Institut supérieur de l'aéronautique et de l'espace

About: Institut supérieur de l'aéronautique et de l'espace is a based out in . It is known for research contribution in the topics: Mars Exploration Program & Seismometer. The organization has 445 authors who have published 644 publications receiving 8049 citations. The organization is also known as: ISAE SUPAERO & National Higher French Institute of Aeronautics and Space.

Robust Filtering Techniques for RTK Positioning in Harsh Propagation Environments.

Abstract: Global navigation satellite systems (GNSSs) play a key role in intelligent transportation systems such as autonomous driving or unmanned systems navigation. In such applications, it is fundamental to ensure a reliable precise positioning solution able to operate in harsh propagation conditions such as urban environments and under multipath and other disturbances. Exploiting carrier phase observations allows for precise positioning solutions at the complexity cost of resolving integer phase ambiguities, a procedure that is particularly affected by non-nominal conditions. This limits the applicability of conventional filtering techniques in challenging scenarios, and new robust solutions must be accounted for. This contribution deals with real-time kinematic (RTK) positioning and the design of robust filtering solutions for the associated mixed integer- and real-valued estimation problem. Families of Kalman filter (KF) approaches based on robust statistics and variational inference are explored, such as the generalized M-based KF or the variational-based KF, aiming to mitigate the impact of outliers or non-nominal measurement behaviors. The performance assessment under harsh propagation conditions is realized using a simulated scenario and real data from a measurement campaign. The proposed robust filtering solutions are shown to offer excellent resilience against outlying observations, with the variational-based KF showcasing the overall best performance in terms of Gaussian efficiency and robustness.

Aerodynamic Modeling of Propeller Forces and Moments at High Angle of Incidence

Abstract: A reduced-order model to estimate the aerodynamic forces and moments of a propeller at incidence angle from 0° to 90° was presented. The objective was to provide an inexpensive and effective approach to analyse propeller performance of a vertical/short take-off and landing aerial vehicle during transition flight. The model was based on blade element theory and was coupled with an extended momentum theory or Pitt & Peters inflow model to include the asymmetrical flow condition. The aerofoil aerodynamic data was provided by an empirical model that extended lift and drag polar to a broad angle-of-attack range suitable in transition flight. Furthermore a rotational stall delay model and a radial flow correction model have been incorporated to include primary 3-dimensional effects. The result has been presented and compared with past experiment and unsteady Reynolds-averaged Navier-Stokes solution under similar conditions.

Probabilistic Block-Matching based 6D camera localization

Abstract: This paper describes a full 6D localization algorithm based on probabilistic motion field. The motion field is obtained by an adaptation of the video compression algorithm known as Block-Matching which provides a sparse optical flow. Such a technique is very fast and allows real time applications. Image is decomposed in a grid of rectangular blocks. For each block, a relative displacement between consecutive images is calculated. Obtained motion flow is analyzed probabilistically in order to extract for each movement detection its uncertainty and to obtain subpixelic information about the area movement. Such motion flow is then used in order to obtain full 6 degrees of freedom camera localization using epipolar geometry based techniques without any 3D landmark reconstruction requirement. The method is applied to real data set obtained from a mobile robot and compared with SIFT and Harris detection.

Single-fed circularly polarized dielectric resonator antenna using a uniaxial anisotropic material

Abstract: A Dielectric Resonator Antenna operating in circular polarization is presented. The proposed antenna is formed by a uniaxial anisotropic dielectric and a ground plane. The optimization of the permittivity tensor and antenna dimensions is performed both theoretically and numerically using an Eigen mode analysis in Ansys HFSS. A good agreement is obtained for the resonant frequencies and quality factors of the different modes. The uniaxial anisotropic DRA radiates two degenerate orthogonal modes, TE111 x and TE111 y , with equal amplitudes and 90° phase difference in order to achieve circular polarization. An impedance bandwidth of 9.8% is accomplished and a broadside radiation pattern with left-hand circular polarization (LHCP) is achieved in simulation. Furthermore, an Axial Ratio (AR) of 0.06 dB at 2.45 GHz and a 3-dB AR bandwidth of 2.04% are obtained. The maximum simulated directivity is equal to 6.56 dBi.

3D-mapping-aided gnss localization for integrity monitoring in urban environments

Abstract: In order to foster the development of Global Navigation Satellite Systems (GNSS) for land navigation services, there is a pressing need for providing a trust level of the localization solution, especially for liability critical applications. In view of such need, integrity monitoring aims to compute protection levels that successfully bounds positioning errors in nominal conditions. Conventional Receiver Autonomous Integrity Monitoring (RAIM) algorithms have been widely used for integrity monitoring especially for aircraft navigation. Conventional RAIM starts out by supposing a Gaussian measurement errors model with known means and variances. However, this assumption does not hold in dense urban environment. Therefore, we propose novel algorithms that dispenses with this classical assumption. We use external information provided by a 3D GNSS simulation to characterize GNSS errors in urban areas. We propose two approaches for protection levels computation based on comparison between predicted 3D pseudo-ranges bias and computed thresholds. These approaches give a new vision on integrity control based on indicators on the pseudo-ranges bias. Experimental results show that proposed algorithms give an acceptable success rate on integrity monitoring in a harsh areas.