Design of a monolithic Michelson interferometer for fringe imaging in a near-field, UV, direct-detection Doppler wind lidar

Herbst, Jonas; Vrancken, Patrick

doi:10.1364/ao.55.006910

Cited by 28 publications

(29 citation statements)

References 60 publications

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“…In the present paper, it is assumed (with no further discussion) that a sensor system is able to measure the vertical wind ahead of the aircraft; therefore, the vertical wind over a small time horizon in the future is known. The interested reader is referred to [16,17,38] and the references therein for further information on the sensor technologies that could provide this capability. This paper focuses rather on the question of the optimal exploitation of the previewed disturbance, and does not tackle the question of how to obtain this information in practice.…”

Section: B Preview Controlmentioning

confidence: 99%

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H_∞Optimal Control with Preview

Khalil

Fezans

2019

AIAA Scitech 2019 Forum

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Most of the gust load alleviation systems (GLAS) of currently-operational aircraft are of feedback-only control architecture based on inertial measurements. In few other aircraft, aerodynamic measurements from air data sensors are additionally included, or presently considered for inclusion, as they usually result in improving the performance of the GLAS. In both sensor types, the control system has very little time to react; and therefore, the performance of the GLAS would be further enhanced if the turbulence or gust could be measured at some distance ahead of the aircraft. Doppler LIDAR (LIght Detection And Ranging) sensors could enable such preview of the turbulence or gust, at a short range (typically between 30 and 200 meters) ahead of the aircraft. In this paper, the availability of a vertical wind profile ahead of the aircraft is assumed, and the paper focuses on the design of a load alleviation controller that exploits this information. The proposed methodology of designing this controller is based on the application of the H ∞ optimal control techniques to a discrete-time preview control problem. Minimizing the H ∞ norm of the transfer function from wind input to loads output, directly leads to the design of an effective load alleviation function. The preview-control formulation enables the design algorithm to synthesize a combined preview-capable feedforward and feedback load alleviation function. For a practical reason, the developed methodology is applied in the course of this paper to a flexible sailplane model (DLR's Discus-2c), although it is intended to be applied to larger airplanes (e.g. transport airplanes and business jets).

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Section: B Preview Controlmentioning

confidence: 99%

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H_∞Optimal Control with Preview

Khalil

Fezans

2019

AIAA Scitech 2019 Forum

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“…This other type of LIDAR systems was for instance investigated in the DELICAT European project [47,48] and further explanations on the different types of forward-pointing LIDAR systems can be found in [46]. For the sake of simplifying the explanations, only a so-called direct-detection pulsed Doppler LIDAR [43,41,46,22,5,21,49] is considered hereafter. Nevertheless, the measurement processing approach and feedforward strategy could easily be adapted to other types/variants of remote wind sensors.…”

Section: Remote Wind Sensing With Doppler Lidarmentioning

confidence: 99%

Gust load alleviation for a long-range aircraft with and without anticipation

Fezans¹,

Joos²,

Deiler³

2019

CEAS Aeronaut J

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This paper presents an overview of the DLR activities on active load alleviation in the CleanSky Smart Fixed Wing Aircraft project. The investigations followed two main research directions: the multi-objective, multimodel, structured controller design for the feedback load alleviation part and the use of Doppler LIDAR technologies for gust/turbulence anticipation. On this latter topic, the prior work made in the AWIATOR European FP6 project constituted a reference in terms of demonstrations and the objective was not to repeat these previous investigations with a real sensor in flight test but to develop new ideas for the exploitation of the Doppler LIDAR measurements for gust alleviation purposes. Very fruitful exchanges between industry partners and research organizations took place during this project and all the work presented in this paper has been made using a generic long-range benchmark provided by Airbus on the basis of the XRF-1 model.

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“…A direct-detection wind lidar can measure atmospheric wind by means of either particulate or molecular backscatter signals, typically offering much higher data coverage of the wind field from ground up to the lower mesosphere. Different spectral discriminators such as Fabry-Pérot interferometers (Chanin et al, 1989;Korb et al, 1992), Fizeau interferometers (McKay, 1998(McKay, , 2002, iodine vapor filters (Liu et al, 2002;She et al, 2007;Baumgarten, 2010;Wang et al, 2010;Hildebrand et al, 2012), Michelson interferometers (Thuillier and Hersé, 1991;Herbst and Vrancken, 2016) and Mach-Zehnder interferometers (Bruneau, 2001;Bruneau and Pelon, 2003;Tucker et al, 2018) can be used for direct-detection wind lidars.…”

Section: Introductionmentioning

confidence: 99%

Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration

et al. 2020

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Abstract. Aeolus, launched on 22 August in 2018, is the first ever satellite to directly observe wind information from the surface up to 30 km on a global scale. An airborne prototype instrument called ALADIN airborne demonstrator (A2D) was developed at the German Aerospace Center (DLR) for validating the Aeolus measurement principle based on realistic atmospheric signals. To obtain accurate wind retrievals, the A2D uses a measured Rayleigh response calibration (MRRC) to calibrate its Rayleigh channel signals. However, differences exist between the respective atmospheric temperature profiles that are present during the conduction of the MRRC and the actual wind measurements. These differences are an important source of wind bias since the atmospheric temperature has a direct effect on the instrument response calibration. Furthermore, some experimental limitations and requirements need to be considered carefully to achieve a reliable MRRC. The atmospheric and instrumental variability thus currently limit the reliability and repeatability of a MRRC. In this paper, a procedure for a simulated Rayleigh response calibration (SRRC) is developed and presented in order to resolve these limitations of the A2D MRRC. At first the transmission functions of the A2D Rayleigh channel double-edge Fabry–Pérot interferometers (FPIs) in the internal reference path and the atmospheric path are characterized and optimized based on measurements performed during different airborne and ground-based campaigns. The optimized FPI transmission functions are then combined with the laser reference spectrum and the temperature-dependent molecular Rayleigh backscatter spectrum to derive an accurate A2D SRRC which can finally be implemented into the wind retrieval. Using dropsonde data as a reference, a statistical analysis based on a dataset from a flight campaign in 2016 reveals a bias and a standard deviation of line-of-sight (LOS) wind speeds derived from a SRRC of only 0.05 and 2.52 m s−1, respectively. Compared to the result derived from a MRRC with a bias of 0.23 m s−1 and a standard deviation of 2.20 m s−1, the accuracy improved and the precision is considered to be at the same level. Furthermore, it is shown that the SRRC allows for the simulation of receiver responses over the whole altitude range from the aircraft down to sea level, thus overcoming limitations due to high ground elevation during the acquisition of an airborne instrument response calibration.

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Design of a monolithic Michelson interferometer for fringe imaging in a near-field, UV, direct-detection Doppler wind lidar

Cited by 28 publications

References 60 publications

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H_∞Optimal Control with Preview

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H_∞Optimal Control with Preview

Gust load alleviation for a long-range aircraft with and without anticipation

Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration

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Design of a monolithic Michelson interferometer for fringe imaging in a near-field, UV, direct-detection Doppler wind lidar

Cited by 28 publications

References 60 publications

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H∞Optimal Control with Preview

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H∞Optimal Control with Preview

Gust load alleviation for a long-range aircraft with and without anticipation

Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration

Contact Info

Product

Resources

About

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H_∞Optimal Control with Preview

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H_∞Optimal Control with Preview