This paper presents a multipurpose UAV (unmanned aerial vehicle) for mountain rescue operations. The multi-rotors based flying platform and its embedded avionics are designed to meet environmental requirements for mountainous terrain such as low temperatures, high altitude and strong winds, assuring the capability of carrying different payloads (separately or together) such as: avalanche beacon (ARTVA) with automatic signal recognition and path following algorithms for the rapid location of snowcovered body; camera (visible and thermal) for search and rescue of missing persons on snow and in woods during the day or night; payload deployment to drop emergency kits or specific explosive cartridge for controlled avalanche detachment. The resulting small (less than 5 kg) UAV is capable of full autonomous flight (including takeoff and landing) of a pre-programmed, or easily configurable, custom mission. Furthermore, the autopilot manages the sensors measurements (i.e. beacons or cameras) to update the flying mission automatically in flight. Specific functionalities such as terrain following were developed and implemented. Ground station programming of the UAV is not needed, except compulsory monitoring, as the rescue mission can be accomplished in a full automatic mode.

A new model of electrodynamic bearings is presented in this paper. The model takes into account the R-L dynamics of the eddy currents on which this type of bearing is based, making it valid for both quasistatic and dynamic analyses. In the quasistatic case, the model is used to obtain the force generated by an off-centered shaft rotating at a fixed speed in a constant magnetic field. The model is then used to analyze the dynamic stability of a Jeffcott rotor supported by electrodynamic bearings. The essential role played by nonrotating damping in ensuring a stable operating range to the rotor is studied by means of root loci. Comparison with literature results is finally used to validate the model.

Electrodynamic bearings are a kind of passive magnetic bearings based on eddy currents that develop between a rotating conductor and a static magnetic field. Relative to active magnetic bearings, their passive nature implies several advantages such as the reduced complexity, improved reliability, and smaller size and cost. Electrodynamic bearings have also drawbacks such as the difficulty in ensuring a stable levitation in a wide speed range. The most common solution to improve the stability is to add a nonrotating damping between the rotor and the stator. Although effective, this solution implies the installation of a dedicated magnet on the rotor. This increases the rotor weight and complexity and rises some concerns about the mechanical resistance. The aim of the present work is to experimentally validate the model of an electrodynamic bearing proposed by the same Authors in a previous paper and to investigate a new solution for the stabilization of electrodynamic bearings based on the introduction of compliant and dissipative elements between the statoric part of the bearing and the ground. The performances of the proposed solution are studied in the case of a simple Jeffcott rotor by means of root loci to investigate the stability of the system. The results show an improved stability relative to the test cases reported in the literature.

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The present paper discusses the use of a Kalman filter-based method to identify fall events during rock climbing activity. The proposed technique relies on the acquisition of three-axis acceleration and altitude by means of a data logger integrated within the climber's sit harness. Time-domain results exhibit the working principle of the algorithm. Furthermore, the data provided by eight climbers is analysed and discussed to validate the method.