Subramanian Ramasamy

4-Dimensional Trajectory Negotiation and Validation System for the Next Generation Air Traffic Management

As part of the ENDEAVOUR project (Evolutionary Network-Centric Technologies for Four Dimensional Trajectory (4DT) Based Operations in Europe: ATM and Avionics Systems for Intent Validation, Real-Time Optimisation and Uncertainty-Resilient Operations), a novel 4DT Planning, Negotiation and Validation (4-PNV) system was developed for integration into the next generation Communications, Navigation and Surveillance/Air Traffic Management (CNS/ATM) environment. The 4-PNV system provides 4DT negotiation and validation capabilities for the Next Generation ATM, in combination with the Next Generation of Flight Management Systems (NG-FMS) and Next Generation Air-to-ground Data-Link (NG-ADL) that are also being developed. The NGFMS generates globally optimal trajectories based on environmental and operational weightings, meeting the combined objectives of the Single European Sky ATM Research (SESAR) and Clean Sky Joint Technology Initiative for Aeronautics and Air Transport programmes. The 4-PNV system receives multiple options of 4DT intents from each aircraft equipped with NG-FMS, and validates them through real-time negotiation, resolving traffic conflicts, thus establishing optimal and safe trajectory solutions for each aircraft.

Next Generation Flight Management System for Real-Time Trajectory Based Operations

This paper presents the concept of operations, architecture and trajectory optimisation algorithms of a Next Generation Flight Management System (NG-FMS). The NG-FMS is developed for Four Dimensional (4D) Intent Based Operations (IBO) in the next generation Communications, Navigation, Surveillance and Air Traffic Management system (CNS+A) context. The NG-FMS, primarily responsible for the aircraft navigation and guidance task, acts as a key enabler for achieving higher level of operational efficiency and mitigating environmental impacts both in manned and unmanned aircraft applications. The NG-FMS is interoperable with the future ground based 4DT Planning, Negotiation and Validation (4-PNV) systems, enabling automated Trajectory/Intent Based Operations (TBO/IBO). After the NG-FMS architecture is presented, the key mathematical models describing the trajectory generation and optimisation modes are introduced. A detailed error analysis is performed and the uncertainties affecting the nominal trajectories are studied to obtain the total NG-FMS error budgets. These are compared with the Required Navigation Performance (RNP) values for the various operational flight tasks considered.

Real-Time Trajectory Optimisation Models for Next Generation Air Traffic Management Systems

This paper presents models and algorithms for real-time 4-Dimensional Flight Trajectory (4DT) operations in the next generation Communications, Navigation, Surveillance/Air Traffic Management (CNS/ATM) systems. In particular, the models are employed for multi-objective optimisation of 4DT intents in ground-based 4DT Planning, Negotiation and Validation (4-PNV) systems and in airborne Next Generation Flight Management Systems (NG-FMS). The assumed timeframe convention for offline and online air traffic operations is introduced and discussed. The adopted formulation of the multi-objective 4DT optimisation problem includes a number of environmental objectives and operational constraints. In particular, the paper describes a real-time multi-objective optimisation algorithm and the generalised expression of cost function adopted for penalties associated with specific airspace volumes, accounting for weather models, condensation trails models and noise models.

A Low-cost Vision Based Navigation System for Small Size Unmanned Aerial Vehicle Applications

A low cost navigation system based on Vision Based Navigation (VBN) and other avionics sensors is presented, which is designed for small size Unmanned Aerial Vehicle (UAV) applications. The main objective of our research is to design a compact, lightweight and relatively inexpensive system capable of providing the required navigation performance in all phases of flight of a small UAV, with a special focus on precision approach and landing, where Vision Based Navigation (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 and MEMS-IMU 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 UAV 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/IMU/GPS) 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/IMU/GPS/ADM) also 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 frequent re-initialisation of the ADM data module, which is strongly dependent on the UAV flight dynamics and the specific manoeuvring transitions performed.

A Laser Obstacle Warning and Avoidance System for Unmanned Aircraft Sense-and-Avoid

This paper presents an overview of the research activities performed to develop a new scaled variant of the Laser Obstacle Avoidance and Monitoring (LOAM) system for small-to-medium size Unmanned Aircraft (UA) platforms. This LOAM variant (LOAM+) is proposed as one of the non-cooperative sensors employed in the UA Sense-and-Avoid (SAA) system. After a brief description of the LOAM system architecture, the mathematical models developed for obstacle avoidance and calculation of alternative flight path are presented. Additionally, a new formulation is adopted for defining the uncertainty volumes associated with the detected obstacles. Simulation case studies are carried out to evaluate the performances of the avoidance trajectory generation and optimisation algorithms, which demonstrate the ability of LOAM+ to effectively detect and avoid fixed low-level obstacles in the intended path.

An innovative navigation and guidance system for small unmanned aircraft using low-cost sensors

Purpose – The purpose of this paper is to design a compact, light and relatively inexpensive navigation and guidance system capable of providing the required navigation performance (RNP) in all phases of flight of small unmanned aircrafts (UA), with a special focus on precision approach and landing. Design/methodology/approach – Two multi-sensor architectures for navigation and guidance of small UA are proposed and compared in this paper. These architectures are based, respectively, on a standard extended Kalman filter (EKF) approach and a more advanced unscented Kalman filter (UKF) approach for data fusion of global navigation satellite systems (GNSS), micro-electro-mechanical system (MEMS)-based inertial measurement unit (IMU) and vision-based navigation (VBN) sensors. Findings – The EKF-based VBN-IMU-GNSS-aircraft dynamics model (ADM) (VIGA) system and the UKF-based system (VIGA+) performances are compared in a small UA integration scheme (i.e. AEROSONDE UA platform) exploring a representative cross-se...

4 Dimensional trajectory functionalities for air traffic management systems

The research presented in this paper focuses on the conceptual design of an innovative Air Traffic Management (ATM) system featuring automated 4-Dimensional Trajectory (4DT) Planning, Negotiation and Validation (4-PNV) functionalities to enable Intent Based Operations (IBO). In order to meet the demanding requirements set by national and international organisations for the efficiency and environmental sustainability of air transport operations, a multi-objective 4DT optimization algorithm is introduced that represents the core element of the 4DT planning functionality. The 4-PNV system interacts with airborne avionics also developed for 4DT-IBO such as the Next Generation Flight Management System (NG-FMS) on-board manned aircraft and Next Generation Mission Management System (NG-MMS) for Remotely Piloted Aircraft Systems (RPAS). In this article we focus on the 4-PNV algorithms, and specifically on the multi-objective 4DT optimization algorithm for strategic and tactical online operations. Simulation case studies are carried out to test the key system performance metrics such as 4DT computational time in online tactical Terminal Manoeuvring Area (TMA) operations.

UAVs assisted delay optimization in heterogeneous wireless networks

In this letter, an optimal placement and distribution of cooperative unmanned aerial vehicles (UAVs) in the next generation heterogeneous networks is presented in order to optimize the overall network delays. The positioning issue is formulated as a minimax facility problem, which is then resolved using the entropy nets by formation of an optimal placement algorithm. The effectiveness of the proposed approach is demonstrated in terms of significant gains including increased UAV positioning accuracy and reduced delays in UAV allocation.

A unified approach to cooperative and non-cooperative Sense-and-Avoid

Cooperative and non-cooperative Sense-and-Avoid (SAA) capabilities are key enablers for Unmanned Aircraft Vehicle (UAV) to safely and routinely access all classes of airspace. In this paper state-of-the-art cooperative and non-cooperative SAA sensor/system technologies for small-to-medium size UAV are identified and the associated multi-sensor data fusion techniques are introduced. A reference SAA system architecture is presented based on Boolean Decision Logics (BDL) for selecting and sorting non-cooperative and cooperative sensors/systems including both passive and active Forward Looking Sensors (FLS), Traffic Collision Avoidance System (TCAS) and Automatic Dependent Surveillance - Broadcast (ADS-B). After elaborating the SAA system processes, the key mathematical models associated with both non-cooperative and cooperative SAA functions are presented. The analytical models adopted to compute the overall uncertainty volume in the airspace surrounding an intruder are described. Based on these mathematical models, the SAA Unified Method (SUM) for cooperative and non-cooperative SAA is presented. In this unified approach, navigation and tracking errors affecting the measurements are considered and translated to unified range and bearing uncertainty descriptors, which apply both to cooperative and non-cooperative scenarios. Simulation case studies are carried out to evaluate the performance of the proposed SAA approach on a representative host platform (AEROSONDE UAV) and various intruder platforms. Results corroborate the validity of the proposed approach and demonstrate the impact of SUM towards providing a cohesive logical framework for the development of an airworthy SAA capability, which provides a pathway for manned/unmanned aircraft coexistence in all classes of airspace.

Cognitive pilot-aircraft interface for single-pilot operations

Abstract Considering the foreseen expansion of the air transportation system within the next two decades and the opportunities offered by higher levels of automation, Single-Pilot Operations (SPO) are regarded as viable alternatives to conventional two-pilot operations for commercial transport aircraft. In comparison with current operations, SPO require higher cognitive efforts, which potentially result in increased human error rates. This article proposes a novel Cognitive Pilot-Aircraft Interface (CPAI) concept, which introduces adaptive knowledge-based system functionalities to assist single pilots in the accomplishment of mission-essential and safety-critical tasks in modern commercial transport aircraft. The proposed CPAI system implementation is based on real-time detection of the pilot’s physiological and cognitive states, allowing the avoidance of pilot errors and supporting enhanced synergies between the human and the avionics systems. These synergies yield significant improvements in the overall performance and safety levels. A CPAI working process consisting of sensing, estimation and reconfiguration steps is developed to support the assessment of physiological and external conditions, a dynamic allocation of tasks and adaptive alerting. Suitable mathematical models are introduced to estimate the mental demand associated to each piloting task and to assess the pilot cognitive states. Suitably implemented decision logics allow a continuous and optimal adjustment of the automation levels as a function of the estimated cognitive states. Representative numerical simulation test cases provide a preliminary validation of the CPAI concept. In particular, the continuous adaptation of the flight decks automation successfully maintains the pilots task load within an optimal range, mitigating the onset of hazardous fatigue levels. It is anticipated that by including suitably designed Psychophysiological-Based Integrity Augmentation (PBIA) functionalities the CPAI system will allow to fulfil the evolving aircraft certification requirements and hence support the implementation of SPO in commercial transport aircraft.