1,720,978 research outputs found
An Overview of Autonomous Optical Navigation for Deep-Space CubeSats
Full text linkA new era of space exploitation is fast approaching. CubeSats have performed a revolution in the way satellites are deployed in interplanetary missions. The exploitation of standardized dimensions and Commercial-Off-The-Shelf components has boosted their utilization by reducing mission costs and development time. The cutting down on the space entry-price grants the democratization of interplanetary exploration. Yet, the flourishing growth of users in space will saturate the ground networks, hindering the traditional navigation through ground-based radiometric tracking. Miniaturized probes that can operate in complete autonomy from the ground represent the solution of this issue. From navigation perspective, a celestial triangulation algorithm fed by optical observations of planets can be exploited to retrieve the probe state. In this work, an autonomous optical navigation algorithm for interplanetary nano-spacecraft applications is developed. In particular, an Extended Kalman Filter featuring line-of-sight acquisitions of planets is adopted as state estimator. The solution accuracy is improved by correcting the planetary light-time and aberration effects and by exploiting the optimal beacons selection strategy. Moreover, an in-depth analysis concerning the numerical precision of the estimator is carried out. Finally, the navigation algorithm is tested on a platform comparable to a CubeSat computer to verify its sustainability and performances. The present work is framed within the EXTREMA project, awarded an ERC Consolidator Grant in 2019
Autonomous Vision-Based Navigation for Deep-Space CubeSats: Algorithm Development and Hardware Validation
Full text linkTowards Validation and Verification of Autonomous Vision-Based Navigation for Interplanetary Spacecraft
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RETINA: a Highly-Versatile Optical Facility for Camera-In-the-loop Testing of Spaceborne Vision-Based Sensors
Full text linkHardware-In-the-loop Validation of Autonomous Interplanetary Navigation Algorithms for Interplanetary Cruises with the Optical Star Stimulator
Full text linkThanks to the rising focus on deep-space exploration and exploitation, the demand for sustainable and efficient navigation approaches has become crucial. Standard ground-based radiometric tracking, while accurate, is expensive and resourceintensive, posing long-term sustainability challenges. Therefore, enhancing spacecraft autonomy is crucial to avoid ground station saturation. Autonomous onboard guidance, navigation, and control (GNC) offer cost reduction and expand interplanetary exploration opportunities. Among various navigation alternatives, vision-based navigation (VBN) stands out for its cost-effectiveness, ground independence, and applicability to different spacecraft classes. Ground testing campaigns are crucial to ensure accurate and robust vision-based navigation algorithms for interplanetary missions. However, obtaining real interplanetary sky-field images for validation is challenging due to limited successful missions and datasets. To overcome these limitations, high-fidelity rendering engines and hardware-in-the-loop (HIL) simulations are necessary to generate image datasets for testing. This work presents the development of a procedure for on-ground testing and validation of autonomous navigation algorithms for interplanetary cruises using Jena Optronik’s Optical Sky Stimulator (OSI) at the DLR GNC Department in Bremen. The proposed paper includes preparation activities, calibration and compensation procedures, and final hardware-in-the-loop simulations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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