Ricerc@Sapienza

In this paper, we consider the problem of disturbance decoupling for a class of non-minimum-phase nonlinear systems. Based on the notion of partially minimum phaseness, we shall characterize all actions of disturbances which can be decoupled via a static state feedback while preserving stability of the internal residual dynamics. The proposed methodology is then extended to the sampled-data framework via multi-rate design to cope with the rising of the so-called sampling zero dynamics intrinsically induced by classical single-rate sampling.

The paper focuses on the time domain output-only technique called Data-Driven Stochastic Subspace Identification (DD-SSI); in order to identify modal models (frequencies, damping ratios and mode shapes), the role of its user-defined parameters is studied, and rules to determine their minimum values are proposed. Such investigation is carried out using, first, the time histories of structural responses to stationary excitations, with a large number of samples, satisfying the hypothesis on the input imposed by DD-SSI.

LEDSAT (LED-based small SATellite) is a 1-Unit CubeSat that will mount Light Emitting Diodes (LEDs) on its six faces, in order to validate, verify and improve the current methodologies for optical orbit determination. The LEDs will also support the CubeSat identification after deployment from the ISS. The satellite is being produced by the S5Lab research group at Sapienza - University of Rome, and it has been accepted for the European Space Agency Fly Your Satellite Programme.

This paper is aimed at demonstrating the possibility of growing a tomato ideotype, fortified in anti-oxidant content (derived from Micro-Tom, a model cultivar for tomato research overexpressing anthocyanins) and specifically developed for spatial environment, in a seed-to-seed cycle (70-90 days) on a CubeSat. To reach this goal, a dedicated micro satellite equivalent to 12 U will be developed to be sent into low-orbit. Growing plants in space is a prerequisite to sustain long-term human exploration of the solar system.

In this paper, the recently developed artificial material single layer (AMSL) method is applied to model a conductive shield for wireless power transfer (WPT) systems. This method is very efficient in the simulation of a complex setup, such as that occurring in the analysis of the magnetic field produced by a WPT system installed in an electrical vehicle (EV). In this application, a critical issue is the efficient and accurate modeling of conductive shields to evaluate the near field magnetic field.

The paper describes a method based on virtual reality tools to achieve the attitude determination of an orbiting object using lightcurve measurements. A virtual model of the orbiting object is propagated in order to reproduce its lightcurve. The differences between the real and simulated lightcurves is used as the cost function to be minimized through a multiobjective genetic algorithm. Lightcurve measurements in different spectral bands, both with monostatic and multistatic optical observations can be used.

A recently emerged driving requirement for microsatellites is a precise and fast attitude maneuvering capability. Agility enhances the operational efficiency of missions requiring a high level of retargeting ability, such as space station and satellite on-orbit servicing, formation flying, Earth monitoring, and space-based space debris observation and tracking. Three-axis stabilized microsatellites are mainly equipped with momentum wheels, barely meeting agility requirements.

In recent years, microsatellites have been designed, constructed, and operated by a considerable number of subjects, either Universities, space agencies, or private ventures. This research presents the overall mission analysis for Lunisat, a nextgeneration microsatellite that is intended to orbit the Moon. The Lunisat mission is assumed to be composed of two main phases: (a) transfer trajectory from a low Earth orbit (LEO) to a low Moon orbit (LMO), and (b) release of nanosatellites around the Moon.

Multistage launch vehicles are commonly employed to place spacecraft in their operational orbits. Several characteristics, i.e. mass distribution and time variation, propulsion, and aerodynamics, affect the overall performance of the ascent vehicle of interest. Thus, it is apparent that accurate modeling is a central issue and an essential prerequisite for trajectory optimization. This research uses the Scout, a launch vehicle of reduced size used in the past, as the reference multistage rocket.