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Saturated Adaptive Output-Constrained Control of Cooperative Spacecraft Rendezvous and Docking

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IEEE/CAA Journal of Automatica Sinica 2019年第6期6卷 1462-1470页

作者： Liang Sun IEEE the Key Laboratory of Knowledge Automation for Industrial Processes Ministry of Education School of Automation and Electrical Engineering and also with the Institute of Artificial Intelligence University of Science and Technology Beijing

This paper investigates the robust relative pose control for spacecraft rendezvous and docking with constrained relative pose and saturated control inputs.A barrier Lyapunov function is used to ensure the constraints of states,so that the computational singularity of the inverse matrix in control command can be avoided,while a linear auxiliary system is introduced to handle with the adverse effect of actuator saturation.The tuning rules for designing parameters in control command and auxiliary system are derived based on the stability analysis of the closed-loop system.It is proved that all closed-loop signals always keep bounded,the prescribed constraints of relative pose tracking errors are never violated,and the pose tracking errors ultimately converge to small neighborhoods of zero.Simulation experiments validate the performance of the proposed robust saturated control strategy.

关键词： Output-constrained control pose tracking control rendezvous and docking saturated control singularity-free control spacecraft control

Continued Fraction Cartesian to Geodetic Coordinate Transformation

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Computer Modeling in Engineering & Sciences 2016年第3期111卷 257-268页

作者： J.D.Turner A.Alnaqeb A.Bani Younes Khalifa University Abu DhabiUAE

A singularity-free perturbation solution is presented for inverting the Cartesian to Geodetic transformation.Conventional approaches for inverting the transformation use the natural ellipsoidal coordinates,this work explores the use of the satellite ground-track vector as the differential correction variable.The geodetic latitude is recovered by well-known elementary means.A high-accuracy highperformance 3D vector-valued continued fraction iteration is constructed.Rapid convergence is achieved because the starting guess for the ground-track vector provides a maximum error of 30 m for the satellite height above the Earth’s surface,throughout the LEO-GEO range of applications.As a result,a single iteration of the continued fraction iteration yields a maximum error for the satellite height of 10??11 km.and maximum error for the geodetic anomaly of 10??9 rad.The coordinate transformation is completed by non-iteratively recovering the satellite height and the geodetic anomaly.No Taylor expansions are introduced and no Jacobian sensitivity calculations are required.For all practical applications the new algorithm provides a closed-form solution.The accuracy and algorithmic performance of the proposed approach is compared with other state of the art algorithms.

关键词： Geodetic transformation continued fraction singularity-free

An Alternative Manifold for Cosmology Using Seifert Fibered and Hyperbolic Spaces

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Applied Mathematics 2014年第6期5卷 1013-1028页

作者： Maria E.Mejía Reinaldo R.Rosa Departamento de Matemáticas Universidad de GuadalajaraGuadalajaraMéxico Laboratório Associado de Computacao e Matemática Aplicada Instituto Nacional de Pesquisas EspaciaisSao Jose dos CamposBrasil

We propose a model with 3-dimensional spatial sections, constructed from hyperbolic cusp space glued to Seifert manifolds which are in this case homology spheres. The topological part of this research is based on Thurston’s conjecture which states that any 3-dimensional manifold has a canonical decomposition into parts, each of which has a particular geometric structure. In our case, each part is either a Seifert fibered or a cusp hyperbolic space. In our construction we remove tubular neighbourhoods of singular orbits in areas of Seifert fibered manifolds using a splice operation and replace each with a cusp hyperbolic space. We thus achieve elimination of all singularities, which appear in the standard-like cosmological models, replacing them by “a torus to infinity”. From this construction, we propose an alternative manifold for cosmology with finite volume and without Friedmann-like singularities. This manifold was used for calculating coupling constants. Obtaining in this way a theoretical explanation for fundamental forces is at least in the sense of the hierarchy.

关键词： Topology Cosmology Thurston’s Theory singularity-free

Model of Universe as Described by Dynamic Universe Model

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Open Journal of Modelling and Simulation 2019年第1期7卷 41-78页

作者： Satyavarapu Naga Parameswara Gupta Bhilai Steel Plant Bhilai India

In this paper we will see the model of Universe according to Dynamic Universe Model of Cosmology by visualizing various processes that are happening in the Universe as per experimental evidences. For simplifying the matter here, we will see in part 1: about the Galaxy life cycle, where the birth and death of Galaxies discussed. Probably Universe gives guidance for the movement of Galaxies. We call this Part 1: Thinking and Reproducing Universe or Mindless Universe? (Galaxy life cycle). We see every day Sun, Stars, Galaxies etc., dissipating enormous energy in the form of radiation by the way of fusion of Hydrogen to helium. So after sometime all the Hydrogen is spent and Universe will die, is it not? … Dynamic Universe Model says that the energy in the form of electromagnetic radiation passing grazingly near any gravitating mass changes in frequency and finally will convert into neutrinos (mass). Hence Dynamic Universe Model proposes another process where energy will be converted back into matter and the cycle energy to mass to energy continues, sustaining the Universe to maintain this present status for ever in this form something like a Steady state model without any expansion. This we will see in Part 2: Energy - Mass - Energy Cycle. After converting energy into mass “how various elements are formed and where they are formed?” will be next logical question. Dynamic Universe Model says that these various particles change into higher massive particles or may get bombarded into stars or planets and various elements are formed. Here we bifurcate the formation of elements into 6 processes. They are for Elementary particles and elements generated in frequency changing process, By Cosmic rays, By Small stars, By Large Stars, By Super Novae and Manmade elements By Neutron Stars. This we will discuss in Part 3: Nucleosynthesis.

关键词： Dynamic Universe Model Hubble Space Telescope (HST) SITA Simulations (SITA-Simulation of Inter Intra Tautness Attraction Forces Used by Dynamic Universe Model) singularity-free Cosmology Blue Shifted Galaxies Red Shifted Galaxies Grazing Radiation Frequency Changes Formation of Elements Nucleosynthesis Dynamic Universe Model Energy to Mass Conversion Methods: N-Body Simulations-Gravitation-Cosmology