spacecraft motion
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Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 126
Author(s):  
Lei Zhang ◽  
Huiliang Shang ◽  
Yandan Lin

The 6D Pose estimation is a crux in many applications, such as visual perception, autonomous navigation, and spacecraft motion. For robotic grasping, the cluttered and self-occlusion scenarios bring new challenges to the this field. Currently, society uses CNNs to solve this problem. The CNN models will suffer high uncertainty caused by the environmental factors and the object itself. These models usually maintain a Gaussian distribution, which is not suitable for the underlying manifold structure of the pose. Many works decouple rotation from the translation and quantify rotational uncertainty. Only a few works pay attention to the uncertainty of the 6D pose. This work proposes a distribution that can capture the uncertainty of the 6D pose parameterized by the dual quaternions, meanwhile, the proposed distribution takes the periodic nature of the underlying structure into account. The presented results include the normalization constant computation and parameter estimation techniques of the distribution. This work shows the benefits of the proposed distribution, which provides a more realistic explanation for the uncertainty in the 6D pose and eliminates the drawback inherited from the planar rigid motion.


Author(s):  
Z.S. Zhumaev

The paper considers a possibility of using a heliothermal propulsion system for constructing constellations of nanosatellites in the CubeSat format. Such a propulsion system implies direct heating of the working fluid by focused solar radiation. In comparison with electric jet engines, the proposed propulsion has orders of magnitude higher thrust, which makes it possible to build a constellation of nanosatellites in low Earth orbit in less than 6 days. In comparison with electrothermal motors, the presented solution achieves higher efficiency of converting the energy of solar radiation into the thermal energy of the working fluid. The spacecraft motion was simulated taking into account the mutual influence of the propulsion system, the orientation and stabilization system, the power supply system, as well as the passage of the shadow sections of the orbit in which there is a loss of electrical and thermal energy.


2021 ◽  
Vol 20 (1) ◽  
pp. 29-45
Author(s):  
L. I. Sinitsin ◽  
I. V. Belokonov

A method is proposed for assessing the results of adjustment maneuvers for a nanosatellite (NS) with an electrothermal propulsion system (ETPS). Using the example of the SamSat-M nanosatellite under development, common causes of maneuvering errors associated with deviations in the manufacturing of the propulsion system are revealed. Probabalistic analysis of the NS maneuvering process was carried out. The design parameters of the ETPS are considered as random factors. Statistical models of the distributions of all random factors are assumed to be equally probable, which is the worst-case scenario, since the true distributions of the design parameters of the ETPS are unknown. The methodological basis of the study is the method of statistical modeling (Monte Carlo method) followed by the use of regression and factor analysis, on the basis of which the influence of the scatter of each of the design parameters on the controlled parameters is determined. Requirements for the design parameters of the ETPS that affect the spread of the projections of the velocity growth vector of the NS and the arising angular motion have been formulated. The presented results can be used to assess the influence of production deviations in the design parameters of propulsion systems on the nature of spacecraft motion, as well as to state requirements for the spread of design parameters to ensure the achievement of the objective.


2021 ◽  
Vol 2 (133) ◽  
pp. 79-88
Author(s):  
Oleksandr Sarychev ◽  
Bogdan Perviy

The task of revealing changes in the non-functioning Sich-2 spacecraft motion is completed using autoregressive models and time series of TLE elements. The developed method is recomended to use for revealing changes in the movement of space objects during their long-term operation.


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