Dr. Roberto Sabatini Profile

Dr. Roberto Sabatini

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Publications (3)

Proceedings Article | 11 May 2012 Paper

Airborne laser systems for atmospheric sounding in the near infrared

Roberto Sabatini, Mark Richardson, Huamin Jia, David Zammit-Mangion

Proceedings Volume 8433, 843314 (2012) https://doi.org/10.1117/12.915718

KEYWORDS: Absorption, Transmittance, Atmospheric particles, Scattering, Atmospheric propagation, Atmospheric laser remote sensing, Carbon dioxide, Near infrared, Atmospheric modeling, Aerosols

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Proceedings Article | 10 May 2012 Paper

Design and integration of vision based sensors for unmanned aerial vehicles navigation and guidance

Roberto Sabatini, Celia Bartel, Anish Kaharkar, Tesheen Shaid

Proceedings Volume 8439, 84390O (2012) https://doi.org/10.1117/12.922776

KEYWORDS: Absorption, Transmittance, Atmospheric particles, Scattering, Atmospheric propagation, Carbon dioxide, Atmospheric modeling, Atmospheric laser remote sensing, Aerosols, Data modeling

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In this paper we present a novel Navigation and Guidance System (NGS) for Unmanned Aerial Vehicles (UAVs) based on Vision Based Navigation (VBN) and other avionics sensors. The main objective of our research is to design a lowcost and low-weight/volume NGS capable of providing the required level of performance in all flight phases of modern small- to medium-size UAVs, with a special focus on automated precision approach and landing, where VBN techniques can be fully exploited in a multisensory integrated architecture. Various existing techniques for VBN are compared and the Appearance-based Navigation (ABN) approach is selected for implementation. Feature extraction and optical flow techniques are employed to estimate flight parameters such as roll angle, pitch angle, deviation from the runway and body rates. Additionally, we address the possible synergies between VBN, Global Navigation Satellite System (GNSS) and MEMS-IMU (Micro-Electromechanical System Inertial Measurement Unit) sensors and also the use of Aircraft Dynamics Models (ADMs) to provide additional information suitable to compensate for the shortcomings of VBN sensors in high-dynamics attitude determination tasks. An Extended Kalman Filter (EKF) is developed to fuse the information provided by the different sensors and to provide estimates of position, velocity and attitude of the platform in real-time. Two different integrated navigation system architectures are implemented. The first uses VBN at 20 Hz and GPS at 1 Hz to augment the MEMS-IMU running at 100 Hz. The second mode also includes the ADM (computations performed at 100 Hz) to provide augmentation of the attitude channel. Simulation of these two modes is performed in a significant portion of the Aerosonde UAV operational flight envelope and performing a variety of representative manoeuvres (i.e., straight climb, level turning, turning descent and climb, straight descent, etc.). Simulation of the first integrated navigation system architecture (VBN/GPS/IMU) shows that the integrated system can reach position, velocity and attitude accuracies compatible with CAT-II precision approach requirements. Simulation of the second system architecture (VBN/GPS/IMU/ADM) shows promising results since the achieved attitude accuracy is higher using the ADM/VBS/IMU than using VBS/IMU only. However, due to rapid divergence of the ADM virtual sensor, there is a need for a frequent re-initialisation of the ADM data module, which is strongly dependent on the UAV flight dynamics and the specific manoeuvring transitions performed. Finally, the output provided by the VBN and integrated navigation sensor systems is used to design a flight control system using a hybrid Fuzzy Logic and Proportional-Integral-Derivative (PID) controller for the Aerosonde UAV.

Proceedings Article | 9 May 2012 Paper

Night vision imaging systems design, integration, and verification in military fighter aircraft

Roberto Sabatini, Mark Richardson, Maurizio Cantiello, Mario Toscano, Pietro Fiorini, Huamin Jia, David Zammit-Mangion

Proceedings Volume 8439, 84390R (2012) https://doi.org/10.1117/12.915720

KEYWORDS: Light sources and illumination, Night vision, Eye, Imaging systems, Signal to noise ratio, Microchannel plates, Image intensifiers, Optical filters, Visualization, Chemical elements

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This paper describes the developmental and testing activities conducted by the Italian Air Force Official Test Centre (RSV) in collaboration with Alenia Aerospace, Litton Precision Products and Cranfiled University, in order to confer the Night Vision Imaging Systems (NVIS) capability to the Italian TORNADO IDS (Interdiction and Strike) and ECR (Electronic Combat and Reconnaissance) aircraft. The activities consisted of various Design, Development, Test and Evaluation (DDT&E) activities, including Night Vision Goggles (NVG) integration, cockpit instruments and external lighting modifications, as well as various ground test sessions and a total of eighteen flight test sorties. RSV and Litton Precision Products were responsible of coordinating and conducting the installation activities of the internal and external lights. Particularly, an iterative process was established, allowing an in-site rapid correction of the major deficiencies encountered during the ground and flight test sessions. Both single-ship (day/night) and formation (night) flights were performed, shared between the Test Crews involved in the activities, allowing for a redundant examination of the various test items by all participants. An innovative test matrix was developed and implemented by RSV for assessing the operational suitability and effectiveness of the various modifications implemented. Also important was definition of test criteria for Pilot and Weapon Systems Officer (WSO) workload assessment during the accomplishment of various operational tasks during NVG missions. Furthermore, the specific technical and operational elements required for evaluating the modified helmets were identified, allowing an exhaustive comparative evaluation of the two proposed solutions (i.e., HGU-55P and HGU-55G modified helmets). The results of the activities were very satisfactory. The initial compatibility problems encountered were progressively mitigated by incorporating modifications both in the front and rear cockpits at the various stages of the test campaign. This process allowed a considerable enhancement of the TORNADO NVIS configuration, giving a good medium-high level NVG operational capability to the aircraft. Further developments also include the design, integration and test of internal/external lighting for the Italian TORNADO "Mid Life Update" (MLU) and other programs, such as the AM-X aircraft internal/external lights modification/testing and the activities addressing low-altitude NVG operations with fast jets (e.g., TORNADO, AM-X, MB-339CD), a major issue being the safe ejection of aircrew with NVG and NVG modified helmets. Two options have been identified for solving this problem: namely the modification of the current Gentex HGU-55 helmets and the design of a new helmet incorporating a reliable NVG connection/disconnection device (i.e., a mechanical system fully integrated in the helmet frame), with embedded automatic disconnection capability in case of ejection.

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