Giulio Avanzini

Spacecraft Attitude Control Using Magnetic and Mechanical Actuation

The aim of this paper is the analysis of simultaneous attitude control and momentum-wheel management of a spacecraft by means of magnetic actuators only. A proof of almost global asymptotic stability is derived for control laws that drive a rigid satellite toward attitude stabilization in the orbit frame when the momentum wheel is aligned with one of the principal axes of inertia. Performance of the proposed control laws is demonstrated by numerical simulations under actuator saturation. Robustness to external disturbances and model uncertainties is also evaluated.

Mixed Newtonian-Lagrangian Approach for the Analysis of Flexible Aircraft Dynamics

A method for deriving low-order models for flexible aircraft by means of a mixed Newtonian–Lagrangian approach is proposed. Lagrange equations are used for flexible degrees of freedom, discretized by means of the Galerkin method. The evolution of transport degrees of freedom (position and attitude variables) is obtained by means of Newton’s second law and a generalized Euler equation. A strong link with conventional rigid aircraft equations of motion is maintained, which allows to highlight those terms less relevant for aircraft response. When negligible, these terms are removed, and a minimum-complexity flexible aircraft model is derived, suitable for real-time simulation and control law synthesis. Numerical results demonstrate how the approach correctly represents flexibility effects on aircraft response for a large transport aircraft model.

Design and development of a vertical take-off and landing uninhabited aerial vehicle

Abstract This paper reports the status of the activities carried out at Polytechnic of Turin and University of Rome “La Sapienza” to design, build and fly a shrouded-fan uninhabited aerial vehicle. The project goal is the realization of a reliable vertical take-off and landing platform to be used for research activities in various fields including autonomous remote sensing, design and development of rapid prototype vehicles, flight control system design and high-fidelity modelling for simulation-based control system validation.

Aircraft equilibrium and response to controls in intrinsic co-ordinates

In this paper we show how the equilibrium conditions, the flight envelope under load and the response to control actions can be advantageously calculated when the set of equations governing the aircraft dynamics are referred to the system of the e.g. intrinsic or Frenet co-ordinates. The response of aircraft speed and of curvature and torsion of the trajectory to controls justifies the uncoupling of the e.g. motion equations from those governing the attitude and provides information about the characteristic times of the airplane dynamics. A method for solving inverse problems which is based on the two time-scales approach is proposed and an application is presented.

Analysis of Helicopter Rotor Nonlinear Dynamics by Numerical Continuation Method

The capability of numerical continuation to trace branches of periodic solutions is exploited in order to investigate the behavior of an articulated rotor blade as design and flight parameters are varied. The aim of the paper is to demonstrate the use of Dynamical System Theory and bifurcation analysis as an innovative tool for supporting rotor design, an approach based on the determination of critical thresholds for motion variables and rotor design parameters that determine unstable or simply undesirable behaviors of the coupled, flap–lag motions. In spite of the relative simplicity of the model presently implemented, the potential of the method is fully demonstrated. The reported results show a reasonable trend in the evolution of blade motion as different parameters are varied with continuity.

A Natural Description of Aircraft Motions

We show how the motion equations of an aircraft can be very properly dealt with after reference is made to the natural coordinates of its center of gravity. The time domain is first divided into intervals, the duration of which is of the order of magnitude of the characteristic time of the slow, flight path variables. Then an analytic solution for the center of gravity position and velocity is immediately obtained over the entire interval in the form of a series expansion. The second step is then to integrate, by a numerical procedure, the fast attitude variables in the same interval. A few applications are presented and discussed to show the reliability and accuracy of the met hod. The proposed procedure appears very promising for those applications where fast flight simulations are required and also for those problems where advantage has to be taken of the time-scale separation. (Author)

A Visual-Haptic Display for Human and Autonomous Systems Integration

This paper introduces a novel concept of visual-haptic display for situational awareness improvement for crowded and low altitude airspace situations. The visual augmentation display that constitutes of Virtual Fences delimiting no-fly zones, and a specific tri-dimensional highlight graphics that enhances visibility of other remotely piloted or autonomous agents, as well as conventional manned aircraft operating in the area is presented first. Then the Shared Control paradigm and the Haptic Force generation mechanism, based on a Proportional-Derivative-like controller applied to repulsive forces generated by the Virtual Fences and other UAVs are introduced and discussed. Simulations with 26 pilots were performed in a photo-realistic synthetic environment showing that the combined use of Visual-haptic feedback outperforms the Visual Display only in helping the pilot keeping a safe distance from no-fly zones and other vehicles.

Development of a Simplied Helicopter Model for Piloted Training Simulation

qualication standards for the simulator, a series of features are added to the baseline model so as to deal with all ight conditions possibly encountered during vehicle operation. These additional features include engine model and governor, a simple undercarriage and ground{eect model, the representation of vortex ring state and icing phenomena. The architecture of both hardware and software for the simulator is presented and discussed.

Design of the flight management system for a shrouded-fan uninhabited aerial vehicle

Abstract Following a brief description of the program involving the realization of a rotary wing uninhabited aerial vehicle (UAV) for science applications, the flight management system of the vehicle is discussed in terms of sensors, flight computer, and software processes. Complicated and unstable dynamics of the baseline airframe, together with relevant uncertainties in the UAV model, prompted use of a robust multi-variable controller for stabilization and control augmentation. Control software is automatically generated and implemented in the onboard computer. Real-time, hardware-in-the-loop simulation is used to test and validate control algorithms as well as to collect data on response to pilot input and, finally, to assess and possibly improve the characteristics of the graphical user interface providing flight and mission data to the ground operator.

Design and Development of the Engine Unit for a Twin-Rotor Unmanned Aerial Vehicle

Advanced computer-aided technologies played a crucial role in the design of an unconventional Uninhabited Aerial Vehicle (UAV), developed at the Turin Technical University and the University of Rome “La Sapienza”. The engine unit of the vehicle is made of a complex system of three two stroke piston engines coupled with two counter-rotating three-bladed rotors, controlled by rotary PWM servos. The focus of the present paper lies on the enabling technologies exploited in the framework of activities aimed at designing a suitable and reliable engine system, capable of performing the complex tasks required for operating the proposed rotorcraft. The synergic use of advanced computational tools for estimating the aerodynamic performance of the vehicle, solid modeling for mechanical components design, and rapid prototyping techniques for control system logic synthesis and implementation will be presented.