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Calibri 83ffff̙̙3f3fff3f3f33333f33333.`TU Delft Repositoryg Euuidrepository linktitleauthorcontributorpublication yearabstract
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departmentresearch group programmeprojectcoordinates)uuid:5bfa9cf493e04b4e81befb970a4271a1Dhttp://resolver.tudelft.nl/uuid:5bfa9cf493e04b4e81befb970a4271a1[Horizontal and vertical thermospheric crosswind from GOCE linear and angular accelerationspVisser, T. (TU Delft Astrodynamics & Space Missions); March, G. (TU Delft Novel Aerospace Materials; TU Delft Astrodynamics & Space Missions); Doornbos, E.N. (TU Delft Novel Aerospace Materials; TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Novel Aerospace Materials; TU Delft Control & Simulation); Visser, P (TU Delft Novel Aerospace Materials)Thermospheric wind measurements obtained from linear nongravitational accelerations of the Gravity field and steadystate Ocean Circulation Explorer (GOCE) satellite show discrepancies when compared to groundbased measurements. In this paper the crosswind is derived from both the linear and the angular accelerations using a newly developed iterative algorithm. The two resulting data sets are compared to test the validity of wind derived from angular accelerations and quantify the uncertainty in accelerometerderived wind data. In general the difference is found to be less than 50 m/s vertically after highpass filtering, and 100 m/s horizontally. A sensitivity analysis reveals that continuous thrusting is a major source of uncertainty in the torquederived wind, as are the magnetic properties of the satellite. The energy accommodation coefficient is identified as a particularly promising parameter for improving the consistency of thermospheric crosswind data sets in the future. The algorithm may be applied to obtain density and crosswind from other satellite missions that lack accelerometer data, provided the attitude and orbit are known with sufficient accuracy.zAngular accelerations; Gravity field and steadystate Ocean Circulation Explorer (GOCE); Thermospheric wind; Vertical windenjournal article
20210201)uuid:65eebe8729934fbabd09f9c91ff6b7d4Dhttp://resolver.tudelft.nl/uuid:65eebe8729934fbabd09f9c91ff6b7d4Distributed approach for aerodynamic model identification of the ice aircraft using the alternating direction method of multipliers in combination with simplotope bsplinesvan den Aarssen, M.S.T. (Student TU Delft); Visser, T. (TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Control & Simulation)High performance control allocation methods for the Innovative Control Effectors (ICE) aircraft require accurate onboard aerodynamic models, with preferably first order continuity. Simplotope BSplines, an extension on Simplex BSplines, have a high approximation power by using local cost functions. However, enforcing global continuity produces computationally expensive optimization problems. This paper presents a distributed approach, using the Alternating DirectionMethod of Multipliers (ADMM), to reduce the complexity of the BCoefficients estimation. ADMM decouples the simplotopes, and introduces coupling coefficients to enforce global continuity, resulting in a parallel estimation algorithm whose complexity is depending solely on the partition size, being independent of refinement of the model tessellation. Results show that for a 3D model, the distributed algorithm converges steadily to the global solution with a good approximation after a couple hundred iterations. Validation results of the distributed approach were similar to those of the global optimal solution for various noise intensities, and the continuity constraints were satisfied with maximum mismatches below 104. The distributed approach has been used to construct a first order continuous aerodynamic model for the ICE aircraft, which has been implemented in Simulink, and proven to perform well compared to the original model.conference paper9781624105784)uuid:b87d25053c8f4e4d8< ed6bb36c8f29c73Dhttp://resolver.tudelft.nl/uuid:b87d25053c8f4e4d8ed6bb36c8f29c73Characterization of Thermospheric Vertical Wind Activity at 225 to 295km Altitude Using GOCE Data and Validation Against Explorer MissionsVisser, T. (TU Delft Astrodynamics & Space Missions); March, G. (TU Delft Astrodynamics & Space Missions); Doornbos, E.N. (TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Control & Simulation); Visser, P.N.A.M. (TU Delft Astrodynamics & Space Missions)Recently, the horizontal and vertical cross wind at 225 to 295km altitude were derived from linear acceleration measurements of the Gravity field and steadystate Ocean Circulation Explorer satellite. The vertical component of these wind data is compared to wind data derived from the mass spectrometers of the Atmosphere Explorer C and E and Dynamics Explorer 2 satellites. From a statistical analysis of the 120s movingwindow standard deviation of the vertical wind ((V<sub>z</sub>)), no consistent discrepancy is found between the accelerometerderived and the mass spectrometerderived data. The validated Gravity field and steadystate Ocean Circulation Explorer data are then used to investigate the influence of several parameters and indices on the vertical wind activity. To this end, the probability distribution of (V<sub>z</sub>) is plotted after distributing the data over bins of the parameter under investigation. The vertical wind is found to respond strongly to geomagnetic activity at high latitudes, although the response settles around a maximum standard deviation of 50m/s at an Auroral Electrojet index of 800. The dependence on magnetic local time changes with magnetic latitude, peaking around 4:30 over the polar cap and around 01:30 and 13:30 in the auroral oval. Seasonal effects only become visible at low to middle latitudes, revealing a peak wind variability in both local summer and winter. The vertical wind is not affected by the solar activity level.Atmosphere Explorers; Dynamics Explorer 2; Gravity field and steadystate Ocean Circulation Explorer (GOCE); thermospheric vertical wind)uuid:3e2024aa3ed54e8fbaa8b74a86d2a94cDhttp://resolver.tudelft.nl/uuid:3e2024aa3ed54e8fbaa8b74a86d2a94c.Torque model verication for the GOCE satelliteVisser, T. (TU Delft Astrodynamics & Space Missions); Doornbos, E.N. (TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Control & Simulation); Visser, P.N.A.M. (TU Delft Astrodynamics & Space Missions); Fritsche, Bent (Hyperschall Technologie Gttingen)
20201101)uuid:7e7b99f4c4974291b1528d82d1258dc3Dhttp://resolver.tudelft.nl/uuid:7e7b99f4c4974291b1528d82d1258dc3IHorizontal and Vertical Wind Measurements from GOCE Angular AccelerationsVisser, T. (TU Delft Astrodynamics & Space Missions); Doornbos, E.N. (TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Control & Simulation); Visser, P.N.A.M. (TU Delft Astrodynamics & Space Missions)UBecause of the highly accurate accelerometers, the GOCE mission has proven to be a unique source of thermosphere neutral density and crosswind data. In the current methods, in which only the horizontal linear accelerations are used, the vertical winds cannot be obtained. In the algorithm proposed in this paper, angular accelerations derived from the individual gradiometer accelerations are used to obtain the vertical wind speeds as well. To do so, the measured angular rate and acceleration are combined to find a measurement of the torque acting on the spacecraft. This measurement is then corrected for modeled control torque applied by the magnetic torquers, aerodynamic torque, gravity gradient torque, solar radiation pressure torque, the torque caused by the misalignment of the thrust with respect to the center of gravity, and magnetic torque caused by the operation of several different subsystems of the spacecraft bus. Since the proper documentation of the magnetic properties of the payload were not available, a least squares estimate is made of one hard and one softmagnetic dipole pertaining to the payload,< on an aerodynamically quiet day. The model for aerodynamic torque uses moment coefficients from MonteCarlo Test Particle software ANGARA. Finally the neutral density, horizontal crosswind, and vertical wind are obtained from an iterative process, in which the residual forces and torques are minimized. It is found that, like horizontal wind, the vertical wind responds strongly to geomagnetic storms. This response is observed over the whole latitude range, and shows seasonal variations.poster)uuid:6c53412db1fa4172856edb6979033321Dhttp://resolver.tudelft.nl/uuid:6c53412db1fa4172856edb6979033321)uuid:2ce07950b1d345c188e29bb15070ba53Dhttp://resolver.tudelft.nl/uuid:2ce07950b1d345c188e29bb15070ba53@System Identification using the Multivariate Simplotope BSplineVisser, T. (TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)In recent research efforts the multivariate simplex spline has shown great promise in system identification applications. It has high approximation power, while its linearity in the parameters allows for computationally efficient estimation of the coefficients. In this paper the multivariate simplotope spline is derived from this spline, and compared to its simplex counterpart in a system identification setting. Contrary to the simplex spline, the simplotope spline allows the user to incorporate expert knowledge of the system in his models. Whereas in the first spline all variables are included in a complete polynomial, in the latter the user can split the variables in decoupled subsets. By fitting models to specifically designed test functions it is shown that this can indeed improve the approximation performance in terms of both the error metrics and the number of Bcoefficients required. This comes at the price of a higher total degree, and therefore an increased sensitivity to Runge's phenomenon in case of poor data distribution. Finally an attempt is made to apply the proposed methods to a set of flight data of the DelFly II, a flapping wing micro aerial vehicle. It is found that the used data set is not suitable for global system identification, as the data in concentrated in lowdimensional clusters in the fivedimensional state space. Therefore it is advised that a more suitable data set is obtained to validate the simplotope spline in a system identification setting.)uuid:8d88e5fb02124f64a0536734c19dd397Dhttp://resolver.tudelft.nl/uuid:8d88e5fb02124f64a0536734c19dd397 GOCE Aerodynamic Torque ModelingVisser, T. (TU Delft Astrodynamics & Space Missions); Doornbos, E.N. (TU Delft Astrodynamics & Space Missions); de Visser, C.C. (TU Delft Control & Simulation); Visser, P.N.A.M. (TU Delft Astrodynamics & Space Missions); Fritsche, B (Hyperschall Technologie Gttingen)In recent studies thermospheric densities and crosswinds have been derived from linear acceleration measurements of the gradiometer on board the GOCE satellite. Our current work is aimed at analyzing also the angular accelerations, in order to improve the thermosphere density and wind data by allowing for the estimation of more unknown parameters. On this poster an overview is provided of the modeling efforts involved in isolating the aerodynamic torque. The intermediate result is a comparison of modeled and measured torques. Each box contains a plot of the torque from a specific source, compared to the measured torque, on October 16th, 2013. A short description of the model for each torque is also provided.
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