Téo Cerqueira Revoredo

Is DNL appropriate for airport noise zoning

The use of the DNL metric in airport noise zoning is based in the works of Schultz, that were later improved by Fidell. The basic idea is to use the percentage of highly annoyed people as a parameter to organize the area around airports. In urban zoning it is recommended to use the equivalent sound level LAEQ, which uses different criteria to day and night periods to define the land use. With regards to airport noise one may use LAD and LAN metrics which are the equivalent sound levels determined for day and night period, respectively. In this case, the maximum levels chosen to the establishment of the zoning are based on the land use. It is possible, through a simple equation, to determine the DNL level associated to a LAD, LAN pair. The inverse problem, however, has not a unique solution, once this relation depends on the number of daily and night flights of the airport. Thus, the use of DNL in airport noise zoning may lead to completely different results for different airports. Exemples are presented and discussed for two main brazilian airports: Recife and Congonhas.

Unmanned Quadcopter Control Using a Motion Capture System

Commercial and research use of unmanned aerial vehicles (UAVs) have been drawing greater attention in the last years mainly due to its low cost implementation. Applications range from transportation and construction to rescue and military missions. In such context, this work presents an unmanned air vehicle control algorithm based on visual servoing using a motion capture system, including the main routines used to implement it. Using an AR.Drone quadrotor and a Vicon motion capture system, an algorithm that integrates both platforms to generate control actions for solving problems in robotics and visual servoing control is developed. Relying on a target tracking problem, on which the goal is to make the vehicle follow a moving target, a discrete time Proportional-Derivative control (PD) algorithm is proposed in which the error signal is the difference between target and vehicle positions obtained by the Vicon system. Experimental results which validate the proposal are shown and illustrate the performance of the control system. Some implementation details are also discussed.

A framework for flight guidance along air streams

With the current performances of aeronautical communication, navigation and surveillance systems, free flight and traffic management through trajectory negotiation become a reality. However, the adoption of free flight in congested airspace leads to an increase of the number of potential traffic conflicts which are solved by diverting aircraft from their original flight plan, limiting the benefits of free flight. In this paper it is proposed to organize traffic in congested airspace along main air streams which are characterized by a flyable 3D track for modern transportation aircraft. Then aircraft position can be given in a local space indexed cylindrical coordinates system which should ease the management of traffic separation and surveillance. This should result in the need to develop new 3D space indexed guidance modes to perform lateral trajectory tracking while insuring time separation between successive aircraft.

Neural Prediction of Aircraft Noise Levels Along a Flight Trajectory

Sustained increase in air transportation as well as urban encroachment have generated noise critical situations around airports. Then the prediction of the noise impact resulting from new departure/arrival procedures and new traffic patterns at airports gains more importance. Until recently this estimation has been performed on statistical grounds through the segmentation of nominal aircraft trajectories. This approach is in general not representative of the temporal dimension of the noise impacts over the airport surrounding population. To go beyond this limitation, a dynamical approach to noise impact estimation taking explicitly into consideration the operated 3D+T aircraft trajectory, is proposed in this communication. This is achieved by taking profit of the differential flatness property of the flight guidance dynamics of transportation aircraft, which allows through inversion to compute the corresponding thrust and aerodynamic conditions which are also responsible for aircraft noise generation. In numerical grounds this is achieved by building a neural network device which produces ground noise levels histories along the trajectories flown by aircraft. The proposed approach is partially validated using for comparison noise levels estimated from the Integrated Noise Model (INM). The proposed tool appears to be useful to analyze the noise impact of complex traffic scenarios including traffic dispersion phenomena.

Design of aircraft space indexed guidance along an airstream

In this study it is considered that in regions presenting high air traffic density, traffic can be organized along main airstreams using common spatial reference tracks. The adoption of such spatial references should ease the traffic separation task. The concept of airstream is introduced as well as the basis for a spatial indexed guidance law allowing accurate lateral trajectory tracking of a 3D spatial reference while spatial and time separations between successive aircraft (relative time RT constraints) present in the same air stream are insured. Here transportation aircraft guidance dynamics are expressed in a local space indexed cylindrical frame and a nonlinear control structure is proposed to achieve the guidance objective. Then standard trajectories within an airstream are characterized and parametrized. Finally the management on a spatial basis of traffic inside the airstream, where feasible and conflict free candidate trajectories are identified, is analyzed and on-line heuristic procedures are proposed.

Aircraft Noise Exposure around Airports A Differential Flat Approach for Trajectory Assessment

The sustained growth of air transportation traffic along the last decades has induced increasing noise exposure for the areas surrounding large and medium airports. International and national regulations regarding noise exposure have been established by civil aviation authorities. So to meet the resulting noise constraints, new departure and arrival procedures have been established locally. The accuracy of the trajectory followed by a given aircraft depends on many parameters such as navigation and guidance systems and trajectory dispersion is a common phenomenon which should modify the expected performance with respect to noise exposure of airport neighbourhood. Since the guidance flight dynamics present a differential flatness property, given the 4D trajectory to be followed by the aircraft, nominal control inputs which are characteristic of the generated and diffused noise, can be established. The generation of deviations from the nominal trajectory can be used to establish more realistic noise level curves at ground level. The proposed approach is illustrated in the case of an approach trajectory at Santos Dummont domestic airport.