Carlo Gerboni

I'm a PhD student of the "" group.

My research interests are focused on the control theory, especially the nonlinear one. My research project aims to find new solutions for making to fly an aerial vehicle as easy as to drive a car. This would be an important step toward future Personal Aerial Vehicles (PAVs). The reference vehicles of my work are the helicopters since they have some features that future PAVs will require. Rotorcrafts behave in a strongly unstable way and controllers are necessary in order to make these vehicles flyable for common people.

I have a B.Sc. in Biomedical Engineering and a M.Sc in Automation and Robotics engineering, both from the University of Pisa (visit the section "Curriculum Vitae"). I started my experience at the MPI doing my master thesis project and then I continued with my Ph.D. My main interest is in the automation field and most specifically in: Lyapunov theory and Lyapunov-based controllers, robust control, control of MIMO systems, mathematical methods for controlling systems, flight mechanics and flight regulation.

Development of a 6 DoF Nonlinear Helicopter Model for the MPI Cybermotion Simulator

Introduction

Studies with simulated rotorcraft dynamics generally make use of simplified linear models to approximate the system response. However, in some instances, such as for system identification or implementation of stability augmentation systems, more complex and realistic helicopter models are preferred.

Goals

The goal of this project is to implement a 6 degree-of-freedom (DoF) nonlinear helicopter model which can be used on the CyberMotion Simulator (CMS) to perform realistic flight scenarios and test new control algorithms.

Methods

The nonlinear helicopter simulation is implemented using equations found in literature [1]. The contribution of the main rotor, the tail rotor, the empennage and the fuselage are considered separately (Figure 1). A desktop simulator is used for an offline validation. Two different simulators are used to test the model with a helicopter pilot in-the-loop: a fixed-base simulator with a large visual display and a motion simulator. The model was evaluated using the American Design Standard ADS-33E-PRF [2]. The model was validated with time and frequency domain analysis to verify the implemented equations and the tuning of unknown model parameters. Furthermore, the model responses are compared with flight test data of the real helicopter. Finally, a pilot performed several maneuvers to assess the handling qualities of the model in both simulators.

Figure 1: Scheme of the model

Initial results

The results in the time domain show that the model response is very similar to the measurement of the real helicopter [3] (Figure 2a). The frequency domain analysis suggests that the model behaves correctly in a qualitative sense, but that improvements are required to reach full compliance with flight test results (Figure 2b). Preliminary tests with a pilot indicated that the overall performance of the model was good. A comparison of the results obtained with the same maneuver in the fixed-base and motion simulator show that helicopter motion supports the pilot in performing his control task.

Figure 2: Time domain validation (a); frequency domain validation (b)

Initial conclusions and future works

The model validations show that the implementation of this nonlinear model represents a first step in the direction of replicating a realistic flight experience. Further tests are required for fully validate the model and use it as framework for future works. Futere steps involve the implementation of nonlinear control strategies in order to make to fly easier and accessible for minimal-trainded pilots.

References

1. Padfield, G. D., Helicopter Flight Dynamics: the Theory and Application of Flying Qualities and Simulation Modelling, Second Edition, Blackwell Publishing, 2007.

2. Baskett, B. J., Aeronautical Design Standard performance specifications Handling Qualities requirements for military rotorcraft, Tech. rep., DTIC Document, 2000.

3. Gerboni, C. A., Geluardi, S., Olivari, M., Nieuwenhiuzen, F. M., Bülthoff, H. H., and Pollini, L., Development of a 6 DoF Nonlinear Helicopter Model for the MPI Cybermotion Simulator, 40th European Rotorcraft Forum, Southampton, UK, September 2014