Dan Ivanescu

European Organisation For The Safety Of Air Navigation | Eurocontrol · Air Traffic Services

A new technique, Point Merge, for merging aircraft without vectoring in terminal areas (TMA), is modelled, and used in fast-time simulations. Four arrival traffic streams are merged for landing on a single runway. A method for designing fast-time models of vectoring and Point Merge is proposed and validated using real-time simulation trajectories....

Aircraft arrival punctuality is a key performance measure of the Single European Sky Air Traffic Management Research (SESAR) target concept. A large source of uncertainty in landing times today is due to the merging of poorly synchronised traffic streams in the terminal area (TMA). The objective of this collaborative study was to evaluate benefits...

Research results from domains such as road highway traffic and military vehicle platoons conclude that string stability cannot be obtained when vehicles use only relative spacing information to maintain constant distance behind a predecessor. Air traffic studies confirm these results but such instability has not been shown for constant time delay b...

The objective of this air traffic management study was to analyse the trade-off between time spacing accuracy and corresponding control effort in a potential future application of airborne separation assistance systems (ASAS). The ASAS application airborne spacing sequencing and merging was simulated in fast-time. Lead aircraft speed profiles were...

This air traffic management study designed a cockpit tool for assisting pilots to achieve a constant time delay behind a lead aircraft. A system architecture for manual and automatic `merge' and `remain' modes was proposed with required design and performance requirements. A manual `merge' guidance mode suggesting calibrated airspeed was developed...

A flight deck tool was designed to assist pilots in acquiring and maintaining a required time delay behind a lead aircraft. A system architecture for manual and automatic ‘merge behind’ and ‘remain behind’ modes is proposed with performance requirements and design constraints. A manual ‘remain behind’ guidance mode suggesting calibrated airspeed wa...

This air traffic management research study analysed the interaction between a potential future airborne spacing application and an existing Airborne Collision Avoidance System (ACAS). The time-based airborne spacing application ‘merge behind’ was simulated in fasttime for a range of merge angles (45°, 90°, 135° and 180°), target spacing times (60 a...

This report presents the results of aircraft guidance model based experiments conducted at the EUROCONTROL Experimental Centre (EEC) in 2002 and 2003. These experiments fitted in with a series of human-in-the-loop and model based validation exercises aimed at investigating the use of spacing instructions (denoted airborne spacing) for sequencing of...

The effect of ADS-B update rate, latency and accuracy on the airborne spacing performance of a sequence of six aircraft in descent was investigated using fast time simulation. Two different spacing criteria based on constant distance (7 nmi) and constant time delay (60 s) were evaluated using a spacing guidance law between aircraft. The performance...

This air traffic management research study analysed the performance of constant time based airborne spacing under different operational conditions using fast time simulation. The effects of mixed aircraft types and wind conditions on the ability of an aircraft to maintain a constant time delay along-track spacing behind a descending lead aircraft w...

This air traffic management research study analysed the range of admissible entry conditions for using airborne spacing to sequence aircraft on multiple trajectories merging at a fixed waypoint. A guidance law was developed capable of merging multiple aircraft in descent under turbulent wind conditions. Effects of initial distances and speeds on th...

This study analysed the performance of constant time based airborne spacing under different operational conditions using fast time simulation. The effects of time based spacing criteria, mixed aircraft types and wind conditions on the ability of an aircraft to maintain a time spacing behind a descending lead aircraft were investigated. The spacing...

This paper focuses on the problem of uniform asymptotic stability of a class of linear neutral systems. Sufficient conditions for delay-dependent stability are given in terms of the existence of solutions of some linear matrix inequalities. Furthermore, the proposed technique extends to neutral systems the results obtained for delay-difference equa...

This paper analyses spacing guidance laws for sequencing aircraft on merging trajectories in the research context of delegating spacing related tasks from air traffic controller to the flight deck. Three different guidance laws were designed for establishing a desired spacing and speed between aircraft at a given waypoint. The performance of each g...

This paper investigates the control problem of a large interconnected power systems in the presence of measurement delays. A remote output feedback controller is designed in order to stabilize the power system and to improve the damping of low‐frequency inter‐area oscillations. Sufficient conditions for closed‐loop stability, f...

This paper focuses on some closed-loop delay-dependent asymptotic stability problems for a large class of nonlinear underactuated mechanical systems subject to delayed inputs. Upper bounds on the delays size such that the closed-loop system stability is guaranteed are obtained in terms of some matrix inequalities. Using a time-domain approach, we s...

This paper investigates the robust stability of linear neutral delay systems. The uncertain time delay neutral systems under consideration are described by functional differential equations of neutral type with norm bounded nonlinear uncertainties and unknown constant delays. The novelty here is to consider a delay dependent robust stability approa...

This paper investigates the control problem of a large interconnected power system in the presence of measurement delays. A remote output feedback controller is designed in order to stabilize the power system and to improve the damping of low-frequency inter-area oscillations. Sufficient conditions for closed-loop stability, functions of the input...

The paper deals with the generalized Popov theory applied to uncertain systems with distributed time delay. Sufficient conditions for stabilizing this class of delayed systems as well as for γ-attenuation achievement are given in terms of algebraic properties of a Popov system via a Lyapunov-Krasovskii functional. The considered approach is new in...

This paper focuses on the problem of uniform asymptotic stability of a class of linear neutral systems. The delays are assumed to be unknown, but constant. Sufficient conditions for delay-dependent stability are given in terms of the existence of symmetric and positive definite solutions of some linear matrix inequalities. Furthermore, the proposed...

This paper presents simple and explicit formulae of an ‘observer-based H∞ controller’ for linear time-delay systems. Based on the LMI approach, we design a dynamical controller which guarantees the asymptotic stability of the closed-loop system and reduces the effect of the perturbation to a prescribed level. The main contribution of the paper is t...

This paper demonstrates the effectiveness of a novel, robust four-input/four-output controller that takes into account input signal delay through application on 4- and 29-machine test systems. The proposed centralized controller was developed for wide-area applications, where issues of maximum power flow and power quality are important. The algorit...

This paper focuses on the Popov generalized theory for a class of some linear systems including discrete and distributed delays. Sufficient conditions for stabilizing such systems as well as for coerciveness of an appropriate quadratic cost are developed. The obtained results are applied for the design of a memoryless state feedback control law whi...

The paper deals with the generalized Popov theory applied to systems with distributed time delay. Sufficient conditions for stabilizing this class of delayed systems as well as for γ - attenuation achievement are given in terms of algebraic properties of a Popov system via a Liapunov - Krasovskii functional. The considered approach is new in the co...

We develop an observer-based H^∞ controller for linear time delay systems. The main contribution is to provide a closed loop stability analysis for the general case when the system time delay is unknown. Our analysis is based on model transformation and on a comparison principle. This allows us to get delay dependent stabilizing condition...

This paper explores the problem of input delay for a robust stabilizing controller including synchronized measurements. The proposed controller replaces a standard power system stabilizer and is shown to maintain the stability of an interconnected power system under both normal and severe operating conditions. This performance is accomplished throu...

In this note, we are concerned with robust LQ control problem for uncertain linear time-delay systems. More precisely, we design a memoryless static state feedback controller such that the closed-loop system is robustly α - stable for all admissible uncertainty. Furthermore, an upper bound for a given performance index is guaranteed. We show that f...

The paper deals with the generalized Popov theory applied to state-delayed systems. Sufficient conditions for stabilizing uncertain time-delay systems as well as for γ — attenuation achievement are given in terms of algebraic properties of a Popov system via a Liapunov — Krasovskii functional. The considered approach, successfully applied to classi...

This paper is concerned with robust linear quadratic control for uncertain linear time-delay systems using a linear matrix inequality (LMI) approach. The objective is to design a memoryless static state feedback controller such that the energy of a specific error output signal is constrained by certain upper bound. We show that feasibility of a pai...