Antonio Giannitrapani

Collective circular motion of multi-vehicle systems

This paper addresses a collective motion problem for a multi-agent system composed of nonholonomic vehicles. The aim of the vehicles is to achieve circular motion around a virtual reference beacon. A control law is proposed, which guarantees global asymptotic stability of the circular motion with a prescribed direction of rotation, in the case of a single vehicle. Equilibrium configurations of the multi-vehicle system are studied and sufficient conditions for their local stability are given, in terms of the control law design parameters. Practical issues related to sensory limitations are taken into account. The transient behavior of the multi-vehicle system is analyzed via numerical simulations.

Mobile robot SLAM for line-based environment representation

This paper presents an algorithm for solving the simultaneous localization and map building (SLAM) problem, a key issue for autonomous navigation in unknown environments. The considered scenario is that of a mobile robot using range scans, provided by a 2D laser rangefinder, to update a map of the environment and simultaneously estimate its position and orientation within the map. The environment representation is based on linear features whose parameters are extracted from range scans, while the corresponding covariance matrices are computed from the statistical properties of the raw data. Simultaneous update of robot pose and linear feature estimates is performed via extended Kalman filtering. Experimental tests performed within a real-world indoor environment demonstrate the effectiveness of the proposed SLAM technique.

Simultaneous localization and map building for a team of cooperating robots: a set membership approach

The problem of simultaneous localization and map building for a team of cooperating robots moving in an unknown environment is addressed. The robots have to estimate the position of distinguishable static landmarks, and then localize themselves with respect to other robots and landmarks, exploiting distance and angle measurements. A novel set theoretic approach to this problem is presented. The proposed localization algorithm provides position estimates and guaranteed uncertainty regions for all robots and landmarks in the environment.

Comparison of EKF and UKF for Spacecraft Localization via Angle Measurements

The performance of two nonlinear estimators is compared for the localization of a spacecraft. It is assumed that range measurements are not available (as in deep space missions), and the localization problem is tackled on the basis of angles-only measurements. A dynamic model of the spacecraft accounting for several perturbing effects, such as Earth and Moon gravitational field asymmetry and errors associated with the Moon ephemerides, is employed. The measurement process is based on elevation and azimuth of Moon and Earth with respect to the spacecraft reference system. Position and velocity of the spacecraft are estimated using both the extended Kalman filter (EKF) and the unscented Kalman filter (UKF). The behavior of the filters is compared on two sample missions: Earth-to-Moon transfer and geostationary orbit raising.

A Set Theoretic Approach to Dynamic Robot Localization and Mapping

This paper addresses the localization and mapping problem for a robot moving through a (possibly) unknown environment where indistinguishable landmarks can be detected. A set theoretic approach to the problem is presented. Computationally efficient algorithms for measurement-to-feature matching, estimation of landmark positions, estimation of robot location and heading are derived, in terms of uncertainty regions, under the hypothesis that errors affecting all sensors measurements are unknown-but-bounded. The proposed technique is validated in both simulation and experimental setups.

Analysis of consensus protocols with bounded measurement errors

This paper analyzes two classes of consensus algorithms in the presence of bounded measurement errors. The considered protocols adopt an updating rule based either on constant or vanishing weights. Under the assumption of bounded error, the consensus problem is cast in a set-membership framework, and the agreement of the team is studied by analyzing the evolution of the feasible state set. Bounds on the asymptotic difference between the states of the agents are explicitly derived, in terms of the bounds on the measurement noise and the values of the weight matrix.

An Experimental Study of the Limitations of Mobile Haptic Interfaces

This paper presents various procedures that can be used in order to numerically evaluate what the maximum Z − width that can be rendered by a mobile haptic interface will be given few parameters that characterize the haptic device and the mobile platform that mak e up such interface. Such procedures are applied to the case of two different mobile haptic interfaces. Results are encouraging, even though limitations to the proposed procedure exist.

Autonomous Low-Earth-Orbit Station-Keeping with Electric Propulsion

is based on an extended Kalman filter, employing gyro, star-tracker, and Global Positioning System measurements. Lyapunov-based and proportional–derivative feedback laws are used for orbit and attitude control, respectively. The performance of the proposed electric propulsion system and guidance, navigation, and control solution is evaluated on a low-Earth-orbit mission.

Dynamic Performance of Mobile Haptic Interfaces

The increasing demand for virtual reality applications in several scientific disciplines feeds new research perspectives dealing with robotics, automation, and computer science. In this context, one of the topics is the design of advanced force-feedback devices allowing not only kinesthetic interaction with virtual objects but also locomotion and navigation inside virtual worlds. This has the main advantage to stimulate human vestibular apparatus, thus increasing the overall realism of simulation. Particularly, this paper deals with mobile haptic interfaces (MHIs), built by combining standard force-feedback devices with mobile platforms. We investigated which factors may affect the transparency of this kind of devices, identifying in mobile robot dynamics a possible cause of loss of transparency. Hence, in this paper, we present a method to analyze dynamic performance of an MHI and some basic guidelines to design controller in order to meet desired specifications. Experimental validation of the theoretical results is reported.

Load forecasting for active distribution networks

This paper addresses the problem of electric load forecasting for distribution networks with Active Demand (AD), a new concept in smart-grids introduced within the EU project ADDRESS. By changing the typical consumption pattern of the consumers, AD adds a new dimension to the problem of load forecasting, and therefore makes currently available load forecasting techniques no more suitable. A new approach to load forecasting in the presence of AD is therefore proposed. The approach is based on a decomposition of the load into its components, namely the base load (representing different seasonal patterns), and a residual term depending both on stochastic fluctuations and AD effects. The performance of the proposed approach is illustrated through a numerical example. Since data sets including AD are not yet available, in the numerical example AD effects are simulated and added to real measurements representing the aggregated load of about 60 consumers from an Italian LV network.