giovanni ulivi | Università Degli Studi Di Roma Tre (original) (raw)

Papers by giovanni ulivi

2021 IEEE International Conference on Robotics and Automation (ICRA), 2021

In this work, we propose a global planning strategy specifically designed for precision agricultu... more In this work, we propose a global planning strategy specifically designed for precision agriculture settings, where field activities may have different requirements ranging from a full orchard inspection to sparse targeted per-plant interventions. This global planning strategy is formulated as a novel Multi-Platform Steiner Traveling Salesman Problem (MP-STSP) where, in order to guarantee the exploitation of multiple moving platforms and the minimization of the overall operational time, the proposed formulation explicitly takes into account the time required to perform each task. By doing so, the computed itineraries attempt to balance the workload among the deployed platforms. Comparative simulations, inspired by the needs of the EU H2020 Project PANTHEON 1, are provided to numerically demonstrate the effectiveness of the proposed planning strategy for an orchard precision agriculture setting.

IFAC Proceedings Volumes, 1989

A light weight optical angular transducer for angular measurements of points of a flexible robot ... more A light weight optical angular transducer for angular measurements of points of a flexible robot arm, with respect to a jOint based reference frame , is presented. The essential parts of the transducer are a pointwise light source , mounted on the flexible arm, a light sensor fixed on the joint and a rotating focusing mirror, actuated by a d.c. motor equipped with an encoder. Experimental data show the actual performance of a transducer implementation.

Antiviral Therapy

Background The extreme flexibility of the HIV type-1 (HIV-1) genome makes it challenging to build... more Background The extreme flexibility of the HIV type-1 (HIV-1) genome makes it challenging to build the ideal antiretroviral treatment regimen. Interpretation of HIV-1 genotypic drug resistance is evolving from rule-based systems guided by expert opinion to data-driven engines developed through machine learning methods. Methods The aim of the study was to investigate linear and non-linear statistical learning models for classifying short-term virological outcome of antiretroviral treatment. To optimize the model, different feature selection methods were considered. Robust extra-sample error estimation and different loss functions were used to assess model performance. The results were compared with widely used rule-based genotypic interpretation systems (Stanford HIVdb, Rega and ANRS). Results A set of 3,143 treatment change episodes were extracted from the EuResist database. The dataset included patient demographics, treatment history and viral genotypes. A logistic regression model ...

IEEE Transactions on Robotics, 2017

In this paper, we consider the problem of general topology control in multi-robot systems with no... more In this paper, we consider the problem of general topology control in multi-robot systems with nonholonomic kinematics. Our contribution is twofold: we first demonstrate the correctness of topology control under the assumption that the network topology can switch arbitrarily and that potential-based mobility is discontinuous with respect to topology changes; we then demonstrate that a multi-robot team under the above listed conditions continues to achieve topology control when actuator saturation is applied and in the presence of arbitrary discontinuous (and possibly non-pairwise) exogenous objectives. Simulation results are given to corroborate our theoretical findings.

World Automation Congress, 2004

This paper presents an application of a well-known SLAM algorithm, based on an augmented state Ka... more This paper presents an application of a well-known SLAM algorithm, based on an augmented state Kalman estimator, to self-localise the robot and builds a fuzzy gridmap of the environment at the same time. In an office-like environment, a vision system is used to single-out on the ceiling some lamps, that are considered as natural landmarks and included in the state

IFAC Proceedings Volumes, 2005

Developed countries rely on many infrastructures as energy transportation, water supply, telecomm... more Developed countries rely on many infrastructures as energy transportation, water supply, telecommunication, etc., which are more and more mutually dependent. This phenomenon represents a new and very dangerous vulnerability: an accidental or malicious (e.g., terroristic attack) fault could spread across, amplifying its negative consequences. This imposes to develop methodologies and tools to support decision makers and infrastructures' stakeholders in the analysis of these new scenarios, and in defining suitable protection strategies. To this end, in this paper, we propose an approach to model interdependent infrastructures which, on the bases of mostly qualitative information, is able to set up a (rather sophisticated) simulator.

Nonlinear Control Systems Design 1989, 1990

Nonlinear control schemes based on inversion techniques are presented ior voltagefrequency contro... more Nonlinear control schemes based on inversion techniques are presented ior voltagefrequency controlled (VFC) induction motors, The selection of different output sets is discussed and the properties of the resulting closed-loop systems are investigated. When the two components of the rotor flux vector are chosen as controlled variables. the system is invertible and has no zero-dynamics. Therefore. the VFC induction motor can be fully linearized and input-output decoupled by means of a dynamic state-feedback law. Two other pairs of outputs are then considered : the torque and the stator or the rotor flux modulus. respectively. An input-output linearizing and decoupling dynamiC compensator can be designed for both cases. The associated closed-loop systems contain an un observable part whose dynamics is shown to be stable. The comparison among the obtained results provides a deeper insight into the structural control properties of the induction motor.

BMC Bioinformatics, 2011

Background: Next-generation sequencing (NGS) offers a unique opportunity for high-throughput geno... more Background: Next-generation sequencing (NGS) offers a unique opportunity for high-throughput genomics and has potential to replace Sanger sequencing in many fields, including de-novo sequencing, re-sequencing, metagenomics, and characterisation of infectious pathogens, such as viral quasispecies. Although methodologies and software for whole genome assembly and genome variation analysis have been developed and refined for NGS data, reconstructing a viral quasispecies using NGS data remains a challenge. This application would be useful for analysing intra-host evolutionary pathways in relation to immune responses and antiretroviral therapy exposures. Here we introduce a set of formulae for the combinatorial analysis of a quasispecies, given a NGS re-sequencing experiment and an algorithm for quasispecies reconstruction. We require that sequenced fragments are aligned against a reference genome, and that the reference genome is partitioned into a set of sliding windows (amplicons). The reconstruction algorithm is based on combinations of multinomial distributions and is designed to minimise the reconstruction of false variants, called in-silico recombinants. Results: The reconstruction algorithm was applied to error-free simulated data and reconstructed a high percentage of true variants, even at a low genetic diversity, where the chance to obtain in-silico recombinants is high. Results on empirical NGS data from patients infected with hepatitis B virus, confirmed its ability to characterise different viral variants from distinct patients. Conclusions: The combinatorial analysis provided a description of the difficulty to reconstruct a quasispecies, given a determined amplicon partition and a measure of population diversity. The reconstruction algorithm showed good performance both considering simulated data and real data, even in presence of sequencing errors.

Proc. of 11th Int. Conf. on Advanced Robotics, 2003

The aim of this paper is to present a vision based algorithm for simultaneous localisation and ma... more The aim of this paper is to present a vision based algorithm for simultaneous localisation and map building (SLAM) for indoor environment. The approach is based on the well known predictor-corrector structure of the Extended Kalman Filter and makes use of vision data in the correction phase. To this aim a low cost vision system is presented, with a fast image processing procedure for features extraction, based on the recognition of artificial sources of light in an officelike environment. Experimental tests, carried out on a robotic ...

IFAC Proceedings Volumes, 1983

The applications of state feedback optimal control techniques to the drives using as an actuator ... more The applications of state feedback optimal control techniques to the drives using as an actuator a frequency controlled induction motor are exciting a great interest. These applications are based on the employment of a microcomputer-based control system, which is characterized by a finite computation time. In addition, during a sampling period, they give as output either the desired values of the modulus and the phase-displacement of the representative vector of the motor supply voltages or the desired values of the prejections of this vector according a pair of orthogonal axes. Owing to this, it is impossible to utilize the usual modulation techniques, which allow imposing the modulus and the angular frequency of the representative vector of the motor supply voltages. The paper describes a modulation technique, which is suitable to be used with three-phase bridge inverters and can be utilized in the aforesaid applications, since it accepts as inputs the projections of the voltage representative vector according to two orthogonal axes fi xed with the stator windings of the motor. The description of an algorithm for the implementation on a microcomputer-based control circuit of the proposed modulation technique and some remarks about the obtained results conclude the paper.

IFAC Proceedings Volumes, 1996

New control methodologies (fuzzy, neural, genetic) are often used to design the control systems o... more New control methodologies (fuzzy, neural, genetic) are often used to design the control systems of mobile robots. This paper analyzes several significant cas. es in the fields of feedback .control, obstacle avoidance, and automotive components and tnes to arrIve to some general conclusIOns.

IFAC Proceedings Volumes, 2003

In this paper we consider the problem of building a new class of metric maps representing the sur... more In this paper we consider the problem of building a new class of metric maps representing the surroundings of a mobile robot moving in an unstructured indoor environment. Maps are conceived with a metric based on a log-polar space representation: this retina-like representation allows a better definition of objects near the robot, giving less importance to far ones. Information provided at each step by ultrasonic sensors has an uncertainty that is conceptualised as a fuzzy measure and is combined with previous data using Smets transferable believe model. The map building algorithm is integrated in a sensor-based robot navigation system able to recognise some characteristics of the environment. A pattern-matching algorithm, based on Mellin transform, takes advantage on the particular retina-like representation.