implemented on Field Programmable Gate Array(FPGA) devices. However, its versatility permits to describe behaviors that deviate from a true FSM leading to systems that are complex to prove, to document and to maintain. The purpose of this work is to propose a language and the associated tools to create FSMs through a dedicated and intuitive textual description. This language is inspired by the dot language used in Graphviz, a tool to define graphs, and adds all the necessary elements required to describe complex FSM models (using for instance memorized or non memorized actions and actions on states or transitions). Moreover some additional elements are proposed to enrich the standard FSM model such as the genericity that permits to define simultaneously multiple states, transitions or actions using a generative description. A multi-platform open source JAVA program named FSMProcess [1] is introduced. Based on the ANTLR parser generator, it achieves the automatic generation of all the required .vhdl files (component, package, instantiation example and testbench) and a .dot file that is used to generate an always up-to-date graphical representation of the model (hence its documentation). This tool also supports simple model checking and integration of additional VHDL code. It can be used conjointly with version control systems and is coupled with the open source GHDL simulator to allow fast prototyping. It can be used either with its Graphical User Interface either as a command line compiler for integration in makefiles.

139879
17107
26/04/2017

Position tracking control for an aerial robot passively tethered to an independently moving platform

M.TOGNON, A.FRANCHI

RIS

Rapport LAAS N°17107, Avril 2017, 7p.

Lien : https://hal.laas.fr/hal-01501919

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We study the control problem of an aerial vehicle moving in the 3D space and connected to an independently moving platform through a physical link (e.g., a cable, a chain or a rope). The link is attached to the moving platform by means of a passive winch. The latter differs from an active winch by producing only a constant uncontrollable torque. We solve the problem of exact tracking of the 3D position of the aerial vehicle, either absolute or with respect to the moving platform, while the platform is independently moving. We prove two intrinsic properties of the system, namely, the dynamic feedback linearizability and the differential flatness with respect to the output of interest. Exploiting this properties we design a nonlinear controller able to exponentially steer the position of the aerial robot along any sufficiently smooth time-varying trajectory. The proposed method is tested through numerical simulations in several non-ideal cases.

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17106
25/04/2017

Visual Marker based Multi-Sensor Fusion State Estimation

J.L.SANCHEZ LOPEZ, V.ARELLANO, M.TOGNON, P.CAMPOY

UPM, RIS

Rapport LAAS N°17106, Avril 2017, 6p.

Lien : https://hal.laas.fr/hal-01501980

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This paper presents the description and experimental results of a versatile Visual Marker based Multi-Sensor Fusion State Estimation that allows to combine a variable optional number of sensors and positioning algorithms in a loosely-coupling fashion, incorporating visual markers to increase its performances. This technique allows an aerial robot to navigate in different environments and carrying out different missions with the same state estimation architecture, exploiting the best from every sensor. The state estimation algorithm has been successfully tested controlling a quadrotor equipped with an extra IMU and a RGB camera used only to detect visual markers. The entire framework runs on an onboard computer, including the controllers and the proposed state estimator. The whole software is made publicly available to the scientific community through an open source implementation.

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