An invited session on SICURA has been organized at the national meeting SIDRA'09 held in Siracusa, on September 18, 2009.

There were six presentations by the project partners, illustrating selected research results obtained during the first year of the project and on-going activities. The session was well attended also by other members of the italian robotics and automatic control communities.

Pdf or pps presentations are available for download in the right column (sorry, none of the shown videos). 
Actual presenters are highlighted.

presentations	pdf/pps
UNIBO Università di Bologna (two presentations) "On designing soft robotic hands adopting compliant joints and viscoelastic covers" Giovanni Berselli, Marco Brandi, Marco Piccinini, Gabriele Vassura Alternative design concepts for the development of soft robotic hands are presented. The hand is composed of an endoskeletal structure made of rigid links and compliant joints and covered by viscoelastic pads. Concerning the compliant joints, the main goal is to search for the maximum achievable integration between the various components in the perspective of a reduction of the assembly complexity. In particular, two different solutions are compared: 1) monolithic structures with fully integral compliant joints shaped as spiral torsion springs; 2) compliant joints made with close-wound steel springs and integrated in structures made of a different material (e.g. plastics). The performance of the joints are evaluated in terms of achievable selective compliance, accuracy of motion, and reliability. Concerning the covering viscoelastic pads, the main goal is to tailor the elastic and viscoelastic properties of the pads with respect to their position within the hand structure (fingertip, intermediate phalanges, or palm), in order to mimic the behavior of the human hand. Differentiation of the pad properties is achieved by adopting a single elastic or viscoelastic material and by dividing the overall thickness of the pad into layers with different structural design (e.g., a continuous skin layer coupled with an internal layer with voids). The communicating voids are eventually filled with a viscous liquid in order to achieve better energy dissipation and faster shape recovery when compared to solutions that simply make use of viscoelastic solid materials. Experimental and analytical results are presented. Finally, the perspective and the problems of the application with respect to safe human-robot interactions are discussed. "Variable stiffness joints based on compliant flexures: Design and control aspects" Gianluca Palli, Claudio Melchiorri, Giovanni Berselli, Gabriele Vassura The development of safe and dependable robots for physical human-robot interaction requires both the mechanical design of lightweight and compliant manipulators and the definition of motion control laws that allow compliant behavior in reaction to possible collisions, while preserving accuracy and performance during the motion in the free space. For these motivations, great attention has been posed in the design of robots manipulators with relevant and programmable joint/transmission stiffness. On the other hand, robotic joints with adjustable stiffness present an higher level of mechanical complexity with respect to conventional rigid joints or elastic joints with constant stiffness, other than requiring two actuators for each joint instead of one. In this work, a suitable trade-off between mechanical complexity, compactness and ease of implementation of variable stiffness joints is considered, taking into account the benefits that suitably designed flexure-based compliant mechanisms can introduce in the development of these devices. Also the problem of designing a joint with a desired stiffness range and profile is addressed. Finally, a robust control strategy for a general class of multi-dof manipulators with variable joint stiffness is presented. The proposed controller is composed by a robot dynamics and gravity compensator, a linear controller and a smooth sliding mode control action to ensure robustness with respect to model uncertainties. The stability of the overall system is proven by means of the direct Lyapunov method and the effectiveness of the proposed approach is demonstrated by simulation analysis.
UNINA Università di Napoli Federico II "Grasping unknown objects with robotics hands using vision and touch" Fanny Ficuciello, Vincenzo Lippiello, Fabio Ruggiero, Bruno Siciliano, Luigi Villani In this work a new method for fast visual grasp of unknown objects is presented. The method is composed of an object surface reconstruction algorithm, a local grasp planner, and an impedance control evolving in parallel. The reconstruction algorithm makes use of images taken by a camera carried by the robot, mounted in an eye-in-hand configuration. An elastic reconstruction sphere, composed by masses interconnected each other by springs, is virtually placed around the object. The sphere is let to evolve dynamically under the action of external forces, which push the masses towards the object centroid. To smoothen the surface evolution, spatial dampers are attached to each mass. The reconstruction surface shrinks toward its center of mass until some pieces of its surface intercept the object visual hull, and thus local rejection forces are generated to push out the reconstruction points until they stay into the visual hull. This process shapes the sphere around the unknown object. Running in parallel to the reconstruction algorithm, the grasp planner moves the fingertips, floating on the current available reconstructed surface, according to suitable quality measures. The fingers keep moving towards local minima depending on the evolution of the reconstruction surface deformation. This process stops when the object has been completely reconstructed and the planner reaches a local minimum, corresponding to the contact points for the fingers. Then, the virtual surface shrinks into the object and  "virtual" contact points are used as references for the impedance control of the fingers, to ensure a tight grasp. Simulations are presented, showing the effectiveness of the proposed algorithm.
UNIPI Università di Pisa "New variable impedance actuators for safety and beyond" Manuel Catalano, Giorgio Grioli, Riccardo Schiavi, Soumen Sen, Antonio Bicchi Actuators with variable transmission impedance have been proposed and implemented for allowing the decoupling of the rotor inertia from the effective impacting mass of the links, with the aim of reducing the risks of collisions in human-robot physical interaction. Though this remains an important application, there are other domains where variable impedance is a promising technology for improved performance: these include, e.g., very dynamic tasks (such as batting a ball or hitting a nail), locomotion and rehabilitation. We present a new series of VIA actuators and the study and experimental results of their application to several tasks.
UNIROMA1 Università di Roma "La Sapienza" "Decoupled motion-stiffness control and collision detection/reaction for variable stiffness devices" Alessandro De Luca, Fabrizio Flacco Variable stiffness actuation devices are being used to jointly address the issues of safety and performance in physical human-robot interaction. We first present a feedback linearization approach that allows the simultaneous decoupled control of link motion and stiffness reference profiles. With reference to two existing single-dof prototypes, the VSA-II of the University of Pisa and the VS-Joint of DLR, we characterize the operative conditions that avoid control singularities. We introduce then a collision detection scheme based on generalized momentum, which does not require joint torque sensing nor information on the time-varying stiffness of the device. Based on the residual signal, different collision reaction strategies are proposed that rapidly let the arm bounce away after detecting the impact, while limiting contact forces. Extensions to the multi-dof case of robot manipulators equipped with variable stiffness actuators of the antagonistic or non-antagonistic type are also considered.
UNIROMA2 Università di Roma "Tor Vergata" "Trajectory tracking for robot manipulators subject to non-smooth impacts" Antonio Tornambè Trajectory tracking for robot manipulators is a challenging problem especially when the robot is subject to non-smooth impacts. For instance, when the end-effector of the robot has to follow a certain closed path, the presence of some non-smooth impacts implies that the joint velocities need not to be continuous at the impact times, and, even if the the prescribed velocity profile presents the same discontinuities, the asymptotic stability of the origin of the tracking error dynamics cannot be ensured. Secondly, the non-smooth impacts can be considered as active inputs to be used for the manipulator control, especially when the robot manipulators is not controllable in absence of impacts.