The ankle represents a fairly complex bone structure, resulting in kinematics that hinders a flawless robot-assisted recovery of foot motility in impaired subjects. The paper proposes a novel device for ankle-foot neuro-rehabilitation based on a mechatronic redesign of the remarkable Agile Eye spherical robot on the basis of clinical requisites. The kinematic design allows the positioning of the ankle articular center close to the machine rotation center with valuable benefits in term of therapy functions. The prototype, named PKAnkle, Parallel Kinematic machine for Ankle rehabilitation, provides a 6-axes load cell for the measure of subject interaction forces/torques, and it integrates a commercial EMG-acquisition system. Robot control provides active and passive therapeutic exercises.

Distributed Generation has become a consolidated phenomenon in distribution grids in the last few years. Even though the matter is very articulated and complex, islanding operation of distribution grid is being considered as a possible measure to improve service continuity. In this paper a novel static converter control strategy to obtain frequency and voltage regulation in islanded distribution grid is proposed. Two situations are investigated: in the former one electronic converter and one synchronous generator are present, while in the latter only static generation is available. In the first case converter control will realize virtual inertia and efficient frequency regulation by mean of PID regulator; this approach allows to emulate high equivalent inertia, hence limiting the ROCOF and maximum frequency deviation, and, in the meantime, to obtain faster frequency regulation, which could not be possible with traditional regulators. In the second situation a Master-Slave approach will be adopted to maximize frequency and voltage stability. Even though the presented results are obtained in a grid with only two generators, the proposed approach can be extended to more general configurations with few generation units. Simulation results confirm that the proposed control allows islanded operation with high frequency and voltage stability under heavy load variations.

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A procedure for the derivation of a black-box model of electromagnetic interference (EMI) filters is proposed and discussed. The modeling approach is assessed by resorting to a real EMI filter. The equivalent circuit of the filter is directly obtained from a rational approximation of the scattering-parameter matrix measured at the filter ports. Therefore, the modeling procedure does not require any information on the internal structure of the filter (e.g., components, electrical/magnetic properties of the involved materials, connections leads, etc.). The circuit model is compatible with SPICE solvers and can be used for the prediction of conducted emissions in both the frequency and time domain. Specifically, the proposed modeling approach allows time-domain simulation and performance analysis of EMI filters in combination with power-electronic equipment (i.e. non-linear, time-variant circuits).

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In this paper a high-quality zonal DC distribution system is proposed. The system layout and the relative power converters are presented in detail and fault analysis is performed in the different sections of the system. Reliability considerations are presented to support the effectiveness of the proposed layout and criteria for protection design are provided. The proposed distribution system allows obtaining high levels of reliability and selectivity with no need for particular switching devices by mean of suitable converters selection and control, overcoming traditional issues of DC distribution systems.

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