arXiv subjects

M. Lorenzini

Publications and source records attributed to M. Lorenzini.

4 recordsLinked to original sources

arXiv2024

A Personalizable Controller for the Walking Assistive omNi-Directional Exo-Robot (WANDER)

Preserving and encouraging mobility in the elderly and adults with chronic conditions is of paramount importance. However, existing walking aids are either inadequate to provide sufficient support to users' stability or too bulky and poorly maneuverable to be used outside hospital environments. In addition, they all lack adaptability to individual requirements. To address these challenges, this paper introduces WANDER, a novel Walking Assistive omNi-Directional Exo-Robot. It consists of an omnidirectional platform and a robust aluminum structure mounted on top of it, which provides partial body weight support. A comfortable and minimally restrictive coupling interface embedded with a force/torque sensor allows to detect users' intentions, which are translated into command velocities by means of a variable admittance controller. An optimization technique based on users' preferences, i.e., Preference-Based Optimization (PBO) guides the choice of the admittance parameters (i.e., virtual mass and damping) to better fit subject-specific needs and characteristics. Experiments with twelve healthy subjects exhibited a significant decrease in energy consumption and jerk when using WANDER with PBO parameters as well as improved user performance and comfort. The great interpersonal variability in the optimized parameters highlights the importance of personalized control settings when walking with an assistive device, aiming to enhance users' comfort and mobility while ensuring reliable physical support.

cs.RO↗

arXiv2012

Scientific Potential of Einstein Telescope

Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ET's potential to influence our understanding of fundamental physics, astrophysics and cosmology.

gr-qc↗

arXiv2010

Sensitivity Studies for Third-Generation Gravitational Wave Observatories

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.

gr-qc↗

arXiv2010

Virgo calibration and reconstruction of the gravitational wave strain during VSR1

Virgo is a kilometer-length interferometer for gravitational waves detection located near Pisa. Its first science run, VSR1, occured from May to October 2007. The aims of the calibration are to measure the detector sensitivity and to reconstruct the time series of the gravitational wave strain h(t). The absolute length calibration is based on an original non-linear reconstruction of the differential arm length variations in free swinging Michelson configurations. It uses the laser wavelength as length standard. This method is used to calibrate the frequency dependent response of the Virgo mirror actuators and derive the detector in-loop response and sensitivity within ~5%. The principle of the strain reconstruction is highlighted and the h(t) systematic errors are estimated. A photon calibrator is used to check the sign of h(t). The reconstructed h(t) during VSR1 is valid from 10 Hz up to 10 kHz with systematic errors estimated to 6% in amplitude. The phase error is estimated to be 70 mrad below 1.9 kHz and 6 micro-seconds above.

gr-qc↗