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Abstract-Myoelectric prostheses are successfully controlled using muscle electrical activity, thereby restoring lost motor functions. However, the somatosensory feedback from the prosthesis to the user is still missing. The sensory substitution methods described in the literature comprise mostly simple position and force sensors combined with discrete stimulation units. The present study describes a novel system for sophisticated electrotactile feedback integrating advanced distributed sensing (electronic skin) and stimulation (matrix electrodes). The system was tested in eight healthy subjects who were asked to recognize the shape, trajectory and direction of a set of dynamic movement patterns (single lines, geometrical objects, letters) presented on the electronic skin. The experiments demonstrated that the system successfully translated the mechanical interaction into the moving electrotactile profiles, which the subjects could recognize with a good performance (shape recognition: 86±8% lines, 73±13% geometries, 72±12% letters). In particular, the subjects could identify the movement direction with a high confidence. These results are in accordance with previous studies investigating the recognition of moving stimuli in human subjects. This is an important development towards closed-loop prostheses providing comprehensive and sophisticated tactile feedback to the user, facilitating the control and the embodiment of the artificial device into the user body scheme.

The paper focuses on the manufacturing technology of modular components for large-area tactile sensors, which are made of arrays of polyvinylidene fluoride (PVDF) piezoelectric polymer taxels integrated on flexible PCBs. PVDF transducers were chosen for the high electromechanical transduction frequency bandwidth (up to 1 kHz for the given application). Patterned electrodes were inkjet printed on the PVDF film. Experimental tests on skin module prototypes demonstrate the feasibility of the proposed approach and reveal the potentiality to build large area flexible and conformable robotic skin. I.

Tactile sensing helps robots interact with humans and objects effectively in real environments. Piezoelectric polymer sensors provide the functional building blocks of the robotic electronic skin, mainly thanks to their flexibility and suitability for detecting dynamic contact events and for recognizing the touch modality. The paper focuses on the ability of tactile sensing systems to support the challenging recognition of certain qualities/modalities of touch. The research applies novel computational intelligence techniques and a tensor-based approach for the classification of touch modalities; its main results consist in providing a procedure to enhance system generalization ability and architecture for multi-class recognition applications. An experimental campaign involving 70 participants using three different modalities in touching the upper surface of the sensor array was conducted, and confirmed the validity of the approach.

In the past few years a new scenario for robot-based applications has emerged. Service and mobile robots have opened new market niches. Also, new frameworks for shop-floor robot applications have been developed. In all these contexts, robots are requested to perform tasks within open-ended conditions, possibly dynamically varying. These new requirements ask also for a change of paradigm in the design of robots: on-line and safe feedback motion control becomes the core of modern robot systems. Future robots will learn autonomously, interact safely and possess qualities like self-maintenance. Attaining these features would have been relatively easy if a complete model of the environment was available, and if the robot actuators could execute motion commands perfectly relative to this model. Unfortunately, a complete world model is not available and robots have to plan and execute the tasks in the presence of environmental uncertainties which makes sensing an important component of new generation robots. For this reason, today's new generation robots are equipped with more and more sensing components, and consequently they are ready to actively deal with the high complexity of the real world. Complex sensorimotor tasks such as exploration require coordination between the motor system and the sensory feedback. For robot control purposes, sensory feedback should be adequately organized in terms of relevant features and the associated data representation. In this paper, we propose an overall functional picture linking sensing to action in closed-loop sensorimotor control of robots for touch (hands, fingers). Basic qualities of haptic perception in humans inspire the models and categories comprising the proposed classification. The objective is to provide a reasoned, principled perspective on the connections between different taxonomies used in the Robotics and human haptic literature. The specific case of active exploration is chosen to ground interesting use cases. Two reasons motivate this choice. First, in the literature on haptics, exploration has been treated only to a limited extent compared to grasping and manipulation. Second, exploration involves specific robot behaviors that exploit distributed and heterogeneous sensory data.

Tactile sensing is considered a key technology for\ud implementing complex robot interaction tasks. The contribution\ud of this article is two-fold: (i) we propose a general-purpose\ud algorithm for the reconstruction of deformation and force\ud distributions for capacitance-based skin-like systems; (ii) realtime\ud performance can be tuned according to available computational\ud resources, which leads to an any-time formulation.\ud Experiments (both in simulation and with real robot skin)\ud provide a quantitative analysis of results

The paper focuses on the manufacturing technology of modular components for large-area tactile sensors, which are made of arrays of polyvinylidene fluoride (PVDF) piezoelectric polymer taxels integrated on flexible PCBs. PVDF transducers were chosen for the high electromechanical transduction frequency bandwidth (up to 1 kHz for the given application). Patterned electrodes were inkjet printed on the PVDF film. Experimental tests on skin module prototypes demonstrate the feasibility of the proposed approach and reveal the potentiality to build large area flexible and conformable robotic skin