Nicola Ceccarelli

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.

Micro UAV Path Planning for Reconnaissance in Wind

The problem addressed in this paper is the control of a micro unmanned aerial vehicle (MAV) for the purpose of obtaining video footage of a set of known ground targets with preferred azimuthal viewing angles, using fixed onboard cameras. Control is exercised only through the selection of waypoints, without modification of the MAVs pre-existing autopilot and waypoint following capability. Specifically, we investigate problems and potential solutions of performing this task in the presence of a known constant wind. Simulations are provided in the presence of randomly perturbed wind, based on the Air Force Research Laboratory equipment and the high fidelity simulator MultiUAV2.

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.

Collective circular motion of multi-vehicle systems with sensory limitations

Collective motion of a multi-agent system composed of nonholonomic vehicles is addressed. The aim of the vehicles is to achieve rotational 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.

Experimental validation of collective circular motion for nonholonomic multi-vehicle systems

This paper presents the experimental validation of a recently proposed decentralized control law, for the collective circular motion of a team of nonholonomic vehicles about a virtual reference beacon. The considered control strategy ensures global asymptotic stability in the single-vehicle case and local asymptotic stability in the multi-vehicle scenario. The main contribution of this work is to evaluate the performance of the proposed algorithm in the presence of a number of uncertainty sources naturally arising in a real-world environment. Both static and moving reference beacons are considered, in a low-cost experimental framework based on the LEGO MINDSTORMS technology. The adopted setup features good scalability and is versatile enough to be adopted for the evaluation of different control strategies. At the same time, it represents a challenging testbed, exhibiting several issues that have to be faced in real-world applications.

Experimental validation of a decentralized control law for multi-vehicle collective motion

The paper presents the results of experimental tests carried out to validate the performance of a decentralized control law, for the collective circular motion of a team of nonholonomic vehicles. The considered control strategy ensures global asymptotic stability in the single-vehicle case and local asymptotic stability in the multi-vehicle scenario. The main purpose of this work is to verify these theoretical properties in a real-world scenario. As a side contribution, a low-cost experimental setup is presented, based on the LEGO Mindstorms technology. The setup features good scalability, it is versatile enough to be adopted for the evaluation of different control strategies, and it exhibits several issues to be faced in real- world applications.

A set theoretic approach to path planning for mobile robots

This paper addresses the path planning problem for mobile robots in a set theoretic framework. Under the assumption of unknown but bounded disturbances, a procedure for computing minimum average uncertainty paths is proposed. The considered scenario is that of a holonomic mobile robot moving in an environment where landmarks can be identified. Practical issues, such as limited visibility of landmarks and obstacle avoidance, are addressed. The proposed technique is validated via numerical simulations.

Set membership localization and map building for mobile robots

Autonomous navigation of mobile robots requires the continuous estimation of the vehicle position and orientation in a given reference frame (localization problem). When moving in unknown environments, the more challenging problem of building a map, while at the same time localizing within it, must be faced (simultaneous localization and map building, SLAM). By adopting a landmark-based description of the environment, both tasks can be cast as a state estimation problem for an uncertain dynamic system, based on noisy measurements.

SPACECRAFT LOCALIZATION VIA ANGLE MEASUREMENTS FOR AUTONOMOUS NAVIGATION IN DEEP SPACE MISSIONS

Abstract This paper addresses the problem of spacecraft localization based on angular measurements, for deep space missions. The dynamic model of the spacecraft accounts for several perturbing effects, such as Earth and Moon gravitational field asymmetry and errors associated with the Moon ephemerides. The measurement process is based on elevation and azimuth of Moon and Earth with respect to the spacecraft reference system. Distance measurements are not employed. Position and velocity of the spacecraft are estimated by using both the Extended Kalman Filter (EKF) and the Unscented Kalman Filter (UKF). The performance of the filters are evaluated on an example of Earth-to-Moon transfer mission.

Experimental analysis of collective circular motion for multi-vehicle systems

Abstract This paper presents an experimental analysis of a recently proposed decentralized control strategy, for collective circular motion of a team of non-holonomic vehicles. Theoretical results ensuring global asymptotic stability in the single-vehicle case and local asymptotic stability in the multi-vehicle scenario, are validated on an experimental setup including the mobile robots Pioneer 3AT and Nomad XR4000. In addition, the role of the control law parameters is discussed and a design procedure is proposed.