1,721,049 research outputs found
Discinesie in corso di trattamento con L-Dopa nella sindrome parkinsoniana (orientamenti terapeutici).
No full textTrajectory Optimization for Quadruped Mobile Manipulators that Carry Heavy Payload
No full textThis paper presents a simplified model-based trajectory optimization (TO) formulation for motion planning on quadruped mobile manipulators that carry heavy payload of known mass. The proposed payload-Aware formulation simultaneously plans locomotion, payload manipulation and considers both robot and payload model dynamics while remaining computationally efficient. At the presence of heavy payload, the approach exhibits reduced leg outstretching (thus increased manipulability) in kinematically demanding motions due to the contribution of payload manipulation in the optimization. The framework's computational efficiency and performance is validated through a number of simulation and experimental studies with the bi-manual quadruped CENTAURO robot carrying on its arms a payload that exceeds 15 % of its mass and traversing non-flat terrain
Whole-Body MPC for Highly Redundant Legged Manipulators: Experimental Evaluation with a 37 DoF Dual-Arm Quadruped
No full textRecent progress in legged locomotion has rendered quadruped manipulators a promising solution for performing tasks that require both mobility and manipulation (loco-manipulation). In the real world, task specifications and/or environment constraints may require the quadruped manipulator to be equipped with high redundancy as well as whole-body motion coordination capabilities. This work presents an experimental evaluation of a whole-body Model Predictive Control (MPC) framework achieving real-Time performance on a dual-Arm quadruped platform consisting of 37 actuated joints. To the best of our knowledge this is the legged manipulator with the highest number of joints to be controlled with real-Time whole-body MPC so far. The computational efficiency of the MPC while considering the full robot kinematics and the centroidal dynamics model builds upon an open-source DDP-variant solver and a state-of-The-Art optimal control problem formulation. Differently from previous works on quadruped manipulators, the MPC is directly interfaced with the low-level joint impedance controllers without the need of designing an instantaneous whole-body controller. The feasibility on the real hardware is showcased using the CENTAURO platform for the challenging task of picking a heavy object from the ground. Dynamic stepping (trotting) is also showcased for first time with this robot. The results highlight the potential of replanning with whole-body information in a predictive control loop
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
An XML Definition Language to Support Scenario Based Requirements Engineering
No full textScenarios are a new way of representing knowledge that has been attracting a lot of attention from practitioners and researchers. In this paper we present the SDML formalism, an XML definition language to support scenario-based requirements engineering. The definition of scenarios through SDML enables to exploit the emerging XML technologies in order to offer powerful ways to create, maintain, distribute and use scenarios. Moreover, we are experimenting the SDML language on a variety of practical case studies
TelePhysicalOperation: Remote Robot Control Based on a Virtual "Marionette" Type Interaction Interface
No full textTeleoperation permits to control robots from a safe distance while performing tasks in a remote environment. Kinematic differences between the input device and the remotely controlled manipulator or the existence of redundancy in the remote robot may pose challenges in moving intuitively the remote robot as desired by the human operator. Motivated by the above challenges, this work introduces TelePhysicalOperation, a novel teloperation concept, which relies on a virtual physical interaction interface between the human operator and the remote robot in a manner that is equivalent to a "Marionette" based interaction interface. With the proposed approach, the user can virtually "interact" with the remote robot, through the application of virtual forces, which are generated by the operator tracking system and can be then selectively applied to any body part of the remote robot along its kinematic chain. This leads to the remote robot generating motions that comply with the applied virtual forces, thanks to the underlying control architecture. The proposed method permits to command the robot from a distance by exploring the intuitiveness of the "Marionette" based physical interaction with the robot in a virtual/remote manner. The details of the proposed approach are introduced and its effectiveness is demonstrated through a number of experimental trials executed on the CENTAURO, a hybrid leg-wheel platform with an anthropomorphic upper body
An XML Environment for Scenario Based Requirements Engineering
No full textThe pervasive use of scenarios in the development of computer systems and software has motivated the need of formalisms and tools for the description and manipulation of scenarios. To this aim, we present SME (Scenario Model Environment), an XML based tool for scenario-based requirements engineering. The tool enables to exploit the emerging XML technologies in order to offer powerful ways to create, maintain, distribute and use scenarios. We have widely experimented SME through several case studies, ranging from small examples, like a library system, to complex industrial applications
Locomotion Adaptation in Heavy Payload Transportation Tasks with the Quadruped Robot CENTAURO
No full textThis paper presents a reactive legged locomotion generation scheme that enables our quadruped robot CENTAURO to adapt to varying payloads while walking. The center-of-mass (CoM) trajectories are generated in real time in a model predictive control (MPC) fashion, trading off large stability margins against evenly stretched legs. Vertex-based zero-moment-point (ZMP) constraints are imposed to ensure quasi-static walking stability. A Kalman filter is then implemented to estimate the CoM states and the impact of external payloads which can vary online and affect/disturb the locomotion differently. The CoM estimation is used to update the MPC motion planner at every replanning instant so that the robot can react to unknown and time-varying payloads on the fly. We validate the proposed scheme through experimental trials where the robot walks on flat ground or steps on different surface levels while carrying heavy payloads. It is shown that the proposed reactive locomotion strategy enables the robot to carry 20 kg payloads, which is close to the maximum capacity of the robot arms
- …
