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在简要介绍了飞行器视觉图像定位导航原理及模型的基础上,针对其非线性模型的推广Kalman滤波的收敛与初始条件有关的问题,将其定位导航的两种模型(线性与非线性模型)组合,提出了双模态双滤波器滤波方法。这种滤波能很好地解决非线性推广Kalman滤波的收敛问题。通过第一个线性滤波器的滤波估计给第二个非线性滤波器提供滤波初值,使这一非线性滤波收敛,并能取得较高的滤波精度。 相似文献
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Fabrizio Nicolosi Agostino De Marco Pierluigi Della Vecchia 《Aerospace Science and Technology》2013,24(1):226-240
This paper presents some results of the flight test campaign conducted on the Tecnam P2006T aircraft, on the occasion of its certification process. This twin-engine propeller airplane is certified under the normal category CS-23 and FAR 23. A prototype of this light aircraft has been tested in flight for a post-design performance optimization and for the assessment of flight qualities. These experiences have led to the application of two winglets to the original wing. The final configuration has been extensively tested for the achievement of CS-23 certification. The longitudinal and lateral-directional response modes have been assessed and quantified. At the same time the longitudinal airplane model, through a dedicated set of flight maneuvers, has been characterized by means of parameter estimation studies. The aircraft stability derivatives have been estimated from the acquired flight data using the identification technique known as Output Error Method (OEM). Some estimated stability derivatives have been also compared with the corresponding values extracted from leveled flight tests and from wind tunnel tests performed on a scaled model of the aircraft. 相似文献
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We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfvén speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfvén wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfvén-speed profile. In a ??=0 plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfvén wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfvén wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfvén wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing. 相似文献
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T.P. Dachev B.T. Tomov Yu.N. Matviichuk P.S. Dimitrov S.V. Vadawale J.N. Goswami G. De Angelis V. Girish 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The RADiatiOn Monitor (RADOM) is a miniature dosimeter-spectrometer that flew onboard the Chandrayaan-1 lunar mission in order to monitor the local radiation environment. Primary objective of the RADOM experiment was to measure the total absorbed dose, flux of surrounding energetic particles and spectrum of the deposited energy from high energy particles both en-route and in lunar orbit. RADOM was the first experiment to be switched on after the launch of Chandrayaan-1 and was operational until the end of the mission. This paper summarizes the observations carried out by RADOM during the entire life time (22 October 2008–31 August 2009) of the Chandrayaan-1 mission and compares the measurement by RADOM with the radiation belt models such as AP-8, AE-8 and CRRESS. 相似文献
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